State of California

Department of Transportation
Engineering Service Center
Division of Structures

Foundation Manual

Issued By
Offices of Structure Construction

November 2008
 ________________________________________Acknowledgements
November 2008

Acknowledgements
The 2008 edition of the Foundation Manual was updated by a group of dedicated Senior
Bridge Engineers from the Offices of Structure Construction (OSC).

Thanks to Rich Foley, P.E., OSC Substructure Committee Chairman, for his
contributions and leadership. Thanks to the OSC Substructure Committee members for
their valuable contributions and teamwork. Members include: Daniel Dait, P.E., David
Keim, P.E., Jeff Kress, P.E., John Walters, P.E., and Mark Woods, P.E. Thanks to
Roman Granados, HQ Office Associate for his contributions and hard work. Thanks to
Mike Beauchamp, P.E., Supervising Bridge Engineer, OSC Substructure Committee
Sponsor, for his contributions and sound guidance.

Special thanks to the Caltrans engineers who drafted the original 1984 Foundation
Manual and to the Caltrans engineers who drafted the 1996 revision. Their vision,
dedication, and research, produced a manual that has been used throughout the
Department.

Signed,

Rob Stott, P.E.

Principal Bridge Engineer
Deputy Division Chief – OSC
California Department of Transportation

Caltrans ● Foundation Manual Acknowledgements

 _________________________________________ Preface
November 2008

Preface
The Foundation Manual is intended to provide the field engineer with information that
may be of some assistance in solving foundation problems and in making engineering
decisions.

Although the field engineer is required to make engineering decisions throughout the life
of a construction project, none is probably more important than the engineer’s decision
regarding the suitability or unsuitability of the foundation material supporting a spread
footing foundation. The engineer must decide if the foundation material encountered at
the planned bottom of footing elevation is, in fact, representative of the material shown
on the Log of Test Borings sheet and therefore suitable for the imposed loads. If not
representative, the engineer must decide what action to take.

This is not to minimize the importance of pile supported foundations, which have their
own unique problems that require decisions based on sound engineering judgement. What
action does the engineer take when pile bearing capacity is not obtained at specified tip or
reaches “refusal” ten feet above tip elevation?

All types of foundations are discussed in the manual along with related problems and
possible solutions. There is no one solution that will always solve a particular problem.
Each situation must be reviewed and a decision made based on the available data and
one’s own experience.

There is no substitute for utilizing sound engineering judgment in solving engineering

problems. If all problems are solved in this manner, then the engineer can be confident
that a good solution was used to solve the problem.

Caltrans ● Foundation Manual Preface

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TABLE OF CONTENTS
Chapter 1 Foundation Investigations 1-1
Introduction 1-1
Who Performs Foundation Investigations 1-2
Foundation Investigation Overview 1-3
Subsurface Drilling Operation 1-4
Log of Test Borings 1-5
Foundation Report 1-6
Applicability of the Log of Test Borings and Foundation
1-7
Report to the Contract
Basic Soil Properties 1-7
Geotechnical Drilling and Sampling Equipment 1-9

Chapter 2 Type Selection 2-1

Chapter 3 Contract Administration 3-1

Footing Foundations 3-5
Pile Foundations 3-6
As-Built Drawings and Pile Records 3-8
Differing Site Conditions 3-9

Chapter 4 Footing Foundations 4-1

General 4-1
Types 4-1
Bearing Capacity 4-3
Failure Modes 4-4
Factors Affecting Bearing Capacity 4-6
Settlement 4-10
Ground Improvement/Soil Modification 4-10
Construction and Inspection 4-11
Excavations 4-12
Open Excavations 4-13
Cofferdams or Shored Excavations 4-15
Wet Excavations 4-17
Bottom of Excavation Stability 4-19
Foundation Inspection & Construction Considerations 4-20
Foundation Problems and Solutions 4-22
Disturbed and/or Contaminated Material 4-23
Unsuitable Foundation Material 4-23
Modifications Due to Disturbed, Contaminated or
Unsuitable Material 4-24
Safety 4-26

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Chapter 5 Pile Foundations – General 5-1

Introduction 5-1
Specifications 5-1
Cast-in-Place Piles 5-2
Driven Piles 5-3
Alternative Piles 5-4

Chapter 6 Cast-in-Place Piles 6-1

Description 6-1
Specifications 6-2
Drilling Equipment 6-2
Drilling Methods 6-10
Drilling Problems 6-10
Inspection and Contract Administration 6-12
Pile Defects 6-15
Safety 6-20

Chapter 7 Driven Piles 7-1

Introduction 7-1
General Specifications 7-2
Pile Driving Definitions 7-4
Hammer Types 7-11
The Drop Hammer 7-12
Single Acting Steam/Air Hammer 7-13
Double Acting Steam/Air Hammer 7-14
Differential Acting Steam/Air Hammer (External
Combustion Hammer 7-16
Diesel Pile Hammers 7-17
Vibratory Driver/Extractor 7-21
Hydraulic Hammer 7-23
General Hammer Information 7-24
Nominal Resistance/Bearing Capacity 7-25
Pile Load Testing 7-26
Dynamic Analysis by Wave Equation 7-26
Manufacturer’s Energy Ratings 7-29
Battered Piles 7-30
Preparing to Drive Piles 7-30
Verification of Hammer Energy 7-32
Materials Checklist 7-33
Steel Piles 7-33
Timber Piles 7-34
Logging of Piles 7-34
Driving Challenges 7-36

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Difficult or Hard Driving 7-36

Soft Piles and Re-Drive 7-39
Alignment of Piles 7-41
Overdriving 7-41
Safety 7-42

Static Pile Load Testing & Dynamic 8-1

Chapter 8
Monitoring
Introduction 8-1
Reasons For Static Load Testing and Pile Dynamic Analysis 8-1
Static Pile Load Tests 8-3
Pile Dynamic Analysis (PDA) 8-4
Contract Administration of Static Pile Load Testing & Pile
8-6
Dynamic Analysis
Inspection Requirements During Static Load Testing and PDA 8-7

Chapter 9 Slurry Displacement Piles 9-1

Introduction 9-1
History 9-1
Slurry Displacement Method 9-2
Principles of Slurry Usage 9-4
Sampling and Testing Drilling Slurry 9-8
Density 9-10
Sand Content 9-11
pH Value 9-12
Viscosity 9-12
Types of Slurry 9-13
Water 9-14
Mineral 9-15
Synthetic 9-20
Equipment 9-25
Specifications 9-29
Minimum Pile Diameter Requirements 9-29
Concrete Compressive Strength & Consistency
Requirements 9-30
Slurry Testing and Cleaning Requirements 9-30
Pile Acceptance Testing Access Requirements 9-33
Pile Concrete Placement Requirements 9-33
Inspection and Contract Administration 9-35
Pile Acceptance Testing 9-38
Defective Piles 9-41
Pile Mitigation and Acceptance 9-45
What Happens When a Pile is Rejected 9-45
Pile Mitigation Methods – Repairs, Replace, Supplement 9-45

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Pile Mitigation Plan Development and Approval

Procedures 9-48
Responsibilities of the Engineer 9-48
Responsibilities of the Contractor 9-49
Responsibilities of the DES Pile Mitigation Plan Review
Committee 9-51
Pile Mitigation Field Procedures and Pile Acceptance 9-52
What to Expect in the Field During Pile Mitigation 9-52
Procedures For Approving the Pile Mitigation Work
Performed in the Field and Pile Acceptance 9-53
Safety 9-53

Chapter 10 Pier Columns 10-1

Description 10-1
Specifications 10-2
Construction Methods 10-2
Excavation 10-2
Problem Areas 10-3
Safety 10-4

Chapter 11 Tiebacks, Tiedowns & Soil Nails 11-1

Introduction 11-1
Tiebacks 11-1
Components 11-1
Sequence of Construction 11-3
Safety 11-4
Tiedowns 11-4
Sequence of Construction 11-5
Testing of Tiebacks and Tiedown Anchors 11-6
Performance Tests 11-7
Proof Tests 11-7
General Acceptance Criteria – Proof & Performance
Tests 11-7
General Construction Control 11-8
Soil Nails 11-8
Sequence of Construction 11-10
Engineer’s Responsibility 11-11
Contractor’s Responsibility 11-11
Testing of Soil Nail Walls 11-11
Verification of Nails 11-11
Proof Testing 11-12
Supplemental Testing 11-12
Safety 11-12

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Chapter 12 Cofferdams and Seal Courses 12-1

General 12-1
Sheet Piles and Bracing 12-1
Excavation 12-5
Seal Course 12-5
Concrete Deposited Underwater (Tremie Placement Method) 12-6
Seal Course Inspections 12-7
Thickness of Seal Course 12-7
Contractor’s Responsibility 12-8
Engineer’s Responsibility 12-8
Dewatering 12-8
Safety 12-9

Chapter 13 Alternative Piles and Special Considerations 13-1

Introduction 13-1
Micropiles 13-1
Micropile Definition and Description 13-1
Applications 13-2
Caltrans Applications 13-3
Seismic Retrofit 13-3
Earth Retention 13-3
Foundation for New Structures (Retaining Walls) 13-4
Construction and Contract Administration 13-4
Measurement and Payment 13-4
Safety 13-5
Changeable Message Signs 13-5

References
List of References R-1

Appendices
Appendix A – Foundation Investigations A-1
Appendix B – Contract Administration B-1
Appendix C – Footing Foundation C-1
Appendix D – Pier Columns & Alternative Pile Types D-1
Appendix E – Driven Piles E-1
Appendix F – Static Pile Load Testing & Dynamic Monitoring F-1
Appendix G – Slurry Displacement Piles G-1
Appendix H – Tiebacks, Tiedowns, and Soil Nails H-1
Appendix I – Cofferdams and Seal Courses I-1
Appendix J – Micropiles J-1

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List of Figures
Figure 4-1 Loaded Footing with Moment 4-2
Figure 4-2 General Shear Failure Concept 4-4
Figure 4-3 Punching Shear Failure 4-5
Figure 4-4 Local Shear Failure 4-5
Figure 4-5 Failure Modes 4-5
Figure 4-6 Influence of Groundwater Table on Bearing
Capacity 4-7
Figure 4-7 Surcharge Load on Soil 4-8
Figure 4-8 Relationship between ø and Bearing Capacity
Factors 4-8
Figure 4-9 Relationship of Bearing Capacity Factors to ø and
N (Standard Penetration Resistance) for
Cohesionless Soils 4-9
Figure 4-10 Slope Setback for Open Excavations/Trenches 4-14
Figure 4-11 Effect of Surcharge Loads for Shored Excavations 4-16
Figure 4-12 Setback Calculation for Shored Excavations when
Surcharges are not Considered in the Shoring
Design 4-17
Figure 4-13 Single Stage Well Point System 4-18
Figure 4-14 Saturated vs. Submerged Unit Weight 4-19
Figure 4-15 Bottom of Excavation Stability Problems due to
Excess Hydrostatic Head Against an Impervious
Layer 4-20
Figure 6-1 Auger - Short Section 6-3
Figure 6-2 Auger – Single Flight 6-3
Figure 6-3 Auger – Double Flight 6-3
Figure 6-4 Drilling Bucket 6-4
Figure 6-5 Drilling Bucket/Cleanout Bucket Comparison 6-4
Figure 6-6 Core Barrel 6-5
Figure 6-7 Down-hole Hammer 6-5
Figure 6-8 Rotator 6-6
Figure 6-9 Oscillator 6-7
Figure 6-10 Reverse Circulation Drilling Equipment 6-8
Figure 6-11 Steel Casing 6-9
Figure 6-12 Drill Rig – Crawler Mounted 6-9
Figure 6-13 Drill Rig – Truck Mounted 6-10
Figure 6-14 Drill Rig – Crane Mounted 6-10
Figure 6-15 Pile Defects – No Cleanout, Tapered Bottom of 6-16
Hole
Figure 6-16 Pile Defects – Smeared Drill Cuttings 6-16
Figure 6-17 Pile Defects – Cave in 6-17
Figure 6-18 Pile Defects – Concrete Segregation 6-17
Figure 6-19 Pile Defects – Adjacent Hole Blowout 6-18

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Figure 6-20 Pile Defects – Water in the Hole 6-18

Figure 6-21 Pile Defects Casing Problems 6-19
Figure 7-1 Early Pile Hammer 7-1
Figure 7-2 Drive Cap System 7-5
Figure 7-3 Typical Pile Rig Configuration 7-6
Figure 7-4 Fixed Lead System 7-7
Figure 7-5 Swinging Lead System 7-8
Figure 7-6 Semi-Fixed Lead System 7-9
Figure 7-7 Lead Configuration for Battered Piles 7-10
Figure 7-8 Lead Types 7-11
Figure 7-9 Drop Hammer 7-13
Figure 7-10 Single Acting Steam/Air Hammer 7-14
Figure 7-11 Double Acting Steam/Air Hammer 7-15
Figure 7-12 Differential Acting Steam/Air Hammer 7-16
Figure 7-13 Single Acting Diesel Hammer 7-19
Figure 7-14 Operational Cycle for Single Acting Diesel 7-19
Hammer
Figure 7-15 Double Acting Diesel Hammer 7-20
Figure 7-16 Vibratory Driver/Extractor 7-23
Figure 8-1 Static Pile Load Test (Five-Pile Array) 8-3
Figure 9-1 Slurry Displacement Method 9-3
Figure 9-2(a)(b) Positive Hydrostatic Pressure 9-5
Figure 9-3(a) Filtration – Loose Ground Formation 9-6
Figure 9-3(b) Filtration – Tight Ground Formation 9-7
Figure 9-3(c) Stabilization with Synthetic Polymer Slurry 9-8
Figure 9-4 Slurry Sampler Schematic 9-9
Figure 9-5 Density Test Kit 9-10
Figure 9-6 Sand Content Test Kit 9-11
Figure 9-7 Marsh Funnel Viscosity Test Kit 9-13
Figure 9-8 Bentonite Slurry 9-16
Figure 9-9 Mineral Slurry Plant 9-18
Figure 9-10 Desanding Centrifuges 9-19
Figure 9-11 Recirculation and Cleaning Schematic 9-19
Figure 9-12 SuperMud Container 9-21
Figure 9-13 SlurryPro CDP Container 9-22
Figure 9-14 ShorePac Container 9-22
Figure 9-15 Novagel Container 9-23
Figure 9-16 Hole Collapse Induced by Pressure Changes 9-26
Figure 9-17 Cleanout Bucket 9-27
Figure 9-18 Airlift Schematic 9-28
Figure 9-19 Use of Casing 9-29
Figure 9-20 Inspection Tubes 9-37
Figure 9-21 Location of Inspection Tubes within the Pile 9-37
Figure 9-22 Gamma-Gamma Logging Test Schematic 9-39
Figure 9-23(a)(b) Defects from Settled Materials 9-42

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Figure 9-24 Defect from Improperly Mixed Mineral Slurry 9-43

Figure 9-25 Defect from Excess Filter Cake Buildup 9-43
Figure 9-26 Defect from Concrete Placement Problems 9-44
Figure 11-1 Tieback Detail 11-2
Figure 11-2 Tiedown Anchor 11-6
Figure 11-3 Soil Nail Schematic 11-9
Figure 11-4 Soil Nail Details 11-10
Figure 11-5 Verification/Test Nail Detail 11-13
Figure 12-1 Single Sheet Piling 12-1
Figure 12-2 Lapped and Wakefield Sheet Piling 12-2
Figure 12-3 Tongue and Groove Wood Sheet Piling 12-2
Figure 12-4 Concrete Sheet Piling 12-2
Figure 12-5 Concrete Sheet Piling with Steel Interlocks 12-3
Figure 12-6 Straight Section Steel Sheet Piling 12-3
Figure 12-7 Arch-Web Steel Sheet Piling 12-3
Figure 12-8 Deep-Arch Steel Sheet Piling 12-4
Figure 12-9 Z-Section Steel Sheet Piling 12-4
Figure 13-1 CMS details from 2006 Standard Plan S116 13-6

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CHAPTER

1 Foundation Investigations

Introduction
The ultimate strength and longevity of any structure depends on the adequacy of
its foundation. Engineers administering projects for the Offices of Structure
Construction have the responsibility of ensuring that the foundation work
performed on their projects is of the quality necessary to allow each and every
structure to sustain the design loadings throughout its design life.

It is essential that all personnel working for the Offices of Structure Construction,
and Structure Representatives in particular, commit themselves to learning the
provisions within the Standard Specifications, Standard Plans, contract plans,
special provisions and all relevant documents related to each structure on which
they are working. It has been proven time and time again that a thorough
understanding of all documents related to a particular project and the effective use
of this information leads to the effective administration of structure contracts.

Bridge Construction Memo 2-2.0 states:

“It is the responsibility of the Structure Representative to clear up any problem

areas prior to the start of construction, or as soon thereafter as possible.”

In order to “clear up” problem areas, Structure Representatives must have a

thorough understanding of the information contained within the contract
documents. They must also know whom to contact for further information or for
advice on resolving project problems.

This chapter will give an overview of the foundation investigation process and
will also show how the Log of Test Borings and Foundation Report for a structure
project are developed. The goal of the chapter is to provide information related to
the foundation investigation process so as to assist the reader in the interpretation
and effective use of the Log of Test Borings and the Foundation Report during the
administration of structure projects.

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Who Performs Foundation Investigations

Foundation investigations for the various structures designed and constructed by
the Division of Engineering Services are performed and coordinated by one of the
four Geotechnical Design Sections of Geotechnical Services. Each of the Design
Sections is responsible for different areas of the State.

• Geotechnical Design Section – North – Districts 1, 2, 3, 5, 6, 9 & 10

• Geotechnical Design Section – West – District 4 & Toll Bridge Program
• Geotechnical Design Section – South 1 – Districts 7 & 12
• Geotechnical Design Section – South 2 – Districts 8 & 11

Personnel from the Geotechnical Design Sections are available to provide support
to Offices of Structure Construction employees throughout the life of a
construction project. These individuals are referred to as geoprofessionals and
they are engineers who specialize in geotechnical engineering and engineering
geology. Some are registered as geotechnical engineers and engineering
geologists. The Engineer is encouraged to schedule pre-construction meetings
with personnel from the appropriate Geotechnical Design Section (Bridge
Construction Memo 2-2.0). The primary purpose of the pre-construction meeting
would be to forge a good relationship with the engineers/geologists
(geoprofessionals) that performed the foundation investigation, wrote the
Foundation Report, and developed the Log of Test Borings. At this time there
should be discussions that outline potential foundation problem areas and risks in
detail. This meeting will prove to be invaluable to Structure Representatives in
their efforts to recognize potential problem areas that may need extra attention
during the foundation work on the project.

Once construction projects are under way, personnel from the Geotechnical
Design Sections lend their expertise as needed and in particular when problems or
challenges occur during foundation work. They advise over the phone and often
visit projects to evaluate difficult foundation installations and recommend
solutions. The Engineer is encouraged to inform the Geotechnical Design
Sections of any problems, changes or differences with structure foundations as
early as possible. Early notification often gives the best chance of resolving
difficult or problem foundations with the most economical solution.

At times, consultant engineers design structure projects. Consultant geotechnical

companies produce foundation investigations for these projects with Departmental
oversight. Issues related to foundations on projects designed by consultants
should be discussed with the Department’s Oversight Engineer assigned to the
project.

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Foundation Investigation Overview

Once the Office of Structure Design begins the design of a new structure,
widening, strengthening or seismic retrofit, the Project Engineer or Designer
sends in a Foundation Investigation Request to the appropriate Geotechnical
Design Section. At that point a geoprofessional is assigned to perform the
foundation investigation.

The individual assigned to perform a foundation investigation for a structure first

collects as much information about the proposed site as possible. They normally
accomplish this by reviewing preliminary structure plans, previously written
foundation reports, as-built plans, information on the historical seismicity of the
area, and historical information on the subsurface conditions in the area of the
proposed structure. This planning phase of the investigation gives the
geoprofessional an idea of what to look for during fieldwork.

Once all of the preliminary information is collected, a drilling plan is generated

that outlines locations for drilling in relation to the structure’s proposed
foundation locations. The main goal in establishing a plan for a foundation
investigation is to collect as much subsurface information at the site as possible
while making efficient use of the available drilling equipment and personnel. The
geoprofessional then directs a foundation drilling crew during the performance of
the subsurface drilling operation (to be described later in this chapter). The
purpose of the subsurface drilling operation is to collect soil samples and perform
in-situ testing at the site.

The soil samples collected during the subsurface drilling operation, results of in-
situ tests, manual field tests, and various observations recorded will provide the
necessary information to develop the Log of Test Borings for the project. Once
the Log of Test Borings is completed, it is transmitted to the Project Engineer for
inclusion in the structure plans.

The information compiled in the Log of Test Borings along with the loads
provided by Structure Design is analyzed by the geoprofessionals in Geotechnical
Services and foundation recommendations are made. The recommended
foundation type as well as other important pieces of information are compiled and
included into a Foundation Report for the structure and transmitted to the Project
Engineer. These recommendations are used to complete the design of the
structure. The Foundation Report is included in the RE Pending File as well as
the Materials Handout for the Contractor at time of bid.

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Subsurface Drilling Operation

The most important aspect of a foundation investigation is the results obtained
from the subsurface drilling operation. Foundation drilling crews conduct one or
more drilling operations at the location of a proposed structure. The general
purpose of the subsurface investigation is to determine the depth of rock, rock
type and quality, soil types, soil strengths, and groundwater levels. The
determination of these various parameters enables the development of a soil/rock
profile, which is a visual representation of the subsurface conditions interpreted
from the subsurface investigations and laboratory testing. The soil/rock profile
can be determined by interpolating between like lenses of material in individual
borings within the Log of Test Borings.

During the subsurface drilling operation, Geotechnical Services is responsible for

the evaluation of the soil and/or rock samples retrieved by the foundation drilling
crew. After visual inspections and manual field tests, the soil or rock samples are
described and written in the field logs. During the drilling operation, elevations
where there are significant changes in material are noted. Soil samples are
usually taken from each of the different soil lenses (layers) for laboratory testing.

The appearance and feel of the cuttings, difficulties or changes of the rate of
advancement of the drilling tools, and other observations help estimate the
mechanical properties or strengths of the soil or rock lenses. These observations
are noted within the field logs. Any groundwater encountered during the drilling
operation is also noted and special care is taken to accurately determine its
elevation and whether or not the groundwater encountered is static or under
pressure (“perched” or in an “artesian” condition). These observations along with
the tests results from field and laboratory testing are used to develop the soil/rock
profile.

Two important facets of the subsurface drilling operation are the recovery of soil
samples retrieved during the drilling operations and the in-situ soil tests. Soil
samples are divided into two categories, disturbed and undisturbed. Disturbed
soil samples are those that have experienced large structural disturbances during
the sampling operation and may be used for identification and classification tests.
Undisturbed samples are those in which structural disturbance is kept to a
minimum during the sampling process. Undisturbed samples are used for
consolidation and strength tests. Examples of these strength tests are direct shear,
triaxial shear, and unconfined compression tests. The strength tests provide shear
strength values, which are then used as design parameters in static analysis for
pile foundations. Consolidation tests provide information needed to estimate
settlements of spread footings or pile groups and are performed on cohesive soils.

Several types of soil samplers are used to retrieve undisturbed samples during
subsurface investigations. Types include the California Sampler (which is the

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primary tool used by Geotechnical Services), the Shelby Tube, the Piston
Sampler, and the Hydraulic Piston Sampler. Undisturbed soil samples provide the
best opportunity to evaluate the soil in its natural undisturbed state. Destructive
testing of these samples provides the most accurate soil data, however undisturbed
samples from non-cohesive, or cohesionless, soils are difficult to obtain, trim, and
test in the laboratory. As such, soft saturated clays, saturated sands and
intermixed deposits of soil and gravel are difficult to sample and test in the
laboratory. To overcome these difficulties, in-situ test methods are used to
measure soil parameters.

When standard drilling and sampling methods cannot be used to obtain high
quality undisturbed samples, in-situ tests are used to provide information on the
characteristics of the material. The most common of these tests is the Standard
Penetration Test (SPT). This test identifies a penetration resistance value, “N”,
which can be used to obtain estimates for the angle of internal friction of a
cohesionless soil, the unconfined compressive strength of a cohesive soil, and the
material’s unit weight (refer to Appendix C). The SPT is performed using a split-
spoon sampler and provides a disturbed sample for visual inspection and
classification. Other in-situ tests include the static cone test, pressure meter test,
vane shear test, and the borehole shear test. They provide soil strength values,
such as cohesion, angle of internal friction, and shear strength.

Design parameters obtained from field and laboratory testing are used for static
analytical design procedures for pile and footing foundations and may also
provide valuable information to the Engineer during the course of administering a
construction project.

Log of Test Borings

After the subsurface investigation and laboratory testing is complete, the Log of
Test Borings is developed for the project. The Log of Test Borings includes a
plan view showing the location of each boring retrieved during the subsurface
drilling operation. It provides a graphic description of the various layers of
geological formations, soils, and the location of the groundwater table (if
encountered). Various soil and rock properties are also described. Each Log of
Test Borings includes a standard legend on the left side of the sheet that describes
the different symbols and notations used within the Log of Test Borings.
Examples of Logs of Test Borings are included in the “Caltrans Soil and Rock
Logging, Classification, and Presentation Manual” provided in Appendix A. It
can also be found on the Offices of Structure Construction website.

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Foundation Report
The foundation report is basically a compilation of all the information retrieved
during the foundation investigation and provides the project engineer with a
description and an evaluation of the geological formations and soils present at the
site of a proposed project. It also describes and evaluates any seismic hazards that
may be present at the site such as the amount of ground shaking that can be
expected and the probability of liquefaction occurring at the site. The report gives
recommendations for the type of foundation that should be used to support the
proposed structure and also recommends seismic design criteria such as peak
horizontal bedrock acceleration that should be used in the seismic analysis. The
report includes the recommendations for bottom of footing elevations, pile type,
size and tip elevations.

Most reports include special comments regarding anticipated foundation related

constructability concerns such as caving, soil compaction problems, expected
variations in pile driving and potential problems due to groundwater. This section
of the report may even suggest that job-specific specifications be included in the
contract special provisions. The Structure Representative should pay particular
attention to these comments as advance knowledge of potential problem areas in
foundation work allows for more effective problem solving and mitigation. The
Foundation Report is normally included in the RE Pending File and is included in
the Materials Handout to the Contractor at time of bid. The Engineer should
contact the Offices of Structure Construction Headquarters in Sacramento if they
do not receive a copy of the Foundation Report for any project assigned to them.

The project plans should be reviewed to verify that the footing elevation, pile tip
elevations, and type of piling recommended in the Foundation Report are shown
on the contract plans. In addition, the Structure Representative should confirm
that any suggested specifications or design features mentioned within the special
comments section of the Foundation Report are included in the contract plans and
specifications. The Project Engineer and Geotechnical Services representatives
should be consulted if there are any discrepancies. Contract change orders will
most likely be required to address these discrepancies.

Constructability issues discussed in the Foundation Report should be discussed

with the Contractor as early as possible. Once the Contractor begins work, the
Structure Representative should observe how the Contractor makes preparations
to deal with the constructability issues discussed in the Foundation Report. Good
documentation of all conversations with the Contractor on these issues will help
in the evaluation of any potential claims submitted by the Contractor.

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Applicability of the Log of Test Borings and Foundation Report to the

Contract
It is very important for Structure Representatives, as well as all Structure
Construction field staff, to be aware of how the Standard Specifications describe
the applicability of the Log of Test Borings, Foundation Report, or any record of
subsurface investigation produced by the State. Section 2-1.03 of the Standard
Specifications describes the contractors’ responsibilities to review these
documents prior to performing work for the Department.

In the past, the Log of Test Borings and other information provided to the
contractor at time of bid were not considered part of the contract and were
provided for information only. The 2006 version of the Standard Specifications
has been revised to change this. In particular, Section 2-1.03 Examination of
Plans, Specifications, Contract, and Site of Work, has undergone a major revision.
While the Contractor is still required to investigate the site and other available
information, as before, it is now understood that the information provided by the
Department will be used by the Contractor to develop a competitive bid. The
accuracy of this information is essential to a claim free contract. It’s important to
note that while the Department is taking responsibility for the information
provided, the Contractor is still required to carefully examine the site and the
information provided and are responsible for the conclusions that are drawn from
that investigation.

Basic Soil Properties

In order to understand and interpret a Log of Test Borings and Foundation Report,
it is important to have a basic understanding of the different types of soils that
may be encountered during foundation investigations. Geotechnical Services has
recently published the “Caltrans Soil and Rock Logging, Classification, and
Presentation Manual”. (Appendix A). It contains information on the field and
laboratory procedures used in soil classification and descriptions. It will help the
Engineer interpret the information presented in the Logs of Test Borings,
Foundation Reports and communicating with Geotechnical Services.

The information presented in Chapter 2 of the Caltrans Soil and Rock Logging,
Classification, and Presentation Manual (Appendix A) is of particular importance
as it outlines the procedure and methodology used to identify and classify rock
and soil samples. The information presented in the logs and descriptions is based
on the ASTM D 2488-06 Standard Practice for Description and Identification of
Soils (Visual-Manual Procedure) and the Engineering Geology Field Manual
published by the Bureau of Reclamation.

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The following is a list of soil particle size definitions used by Geotechnical

Services:

CLASSIFICATION DEFINITION
Boulders Particles of rock that will not pass a 12-inch square opening.
Cobbles Particles of rock that will pass a 12-inch square opening but will be
retained on a 3-inch sieve.
Course Gravel Particles of rock that will pass a 3-inch sieve but will be retained on
a 3/4-inch sieve.
Fine Gravel Particles of rock that will pass a 3/4-inch sieve but will be retained
on a No. 4 sieve.
Course Sand Particles of rock that will pass a No. 4 sieve but will be retained on
a No. 10 sieve.
Medium Sand Particles of rock that will pass a No. 10 sieve but will be retained on
a No. 40 sieve.
Fine Sand Particles of rock that will pass a No. 40 sieve but will be retained on
a No. 200 sieve.
Silt Soil passing a No. 200 sieve that is non-plastic or very slightly
plastic and exhibits little or no strength when air-dried. Silts that
exhibit some plastic properties are qualified as elastic silts
Clay Soil passing a No. 200 sieve that can be made to exhibit plasticity
(puttylike properties) within a range of water contents, and that
exhibits considerable strength when air-dried. A clay is qualified as
fat or lean depending an the amount of plasticity
Organic Soil A soil with sufficient organic content to influence the soil
properties.
Peat A soil composed primarily of vegetable matter in various stages of
decomposition. This soil usually has an organic odor, is dark brown
to black in color, has a spongy consistency, and a texture ranging
from fibrous to amorphous.

Geoprofessionals describe soils by name, group symbol and also provide

descriptive components to complete the identification. Some descriptive
components such as consistency, apparent density and percent or proportion of
soils are mandatory while others such as particle shape are not. Refer to Figure 2-
3 “Identification and Description Sequence” of the Caltrans Soil and Rock
Logging, Classification, and Presentation Manual for a complete list of
descriptive components (Appendix A). An example of a complete descriptive
sequence for a sample is shown below:

Well-graded SAND with GRAVEL (SW), medium dense, brown to light gray,
wet, about 20% coarse subrounded to rounded flat and elongated GRAVEL,
about 75% coarse to fine rounded SAND, about 5% fines, weak cementation.

Visual inspection is generally sufficient to differentiate between the coarse

grained soils. However, the distinctions between soil particles such as silts and
clays can be difficult. Several simple field exercises utilizing measures of
settling, plasticity, dry strength, and permeability characteristics of the soil permit

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a more accurate classification of these soils. In addition, soil samples can be

taken to the laboratory and tested to determine plasticity, unit weight, unconfined
compressive strengths and other mechanical properties to refine field
classification. In lieu of that, the following can be used in the field to help
classify soils in the field:

• Once a soil is dispersed in water, sand grains settle rapidly, usually in less
than one minute. Silt settles more slowly, usually from 10 to 60 minutes.
Clay will remain in suspension for several hours.

• Sand, having little to no plasticity, will not form a plastic thread by rolling it
on a smooth surface. Silt will form a thread when rolled, but it is weak and
crumbles as it dries. Clay forms a plastic thread of high strength, which dries
slowly and usually becomes stiff and tough as it dries.

• Sand has no unconfined dry strength. Silt has very little dry strength and
easily powders when rubbed. Clay has a high dry strength and will not
powder easily.

• A rough indication of the plasticity (clay content) of a soil can be determined

by observing a sample’s reaction to shaking or patting. For example, when a
sample of silt is subjected to this type of movement, water appears on the
surface. However, when shaking or patting a sample of clayey soil, this
reaction occurs slowly or not at all due to the level of plasticity of the sample.

Geotechnical Drilling and Sampling Equipment

Many different tools are used by foundation drilling crews and geoprofessionals
to obtain samples and evaluate subsurface conditions.

It is important for Structure Construction employees to have a good working

knowledge of the equipment used during the subsurface drilling operation for
their projects. The different tools used to perform the drilling operation have
different levels of reliability. The reliability of the tool used during the subsurface
investigation is an important factor in determining the accuracy of the information
provided in the Foundation Report.

The following is a brief description of the various pieces of equipment used by

Geotechnical Services as well as consultant geotechnical companies.

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DESCRIPTION
2¼-Inch Cone The 2¼-Inch Cone Penetrometer is an in-situ testing apparatus that
Penetrometer drilling crews use during subsurface drilling operations. The test is
conducted using an air compressor to drive the testing apparatus through
the soil.

The Engineering Geologist records the drilling rate in seconds per foot
of penetration. The results of the test are shown graphically to give an
indication of the soil’s varying densities as the cone penetrates the
different layers of soil.
Sample Boring The Sample Boring is a manual boring technique where a 1-inch sample
tube is driven using a 28-pound hand hammer with a 12-inch free fall.

The blows per foot are recorded by the Engineering Geologist in a

manner similar to the Cone Penetrometer test.

This technique is used only for soft soil sites and in areas where it is
difficult to get a drilling rig on the site.
Rotary Boring The Rotary Boring is a rapid drilling method used for penetrating soil
and rock. Borings up to 200 feet and more in depth can be taken using
this method.

The hole is advanced by the rapid rotation of the drilling bit, and water
or drilling mud is used to flush out the drill cuttings and to lubricate the
cutting tool.
Auger Borings An Auger Boring can be advanced without water or drilling mud and
provides a dry hole. It gives a good indication of material that is likely
to cave in during an excavation or drilling operation. It also gives an
accurate reading of where the groundwater elevation is. Most
equipment can drill to depths of 100 to 200 feet.
Diamond Core A Diamond Core Boring is used when rock is encountered during a
Boring drilling operation. It allows the drilling crew to recover continuous
sections of rock cores.

The Engineering Geologist can inspect the cores to determine the

competency of the rock.
Electronic Cone The Electronic Cone Penetrometer is an apparatus that drives a cone into
Penetrometer soil similar to the 2¼-inch cone penetrometer, but it is capable of
providing other soil parameters, such as soil type, shear strengths,
stiffness, bearing capacities, pore water pressures, relative densities, and
shear wave velocities.
Bucket Auger The Bucket Auger is a drilling tool that is used to excavate a larger
diameter hole (24 to 36 inches). It is considered to be the best indicator
for the presence of cobbles and boulders. It is also a good indicator for
the presence of material that is likely to cave in during an excavation.

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CHAPTER

2 Type Selection

All structure foundations have one fundamental characteristic in common; that is,
they provide a means whereby service and ultimate loads are transmitted from the
structure into the supporting geologic medium. The appropriateness of the
different types of structure foundations are governed by loading requirements,
site-specific geologic conditions, site accessibility, overhead clearance, existing
utilities and the proximity of existing facilities such as buildings and railroads as
well as site considerations such as vertical clearances and noise restrictions.

The Foundation Report is the primary source for information about the structure
foundations on a project. It is prepared by Geotechnical Services in the Division
of Engineering Services. The project engineer selects the appropriate foundation
type based upon data and recommendations contained in this report. The
Foundation Report may include recommendations and engineering data for
several foundation types. In this case, field conditions and/or economics will
generally determine the foundation type.

Structure foundations can generally be classified in the following categories: (1)

footing foundations (frequently referred to as spread footings), (2) pile-supported
foundations (driven and non-driven piles), and (3) special case foundation types
that would include micro-piles, tie-backs and tie-downs. Pier columns were once
considered specialty foundation types but their use has become more prevalent
over the years as they are thought to behave well seismically.

Seal courses are frequently specified as a foundation aid when groundwater and
soil heave is anticipated. Seal course concrete is placed under water, the general
purpose being to seal the bottom of a tight cofferdam against hydrostatic pressure.
After the concrete cures, the water is pumped out of the cofferdam and
construction of the footing can occur “in the dry.”

Generally, footing foundations are more economical than pile supported

foundations. Cast-in-Drilled Hole (CIDH) concrete piles that are constructed “in
the dry” tend to be the most economical pile-supported foundation with large
diameter steel pipe piles generally being the most expensive.

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Various geologic and non-geologic features affecting type selection are discussed
in the following table. Most of these items will be discussed in more detail
elsewhere in this manual.

TYPE USE
SELECTION
Footing …are virtually unlimited in use. Geologic considerations include the soil
Foundations profile, the location of the water table and any potential fluctuation, and the
potential for scour or undermining. Non-geologic considerations include
the size and shape of the footing, adjacent structures, and existing utilities.
Driven Piles …are used where foundation material will not support a footing foundation
or discourages the use of Cast-In-Drilled Hole (CIDH) concrete piles. Pile
types are precast concrete, steel structural sections, steel pipe, and timber.
Geologic considerations include the soil profile, driving difficulties, and
corrosive soils. Non-geologic considerations include adjacent structures,
existing utilities, required pile length, restricted overhead clearances,
accessibility, and noise restrictions.
Non-Driven …consist of Cast-in-Drilled Hole (CIDH) concrete piles and alternative
Piles footing design piles. CIDH piles are used extensively where piles are
required and foundation conditions permit their use. The slurry
displacement method of construction of CIDH piles is used where driven
piles are impractical and ground conditions necessitate its use. Alternative
footing design piles are used on an experimental basis when conditions
warrant their use. Geologic considerations include location of the water
table and potential fluctuation, potential for caving and the soil profile.
Non-geologic considerations include adjacent structures, existing utilities,
restricted overhead clearances, and accessibility.
Special Case
Foundations …represent special applications and, therefore, have limited use.

Pier Columns …are an extension of the pier to a planned elevation into rock. They
generally used for hillside structures, thus eliminating the extensive
excavation that would be required for large spread footings. The location
and type of existing structures may restrict excavation limits.
Tiebacks and …are used for earth retaining structures where it is not feasible to excavate
Soil Piles and construct a footing foundation or pile cap for a conventional retaining
wall. Geologic considerations include the soil profile and corrosive soil
problems. Non-geologic considerations include adjacent structures,
accessibility, and existing utilities.
Tiedowns or …are used, in general, to address uplift concerns in seismic zones and for
Tension Piles seismic retrofitting of existing footing foundations where uplift and
overturning must be prevented.
Micro Piles …are small diameter piles (less than 12 inches) that are drilled and filled
with reinforcement and grout.

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CHAPTER

3 Contract Administration

The design and construction of structure foundations is one of the most difficult
and challenging responsibilities of the Department. A great deal of time and
effort is taken in the design phase to adequately describe the existing soils;
however the complex and variable geology found in many portions of the State of
California tends to complicate these investigations. The investigations and
recommendations made by Geotechnical Services are used by the Office of
Structure Design to develop a design for a structure. The design should permit
the structure to last throughout the years, withstand earthquakes and large storms
that may undermine foundations through liquefaction, scour and the like.

Section 5-1.01 Authority of the Engineer of the Standard Specifications states

that,

“The Engineer shall decide all questions… as to the acceptable fulfillment of the
contract on the part of the Contractor; and all questions as to compensation”.
Contract Administration may be defined as the sum total of all actions required by
the Engineer to ensure that the contemplated work is constructed and completed
by the Contractor in accordance with all terms of the contract.

These actions include, but are not limited to: (1) interpretation and enforcement of
the plans and specifications, (2) ensuring compliance with applicable Caltrans
policies and procedures, (3) objective and subjective decision making (i.e.
Engineering Judgment), 4) sampling, testing and inspection of the work, (5)
problem solving that may result in changes to the contract to meet design intent,
and (6) proper documentation to defend the Department’s position regarding the
accuracy of the information provided at the time of bid.

A well-administered contract does not always produce a situation where the

contract is free from challenges and difficulty but it will provide a foundation that
is in the best interest of the structure and therefore the Department. Foundation
operations are “high risk” activities for all parties involved as they have the
potential to impact construction budgets and schedules. Although it is the
Contractor’s contractual obligation to construct and complete the project in
accordance with the contract documents, changes to the contract are sometimes
necessary to meet the intent of the Designer. Therefore, the best results are

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generally obtained when the Department and the Contractor have an attitude that
is one of cooperation; that focuses on identifying issues as early as possible and
that promotes working together to resolve them. The Department promotes the
formation of a “Partnering” relationship with the Contractor in order to effectively
complete the contract to the benefit of both parties. The purpose of this
relationship will be to maintain cooperative communication and mutually resolve
conflicts or challenges at the lowest possible level. This process is particularly
important in foundation work where risks to the project are high and contract
change orders may be required to effectively administrate the contract.

In order for the Engineer to decide the question of acceptable fulfillment of the
contract on the part of the Contractor (i.e., successfully administer the contract),
the contemplated work must be thoroughly understood. To achieve this, a
detailed study of the contract documents must be made. This includes the
Standard Specifications, Standard Plans, contract plans, and special provisions,
the Log-of-Test Borings and the Foundation Report. The Engineer must become
completely familiar with the contract plans and their requirements as well as the
Contractor’s construction schedule. In addition, the Engineer should check
footing elevations, ensure that there is adequate cover, verify design bearing
pressures, look for special treatment of foundation provisions, proximity of
utilities, existing structures, highways and railroads, etc. The order of work and
construction sequences must be thoroughly understood. A field investigation
should be made of the proposed project site and, to the extent possible, the
location of all utilities and obstructions should be verified prior to the start of
construction in the area. Note any conflicts or potential problems and
communicate them to the appropriate parties so that a path to resolution may
begin.

In addition to the information described above, other documents to be reviewed

are:

DOCUMENT DESCRIPTION
Log of Test Prepared by Geotechnical Services and provides the results of the
Borings geotechnical investigation. It provides a description of the soil or rock
sampled in the field, test results for laboratory-tested samples and
groundwater elevations. It can be used to obtain soil profiles.
RE Pending File Contains all the correspondence relative to a particular project and,
therefore, provides not only a historical outline of its development, but
information relative to existing or proposed utilities, potential problems and
any other special considerations.
Preliminary Prepared by the Preliminary Investigations Unit of the Project Management
Report Branch, Office of Program/Project Management and Support. The report is
based on information furnished by the District and by data obtained during a
field investigation of the proposed site. The report furnishes the Project
Designer with the required roadway geometrics, clearances, proposed and
existing utilities and/or obstructions, and will discuss any potential problems
or other special considerations.

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DOCUMENT DESCRIPTION
Foundation Prepared by Geotechnical Services, it provides detailed information about
Report the foundation investigation done for the structure or project. It is a part of
the RE Pending File and included in the Materials Handout to Contractors.
This report will contain a description of the area geology, a Log of Test
Borings for selected locations and recommendations for foundation types
and construction considerations. This report is very informative and should
be thoroughly reviewed.
As-Built Prepared by the Office of Structure Construction after successful completion
Drawings of a contract. These documents can be useful when constructing widenings
or when constructing new structures near or adjacent to existing structures.

The contract plans and specifications, the documents previously mentioned and a
field investigation of the site must all be reviewed for compatibility. It is
important that all ambiguities, discrepancies and/or omissions be resolved
expeditiously so as to avoid unnecessary delays to the work.

In the past, the Log of Test Borings and other information provided to the
Contractor at time of bid were not considered part of the contract and were
provided for information only. The 2006 version of the Standard Specifications
has been revised to change this. In particular, Section 2-1.03 Examination of
Plans, Specifications, Contract, and Site of Work, has undergone a major revision.
While the Contractor is still required to investigate the site and other available
information, as before, it is now understood that the information provided by the
Department will be used by the Contractor to develop a competitive bid. The
accuracy of this information is essential to a claim free contract. It is important to
note that while the Department is taking responsibility for the information
provided, the contractor is still required to carefully examine the site and the
information provided and are still responsible for the conclusions that are drawn
from these materials.

It is imperative that the Engineer meets with the Project Engineer and the
geoprofessional from Geotechnical Services to discuss substructure
considerations and foundation details. If an on-site meeting is impractical, the
meeting should be held by telephone/teleconference. Clarify and resolve any
questions or inconsistencies and get a clear understanding of the foundation
material as well as the potential risks or challenges anticipated in constructing the
foundations. This would also be the appropriate time to discuss the project with
the Bridge Construction Engineer, preferably at the job site.

Once the contract documents have been reviewed and meetings held, the Engineer
should have a firm grasp of the technical and contractual requirements for the
project, as well as the subsurface conditions that are expected to be encountered at
the various foundation locations within the jobsite. Special attention should be
given to those locations requiring extreme care in performing the work and
resolving any remaining issues concerning utility relocations. These challenges
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and concerns should be presented at the pre-construction conference(s) to be held

with the Contractor and other interested parties/agencies.

Pre-construction conferences are usually held at about the same time that the
Contractor begins mobilizing at the site, but well before work actually starts on
the job. Five general subjects are normally covered: (1) safety, (2) labor
compliance and affirmative action, (3) utilities, (4) environmental considerations
and (5) matters related to the performance of the work itself. Depending on the
individual policies of a particular District and the complexity of the project, more
than one meeting may be appropriate so as to limit the scope and the number of
individuals present. From this meeting should come a common understanding of
the proposed work, the risks, challenges and potential solutions that may be
expected during the life of the contract.

The pre-construction conference presents an excellent time to focus on inherent

risks in foundation work, specific project challenges and specifications that could
have significant impacts on the Contractor’s operations. Since contracts vary and
many specifications govern foundation work, it is impossible to list all of the
items that might apply. However, the following list covers some of the areas that
must be understood for effective contract administration:

ITEM REFERENCE
Test Boring Information Standard Specifications, Section 2-1.03
Excavation Safety Plans; Trench Safety Standard Specifications, Sections 5-1.02A & 7-1.01E
Differing Site Condition Standard Specifications, Section 5-1.116
Source of Materials Standard Specifications, Section 6-1.01
Water Pollution Standard Specifications, Section7-1.01G
Sound Control Requirements Standard Specifications, Section7-1.01I
Public Safety Standard Specifications, Section 7-1.09
Preservation of Property Standard Specifications, Section 7-1.11, 19-1.02
Contractor’s Responsibility for the Standard Specifications, Section 7-1.16
Work and Materials
Protection of Utilities Standard Specifications, Section 8-1.10
Cofferdams Standard Specifications, Section 19-3.03
Water Control & Foundation Treatment Standard Specifications, Section 19-3.04
Foundation Inspection Standard Specifications, Section 19-3.05
Foundation Revisions Standard Specifications, Sections 19-3.07 & 51-1.03
Piling Standard Specifications, Section 49
Seal Course Standard Specifications, Section 51-1.10
Special Concrete Mix Designs Special Provisions
Applicable Caltrans Policies Various Manuals
Hazardous Waste Material special provisions

All utility locations shown on the plans should be verified with the utility
representative. Utilities constructed by local municipalities and the Department
are not verified by the Utilities Service Alliance (USA) and will require the
efforts of the Department and each individual municipality to identify and locate.
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The Engineer should request as-built plans from local municipality and conduct
field meetings to verify the locations of these existing facilities prior to
excavation.

The Contractor is required to notify the proper agencies to have the existing
underground utilities located in the field prior to commencing excavation
operations. The status of utilities not yet relocated and field evidence of
additional existing utilities must also be discussed. Problems in this area could
result in serious delays. If not solved at the pre-construction conference, these
utility issues should be resolved at the earliest possible time.

The Contractor’s proposed methods of performing foundation work adjacent to

utilities should also be discussed at the pre-construction conference. All those
present should be advised of any proposed change orders that may potentially
affect their work or property.

All pre-construction conferences should be well documented. When appropriate,

minutes of the meeting should be distributed to all attendees. This serves to
confirm positions and/or agreements made at the meeting.

Proposed foundation changes, whether the result of geologic or non-geologic

conditions, should be discussed with the Bridge Construction Engineer.
Depending on the extent of the proposed change, it may be advisable to consult
with Structure Design and Geotechnical Services.

Footing Foundations

Certain revisions in excavation limits, footing elevations and sizes, and changes to
or elimination of seal course concrete are discussed in the contract documents.
This gives the Engineer the authority to give written direction to the Contractor to
implement various changes in the field. As most items are final pay items, a
change order will ultimately be needed in order to allow the quantity change for
the items affected by this revision (Bridge Construction Memo 2-9.0). Once it is
determined that a change is necessary, the Contractor is issued a change order
describing the work to be done, the basis of compensation and the extent of any
time extension.

To eliminate any possible misunderstanding about field revisions of foundations,

a letter should be sent to the Contractor prior to commencing foundation
operations (Bridge Construction Memo 2-9.0). An example of this letter is
provided in Appendix C. The letter should advise the following:

ITEM REMINDER/STATEMENT
1 A reminder that Section 51-1.03 of the Standard Specifications reserves to the
Engineer the right to revise, as may be necessary to secure a satisfactory

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ITEM REMINDER/STATEMENT
foundation, the footing size and bottom of footing elevations shown on the plans.
2 On projects involving seal courses, a reminder that Section 51-1.22 of the Standard
Specifications allows the Engineer to revise or eliminate seal course shown on the
plans.
3 A statement to the effect that final footing elevations and/or the need for seal
courses will be determined by the Engineer at the earliest possible time consistent
with the progress of the work, and that the Contractor will be notified in writing of
the Engineer’s decision.
4 Caution the Contractor that work done or materials ordered prior to receiving the
Engineer’s decision regarding foundations is done at their risk, and that they
assume the responsibility for the cost of alterations to such work or materials in the
event revisions are required.

Pile Foundations

In accordance with Section 49-1.08 “Pile Driving Acceptance Criteria” of the

Standard Specifications, driven piles must achieve the required nominal driving
resistance and penetrate to the specified tip elevation unless otherwise permitted
in writing by the Engineer. Nominal Resistance is usually determined from the
equation provided in this Section and is also know as the Gates Formula.
Additional information regarding this formula can be found in Chapter 7 of this
Manual and in BCM 130-4. The nominal resistance for large diameter piles is
determined from non-destructive testing such as the pile driving analyzer (PDA)
or static pile load tests. Driven piles that are to be load tested need to be driven to
the specified tip elevation shown on the plans. The nominal driving resistance
will be determined from the pile load test. Revisions to specified tip elevations
may be required as a result of the values obtained during testing. Procedures for
load testing piles are discussed in Chapters 7 & 8 of this Manual.

During pile driving operations one of the following scenarios will occur: (1) The
pile will achieve the required nominal driving resistance but falls short of the
specified tip elevation. (2) The pile will achieve the required nominal driving
resistance and specified tip elevation. (3) The pile will not achieve the required
nominal driving resistance at the specified tip elevation. As a result of this
variability, the contractor may decide to furnish piling of longer lengths than
those shown on the contract plans. Sometimes the contractor will elect to
continue driving the pile beyond the specified tip elevation even though the
required nominal resistance has been achieved. This is often done to avoid the
cost of cutting off the extra length of pile so that the top of the pile is at the
specified cutoff elevation. In these situations, the Contractor should be notified in
writing that the cost of additional driving and length of pile are at the Contractor’s
expense.

The Engineer may revise the specified tip elevation as provided in Section 49-
1.08 “Pile Driving Acceptance Criteria” of the Standard Specifications either to

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allow the acceptance of piles that do not reach the specified tip elevation or to
require continued driving until the required nominal penetration is achieved.
When considering revisions to the specified tip elevation pay particular attention
to the information provided on the pile data sheets of the contract plans. These
sheets contain information on the design requirements/constraints for the piles and
may include design tip elevations for compression, tension, lateral, downdrag,
liquefaction and scour potential among others. The specified tip elevation is the
deepest elevation of the foundation and is the one that controls the design.
Revisions to tip elevations may impact the performance of the pile and need to be
discussed with Structure Design and Geotechnical Services. This is particularly
important when compression doesn’t control the design.

There have been changes made to Section 49-6.01 Measurement in the 2006
Standard Specifications in regard to measurement for piling. The changes are as
follows:

The length of timber, steel, and precast prestressed concrete piles, and of
cast-in-place concrete piles consisting of driven shells filled with concrete,
shall be the greater of the following:

A. The total length in place in the completed work, measured along

the longest side, from the tip of the pile to the plane of pile cut-off.

B. The length measured along the longest side, from the tip elevation
shown on the plans or the tip elevation ordered by the Engineer, to
the plane of pile cut-off.

Piling that extend beyond the tip elevation shown on the plans as ordered by the
Engineer to meet design requirements will be paid under the provisions of part
“A” while piling that fails to reach the tip elevations shown on the plans but has
been determined to be suitable for the design will be measured in accordance with
part “B”. (Bridge Construction Memo 130-6)

When steel “H” piles exhibit a trend where the piles need to penetrate beyond the
specified tip elevation in order to achieve the required nominal resistance, the
Engineer should consider using lugs in order to reduce the additional pile length
required. Lugs are pieces of steel that are welded to the pile to increase the
surface area and provide greater driving resistance. When the Engineer orders
lugs, the cost of furnishing and welding steel lugs to piles is paid for by extra
work at force account or agreed price. Bridge Construction Memo 130-5.0
describes this process and shows a detail of a pile lug.

On projects involving Cast-In-Drilled-Hole (CIDH) concrete piles, the Contractor

should be notified in writing that CIDH piles must penetrate at least to the
specified tip elevation shown on the plans or as ordered by the Engineer and that

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no additional payment will be made for piles that penetrate below the specified or
ordered tip elevation. Any ordered change by the Engineer must be in writing.

In certain instances, the Contractor has the option to submit a proposal to increase
the diameter and revise the tip elevation of CIDH piling. These revisions shall be
made in accordance with Section 49-4.03 of the Standard Specifications. In this
instance, the Contractor is paid for the theoretical length of the specified pile to
the specified tip elevation. The Engineer should consult with Structure Design
and Geotechnical Services before agreeing to this change.

Cast-In-Drilled-Hole (CIDH) concrete piles are sometimes constructed in the

presence of groundwater or “in the wet”. This operation uses a drilling slurry to
control groundwater and to maintain the stability of the drilled hole. The concrete
is placed/poured under tremie and visual inspection is not possible. The
Department uses non-destructive testing for these pile types to verify pile
integrity. Chapter 9 of this Manual describes this process and outlines the roles
and responsibilities of the Engineer to get the piles tested and to address the repair
of any anomalous material identified by the testing.

As-Built Drawings and Pile Records

The Engineer is required to monitor the installation of piles during foundation

operations that involve Driven or CIDH piling and keep accurate records of these
activities. Bridge Construction Memo 3-7.0 discusses and explains the various
forms that are to be completed during these activities. The information recorded
on the forms is valuable to the Department as it may be used to help assist in the
acceptance of piling that does not reach specified tip elevation/nominal resistance
or to provide information for the resolution of construction claims. The
information will also be used by Geotechnical Services to refine
recommendations for future projects. In addition to the forms, OSC Headquarters
keeps a database for various aspects of CIDH Piling constructed using the “wet”
specification. (Bridge Construction Memo 130-13.0)

Bridge Construction Memo 9-1.0 incorporates As-Built plans as a part of the final
records and reports. As-Built plans should provide an accurate portrayal of what
was constructed. This information is important when changes are made to the
structure after original construction is complete. For example, footing overpours
need to be shown on the As-Built plans, as they could eventually become a
problem during the construction of footing widenings and seismic retrofits. Other
problems have resulted when existing shoring and utilities that are moved or left
in place were not shown on As-Built plans. These issues among others have
added to the cost of projects involving improvements to existing structures.

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Differing Site Conditions

The concept of a differing site condition is unique to substructure and foundation

work. Differing Site Conditions (DSC) can be identified by either party and are
defined in Section 5-1.116 of the Standard Specifications. DSC occur when
subsurface or latent physical conditions encountered at the site differ materially
from those indicated in the contract; or when unknown physical conditions of an
unusual nature that differ materially from those ordinarily encountered and are not
generally recognized as inherent in the work are found.

According to Section 5-1.116, Differing Site Conditions, of the Standard

Specifications, timely notification, documentation, and response is of the utmost
importance. Each claim for differing site conditions is handled per project or
individually. The Division of Construction has issued Construction Program
Directive 01-12 (CPD 01-12) to outline the procedures to be followed should the
Engineer receive a notice of a Differing Site Condition. Essentially the Engineer
will draft a response and submit it to Management for review and approval prior
to the actual response to the Contractor. The timelines for this process are very
specific and proactive means will be required to achieve them. Individual
Districts may have protocols in place to streamline this process. Consult with the
Resident Engineer and the Bridge Construction Engineer immediately upon
receipt of a Notice of Differing Site Condition.

There may be a situation where, after Management review, it is decided that the
Contractor’s Notice of Differing Site Condition has no merit. Should this occur,
the Contractor has a timeframe, within which, to submit a protest of the decision
with a Notice of Potential Claim. If the Contractor opts to pursue the issue, the
timelines established in Section 9-1.04 “Notice of Potential Claim” of the
Standard Specifications and applicable sections of the Contract Special Provisions
will need to be followed.

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CHAPTER

4 Footing Foundations

General
Footing foundations, also known as spread, combined or mat footings transmit
design loads into the underlying soil mass through direct contact with the soil
immediately beneath the footing. In contrast, pile-supported foundations transmit
design loads into the adjacent soil mass through pile friction, end bearing, or both.
This Chapter addresses footing foundations while pile foundations are covered in
Chapter 5 of this Manual.

Each individual footing foundation must be sized so that the maximum soil
bearing pressure does not exceed the allowable soil bearing capacity of the
underlying soil mass. As the load bearing capacity of most soils is relatively low
[2 to 5 Tons per Square Foot (TSF)], the result is footing areas that can be large in
relation to the cross section of the supported member. This is particularly true
when the supported member is a bridge column.

In addition to bearing capacity considerations, footing settlement must also be

considered and must not exceed tolerable limits established for differential and
total settlement. Each footing foundation must also be structurally capable of
spreading design loads laterally over the entire footing area.

Since the foundation will be supported only by the supporting soil mass, the
quality of the soil is extremely important. The Standard Specifications allow the
Engineer to revise elevation of footing foundations to ensure they are founded on
quality material. Refer to Chapter 3 “Contract Administration” of this Manual for
information on the responsibility of the Engineer as it applies to footing
foundations.

Types
Footing foundations can be classified into two general categories: (1) footings that
support a single structural member; frequently referred to as “spread footings”,
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and (2) footings that support two or more structural members; referred to as
“combined footings.”

Typically, columns are located at the center of spread footings, whereas retaining
walls are eccentrically located in relation to the centerline of a continuous footing.
Locating a load away from the centroid (center) of the footing creates an
eccentricity that changes the distribution of loads in the soil and may result in a
bearing pressure that exceeds the allowable bearing capacity. These undesirable
loading conditions increase the further the column is placed from the centroid or
as the eccentricity increases. The worst of these cases is an edge-loaded footing
where the edge of the column is placed at the edge of the footing. The major
consideration for these footings is excessive settlement and/or footing rotation on
the eccentrically loaded portion of the footing. The effect of column eccentricity
on footing rotation and soil bearing pressures is similar to a centrally loaded
footing with a moment. This will also cause an unbalanced load transfer into the
soil as shown in Figure 4-1.

FIGURE 4-1 Loaded footing with moment

In Figure 4-1, the moment (M) may come from a loading condition that needs to
be transferred into the soil mass or may be the resultant of the length of the
eccentricity multiplied by the load (P). The phrase “outside the kern” refers to a
situation when the eccentricity is so great that there is no compression, or worse
yet, tension on one side of the footing.

The problems resulting from eccentricities can be addressed by combining two or

more columns onto a single footing. This is generally accomplished by one of
two methods. In the first method, a single rectangular or trapezoidal footing
supports two columns (Combined Footing). In the other method, a narrow
concrete beam structurally connects two spread footings. This type is referred to
as a cantilever or strap footing.

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Combined footings are generally required when loading conditions (magnitude

and location of load) are such that single column footings create undesirable
loading conditions, are impractical, or uneconomical. Combined footings may
also be required when column spacing is such that the distance between footings
is small or when columns are so numerous that footings cover most of the
available foundation area. Generally, economics will determine whether these
footings should be combined or remain as individual footings. A single footing
supporting numerous columns and/or walls is referred to as a mat footing and is
commonly seen in building work.

The Department performed seismic retrofits of spread footings extensively

throughout the 1990’s. Although this is not a separate category, it’s important to
understand that foundation work sometimes entails modifications of an existing
structure. While the retrofit program is for the most part complete there are still
structures that may need upgrades either for seismic concerns, scour or bridge
widenings. Details of previous footing retrofit strategies are shown in Appendix
C.

Footing foundations encountered in bridge construction almost always support a

single structural member (column, pier or wall) and are invariably referred to as
spread footings. Although closely spaced columns do occur in multiple column
bents, they are rarely supported on a combined footing. However, recent seismic
and scour retrofit projects have incorporated designs that have joined adjacent
footings together.

Bearing Capacity
The ultimate bearing capacity of a soil mass supporting a footing foundation is the
maximum pressure that can be applied without causing shear failure or excessive
settlement. Ultimate bearing capacity solutions are based primarily on the Theory
of Plasticity; that is, the soil mass is assumed to be incompressible (does not
deform) prior to shear failure. After failure, deformation of the soil mass occurs
with no increase in shear (plastic flow).

The implication of the previous statements is that theoretical predictions can only
be applied to soils that are homogeneous and incompressible. However, most
soils are neither homogeneous nor incompressible. Consequently, known
theoretical solutions used in bearing capacity analyses have been modified to
provide for variations in soil characteristics. These modifications are based
primarily on data obtained empirically and through small, and more recently
large, scale testing.

The ultimate strength of the soil is referred to as Gross Ultimate Bearing

Resistance (qn) in Load Resistance Factor Design (LRFD) and Ultimate Gross

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Bearing Capacity (qult) when working with Working Stress Design (WSD). Once
qn and qult are calculated, the value is reduced by a factor of safety. The revised
value is referred to as Allowable Bearing Capacity (qall).

Failure Modes

The mode of failure for soils with bearing capacity overloads is a shear failure of
the soil mass supporting the footing foundation. It will occur in one of three
modes: (1) general shear, (2) punching shear, or (3) local shear. The Theory of
Plasticity describes the general shear failure mode. The other two failure modes,
punching and local shear have no theoretical solutions.

A general shear failure is shown in Figure 4-2 and can be described as follows:
The soil wedge immediately beneath the footing (an active Rankine zone acting as
part of the footing) pushes Zone II laterally. This horizontal displacement of
Zone II causes Zone III (a passive Rankine zone) to move upward.

FIGURE 4-2 General shear failure concept

General shear failure is a brittle failure and is for the most part sudden and
catastrophic. Although bulging of the ground surface may be observed on both
sides of the footing after failure, the failure usually occurs on one side of the
footing. For example, (1) an isolated structure may tilt substantially or
completely overturn; (2) a footing restrained from rotation by the structure will
see increased stresses in the footing and column portions of the structure which
may lead to excessive settlement or collapse.

A punching shear failure (Figure 4-3) presents little, if any, ground surface
evidence of failure, since the failure occurs primarily in soil compression
immediately beneath the footing. This compression is accompanied by vertical
movement of the footing and may or may not be observed, i.e., movement may be
occurring in small increments. Footing stability is usually maintained throughout
failure (no rotation).

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Local shear failure (Figure 4-4) may exhibit both general and punching shear
characteristics, soil compression beneath the footing, and possible ground surface
bulging.

FIGURE 4-4
FIGURE 4-3
Local shear failure
Punching shear failure

Refer to Figure 4-5 for photographs of actual test failures using a small steel
rectangular plate (about 6 inches wide) and sand of different densities.

FIGURE 4-5 Failure modes

The mode of failure mode for a given soil profile cannot be predicted. However,
it can be said that the mode of failure depends substantially on the compressibility
or incompressibility (Relative Density) of the soil mass. This is not to imply that
the soil type of the underlying material alone determines failure mode. For
example, a shallow footing supported on very dense sand will usually fail in
general shear, but the same footing supported on very dense sand that is underlain
by a soft clay layer may fail in punching shear.

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The ultimate bearing capacity of a given soil mass under spread footings is
usually determined by one of the variations of the general bearing capacity
equation which was derived by Terzaghi and later modified by Mererhof. It can
be used to compute the ultimate bearing capacity as follows:

γB
qult = Nγ + cNc + γDfNq (Terzaghi)
2
Where: qult = ultimate bearing capacity
γ = soil unit weight
B = foundation width
Df = depth to the bottom of the footing below final grade
c = soil cohesion, which for the undrained condition equals:

1
c = s = qu
2
Where: s = soil shear strength
qu = the unconfined compressive strength

In the above equation, Nγ, Nc, and Nq are dimensionless bearing capacity factors
that are functions of the angle of internal friction. The term containing factor Nγ
shows the influence of soil weight and foundation width. The term containing
factor Nc shows the influence of the soil cohesion, and that of Nq shows the
influence of the surcharge.

Factors Affecting Bearing Capacity

Several factors can affect the bearing capacity of a particular soil. They include
soil type, relative density or consolidation, soil saturation and location of the
water table and surcharge loads. These factors can act individually or in concert
with each other to increase or decrease the bearing capacity of the underlying soil.

When the supporting soil is a cohesionless material (sands), the most important
soil characteristic in determining the bearing capacity is the relative density of the
material. An increase in relative density is accompanied by an increase in the
bearing capacity. Relative density is a function of both ø and γ; the angle of
internal friction and unit weight, respectively. In cohesive soils (clays), the
unconfined compressive strength (qu,) is the soil characteristic that affects bearing
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capacity. The unconfined compressive strength (qu) is a function of clay

consistency. The bearing capacity increases with an increase in qu values.

The bearing capacity of both sands and clays are influenced by the location of the
water table with respect to the bottom of footing. When the distance to the water
table from the bottom of the footing is greater than or equal to the width of the
footing B, the soil unit weight is used in the general bearing capacity formula. At
these depths, the bearing capacity is only marginally affected by the presence of
water and can therefore be neglected. When the water table is at or below the
base of the footing, a ratio between the unit weight of the soil above the water
table and the submerged unit weight is used in the first term of the bearing
capacity equation. (Refer to Figure 4-6). The impact of the water table on the
bearing capacity of the soil beneath the bottom of the footing is substantial as it
effectively reduces the first term of the equation by approximately 50%. The
submerged unit weight γ’ or γsub as it is sometime called is determined as follows:

γ' = γsat - γw

Where: γ' = Submerged unit weight

γm = Saturated unit weight (Sometimes shown at γsat)
γw = Unit weight of water

for zw > B : use γ = γm (no effect)

for zw < B : use γ = γ’ + (zw/B)*( γm- γ’)
for zw < B : use γ = γ’

FIGURE 4-6 Influence of groundwater table on bearing capacity

It is apparent that bearing capacity of both cohesionless and cohesive soils will be
reduced, as the water table gets closer to the bottom of footing. This is validated
by the general bearing capacity formula as lower capacities will occur when the

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lighter submerged unit weight of soil is substituted for the dry unit weight.
Therefore, the effects of the water table on the bearing capacity of the footing soil
mass, at any time during construction, must be considered.

FIGURE 4-7 Surcharge load on soil

The depth of the footing below original ground or future finished grade is yet
another factor that affects the bearing capacity of the soil beneath the foundation.
The term Df is used in determining the overburden, or surcharge load acting on
the soil at the plane of the bottom of footing (Figure 4-7). This surcharge load has
the net effect of increasing the bearing capacity of the soil by restraining the
vertical movement of the soil outside the footing limits.

FIGURE 4-8 Relationship between ø and bearing capacity factors

Lastly, the shape of the footing foundation affects the bearing capacity of the soil.
Theoretical solutions for ultimate bearing capacity are limited to continuous
footings (LENGTH/WIDTH>10). Shape factors for footings other than
continuous footings have been determined primarily through semi-empirical
methods. In general, the ultimate bearing capacity of a foundation material
supporting a square or rectangular footing is greater than the capacity of a
continuous footing when the supporting material is cohesive (clay) and less than

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the bearing capacity of a continuous footing when the supporting material is

cohesionless (sand).

FIGURE 4-9 Relationship of bearing capacity factors to ø and N (standard

penetration resistance) for cohesionless soils

The general bearing capacity equation can also be used to give a field estimate of
the ultimate bearing capacity of temporary footings, such as falsework pads. For
cohesionless soils, a relationship between the standard penetration resistance, N,
and the bearing capacity factors, Nγ and Nq, is shown in Figure 4-9. The
relationship between N and the angle of internal friction, ø, can be also
determined from Figure 4-9. When soils are known to have some cohesion, the
value of ø determined from Figure 4-9 can then be used in the chart shown in
Figure 4-8 to determine the bearing capacity factors, Nγ, Nc, and Nq. Values for ø,
qu, N, and γ can be found on the log of test borings or can be approximated by
using the tables for granular and cohesive soils shown in Appendix A.

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Settlement
Footing foundations will settle over time as the soil densifies from the additional
weight it is required to support. The Department’s current practice is to limit total
permissible settlement for a shallow footing to one inch for multi-span structures
with continuous spans or multi-column bents, one inch for single span structures
with diaphragm abutments, and two inches for single span structures with seat
abutments. To achieve this, allowable bearing pressures are generally reduced to
25% to 33% of the ultimate bearing capacity as determined by the general bearing
capacity formula. This reduction essentially places a factor of safety on the
ultimate bearing capacity and is in line with the reductions discussed above to
obtain allowable and nominal bearing capacities.

Cohesionless soils will densify under the pressure of the foundation as the
individual soil particles are pushed together, effectively compacting it. In general,
soils with low relative densities will see more settlement than well-compacted
soils that have higher relative densities. Settlement in cohesionless materials is
for the most part immediate. Cohesive soils, however, consolidate over time as
the pressure of the overlying foundation forces water from the soil thereby
relieving excess pore water pressures.

Ground Improvement/Soil Modification

Frequently bridges need to be constructed at locations where the in-situ material is
not suitable for the intended purpose. Instead of utilizing a pile foundation,
Geotechnical Services will specify ground modification of the foundation area to
“engineer” it for its intended use. Economics, soil type and engineering loads will
drive the decision to use ground modification and avoid the additional cost of a
pile foundation.

Ground modification techniques are used to increase the bearing capacity of the
foundation material by increasing the relative compaction of the material either
through densification or the introduction of grouts to compress and bind the soils.
Ground modification techniques generally lend themselves to cohesionless
materials. These techniques can include the following: settlement periods, vibro-
compaction, jet grouting, stone columns, dynamic compaction and wick drains
among others. In general these modification techniques improve the bearing
capacity of the soil by increasing the relative density of the soil through external
means or by adding materials such as a cement or chemical grout to achieve a
similar result. Modification of cohesive soils can be achieved; however, these
methods are often time consuming and are often limited to wick drains and
settlement periods. As discussed latter on in this chapter, the replacement of poor

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quality soils by over-excavation and replacement with competent material may be

appropriate.

Some modification techniques involve a settlement period where the underlying

foundation is preloaded with a surcharge for a specified length of time prior to the
construction of the foundation. The loading typically consists of an embankment
constructed to specified limits. Geotechnical Services will determine the need to
preload the foundation area, specify the limits of the embankment, and set forth
the duration of the settlement period in the contract special provisions.

When settlement periods are less than 60 days, the Engineer should install
settlement hubs in the top of the bridge embankments. The hubs should then be
monitored (surveyed) and changes to the original elevations recorded. The
Engineer is responsible for terminating a settlement period. Data from the hub
elevation surveys will be used to determine when this should take place. If
settlement is still taking place at the end of the 60-day period, then the settlement
period should be extended until the settlement has ceased. However, if no
settlement occurred during the last week or two of the settlement period, the
settlement period should be terminated at the end of the 60 day period or to
shorten the length of the settlement period. The Contractor should be notified of
this decision in writing.

Settlement platforms will usually be required when settlement periods greater

than 60 days are specified. Geotechnical Services has a Geotechnical
Instrumentation Branch that will furnish and provide advice for the installation of
the settlement platforms (Refer to BCM 130-13 for additional information and
Appendix C for California Test 112 - Method for Installation and Use of
Embankment Settlement Devices). Unless this work is outlined in the special
provisions, the Engineer will need to write a change order to compensate the
Contractor for the initial installation of the settlement platforms.

Construction and Inspection

As discussed in Chapter 3 of this Manual, the Engineer should have a complete
understanding of all contract documents as early as practical in the construction
process. This will ensure that potential impacts to projects with regard to the
foundations are identified early and paths to resolution are begun before actual
construction begins.

The Engineer should write a letter reminding the Contractor of the provisions
stated in Section 51-1.03 of the Standard Specifications (Refer to Appendix C for
sample letter). This reminds the Contractor that footing elevations and seal
courses shown on the plans are approximate only and foundation modifications
may be required (Bridge Construction Memo 2-9.0).

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The Engineer should review and become familiar with the following documents
as described in Chapter 3. What follows are particular sections of the Standard
Specifications to be considered for footing foundations:

Specification Issue
Section 19-3.04 Discusses acceptable methods for water control and foundation
treatment.
Section 19-3.05 The Contractor shall notify the Engineer when the excavation is
substantially complete and is ready for inspection. No concrete
shall be placed until the Engineer has approved the foundation.
Section 19-3.07 Discusses measurement of excavation limits and how to address
revisions to excavations limits required to meet Design intent.
Section 19-5.03 Relative Compaction of not less than 95% is required for
embankments within 150 feet of bridge abutments or retaining wall
footings not supported on piles.
Section 19-6.01 When bridge footings are constructed in embankment, the
embankment shall be constructed to the elevation of the grading
plane and the finished slope extended to the grading plane before
excavating for the footings.
Section 19-6.025 When a surcharge and settlement period is specified in the Special
Provisions, the embankment shall remain in place for the required
period before excavating for footings. Also defines the minimum
limits of embankment that must be constructed before the
settlement period can begin.
Section 51-1.03 Plan footing elevations and seal courses are considered approximate
only and the Engineer may order changes in dimensions and/or
elevations of footings as may be necessary to obtain a satisfactory
foundation. (Bridge Construction Memo 2-9.0).
Section 51-1.04 Pumping of groundwater from foundation enclosures shall be done
in such a manner as to prevent removal of any portion of concrete
materials. Pumping is not permitted during concrete placement, or
for 24 hours thereafter, unless it is done from a suitable sump
separated from the concrete work.
Section 51-1.09 After placing, vibrating, and screeding concrete in footings that
have both a top mat of rebar and are over 2-1/2 feet deep, the top
one foot of concrete shall be reconsolidated as late as the concrete
will respond to vibration, but no sooner than 15 minutes after the
initial screeding.

Excavations
Construction of excavations or trenches is inherent in the construction of
foundation elements such as footing foundations. The Caltrans Trenching and
Shoring Manual provides information on the complete process for administering,
designing and reviewing excavation work and plans. What follows is a brief
description of what to consider prior to the start of excavation.

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Open Excavations

The open excavation or trench is a potentially dangerous area in a construction

site. Worker safety must be considered and addressed during excavation
operations and/or shoring construction. The Division of Occupational Safety and
Health (DOSH), better known as Cal-OSHA, requires each employee in an
excavation be protected from cave-ins by an adequate protective system. The
protective system can consist of metal or timber shoring, a shield system, or a
sloping and benching system. When a sloping and/or benching system is
substituted for shoring or other protective systems, and the excavation is less than
20 feet deep, DOSH requirements can be selected by the Contractor in accordance
with the requirements of Section 1541.1(b) of the Construction Safety Orders.
Section 1541.1(b)(1) allows slopes to be constructed (without first classifying the
soil) in accordance with the requirements for a Type C soil (1½:1 maximum).
Section 1541.1(b)(2) requires the Contractor’s “competent person” to first classify
the soil as either a Type A, B, or C soil or stable rock, before selecting the
appropriate slope configuration. Section 1541.1(b)(3) allows the use of tabulated
data under certain conditions and Section 1541.1(b)(4) addresses engineered
plans. The Engineer should refer to the Caltrans Trenching and Shoring Manual
or go directly to the website (http://www.dir.ca.gov/samples/search/query.htm)
when reviewing a Contractor’s excavation safety plan for compliance with the
construction safety orders.

Surcharge loads from materials, equipment or excavation spoils must be located a

sufficient distance back from the edge of excavations to maintain slope stability.
For sloped excavations, the minimum setback can be determined from Figure 4-
10.

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H = 20’
θ = 53 degrees (3/4:1)
ϕ = 46 degrees

20’/tan(46) = 19.31’
20’/tan(53) = 15.07’

X = 19.31’ – 15.07’ = 4.24’

FIGURE 4-10 Slope setback for open excavations/trenches

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Cofferdams or Shored Excavations

Cofferdams and/or shored excavations require an engineered plan stamped by a

registered Civil Engineer. The Contractor is responsible for designing these
elements and the Engineer is responsible for review and approval. The Trenching
and Shoring Manual goes over the procedures for reviewing and approving these
plans. An important consideration in shored excavations is the minimum setback
for a surcharge when on level ground. In general this setback is equal to the depth
of excavation unless specific surcharge loads are considered in the shoring design.
The “Bousineaq” strip load formula is recommended for calculating the lateral
pressures due to surcharge. (Figure 4-11). For example, no minimum setback of
the surcharge load would be required if the earth support system is designed for
the summation of lateral pressures due to the surcharge and earth pressures.
However, a barrier should be provided to prevent material from entering the
excavation. The Trenching and shoring Manual has several examples how this
formula is used and the OSC Website has a spreadsheet that can be used to
calculate the pressures.

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FIGURE 4-11 Effect of surcharge loads for shored excavations

If the earth support system is not designed for lateral pressures due to surcharge,
then a setback distance must be used. It can be calculated as shown in Figure 4-
12. Setback information should be shown on the approved shoring plans and
clearly designated in the field. Refer to the Caltrans Trenching and Shoring
Manual for information regarding shoring design and construction.

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FIGURE 4-12 Setback calculation for shored excavations when surcharges are
not considered in the shoring design

Wet Excavations

Section 19-3.04 “Water Control and Foundation Treatment” describes methods to

be utilized when water is encountered in excavations and seal courses are not
shown on the plans. The means and methods used to control groundwater are at
the option of the contractor. These means and methods need to be clearly
understood, as there are environmental considerations when dealing with the
control of groundwater. The special provisions have sections that address the
control and disposal of ground water. All employees of the Office of Structure
Construction have the responsibility to inspect structure work for compliance with
environmental regulations; as such, these operations should be discussed with the
Resident Engineer to ensure that the environmental considerations are addressed
prior to commencement of work.

Sump pumps are frequently used to remove surface water that enters an
excavation and minor infiltrations of groundwater. The sumps and any
connecting interceptor ditches should be located well outside the footing area and
below the bottom of footing so that the groundwater will not disturb the bearing
surface of the foundation.

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In cohesionless (granular) soils, it is important to make sure that the fine particles
within the soil mass are not carried away by the pumping operation. Loss of fines
may impair the bearing capacity of the soil for the foundation under construction
and may also lead to settlement of existing structures adjacent to the operations.
The amount of soil particles carried away can be determined by periodically
collecting discharge water in a container and observing the amount of sediment.
If there is a large flow of groundwater and/or prolonged pumping is required, the
sump(s) should be lined with a filter material to prevent or minimize the loss of
fines.

In some excavations the use of sumps may not be sufficient to address the
infiltration of groundwater into the excavation. When this is the case, cofferdams
are generally used; however some contractors will opt to lower the groundwater
table. One commonly used method to achieve this is with the single stage well
point system (Figure 4-13).

FIGURE 4-13 Single stage well point system

A well point is a section of perforated pipe about 2 to 3 inches in diameter and 2

to 4 feet in length. The perforations are covered with a screen and the end of the
pipe is equipped with a driving head and/or holes for jetting. Several well points
are installed around the perimeter of the excavation, generally spaced at 2 to 5
foot centers. They are connected to 2 to 3 inch diameter riser pipes and are
inserted into the ground by driving and/or jetting. The riser pipes are connected
to a header pipe that is connected to a pump. A single stage well point system can
lower the water table 15 to 18 feet below the elevation of the header pipe. For
greater depths a multiple stage system must be used. A single or multiple stage
well point system is effective in fine to medium granular soils or soils containing
seams of such material. In stratified clay soils, vertical sand drains (auger holes

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backfilled with sand) may be required to draw water down from above the well
points.

Another system for lowering the water table is a deep well. Deep wells consist of
either a submersible pump, turbine or water ejector at the bottom of 6 to 24 inch
diameter casings, either slotted or perforated. The units are screened but filter
material should be provided in the well to prevent clogging and loss of fines.

Deep wells can be spaced 25 to 120 feet apart and are capable of lowering a large
head of water. They can be located a considerable distance from the excavation
and are less expensive than the multiple stage well point system for dewatering
large areas however they are only appropriate in certain soils.

If a soft clay strata overlying sand is encountered and dewatering is contemplated,

it is cautioned that lowering the water table by pumping from underlying layers of
sand may not be a preferred option as it will cause large progressive settlement of
the clay strata in the surrounding area. By lowering the watertable in the sand lens
the condition in the clay lens switches from an undrained condition to a drained
condition. This allows excess pore water pressures to be dissipated more quickly
and to a greater extent than it would have been had the watertable not been
lowered. Essentially there is an increase in the effective pressure acting on the
saturated clay, i.e., density of clay above the lowered water table will increase
from a submerged unit weight to a saturated unit weight, an increase of 62.4
Pounds per Cubic Foot (PCF) (Figure 4-14).

FIGURE 4-14 Saturated vs. submerged unit weight

Bottom of Excavation Stability

The control of groundwater can be essential to the stability of a shoring system

and the underlying soil intended to support the new foundations. In addition to
controlling groundwater to facilitate construction operations, the Engineer must
also consider soil heave and piping as they relate to the stability of the bottom of
the excavation.

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Heave is the phenomena whereby the static or hydraulic pressures (head) of the
surrounding material cause the upward movement of the material in the bottom of
the excavation. This corresponds with a settlement of the surrounding material.
Heave generally occurs in soft clays when the hydrostatic head, 62.4(h + z), is
greater than the weight of the overburden at the bottom of the excavation, γz
(Figure 4-15).

FIGURE 4-15 Bottom of excavation stability problems due to excess hydrostatic

head against an impervious layer

Piping is generally associated with pervious materials and can occur when an
unbalanced hydrostatic head exists. This unbalanced head may cause large
upward flows of water into the excavation, transporting material in the process,
and may result in settlement of the surrounding area. Review the Caltrans
Trenching and Shoring Manual if instability problems are expected at the bottom
of excavations.

Foundation Inspection & Construction Considerations

Inspection should include determination of the following:

1) Stability of slopes and sides of excavations conform to Cal-OSHA

requirements.

2) Verification that the foundation material conforms to the information shown

on the Log of Test Borings (allowance should be made for some non-
uniformity such as small pockets and lenses of material having somewhat
different properties).

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3) Condition of the foundation-bearing surface (undisturbed by excavation

operations and uncontaminated by sloughing and/or entrance of water).

4) Proximity of structures, highways, railroads, and other facilities that may

require shoring or underpinning. (Should be done prior to excavation)

5) Foundation element forms conform to layout, depth, dimensions, and

construction grade shown on the plans. Forms are mortar tight.

6) Reinforcing steel is firmly and securely tied in place, shear steel hooked to
both top and bottom rebar mats and securely tied. Proper concrete cover
over top rebar mat.

7) During concrete placing operations ensure that the concrete has the proper
mix number, truck revolutions, concrete temperature and back-up alarm.
Wet down rebar and forms, do not allow concrete to drop over 8 feet.
Reconsolidate and finish top one foot of concrete no sooner than 15 minutes
after initial screeding, then cure.

8) A bench of sufficient width to prevent sloughing or cave-in should be

provided around the excavation for access and work area.

The footing forms are either built out of timber or consist of prefabricated panels.
The forms are generally secured at the bottom by stakes, horizontal kickers or ties
and are externally braced, tied or strapped at the top. If the forms extend above
the top of footing elevation, a pour strip or similar device must be attached to the
forms to designate the top of footing elevation.

The footings for shored excavations are often excavated and placed/poured “neat”
which means that the excavation limits are essentially the footing limits. The
concrete is placed against the sides of the excavation thereby eliminating the need
for footing forms. Top of footing grades must be clearly delineated with stakes or
flagged spikes driven into the sides of the excavation. Ensure that “neat”
excavations conform to the planned footing dimensions. If they vary, then place
the exact, as-constructed footing dimensions on the “as-built” drawings. Previous
seismic retrofit projects and footing widenings were not “as-built” properly and
costly contract change orders were required to address these undocumented
overpours. Care should betaken to make sure that the footing concrete isn’t
damaged during shoring removal operations.

Whether footings are formed or excavated “neat”, a template should be

constructed to ensure that the positioning of the vertical reinforcing steel is
maintained during concrete placement. All reinforcing steel must be securely
blocked and tied to prevent vertical and/or lateral displacement during concrete
placement. Reinforcing steel should not be hung or suspended from the

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formwork or templates as the weight of the suspended rebar can cause settlement
in the form panels affecting pour grades and displace during concrete placement.
Top reinforcing steel mats supported should be blocked to the forms or sides of
the excavation. The bottom reinforcing steel mat that supports the vertical column
steel should be adequately blocked to prevent any settlement. In addition,
reinforcing steel dowels are required to be tied in place prior to concrete
placement and not “stabbed in” during or after concrete placement.

The effective depth of reinforcing steel is critical and must always be verified.
For a footing supporting a single column, pier or wall, the effective depth is the
distance from the centroid of the reinforcing steel to the top of the concrete
footing. The bottom mat should be located at the design depth, even for over-
excavated footings, since the bottom mat supports the vertical column
reinforcement and the location of the top mat is tied to the bottom mat by the
shear hooks. Lowering the bottom mat is not desirable as it would require longer
vertical steel, longer shear hooks, and may require mechanical or welded splices
on the longitudinal bars. It should be noted that the additional concrete placed
below the bottom steel mat in over-excavated footings does not increase the
design depth of the footing but should be noted on the as-built plan sheets.

Footing inspections should occur as the work progresses so that deviations and
non-compliant issues can be addressed in a timely manner. However, it is
important to inspect the footing just prior to concrete placement to ensure that
nothing has changed. All material that has sloughed into the excavation must be
removed prior to placing concrete. Verify that settlement of the rebar cage hasn’t
occurred by re-inspecting minimum clearances between the bottom of the
excavation and the bottom reinforcing steel mat. The foundation material should
be wet down but not saturated. The ends of the concrete pour chutes should be
equipped to prevent free fall of concrete in excess of 8 feet. This will prevent
segregation of the concrete and may include a hopper and/or length of tremie
tube.

Foundation Problems and Solutions

Inspection of the excavated surface at the planned footing elevation after the
excavation is completed is mandatory (Section 19-3.05 of the Standard
Specifications requires the Contractor to notify the Engineer after the excavation
is completed). A thorough physical inspection of the foundation material by the
Engineer is required to determine if the foundation is suitable, disturbed and/or
contaminated, or unsuitable. Addressing contaminated material is the
responsibility of the Contractor while unsuitable material is the responsibility of
the Department. The phrase “contaminated material” as used here should not be
confused with materials contaminated with lead, hydrocarbons, heavy metals, etc.

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Information on environmentally contaminated materials will be addressed in the

contract plans and special provisions.

Disturbed and/or Contaminated Material

Disturbed or contaminated foundation material encountered at the planned bottom

of footing elevation is unacceptable and must be corrected even if the material
itself is suitable. Disturbance of the foundation-bearing surface is usually caused
by the excavation means and methods. It may include excavating below the
footing elevation or disturbing the grade with the teeth on the excavator bucket.
Contamination is usually due to the presence of water (typically uncontrolled) or
sloughing. All disturbed or contaminated material must be removed to expose a
suitable foundation surface. The foundation shall then be restored by the
Contractor, at the Contractor’s expense, to a condition at least equal to the
undisturbed foundation as determined by the Engineer.

The following precautionary measures can be taken during excavation and

construction in order to avoid or minimize the disturbance and/or contamination
of the foundation surface:

1) Under-excavate with mechanical equipment and excavate to bottom of

footing by hand or by using a cleanup bucket.

2) Divert surface water away from the excavation.

3) Minimize exposure of the foundation material to the elements by

constructing footings as soon as possible after excavation.

Unsuitable Foundation Material

The importance of suitable foundation material cannot be overstated. The

Engineer is responsible for determining the suitability of the foundation as it
relates to the design intent. That is, the foundation material has to have the
minimum material properties required for the structure to behave as the designer
intended. Simple tests can be performed in the field to determine the bearing
capacity and verify the suitability of the foundation material. They are discussed
in the “Caltrans Soil and Rock Logging, Classification, and Presentation Manual”
and include:

1. Penetration tests - granular soils

2. Finger tests - cohesive soils

3. Pocket penetrometer - cohesive soils

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Note that these simple and expeditious tests give only an approximate evaluation
of the soil at or immediately below the surface.

The Log of Test Borings should be reviewed when the Engineer determines that
the undisturbed original material encountered at planned footing elevation is
either unsuitable or of a questionable nature. It may be that the anticipated
suitable material may well be just below the excavated surface. If the Engineer is
certain that the material encountered at the planned footing elevation is
unsuitable, then hand-excavating a small exploratory hole to determine the limits
of the unsuitable material may be appropriate. Contact Geotechnical Services and
the project engineer and discuss the questionable material, related concerns and
possible resolutions.

Modifications Due to Disturbed, Contaminated or Unsuitable Material

Corrective action is required whenever changes in the bottom of footing

elevations are made to address disturbed, contaminated or unsuitable material.
Corrective action required to address disturbed or contaminated material is the
responsibility of the Contractor and addressing unsuitable material is the
responsibility of the Engineer. The corrective actions are similar in either
situation. They fall into two categories: replacement of the original foundation
material to achieve the original bottom of footing elevation and revisions to the
structure to address a different bottom of footing elevation. There are
engineering/design considerations in either of these paths and it is important to
discuss considerations and consequences with the project engineer, Geotechnical
Services and the Contractor and work toward a solution that fulfills the design
intent and keeps the job moving.

Options that can be used to restore the foundation material at the bottom of
footing elevation to its specified elevation after removal of unsuitable or
contaminated material are as follows:

1. Excavate to a stratum that has sufficient bearing capacity, replace the

removed unsuitable material with concrete, and then construct the footing
at the planned footing elevation.

2. Excavate to a stratum that has sufficient bearing capacity, replace the

removed unsuitable material with aggregate base or structure backfill to
95% compaction, and then construct the footing at the planned footing
elevation.

Revisions to the structure to address a different bottom of footing elevation or a

lower than anticipated bearing capacity should be discussed with the project
engineer. The revisions may require a redesign of the structure and are not minor

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in nature. These options, while possible, may not be the best alternatives in real
construction situations. They are as follows:

1. Maintain top of footing as planned and overform footing depth. The rebar
cage will remain at the theoretical elevation shown on the plans however
the depth between the bottom of footing and the bottom mat of the rebar
cage will be increased by the amount of over-excavation. This option is
similar to previously described methods. It essentially exchanges the use
of larger/taller footing forms for a reduction in the number of concrete
pours. This option may well be the preferred option for minor revisions to
bottom of footing elevations.

2. Excavate down to a stratum that has sufficient bearing capacity and

increase the height of the column or wall. This method may not be
acceptable if the increase in height necessitates redesign of the column or
wall. This decision should be discussed with the project engineer.

3. Increase the footing size so that the bearing pressure does not exceed the
allowable bearing capacity of the foundation material encountered at the
planned footing elevation. Settlement must also be considered, as it
cannot exceed tolerable limits. This decision should be discussed with the
project engineer and Geotechnical Services.

Although footing revisions are contemplated by the contract documents, footing

revisions made necessary due to unsuitable material encountered at the planned
footing elevation will require a change order. Impacts to the construction
schedule must also be considered when making these decisions. The Resident
Engineer should be kept aware of these issues. The preferred method for
compensating the Contractor for the cost of the corrective work is by adjustment
of contract items at contract unit prices and is the specified method of payment for
the following revisions (Standard Specifications - Section 19-3.07):

1. Raising the bottom of a spread footing above the elevation shown on the
plans.

2. Lowering the bottom of a spread footing 2 feet or less below the elevation
shown on the plans.

For other revisions, agreed price or force account methods should be used when
the Engineer determines that the above method is unsatisfactory or doesn’t
address changes to the character of the work as a result of the changes.

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Safety
As stated previously excavations are a potentially dangerous construction activity.
Cal-OSHA has requirements that must be followed prior to the start of any
excavation that is 5 feet, or more, in depth into which a person is required to
descend. This information is fully described in the Caltrans Trenching and
Shoring Manual; however a brief overview is provided below.

Prior to the start of excavation work, the Contractor is required to:

• Obtain a Cal-OSHA excavation permit.

• Identify a “competent person” responsible for the excavations.

• Provide an excavation plan to the Engineer for review and approval prior
to starting excavation. (Section 5-1.02A “Excavation Safety Plans” of the
Standard Specifications)

• Provide an engineered system stamped by an engineer registered in the

State of California for any engineered shoring system.

• An engineer registered in California must stamp any sloping or benching

system that is greater than twenty feet.

Once approved, the excavation needs to be inspected to ensure compliance with

the approved plan and Cal-OSHA requirements. Daily inspections (prior to start
of shift and after any hazard-increasing occurrence such as rain) of excavations or
protective systems shall be made by the Contractor’s “competent person” for
evidence of any condition that could result in cave-ins, failure of a protective
system, hazardous atmospheres, or any other hazardous condition. When any
evidence of a situation is found that could result in a hazardous condition,
exposed employees shall be removed until the necessary precautions have been
taken to ensure their safety.

Safety railings must be located around the excavation perimeter, preferably

attached to the shoring that extends above the surrounding ground surface. If the
shoring does not extend above the ground, then the railing must be located a
sufficient distance back from the excavation lip to adequately protect the
workmen in the excavation from being injured by falling objects or debris.
Locating the safety rail back away from the excavation lip usually provides more
stable ground to anchor the rail posts. Spoil piles must be located more than 2
feet away from the excavation lip for excavations deeper than 5 feet unless there
is an adequate retaining device in place to prevent materials from entering the
excavation.

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Although the vertical side of a non-shored excavation must be less than 5 feet in
height, care must be exercised when working around the perimeter to avoid
falling into the excavation because of sloughing or slip-out of the material at the
excavation lip. Spoil piles must be located at least one foot away from the
excavation lip for trenches less than 5 feet in depth.

Excavations can be considered confined spaces, as they are prone to hazardous

atmospheres with limited access and egress. Cal-OSHA requires the Contractor
to take adequate precautions to ensure that oxygen levels and atmospheric
contaminants are within acceptable limits. Employees entering excavations
should be trained in confined space protocols.

Whenever work is proceeding adjacent to or above the level of vertical

projections of exposed rebar, workers shall be protected against the hazards of
impalement on the exposed ends of the rebar. The impalement hazard can be
eliminated by either bending over the ends of the projecting rebar, or by use of
one of the following methods:

1) When work is proceeding at the same level as the exposed protruding rebar,
worker protection can be provided by guarding the exposed ends of rebar
with Cal-OSHA approved protective covers, troughs, or caps. Approved
manufactured covers, troughs, or caps will have the manufacturer’s name,
model number, and the Cal-OSHA approval number embossed or stenciled
on the cover, trough, or cap. Any manufactured protective device not so
identified is not legal.

2) When work is proceeding above any surface of protruding rebar,

impalement protection shall be provided by the use of: (1) guardrails, (2) an
approved fall protection system, or (3) approved protective covers or
troughs. Caps are prohibited for use as impalement protection for workers
working above a level of 7 ½ feet above the protruding rebar.

Protective covers used for the protection of employees working above grade shall
have a minimum 4 x 4 inch square surface area or 4 ½ inches in diameter if round.
Protective covers or troughs may be job-built, provided they are designed to Cal-
OSHA minimum standards, that the design of the cover or trough was prepared by
an Engineer currently registered in the State of California, and a copy of the
approved design is on file in the job records prior to their use.

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CHAPTER

5 Pile Foundations - General

Introduction
Pile foundations are used when the underlying soils are incapable of resisting the
loads from the structure. The piling is placed in the ground through poor quality
materials to bear on competent soils. The piles are either driven into the ground
or holes are drilled and filled with reinforced concrete. The piles transfer load by
bearing on competent material or through the friction between the soil and the pile
(skin friction).

Pile foundations can be categorized into two general types: displacement piles and
replacement piles. A displacement pile is a pile that is driven or vibrated into the
ground and displaces the surrounding soil during installation. Whereas a
replacement pile is a pile that is placed or constructed within a previously drilled
borehole and replaces the excavated soil. Displacement, or driven, piles are
discussed in Chapter 7 of this Manual while Chapter 6 discusses replacement, or
cast-in-place, piles.

Driven piles are braced, structural columns that are driven, pushed or otherwise
forced into soil. Two types of pile foundations were developed through the ages to
support structures on poor quality soil: piles and piers. Piles are more commonly
used and are essentially small diameter piers that work in groups. Pier
foundations are large in diameter and tend to work independently. They have
gained favor over the last several years as they behave very well seismically.
Piles/Piers can be classified as friction piles, end bearing piles, or a combination
of the two. They can also provide lateral stability in foundations. Friction piles
can transfer both tensile and compressive forces to the surrounding soil.

Specifications
The specifications for piling are contained in Section 49 of the Standard
Specifications. Project specific requirements and revisions to the Standard
Specifications are included in the contract special provisions. The project plans

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and Standard Plans are additional contract documents needed for pile work and
describe what piling goes where for each structure.

In general the contract plans describe the intended pile type, specified tip
elevation(s) and a minimum nominal resistance. The special provisions provide
requirements on how to perform the work. These documents also include specific
requirements for activities such as embankment pre-drilling, load testing and
other items specific to a project. For example, if difficult driving is anticipated,
the project engineer may provide the option of using either steel “H” piling or
precast concrete piles. When this option is written into the contract, other
conditional clauses are usually provided (no additional compensation for piling
driven below specified tip, etc.) and the contractor is allowed to choose the most
economical option. If specifications allowing options are not included in the
contract, then changes from one pile type to another cannot be made without a
contract change order and concurrence from the project engineer.

Details for the different classes of typical piles are found in the Standard Plans
while details for atypical or nonstandard piles are shown on the contract plans.
The Standard Plans also provide options and alternative details for the different
classes of piles. Note that different pile classes are not interchangeable. For
example, when Class 140 piles are specified, the contractor can select either of the
alternatives shown in the Standard Plans for Class 140 piles but cannot select an
option from a different class of piles such as Class 90 or 200. Occasionally, the
Project Engineer may decide to exclude some of the alternatives for a given class
of pile. In this situation, the excluded alternatives will be noted in the Special
provisions or project plans. (Note: The names of the different classes of Standard
Plan piles were revised in the 2006 version of the Standard Plans)

The Standard Specifications contain the general information for pile work. This
includes specifics for types of materials to be used, methods of construction,
measurement, payment, etc. It is important to remember that the special
provisions and the contract plans have precedence over the Standard Plans and
Standard Specifications. For this reason, it is imperative that all contract
documents be thoroughly reviewed well in advance of the work and
inconsistencies resolved prior to start of work.

Cast-in-Place Piles
The 2006 version of the Standard Specifications identifies four (4) different types
of cast-in-place piles. They are as follows:

• Steel shells driven permanently to the required nominal resistance and

penetration and filled with concrete.
• Steel casings installed permanently to the required penetration and filled
with concrete.

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• Drilled holes filled with concrete.

• Rock sockets filled with concrete.

The first two types involve the installation of a permanent steel casing or shell,
removal of the soil inside the casing and subsequently filling with reinforced
concrete. Steel shells add to structural capacity to the pile while casings assumed
to have no structural value and are only used to facilitate construction. The third
type is typically known as a Cast-in-Drilled-Hole (CIDH) Pile. The last type is
essentially a CIDH pile drilled in rock. Sometimes combinations of two or more
type of cast-in-place piles are used to construct a single pile. This can happen
when soft materials such as clays overlay rock formations.

Cast-In-Drilled-Hole (CIDH) piles are made of reinforced concrete that is cast

into holes drilled in the ground to a specified tip elevation. Diameters generally
range from 12 to 168 inches and lengths range from 10 feet to well over 200 feet.
They are satisfactory in suitable material and are generally more economical than
most other types of piling. They are especially advantageous where vibration from
a pile driving operations might damage adjacent structures such as pipelines,
buildings, etc. The geological ground formations into which the holes are drilled
must be capable of retaining their shape during drilling and concrete placement
operations and no ground water should be present.

If there are concerns about the presence of ground water, the slurry displacement
method specifications may need to be incorporated into the contract. CIDH piles
are discussed in more detail in Chapters 6 and 9 of this manual. Special
consideration piles such as those for changeable message signs (CMS) are
discussed in Chapter 13.

Driven Piles
Driven piles typically consist of three different types: (1) concrete, (2) steel, and
(3) timber. A general description of each type is given on the following page.
Driven piles are discussed in more detail in Chapter 7 of this manual.

TYPE OF DESCRIPTION
PILE
Driven Piles Driven concrete piles come in a variety of sizes, shapes and methods of
– Concrete construction. In cross section, they can be square, octagonal, round, solid or
hollow. These piles generally vary in sizes from 10 to 60 inches. They can be
either conventionally reinforced or prestressed (most common). They can also be
either precast (most common) or they can be cast in driven steel shells. The types
of steel shells vary from 10 to 120 inches in diameter for heavy walled pipe that
are driven directly with the hammer, to thin walled or step-taper pipes which are
driven with a mandrel. The steel shell may have a flat bottom or be pointed, and
may be step-tapered or a uniform section.

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Caltrans has standard details for splicing precast concrete piles but it is a
difficult, time consuming, expensive procedure. Hence, this almost precludes the
use of precast piles where excessively long piles are required to obtain necessary
bearing.

The unit cost to furnish concrete piles is usually lower than the steel equivalent.
But this cost is often offset by the requirement for a larger crane and hammer to
handle the heavier pile. This is particularly true when there are a small number of
piles to drive.
Driven Piles Steel piling includes “H” piles and pipe piles (empty or concrete filled). The pipe
– Steel section is a standard alternate for the Class 45 and 70 piling, but is seldom used.
Although steel piling is relatively expensive on a “per foot” furnish basis, it has a
number of advantages. The steel piles come in sizes varying from HP 8x36 to HP
14x117 rolled shapes or may consist of structural steel plates welded together.
They are available in high strength and corrosion-resistant steels. They can
penetrate to bedrock where other piles would be destroyed by driving. However,
even with “H” piles, care must be taken when long duration hard driving is
encountered as the pile tips can be damaged or the intended penetration path of
the pile can be drastically deflected. Using a reinforced point on the pile can
sometimes prevent this type of damage. Due to the light weight and relative ease
of splicing, they are useful where great depths of unstable material must be
penetrated before reaching the desired load carrying stratum and in locations
where reduced clearances require use of short sections. They are useful where
piles must be closely spaced to carry a heavy load because they displace a
minimal amount of material when driven.

Splice details are shown on the Standard Plans or project plans for contracts that
permit the use of steel piling. Pile welding work requires the submittal and
approval of a Welding Quality Control Plan. The requirements for the Welding
Quality Control Plan are addressed in the contract special provisions

Sometimes “H” piles must be driven below the specified tip elevation before
minimum bearing is attained. This can present an administrative problem (cost) if
the length driven below the specified tip elevation is significant. Steel lugs
welded to the piles are commonly used to solve this problem. This subject is
covered in detail in Bridge Construction Memo 130-5.0.
Driven Piles Untreated timber piles may be used for temporary construction, revetments,
– Wood fenders and similar work; and in permanent construction where the cutoff
elevation of the pile is below the permanent ground water table and where the
piles are not exposed to marine borers. They are also sometimes used for trestle
construction, although treated piles are preferred. Timber piles are difficult to
extend, hard to anchor into the footing to resist uplift, and subject to damage if
not driven carefully. Timber piles also have a maximum allowable bearing
capacity of 45 Tons, whereas most structure piles are designed for at least 70
Tons.

Alternative Piles
Currently there are several alternative piles that have been approved for use by the
Department. They are used on a site-specific basis. There are three (3) types of
Micro-piles (DBM, Malcolm and Nicholson). The Tubex Grout Injection Pile is
another alternative pile system. These systems have generalized drawings and

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have been successfully system tested by the Department. The GeoGrout

Foundation System has pile system load test results on file with the Department
but no generalized drawings. Refer to Chapter 13 and Appendix D for
information, drawings and schematics of the various alternative piles.

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CHAPTER

6 Cast-In-Place Piles

Description
Few terms are as self-descriptive as the one given the Cast-In-Drilled-Hole
(CIDH) pile. They are simply reinforced concrete piles cast in holes drilled to
predetermined elevations. Much experience has been gained with this pile type
because of their extensive use in the construction of bridge structures. While they
probably are the most economical of all commonly used piles, their use is
generally limited to certain ground conditions.

CIDH piling can be grouped in two categories: the first is CIDH piling without
inspection pipes (dry method), and the second is CIDH piles with inspection pipes
(wet method). This chapter is applicable for both the dry and wet method of
CIDH pile construction. Chapter 9 of this manual provides supplemental
information on the wet method of CIDH pile construction. Note that piling
dewatered with the help of a temporary casing requires inspection pipes even if
the piling is poured dry.

The ground formation in which the holes for CIDH piles are to be drilled must be
of such a nature that the drilled holes will retain their shape and will not cave in
when concrete is placed. Because of cave-in and concrete placement difficulties,
these piles are not recommended for use as battered piles. Other pile types should
be considered where groundwater is present, unless dewatering can be done with
a reasonable effort and unless concrete can be placed without a permanent casing.
If groundwater or caving conditions are present, the piles can be constructed by
the slurry displacement method if permitted in the contract specifications. The
slurry displacement method is described in detail in Chapter 9 of this manual.

A dry hole, by definition, typically contains no standing groundwater within the

drilled hole, although the material at the bottom of the drilled hole may be damp
or wet. However, the dry method of construction may still be used when a small
amount of groundwater is present in the drilled hole. Refer to Bridge
Construction Memo 130-7.0 for information on the specific definition of a “dry”
drilled hole.
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Specifications
The Standard Specifications describe four different types of cast-in-place pile.
The first type is the cast-in-drilled-hole pile, which is described further in this
chapter. The second type is the cast-in-driven-steel-shell pile. For this type of
pile, a steel shell is driven to a specified tip elevation and bearing value. The
ground material within the steel shell is then removed and the steel shell is filled
with reinforced or non-reinforced concrete. Refer to Chapter 7 of this Manual for
additional information on driven piles. The third type of pile is concrete cast
within a permanently installed steel casing. For this type of pile, a steel casing is
installed to a specified tip elevation using any approved means; the soil inside the
casing is removed by drilling and then filled with reinforced concrete. The fourth
type is a rock socket filled with concrete; which is similar to a cast-in-drilled-hole
pile, but placed in rock and usually below a permanently installed steel casing that
has had the rock removed and ultimately filled with reinforced concrete.

The Standard Specifications contain much of the information necessary to

administer the construction of CIDH piles. Section 49-4 contains information on
the construction methods. Section 52 contains information on pile bar
reinforcement. Section 90 contains information on the concrete mix design,
transportation of concrete, and curing of the concrete used for CIDH piles.

The special provisions contain job-specific requirements and revised

specifications. Because the CIDH pile specifications are continually updated and
ground conditions vary from project to project, it is very important that the
Engineer carefully review the special provisions and any revised specifications
noted should be discussed with the Contractor.

Drilling Equipment
The drilling auger is the most commonly used drilling tool for drilling holes for
CIDH piles. Augers may be used in granular and cohesive materials.

There are two basic varieties of augers—the standard short section (Figure 6-1)
and continuous flight. Both have flights of varying diameter and pitch.
Continuous flight augers have flight lengths that are longer than the hole to be
drilled. They are generally lead-mounted. The power unit is located at the top of
the auger and it travels down the leads with the auger as the hole is drilled.
Drilling is performed in one continuous operation. As the auger moves down the
hole, the drilling action of the flights forces the drill cuttings up and out of the
hole. Hence, much material has to be shoveled away from around the drilled
hole. Continuous flight augers are most commonly used for short piles, such as

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those used to support soundwalls or standard retaining walls, or for predrilling

driven piles. They may also be used where overhead clearance is not a problem.

FIGURE 6-1 FIGURE 6-2 FIGURE 6-3

Auger – short Auger - single flight Auger – double
section flight

Short flight augers are powered by “Kelly Bar” units fixed to the drill rig. The
lengths of these augers generally vary between 5 and 8 feet. The auger is attached
to the end of the Kelly Bar and, as drilling progresses; the auger (and material
carried on the flights) must be removed frequently. After the auger is removed
from the drilled hole, the material is “spun” off the flights onto a spoil pile and the
operation is repeated. Short flight augers are generally used for smaller diameter
piles (less than 48” in diameter), although they have been successfully used for
larger diameter piles.

There are a variety of different auger shapes/styles that may be used in different
situations. Augers may be single flight (Figure 6-2) or double flight (Figure 6-3).
Double flight augers are better balanced than single flight augers and are more
useful when alignment and location of the drilled hole are important due to
clearance or right-of-way problems. Soil augers are equipped with a cutting edge
that cuts into the soil during rotation. The drill cuttings are carried on the flights
as the auger is removed from the drilled hole and are then “spun” off. The pitch
of the flights can vary and should be chosen for the type of material encountered.
Soil augers may not work well in cohesionless materials, as the soil may not stay
on the flights during auger extraction. They may also have issues in highly
cohesive materials where the auger may become clogged.

Rock augers differ from soil augers in that they are equipped with high-strength
steel cutting teeth that can cut through soft rock. These augers typically have
flights with a very shallow pitch so that rock pieces, cobbles and boulders can be

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extracted. For this reason, rock augers are generally the preferred tool for drilling
in materials that have a high concentration of cobbles or boulders.

FIGURE 6-5
Drilling bucket/cleanout bucket comparison
FIGURE 6-4
Drilling bucket

Drilling buckets (Figure 6-4) are drilling tools used when augers are not able to
extract material from a drilled hole. This can happen when wet materials or
cohesionless materials are encountered. Drilling buckets may also be appropriate
when heavy gravel or cobbles are encountered. Drilling buckets have a cutting
edge that forces material into the bucket during rotation. When the drilling bucket
is full, the bucket is spun in the direction opposite of drilling, which closes the
built-in flaps. This prevents the cuttings from falling out of the bucket. The
bucket is then extracted from the drilled hole and emptied.

Cleanout buckets are specialized drilling buckets that are used to clean loose
materials from the bottom of a drilled hole and to flatten the bottom. This ensures
that the tip of the pile is founded on a firm flat surface. These buckets have no
cutting teeth but are similar to drilling buckets in other aspects. Figure 6-5 shows
the difference between the cleanout bucket and the drilling bucket. Specialized
cleanout buckets can be used to extract loose materials when groundwater or
drilling slurry is present. These buckets, referred to as “muckout” buckets, allow
fluid to pass through them while retaining the loose materials from the bottom of
the drilled hole.

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FIGURE 6-6 Core barrel

Core barrels (Figure 6-6) are used to drill through hard rock formations, very
large boulders or concrete. This type of drilling tool consists of a steel cylinder
with hard metal cutting teeth on the bottom. Rock cores are broken off and
extracted from the drilled hole as a single unit, or may be broken up with a rock
breaker and then extracted with a drilling bucket or clamshell.

Down-hole hammers (Figure 6-7) are also used to drill through hard rock
formations. This type of drilling tool uses compressed air or hydraulic-powered
percussion drilling heads to pulverize the formation and blow the resulting debris
from the drilled hole.

FIGURE 6-7 Down-hole hammer

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Rotators (Figure 6-8) and oscillators (Figure 6-9) are specialized drilling
equipment used to advance a drilled hole through difficult ground formations.
Each machine uses a hydraulic-powered apparatus to simultaneously rotate and
push down on a drilling casing. Drilling casings are sections of steel pipe, usually
20 feet in length, designed specifically for the rotator or oscillator model, with
attachments for cutting teeth or splicing of additional sections. Additional
sections of drilling casing are attached as the drilled hole is advanced to tip. As
the drilled hole is advanced, the materials within the drilling casing are extracted
using a clamshell or drilling bucket. The major difference between a rotator and
an oscillator is that the rotator rotates the drilling casing in one direction, while
the oscillator rotates the drilling casing in two directions, never making a
complete rotation in either direction. The advantage provided by the rotator and
oscillator is the drilling casing provides a temporary casing that preserves the
integrity of the drilled hole, even in unstable or wet ground formations. The
drilling casing remains in the drilled hole until pile concrete is placed, at which
time the drilling casing is extracted from the drilled hole in a similar manner as
any other temporary steel casing as described below.

FIGURE 6-8 Rotator

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FIGURE 6-9 Oscillator

Reverse circulation drilling equipment (Figure 6-10) is used to advance a drilled

hole through difficult wet ground formations. The drilled hole must be full of
water or other drilling fluids. The drilling head is self-contained and is driven
hydraulically or by compressed air. As the hole is advanced, the drill cuttings are
suspended in the water or drilling fluid. The water or drilling fluid is
continuously circulated out of the drilled hole, where the drill cuttings are
removed and disposed, and then recirculated back into the drilled hole to repeat
the process.

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FIGURE 6-10 Reverse circulation drilling equipment

Temporary steel casings (Figure 6-11) are used to support drilled holes when
unstable conditions are encountered. Various methods are used to advance steel
casings into the hole. Among them, spinning the casing with the Kelly Bar while
applying some vertical force, driving the casing with whatever means are
available as the hole is drilled, or using a vibratory hammer. Steel casings are
generally extracted from the hole in the manner specified in the contract
specifications as concrete is placed.

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FIGURE 6-11 Steel casing

Drilling is performed almost exclusively with portable drilling rigs. These units
can be self-propelled (Figure 6-12), truck-mounted (Figure 6-13), or crane-
mounted (Figure 6-14).

FIGURE 6-12 Drill rig – crawler mounted

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FIGURE 6-14
Drill rig – crane mounted
FIGURE 6-13
Drill rig – truck mounted
Drilling Methods
Various other materials are used to supplement the drilling work. Water or other
drilling fluid is sometimes added to certain ground formations to assist drilling
and lifting materials from the hole. Soil may be placed back into the hole to dry
out supersaturated materials. The drilling tool is used to agitate the materials so
they can be extracted from the hole. This is known as “processing” the hole.

Drilling Problems
The difficulties encountered in drilling can include cave-ins, groundwater, and
utilities. The following briefly describes some actions that can be taken in these
situations.

In the case of cave-ins, the following action or combination thereof may be

required:

ITEM ACTION
1 Placement of a low cement/sand mix and redrilling the area of the
cave-in.
2 If permitted by the contract special provisions, use a drilling slurry
(refer to Chapter 9 of this manual).
3 Use of a casing, which is pulled when placing concrete.

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In the case of groundwater, the following action or combination thereof may be

required:

ITEM ACTION
1 Placement of a low cement/sand mix and redrilling the hole.
2 Drilling to tip elevation, using a pump to remove the water and
cleaning out the bottom of the pile. (See BCM 130-7.0 for
information on the specific definition of a "dry" drilled hole)
3 If permitted by the contract special provisions, use drilling slurry
(refer to Chapter 9 of this manual).
4 Placement of a casing, again using a pump to remove the water, and
pulling casing during concrete placement (keeping bottom of casing
below the concrete surface). See BCM 130-7.0 for information on
the specific definition of a "dry" drilled hole
5 Dewatering the entire area using well points, deep wells, etc. This
should be thoroughly discussed with the Bridge Construction
Engineer and the project geoprofessional.
6 By contract change order, substitute an alternative type of piling.
Again, this should be discussed with the project designer, the project
geoprofessional, and the Bridge Construction Engineer.

Construction operations should proceed with caution when drilling near utilities
known or thought to be in close proximity. The Contractor should contact the
area Underground Service Alert (USA) or the utility company and have the utility
located. The Contractor should also pothole and physically locate the utility prior
to drilling. Relocation of the utility may be required. Minor adjustments in pile
location might be feasible in order to avoid conflict. Any proposed revisions to
the pile layout should be discussed with the Project engineer, Geoprofessional,
Resident Engineer and the Bridge Construction Engineer.

Under certain conditions, the Standard Specifications allow the Contractor to

propose increasing the pile diameter in order to raise the pile tip. This can be
used to address problems with groundwater, cave-ins or obstructions in the lower
portion of the hole. Before allowing this, the Engineer should consult with the
project designer and project geoprofessional to see if this is feasible, and if so, to
obtain the revised tip elevation. Appropriate pay provisions are also included in
the contract specifications and a change order is not required.

Ordinarily, the above drilling problems would stimulate the Contractor’s action
and a change would be proposed to the Engineer. Sometimes the drilling problem
is the result of unanticipated ground conditions or unanticipated utility conflicts.
In such cases, a differing site condition or a buried manmade object may exist,
and it will be the Engineer’s responsibility to resolve the problem.

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Inspection and Contract Administration

Before drilling begins, the Engineer should have a pre-construction meeting with
the Contractor and any subcontractors that will be involved in the work. Items to
be discussed should include any recently revised contract specifications, the
contract pay limits, the Contractor’s planned method of operation and schedule,
the equipment to be used, the plan for avoiding existing utilities (if any), and
safety precautions to be taken during the work.

The Engineer should review the contract plans, the Foundation Report and the
Log of Test Borings thoroughly. If there are any discrepancies noted between the
pile type shown on the plans, the pile type called for in the Foundation Report,
and/or the soil materials/profile and groundwater level shown on the Log of Test
Borings, the project engineer should be contacted for clarification.

CIDH piles are designed to resist compressive loads, tensile loads, and lateral
loads. Most CIDH piles are designed to resist these loads using skin friction, with
minimal or no contribution from end bearing. The project engineer should be
contacted to determine the manner in which the pile was designed to transfer load.

The specifications require the Contractor to submit a Pile Placement Plan to the
Engineer for review and approval. The Pile Placement Plan should provide
sufficient detail for the Engineer to grasp the means, methods and materials that
the Contractor plans to use to successfully complete CIDH pile placement.
Typical requirements for all CIDH piling include the following:

ITEM PILE PLACEMENT PLAN REQUIREMENT & REASONING

1 Concrete mix design, certified test data, and trial batch reports.
Reasoning: CIDH pile concrete is designated by compressive
strength.
2 Drilling or coring methods and equipment.
Reasoning: This gives the Engineer advance knowledge of
what equipment the Contractor proposes to use to drill the
CIDH pile and whether the proposed equipment is
appropriate.
3 Proposed methods for casing installation and removal when
necessary.
Reasoning: This gives the Engineer advance knowledge of
whether the Contractor plans to use casing and if so, how it
will be installed and removed and whether the proposed
installation and removal methods are appropriate.
4 Plan view drawings of pile showing reinforcement and inspection
pipes, if required.
Reasoning: This gives the Engineer advance knowledge of
how the Contractor plans to install the inspection pipes within

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ITEM PILE PLACEMENT PLAN REQUIREMENT & REASONING

the pile bar reinforcement cage and whether the proposed
method of installation is appropriate. Inspection pipes are
required when the Contractor proposes to use casing
primarily to control ground water.
5 Methods for placing, positioning, and supporting bar reinforcement.
Reasoning: This gives the Engineer advance knowledge of
how the Contractor plans to assemble and install the pile bar
reinforcement cage and whether the proposed method of
installation is appropriate.
6 Methods and equipment for accurately determining the depth of
concrete and actual and theoretical volume placed, including effects
on volume of concrete when any casings are withdrawn.
Reasoning: This is necessary so the Engineer and Contractor
can determine whether an unplanned event, such as a cave-in,
has occurred during concrete placement. If such an event
happens, the actual volume of concrete placed will be
substantially different from the theoretical volume at the
location of the event and the Engineer and Contractor will be
able to pinpoint the location of the event for mitigation if
necessary.
7 Methods and equipment for verifying that the bottom of the drilled
hole is clean prior to placing concrete.
Reasoning: Over 50% of all pile defects occur at the bottom
of the drilled hole due to the presence of loose soil cuttings
that were not removed prior to concrete placement. This
gives the Engineer advance knowledge of how the Contractor
plans to remove these loose materials, verify that they were
removed, and whether the proposed methods of removal and
verification are appropriate.
8 Methods and equipment for preventing upward movement of
reinforcement, including the Contractor’s means of detecting and
measuring upward movement during concrete placement operations.
Reasoning: Pile bar reinforcement cages have been known to
shift laterally or upward during concrete placement. This
gives the Engineer advance knowledge of how the Contractor
plans to prevent movement of the pile bar reinforcement cage
and whether the proposed methods are appropriate.

The Contractor is required to layout the pile locations at the site prior to drilling.
The Engineer should verify the layout is correct prior to drilling and set reference
elevations in the area so pile lengths and pile cutoff can be ascertained.

During the drilling operation, the Engineer should verify that the piles are in the
correct location and drilled plumb. Usually, the Contractor will check the Kelly

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bar with a carpenter’s level during the drilling operation. The Engineer should
also evaluate the material encountered and compare it to the Log of Test Borings.
If the material at the specified tip elevation differs from that anticipated, the
project engineer should be consulted, as a change in pile length might be needed.
A written record of the drilling progress should be kept in the project daily report
and the record utilized to investigate any differing site condition claims submitted
by the Contractor.

When the hole has been drilled to the specified tip elevation, the Contractor
should use a cleanout bucket or other means as described in the Pile Placement
Plan to remove any loose materials and to produce a firm flat surface at the
bottom of the drilled hole.

The depth, diameter and plumbness/straightness of the drilled hole must be

checked and verified after drilling is completed. The drilled hole should be
checked using a suitable light, furnished by the Contractor, or a mirror. At this
time, the Engineer should measure and record the length of each pile. Unless the
Engineer orders the Contractor, in writing, to change the specified tip elevation,
no payment will be made for any additional depth of pile below the specified tip
elevation.

For large diameter piles, it may be necessary for the Engineer or the project
geoprofessional to inspect the bearing surface at the bottom of the drilled hole.
All pertinent requirements of the Construction Safety Orders and Mining and
Tunneling Safety Orders shall be met before anyone enters a drilled hole. Note
that CIDH piles over 20 feet in depth and 30 inches in diameter, Cal-OSHA
Mining and Tunneling Safety Orders apply. Construction Procedure Directive
CPD 04-6 addresses this and is included in Appendix B.

Pile bar reinforcement cage clearances and blocking should be checked

immediately after the cage is placed and secured in the drilled hole. In addition,
the reinforcing cage must be adequately supported as described in the Pile
Placement Plan and some means must be devised to ensure concrete placement to
the proper pile cutoff elevation.

Immediately before placing concrete, the bottom of the drilled hole should be
checked for loose materials or water. Loose materials and small amounts of water
can be removed with a cleanout bucket before placing the pile bar reinforcement
cage. Large amounts of water may need to be pumped out. Its important to note
that it may be necessary to remove the pile bar reinforcement cage to accomplish
this. Failure to do so could affect the quality of the pile. Refer to BCM 130-7.0
for information on the specific definition of a "dry" drilled hole.

Concrete placement warrants continuous inspection. Those involved in the work

should thoroughly review Standard Specifications Sections 49-4 and the contract

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special provisions. Applicable portions of Section 90 should also be reviewed

with respect to concrete mix design, consistency of the concrete mix, and concrete
curing requirements.

Pile Defects
The drilling problems mentioned previously, if not corrected, can cause CIDH
piles to be defective. There are also problems that can occur during concrete
placement or casing removal that can cause defective CIDH piles.

The following drilling problems can cause pile defects:

ITEM DRILLING PROBLEM/RESULTING PILE DEFECT

1 A cleanout bucket is not used to clean up the bottom of the drilled
hole
Result: This can result in the pile bearing on soft material.
For CIDH piles designed for end bearing, this flaw can
seriously compromise the value of the pile. This defect is
shown in Figure 6-15.
2 A tapered auger is used to advance the drilled hole to the specified tip
elevation but a cleanout bucket is not used to flatten the bottom of the
hole.
Result: Concrete may crush at the tip of the pile, which would
reduce its capacity and possibly cause differential settlement.
There may also be soft material at the tip of the drilled hole,
which would cause the problems mentioned previously. This
defect is also shown in Figure 6-15.
3 The drilling operation smears drill cuttings on the sides of the drilled
hole.
Result: This can result in the degradation of the pile’s capacity
to transfer loads through skin friction. This may be critical if
the pile is designed as a tension pile. This condition is most
likely to occur in ground formations containing cohesive
materials. This defect is shown in Figure 6-16.

These problems are preventable. Adherence to the contract specifications and

timely inspection will ensure the best quality pile and mitigate most of these
problems.

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FIGURE 6-15 FIGURE 6-16

Pile defects - no cleanout, tapered bottom of Pile defects - smeared drill cuttings
hole

The following concrete placement problems can cause pile defects:

ITEM PLACEMENT PROBLEM/RESULTINGPILE DEFECT

1 A cave-in at a location above the top of concrete or sloughing
material from the top of the drilled hole occurs during concrete
placement.
Result: Degraded concrete at the location, thus reducing the
capacity of the pile. This defect is shown in Figure 6-17.
2 The Contractor tailgates concrete into the drilled hole without the use
of a hopper or “elephant trunk” to guide it. The concrete falls on the
pile bar reinforcement cage or supporting bracing and segregates.
Result: Defective concrete, thus reducing the capacity of the

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ITEM PLACEMENT PROBLEM/RESULTINGPILE DEFECT

pile. This defect is shown in Figure 6-18.
3 A new hole is drilled adjacent to a freshly poured pile or concrete is
placed in a drilled hole that is too close to an adjacent open drilled
hole.
Result: This can result in the sidewall blowout of a freshly
poured pile into the adjacent drilled hole. This would probably
cause the pile bar reinforcement cage to buckle. This defect is
shown in Figure 6-19.
4 The Contractor does not remove groundwater from the drilled hole.
Result: Groundwater mingles with the concrete leading to
defective concrete at the bottom of the pile. If the pile were
designed for end bearing, the capacity would be reduced. This
defect is shown in Figure 6-20.

As with the drilling problems, most of these placement problems are preventable.
Adherence to the contract specifications and timely inspection will prevent most
of these problems. However, if a cave-in occurs during concrete placement, the
Contractor may need to remove the pile bar reinforcement cage and concrete, and
then start over.

FIGURE 6-17 FIGURE 6-18

Pile defects - cave in Pile defects - concrete segregation

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The following casing removal problems can cause pile defects:

ITEM CASING REMOVAL PROBLEM/PILE DEFECT

1 The Contractor waits too long to pull the casing during concrete
placement. This may result in three problems: (1) the concrete sets
up and comes up with the casing as shown in Figure 6-21(a), (2) the
concrete sets and the casing cannot be removed as shown in Figure 6-
21(b), and (3) the concrete sets up enough so that it cannot fill the
voids left by the casing as it is removed, as shown in Figure 6-21(c).
The first problem may result in a void being formed in the pile at the
bottom of the casing. It is possible that the suction created may cause
a cave-in at this location. The second and third problems result in the
loss of the pile’s capacity to transfer skin friction to the ground.

FIGURE 6-19 FIGURE 6-20

Pile defects - adjacent hole blowout Pile defects - water in the hole

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Historically, problems with casings have produced the worst type of CIDH pile
defects. Again, these problems are preventable. Adherence to the contract
specifications and timely inspection will prevent most of these problems. It is
recommended the penetration value of the concrete placed in the pile to be at the
high end of the allowable range. Research has shown that concrete with higher
fluidity will consolidate and fill in the voids better than concrete with lower
fluidity. As there is an increased risk in pouring piles with temporary casings,
under certain circumstances, piles poured with this method need to undergo non-
destructive testing prior to acceptance. The CIDH pile contract specifications
require that all CIDH piles constructed with the use of temporary casings to
control groundwater undergo acceptance testing prior to acceptance. The pile
testing methods used to test piles constructed by the slurry displacement method
(as described in Chapter 9 of this manual) would be used in this circumstance.

(a) (b) (c)

FIGURE 6-21 Pile defects casing problems

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Safety
As with all construction activities, the Engineer should be aware of safety
considerations associated with the operation. As a minimum, the Engineer shall
review the Construction Safety Orders that pertain to this work. A tailgate safety
meeting should be held to discuss the inherent dangers of performing this work
before the work begins.

The primary and obvious hazard encountered with CIDH pile construction is the
open drilled hole. Common practice is to keep the drilled hole covered with
plywood, especially if the drilled hole is left open overnight. This provides
protection not only for the construction crew working in the area, but also the
public. In urban areas, more stringent measures may be required to secure the
site.

As with any other type of operation, common sense safety practices should be
used when working around this equipment. If you do not need to be there, stay
away from the equipment. If a crane-mounted drilling rig is used, the crane
certificate should be checked.

In addition, footing excavations should be properly sloped or shored as discussed

in Chapter 4 of this Manual. Imposed loads, such as those from cranes and transit
mix concrete trucks, must be kept a sufficient distance from the edge of the
excavation. If the Contractor intends to place equipment of this type adjacent to
the excavation, the load must be considered in the shoring design and/or in
determining the safe slope for unshored excavations. Additional information on
excavations can be found in the Trenching and Shoring Manual

Worker and public safety must be enforced during drilling and excavating
operations. A full body harness should be used when working near open holes.
Personnel not directly involved in the construction operation should not stand
next to an open hole to avoid falling in or if the edge collapses.

For CIDH piles over 20 feet in depth and 30 inches in diameter, Cal-OSHA
Mining and Tunneling Safety Orders apply. Construction Procedure Directive
CPD 04-6 addresses this and is included in Appendix B.

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CHAPTER

7 Driven Piles

Introduction
Driving piles for structure foundations has occurred for centuries. Originally,
timber was used for piles. In 1897, the first concrete piles were introduced in
Europe, and the Raymond Pile Company drove the first concrete piles in America
in 1904. These new concrete piles were designed for 30 Tons and over. Steel H-
Piles and pipe piles are also used. These piles are expensive but their ability to
transfer greater loads has made them economical, particularly in large structures.

Pile driving is the operation of forcing a pile into the ground thereby displacing
the soil mass across the whole cross section of the pile. Historically, the oldest
method of driving a pile, and the method most often used today, is by use of a
hammer.

FIGURE 7-1 Early pile hammer

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The first hammers were drop hammers and they were used exclusively until the
invention of the steam engine, which eventually resulted in steam hammers.
Subsequent technological advances have lead to the development of air, diesel
and hydraulic powered impact hammers plus vibratory and sonic hammers.
Modern day requirements for construction have also resulted in various
adaptations of the aforementioned pile driving techniques.

The remainder of this chapter is intended to outline specifications, equipment,

techniques and safety items that a bridge engineer can expect to encounter during
typical pile driving operations.

General Specifications
The following is a partial list of some of the more important pile driving
specifications. Before starting a project, the Engineer should thoroughly review
the Standard Specifications for general requirements and the special provisions
for information tailored to the needs of the specific project.

Typical sections of the Standard Specifications to be reviewed are as follows:

• Section 19: Earthwork

• Section 49: Piling

• Section 58: Preservative Treatment of Lumber, Timber and Piling

The following are taken from the May 2006 Standard Specifications and should
be reviewed as applicable:

Section 19-6.01:

• Rocks, broken concrete or other solid materials larger than 0.33 foot
are not allowed in fill where piles are to be driven.

• When bridge footings are to be constructed in embankment, the

embankment shall be constructed to the elevations of the grading plane
and the finished slope extended to the grading plane before driving
piles or excavating for the footing.

Section 19-6.025:

• Where an embankment settlement period is provided for in the special

provisions, the embankment shall remain in place for the required

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settlement period before excavating for the abutment, wingwall, or

retaining wall footings or driving foundation piles at each location.

Section 49-1.03:

• Foundation piles of any material shall be of such length as is required

to obtain the specified penetration, and to extend into the cap or
footing block as shown on the plans or specified in the special
provisions.

• For driven piling, the Contractor shall furnish piling of sufficient

length to obtain the specified tip elevation shown on the plans or
specified in the special provisions.

Section 49-1.05:

• Driven piles shall be installed with impact hammers that are approved
in writing by the Engineer. Impact hammers shall be steam, hydraulic,
air or diesel hammers. Impact hammers shall develop sufficient
energy to drive the piles at a penetration rate of not less than 1/8 inch
per blow at the specified nominal resistance.

• Steam or air hammers shall be furnished with a boiler or air capacity

that is at least equal to that specified by the manufacturer of the
hammer to be used. The boiler or compressor shall be equipped with
an accurate pressure gauge at all times. The valve mechanism and
other parts of steam, air, or diesel hammers shall be maintained in first
class condition so that the length of stroke and number of blows per
minute for which the hammer is designed will be obtained. Inefficient
steam, air, or diesel hammers shall not be used.

Section 49-1.06:

• Piles, to be driven through embankments constructed by the

Contractor, shall be driven in holes drilled or spudded through the
embankment when the depth of new embankment is in excess of 5
feet. The hole shall have a diameter of not less than the greatest
dimension of the pile cross-section plus 6 inches. After driving the
pile, the space around the pile shall be filled to ground surface with dry
sand or pea gravel. (This is to prevent frictional down drag on the
piles due to differential settlement between the new embankment and
original ground and to ensure that the pile path is free from large
diameter embankment material obstructions).

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Section 49-1.08

• Except for piles to be load tested, driven piles shall be driven a value
of not less than the nominal resistance shown on the plans unless
otherwise specified in the special provisions or otherwise permitted in
writing by the Engineer. In addition, when a pile tip elevation is
specified, driven piles shall penetrate at least to the specified tip
elevation unless otherwise permitted in writing by the Engineer.

The preceding specifications indicate that there are two different pile driving
acceptance criteria: (1) A specific pile tip penetration, and (2) a prescribed
bearing value. In all but a few cases both of these criteria must be met in order to
accept the pile.

Pile Driving Definitions

The following is a partial list of some of the definitions unique to the pile driving
trade. These are the most common terms used and should be of benefit to those
new to pile driving work. Refer to Figures 7-2 through 7-8 for the location of the
defined terms.

TERM DEFINITION
Anvil The bottom part of a hammer that receives the impact of the ram and transmits
the energy to the pile.
Butt of Pile The term commonly used in conjunction with the timber piles—the upper or
larger end of the pile, the end closest to the hammer.
Cushion Usually plywood pads placed on top of precast concrete piles to eliminate
Blocks spalling.
Cushion Pad A pad of resilient material or hardwood placed between the drive cap insert, or
helmet, and drive cap adapter.
Drive Cap A steel unit designed to connect specific type of pile to a specific hammer. It is
Adapter usually connected to the hammer by steel cables.
Drive Cap The unit that fits over the top of pile, holding it in line and connecting it to the
Insert adapter.
Drive Cap The assembled components used to connect and transfer the energy from the
System hammer to the pile.
Follower An extension used between the pile and the hammer that transmits blows to the
pile when the pile head is either below the reach of the hammer (below the
guides/leads) or under water. A follower is usually a section of pipe or “H”
pile with connections that match both the pile hammer and the pile. Since the
follower may absorb a percentage of the energy of the hammer, the Standard
Specifications (Section 49.1.05) require the first pile in any location be driven
without the use of a follower so as to be able to make comparisons with
operations utilizing a follower. In water, the first pile to be driven should be
one sufficiently long to negate the need for the follower. The information from
the first pile can be used as base information when using the follower on the
rest of the piling. Beware of soil strata that may change throughout the length
of a footing. Underwater hammers and extensions to the leads can be used as
alternatives to driving with a follower

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TERM DEFINITION
Hammer The amount of energy available to be transmitted from the hammer to the pile.
Energy Usually measured in foot-pounds.
Leads A wooden or steel frame with one or two parallel members for guiding the
hammer and piles in the correct alignment. There are three basic types of
leads:
• Fixed, which are fixed to the pile rig at the top and bottom. Refer to
Figure 7-4.
• Swinging, which are supported at the top by a cable attached to the crane.
Refer to Figure 7-5.
• Semi-Fixed or Telescopic, which are allowed to translate vertically with
relation to the boom tip. Refer to Figure 7-6.
Mandrel A full-length steel core set inside a thin-shell casing. It increases the capacity
of the casing so that it can be driven. It helps maintain pile alignment and
prevents the casing from collapsing. It is removed after driving is completed
and prior to placing reinforced concrete.
Moonbeam A device attached to the end of a lead brace that allows a pile to be driven with
a side batter.
Penetration The downward movement of the pile per blow.
Pile Butt A member of the pile crew other than the operator and oiler.
Pile Gate A hinged section attached to the pile leads, at the lower end, which acts to keep
the pile within the framework of the pile leads.
Pile Hammer The unit that develops the energy used to drive piles, the two main parts of
which are the ram and the anvil.
Pile Rig The crane used to support the leads and pile driving assembly during the
driving operation.
Ram The moving parts of the pile hammer, consisting of a piston and a driving head,
or driving head only.
Rated Speed The number of blows per minute of the hammer when operating at a particular
maximum efficiency.
Spudding Spudding is the driving of a short and stout section of pile-like material into the
ground to punch through or break up hard ground strata to permit pile driving.
Used extensively in the driving of timber piles.
Striker Plate A steel plate placed immediately below the anvil. Also known as an anvil.
Stroke The length of fall of the ram.
Tip of Pile The first part of the pile to enter the ground.

FIGURE 7-2 Drive cap system

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FIGURE 7-3 Typical pile rig configuration

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FIGURE 7-4 Fixed lead system

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FIGURE 7-5 Swinging lead system

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FIGURE 7-6 Semi-fixed lead system

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FIGURE 7-7 Lead configurations for battered piles

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FIGURE 7-8 Lead types

Hammer Types
Many different types of pile driving hammers are used in the pile industry today.
In past, single acting diesel hammers were used on most projects. With the onset
of retrofit work and new construction in areas with low overhead clearances, the
use of double/differential acting hammers and hammers that require only a limited
overhead clearance are finding their way to the job site. Site specific construction
challenges, be it limited space, noise levels, or unusual tip or bearing
requirements will tend to dictate the type of hammer used.

The pile hammer is not only the production tool for the Contractor; it is also a
measuring device for the Engineer. The energy transmitted to the pile advances it
toward the specified tip elevation. The amount of energy and the penetration per

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blow can be used to determine the bearing capacity of the pile. A working
knowledge of pile hammers, their individual parts and accessories, and their basis
for operation and the associated terminology is essential for the Engineer.

Following is a partial list of different types of hammers available today with a

brief description of their limiting characteristics.

The Drop Hammer

Invented centuries ago, the drop hammer is still in use today. Although
modernized somewhat, the basic principle of operation remains the same. A
weight is lifted a measured distance by means of a rope or cable and allowed to,
freefall, or drop, and strike a pile cap block. The available potential energy is
calculated by multiplying the weight and the distance of the fall.

One variation of the drop hammer currently finding its way to the job site is one
that requires only a minimal amount of headroom. The idea utilizes a closed-
ended pipe pile with a large enough diameter to allow the drop hammer run inside
the pipe’s walls. The hammer impacts onto a “stop” built into the bottom, inside
of the pipe pile. As the pile is driven, the impact occurs near the tip of the pile.
In fact the pile is actually pulled down into position in lieu of being pushed. This
configuration minimizes the need for the additional overhead clearance (leads,
crane, etc.).

Drop hammers are not typically used and are permitted only when specifically
allowed by the special provisions. Hammer weight and stroke restrictions will be
found in Section 49-1.05 of the Standard Specifications.

When using a drop hammer the Engineer should:

NO. ITEM DESCRIPTION

1 Ensure that you have the correct weight for the hammer being used. If in doubt, have
it weighed.
2 Ensure the drop hammer lead sections are properly aligned and that all lead
connections are properly tightened.
3 Ensure, while in use, that the hoist line is paying out freely.

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FIGURE 7-9 Drop hammer

Single Acting Steam/Air Hammer

The single acting steam/air hammer is the simplest powered hammer. Invented in
England by James Nasmyth in 1845, it has been used in this country since 1875.

As shown in Figure 7-10, the hammer consists of a heavy ram connected to a

piston enclosed in a chamber. Steam or air is supplied to lift the ram to a certain
height. The lifting medium is then exhausted and the ram falls by its own weight.
The rated energy of the single acting steam/air hammer is calculated by
multiplying the ram weight (total weight of all moving parts: ram, piston rod,
keys, slide bar, etc.) times the length of fall (stroke).

These hammers have a stroke of 30 to 40 inches and operate at 60 to 70 strokes

per minute. They are rugged and deliver a relatively low velocity heavy blow.
The only necessary changes in operation from steam to air are a change in the
general lubrication and the hose line specification.

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When using a single acting steam/ air hammer the Engineer should:

NO. ITEM DESCRIPTION

1 Have the manufacturer’s current specifications for the type and model of hammer
being used.
2 Ensure all required parts of the hammer are intact and in good operating condition.

FIGURE 7-10 Single acting steam/air hammer

Double Acting Steam/Air Hammers

The double acting steam/air hammer employs steam or air, not only to lift the
piston to the top of its stroke, but also to accelerate the piston downward faster
than by gravity alone. The additional energy put into the downward stroke by the
compressed air/steam increases the effectiveness of the hammer. The advantage
of the double-acting hammer is that stroke lengths can be reduced making them
ideal in low overhead clearance situations. The stroke typically ranges from 10 to
20 inches, or about half that of a single-acting hammer. The blow rate is more

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rapid than the single acting hammer, somewhere between 120 and 240 blows per
minute. Refer to Figure 7-11.The rated available energy of the double acting
steam/air hammer is calculated by multiplying the ram weight times the length of
stroke and adding the effective pressure acting on the piston head during the down
stroke.

In addition to being an ideal hammer in low overhead situations, this type of

hammer does not use a cushion block between the ram and the anvil block.
Another advantage is that some of these hammers are entirely enclosed and can be
operated submerged in water. With this type hammer, it is essential that the
hammer is operating within the manufacturer’s specifications. Since pressure is
used to drive the hammer, it’s imperative that operating pressures are known. The
pressures recorded will correlate to an impact energy found on a chart/table
provided with the hammer.

When using a double acting steam hammer the Engineer should:

NO. ITEM DESCRIPTION

1 Have the manufacturer’s current specifications for the type and model of hammer
being used.
2 Ensure all required parts of the hammer are intact and in good operating condition.
3 Have chart available declaring rated energy vs. operating speed of hammer.

FIGURE 7-11 Double acting steam/air hammer

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Differential Acting Steam/Air Hammer (External Combustion Hammer)

The differential acting steam/air hammer is similar to a double acting hammer.

Compressed air/steam is introduced between large and small piston heads to lift
the ram to the top of its stroke. The valves are then switched so that the medium
(motive fluid) used to lift the ram accelerates it in its down stroke. Refer to
Figure 7-12. When hydraulic fluid is used as a motive fluid it is called a
double/differential acting hydraulic hammer.

The rated striking energy delivered per blow by a differential acting steam/air
hammer is calculated by adding the differential force due to the motive fluid
pressure acting over the large piston head to the weight of the striking parts and
multiplying this sum by the length of the piston stroke in feet. The differential
force results from the fluid pressure acting on the top piston head surface minus
the same pressure in the annulus acting on the bottom surface and is equal to the
area of the small piston head times the fluid pressure. This type of hammer uses a
cushion block between the ram and the helmet.

FIGURE 7-12 Differential acting steam/air hammer

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When using a differential acting steam/air hammer the Engineer should:

NO. ITEM DESCRIPTION

1 Have the manufacturer’s current specifications for the type and model of hammer
being used.
2 Ensure all required parts of the hammer are intact and in good operating condition.
3 Have chart available declaring rated energy vs. operating speed of hammer.

Diesel Pile Hammers

In the early 1950’s a new type of pile driving hammer was introduced - the Diesel
Hammer. Basically, it is a rudimentary one-cylinder diesel engine. It is fed from
a fuel tank by a pump mounted directly on the hammer, in contrast to air and
steam hammers, which require an external energy source. Simple to operate,
diesel hammers are commonly used on most bridge contracts today.

Single Acting Diesel Hammers. The fundamental makeup and operation of all
diesel hammers are similar. They consist of a cylinder-encased ram, an anvil
block, a lubrication system, and a fuel injection system that regulates the amount
of fuel to each cycle. New models added a variable fuel metering system that can
change the energy delivered by the ram, thereby making them more versatile for
varying soil conditions. The energy imparted to the driven pile is developed from
gravitational forces acting on the mass of the piston. Refer to Figure 7-13. The
operational cycle of the single acting diesel hammer is shown on Figure 7-14 and
is described in the following paragraphs.

To start operations, a cable from the crane lifts the ram. At the top of the stroke,
the lifting attachment is “tripped” and the ram allowed to drop. The ram falls by
virtue of its own weight and activates the cam on the fuel injector that injects a set
amount of fuel into the cup-shaped head of the impact block. As soon as the
falling ram passes the exhaust ports, air is trapped in the cylinder ahead of the
ram, and compression begins. The rapidly increasing compression pushes the
impact block (anvil) and the helmet immediately below it against the pile head
prior to the blow.

Upon striking the impact block with its spherically shaped leading end, the ram
drives the pile into the ground and, at the same time atomizes the fuel which then
escapes into the annular combustion chamber. The highly compressed hot air
ignites the atomized fuel particles and the ensuing two-way expansion of gases
continues to push on the moving pile while simultaneously recoiling the ram.

As the upward flying ram clears the exhaust ports, the gases are exhausted and
pressure equalization in the cylinder takes place. As the ram continues its upward
travel, fresh air is sucked in through the ports, thoroughly scavenging and cooling
the cylinder. The cam on the fuel injector returns to its original position allowing
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new fuel to enter the injector for the next working cycle. The operator may stop
the hammer manually by pulling a trigger, which deactivates the fuel supply.

The diesel hammer is difficult to keep operating when driving piles in soft
material. Large downward displacements of the pile absorb most of the energy;
therefore, little remains to lift the ram high enough to create sufficient
compression in the next downstroke to ignite the fuel. To resume operation, the
cable hoist must again raise the ram.

It is generally accepted that the energy output of an open-end diesel hammer is

equal to the ram weight times the length of stroke. This combination ignores any
component of the explosion that acts downward. In production pile driving, the
stroke is really a function of the driving resistance, the pile rebound, and the
combustion chamber pressure. The combustion chamber pressure is affected by
the general condition of the hammer as well as the fuel timing and the efficiency
of combustion. Accordingly, manufacturer’s energy ratings are based upon the
hammer operating at refusal with almost all the energy of combustion developing
the upward ram stroke leaving just the weight of the ram and the stroke left to
determine energy.

Diesel hammers are very versatile. They may be connected to almost any set of
leads. They do not require an additional energy source, such as steam or air so the
size of the pile crew can be reduced. On occasion, piles are driven with crews
containing as few as three workers, including the crane operator. These hammers
typically operate within a speed of 40 to 60 blows per minute and can have
strokes in excess of 10 feet. Although these hammers will drive any type of pile,
their stroke is dependent on soil conditions. Hard driving in harder soils results in
increasing stroke lengths, thus providing increasing hammer energies; while easy
driving in softer soils results in lower stroke lengths and lower hammer energies.
It should be noted that diesel hammers are noisy and they tend to spew oil and
grease throughout. They can also emit unsightly exhaust, although newer models
have been designed to be somewhat more environmentally friendly.

When using a diesel hammer the Engineer should:

NO. ITEM DESCRIPTION

1 Have the manufacturer’s current specifications for the type and model of hammer
being used.
2 Ensure all required parts of the hammer are intact and in good operating condition.
3 Have chart available declaring rated energy vs. operating speed of hammer.
4 Be aware of the actual stroke of the hammer during driving and that it will vary
depending on soil resistance.

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FIGURE 7-13 Single acting diesel hammer

FIGURE 7-14 Operational cycle for single acting diesel hammer

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Double Acting Diesel Hammer. The double acting diesel hammer is similar in its
operations to other double acting hammers. The top of the cylinder is capped so
that pressures can be developed on the downward stroke. The energy transferred
is more than just a function of gravity. As the ram nears the top of its upward
stroke, air is compressed in a “bounce chamber”. This halts the upward flight of
the ram as pressure increases. The downstroke energy now becomes a function of
both gravity and the internal pressure generated in the “bounce chamber”. The
hammers have a stroke that is around 3 to 4 feet and operate at a much
higher/quicker blow rate compared to the single acting diesel hammer. Refer to
Figure 7-15.

These hammers normally have a manually operated variable fuel injector, which
is controlled by the crane operator. Unless the control is wide open, the energy
delivered is difficult to determine. The rated energy needs to be computed from a
formula incorporating the length of the free fall downstroke of the ram multiplied
by the sum of its weight and adding the effects of changes in pressures and
volumes of air in the bounce/scavenging chambers of the hammer. Manufacturers
have plotted the solutions to the formulae for each model of hammer for various
pressure readings in the bounce chamber.

FIGURE 7-15 Double acting diesel hammer

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When using a double acting diesel hammer the Engineer should:

NO. ITEM DESCRIPTION

1 Have the manufacturer's current specifications for the type and model of hammer
being used.
2 Ensure all required parts of the hammer are intact and in good operating condition.
3 Ensure the energy chart made available by the manufacturer is the correct one for the
model of hammer being used and that there has been a recent calibration or
certification of the bounce chamber gauge.

Vibratory Driver/Extractor

Vibratory pile drivers/extractors could be likened to mini-stroke, high blow rate

hammers. However, the familiar vibratory pile drivers in standard use today do
not contain linearly reciprocating weights or rams. Instead, they employ two
balanced rotating weight sets, which are eccentric from their centers of rotation.
Moving in opposite directions, they impart a vibration that is entirely vertical.
This motion is transmitted to the pile through the hydraulic clamps of the driving
head. The pile in turn transmits the vibratory action to the soil allowing the soil
granules to be more readily displaced by the pile tip. The same action works even
more effectively for extracting piles. Refer to Figure 7-16.

The effectiveness of a vibratory unit is dependent upon the interrelationship of the

performance factors inherent to the unit. The larger the eccentric moment, the
more potential vibratory force the driver possesses. In order to realize this
potential force, the driver must operate with the proper frequency and amplitude.

With heavier piles, there is a higher vibratory weight supported by the hammer.
This tends to reduce the amplitude. So as piles get larger, it is necessary to use
drivers with larger eccentric moments. The non-vibratory weight has the effect of
extra weight pushing the pile downward.

Vibratory drivers are most effective in granular soil conditions, but recent
developments and new techniques have also made them effective in more
cohesive soils. They can handle a variety of piling, including steel sheets, steel
pipe, concrete, timber, wide flange sections, “H” piles, as well as caissons. They
do not create as much large amplitude ground vibration as the pile driving
equipment discussed above. This makes the vibratory hammer desirable in areas
where excessive ground motions could possibly cause damage to adjacent
structures.

Section 49-1.05 of the Standard Specifications prohibits the use of the vibratory
hammer for driving permanent contract piles because there is no way to determine
the amount of energy delivered to the pile. However, contractors frequently use

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vibratory hammers are to install temporary works. (i.e. placing and extracting
sheet piles for shoring, etc.) These hammers are also used to extract piles.

Although vibratory hammers cannot be used when there is a nominal resistance

requirement, the vibratory hammer has occasionally been permitted to install a
bearing pile to a point above the expected final penetration. An impact hammer
approved for this operation is then placed upon the pile to drive it to acceptable
bearing and final penetration values. A situation where this technique is useful is
where alignment of a pile is critical. The vibratory hammer allows the operator to
minimize the rate of penetration of a pile, thereby allowing for more precise
alignment of a pile as it gets started into the ground.

There have been comparisons made in the recent past indicating variances in
bearing capacities of piles when comparing a pile driven to the same elevation
with a vibratory hammer and one driven with an approved impact hammer. Items
of interest and discussion include the “set” of the pile and the disturbance of the
soil mass. The vibration of the pile against the soil may reduce the amount of
skin friction on the pile leading to lower nominal resistances than what would
have occurred if the pile were driven without vibratory means. This condition
may be temporary. Depending on the soil, the skin friction may return in full or
in part as the soil remolds or sets over time.

When a request is made to use a vibratory hammer to start a pile, the Engineer
should:

NO. ITEM DESCRIPTION

1 Be aware of specific pile requirements and limitations stated in the special provisions
and the Standard Specifications.
2 Discuss the proposal with the Bridge Construction Engineer, the project designer, and
the geoprofessional.

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FIGURE 7-16 Vibratory driver/extractor

Hydraulic Hammers

A hydraulic hammer incorporates an external energy source to lift the hammer to

the top of its stroke. For the single acting hydraulic hammer, the free-falling
piston provides the energy induced into the pile, much the same as a drop hammer
or a single acting diesel hammer. The rated energy for the differential acting
hydraulic hammer is found by means similar to other differential acting hammers.
Refer to the previous section on differential acting steam/air hammers.

The theories of energy delivery and transfer vary between differential hydraulic
hammers. For example, one particular hydraulic hammer manufacturer utilizes a
ram made of composite material. In this case it is made of lead wrapped in steel.
The theory behind the lead ram is that a heavier weight falling a similar distance
should produce blows with longer impact durations. This longer impact duration
produces a compression wave that is low in amplitude and long in duration. It is
thought that this type of blow is more efficient in terms of delivering driving
energy to the tip of the pile (relative to a light weight hammer with a longer
stroke).

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The hydraulic hammer has a variable stroke, which is readily controlled from a
control box located in the cab with the crane operator or in a separate cab, as is
the case for larger hammers. With the control box the stroke can be varied,
finitely (reported to be in the centimeter range), such that the stroke can be
optimized so that it matches the dynamic spring constant of the hammer and pile.
Manufacturers have stated that the ability to vary the stroke and frequency enables
these hammers to perform more efficiently than other types of hammers.

The general theory behind the hammer is as follows. Every ram body, depending
on material and cross sectional area, has its own dynamic spring constant.
Likewise, each pile, based on different materials and sizes, has its own dynamic
spring constant or acoustic impedance. As the dynamic spring constants for the
pile and the hammer converge, higher efficiencies can be achieved. Energy will
be transmitted through the pile to the tip with fewer losses and at lower internal
stresses. Essentially all the hammer energy will go into moving the pile since the
losses in the pile were minimized. The greatest efficiency is achieved when the
hammer impedance is the same as the pile impedance. If this were to occur, a pile
cushion would be unnecessary and driving would be further optimized.

The manufacturer data sheets for these types of hammers state the following:

NO. ITEM DESCRIPTION

1 Hammer efficiencies in the range of 80% to 98%, while saying that diesel hammers
have efficiency in the range of 30% to 40%.
2 Due to the increased efficiency of the hammers and because more energy is
transmitted through the hammer, there is less internal stress of the pile, less pile
damage, etc.
3 They claim the operation to be quieter than the typical diesel hammer.
4 The typical exhaust of the diesel hammer is eliminated, since only the motor driving
the hydraulics is the source of exhaust.
5 Avoids diesel hammer problems of soft ground starting and operating in extreme
climates.

General Hammer Information

Section 49-1.05 of the Standard Specifications requires that the Contractor furnish
an approved hammer having sufficient energy to drive piles at a penetration rate
of not less than 1/8-inch per blow at the required bearing value. In effect, this
specification places a lower limit on the hammer size because hammer size, in
most cases, is related to energy. An upper limit is not specified; however some
hammers my be too large for the intended use and may damage the pile during
installation.

Economics often dictate the selection of hammer size and type. Large hammers
provide vast amounts of energy that will advance the pile quickly and reduce

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driving time. They also help achieve specified tip elevations when hard driving is
encountered, thus enabling completion of the work without the need of
supplemental measures such as jetting or predrilling. On the other hand, heavy
hammers require heavy leads and heavy cranes; the result being decreased
mobility and increased equipment costs. Another consideration is that larger
hammers deliver more energy to the pile. Hence, the probability of pile damage
(heavy spalling, buckling or other) increases as the hammer size increases. Ram
impact velocity is another important factor. In general, a large ram weight with a
short stroke and low velocity at impact will not produce the magnitude of pile
stress that a light ram with a long stroke and high velocity will induce. Generally,
at constant driving energy, the driving stress on the pile will decrease as the ram
weight increases. Though there are situations where the “bigger hammer” may be
too big and will overstress the pile. However the option to run a bigger hammer
at less than the maximum capacity, with a shortened stroke, may help, as the
impact durations are different. Refer to the section on hydraulic hammers for
more information on impact duration.

Nominal Resistance/Bearing Capacity

Pile driving formulas have been developed over the years to determine the
nominal resistance of driven piles. There are many different (at least 450) pile
driving formulas, the more notable of these being the Gates, Hiley, Pacific Coast
Uniform Building Code, Janbu, and the ENR. Refer to Appendix E for examples.
They have been empirically developed through testing and research. They utilize
known information such as the energy delivered per blow, the resistance to the
movement of the pile per blow, pile penetration, and some acknowledgement or
estimates of the unknown or unquantifiable that serves to drive and/or resist the
pile. All of the driving formulas make use of the conservation of energy theory:

(HAMMER ENERGY) – (ENERGY LOSSES) = (WORK PERFORMED)

Soil resistance multiplied by pile penetration represents work performed, hammer

stroke multiplied by ram weight represents hammer energy, and various factors
and/or constants in driving formulas are derived to represent energy losses in the
piling system. The desired objective is to account for the most significant energy
losses so that soil resistance can be estimated. Some of the energy losses
associated with pile driving are hammer combustion and mechanical inefficiency,
hammer and pile cushion restitution, dynamic soil resistance and pile flexibility.
No pile driving formula accounts for all energy losses, and the major difference
between formulas is which losses each considers.

Section 49-1.08 of the Standard Specifications requires that the bearing value of
driven piles be determined using the Gates formula as follows (Refer to Appendix
E for examples):

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Ru = (1.83 × ( Er )1 2 × log 10(0.83 × N )) − 124

Where:
Ru = the nominal resistance in kips,
Er = the manufacturer’s rating for foot-pounds of energy developed by the
hammer at the observed field drop height
N = the number of hammer blows in the last foot (maximum value for N is 100)

This formula is appropriate for most piles and Standard Plan piles in particular.
Acceptance criteria that require larger capacities than Standard Plan piles may be
determined by other methods. The other methods for determining the load-
bearing capacity of a pile depend on detailed knowledge of how energy is
transmitted to a pile during driving. These exercises are much more detailed than
the pile driving formulas. These methods and procedures typically obtain more
accurate representations of the pile’s bearing capacity and can be categorized into
three areas: (1) Pile Load Testing, (2) wave equation analysis of pile driving, and
(3) dynamic pile driving analysis. The processes are explained in detail in the
next chapter but a brief description of each one follows.

Pile Load Testing

The most accurate way to determine the axial capacity of a pile is to perform a
static load test on it. The method is time consuming and expensive so it is
reserved for locations where the underlying geology is variable and complex.
Load tests are useful in determining the capacities of large diameter piles as the
traditional method of using pile-driving formulas loses accuracy as the diameter
of the pile increases. Typically, the load test pile is pushed and pulled by
hydraulics that are attached to a resisting beam to a point were design loads or
ultimate capacity is achieved.

Dynamic Analysis by Wave Equation

Wave equation analysis is used to create site-specific model of the interaction of

the pile, hammer and soil. It is a one-dimensional finite difference analysis
method which models the transmission of a hammer’s impact wave down a pile
and into the soil. Several versions of the program are available. The program
used by the Department is one of the most widely known. It was developed by a
company called GRL and is called Wave Equation Analysis of Piles (GRL
WEAP).

Wave equation analysis models the pile and the driving system as well as the
different soil lenses that the pile is expected to drive through. The soil is modeled
as a series of elastic plastic springs and linear dashpots. The relative sizes of the
springs and masses depend on the actual soil properties shown on the Log of Test
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Borings. Driving system characteristics are embedded in the program and pile
characteristics such as diameter and wall thickness are input by the user. After
modeling, a dynamic analysis is performed. To date wave equation analysis has
been used for driveability studies, hammer acceptance studies, and to develop
site-specific curves that relate nominal resistance with pile blow counts and
energy. The wave equation analysis method has been shown to provide a more
accurate indication of actual nominal resistance than by pile driving equations.

Driveability Study. The wave equation analysis can be used as a driveability

study during the design phase to validate design assumptions for things like wall
thickness on pipe piles and hammer sizes and types. Geoprofessionals from
Geotechnical Services’ Foundation Testing Branch create the driving system
model. The input information consists of soil characteristics taken from the Log
of Test Borings, the length and other material properties of the pile obtained from
the Designer. In addition, hammer data such as type and cushion properties for
the different hammers likely to be used in the actual construction operations is
input.

The output information provides the internal stresses of the pile as it travels
through the varying strata and as it approaches the specified tip elevation. The
output also gives information on driving rates for specific hammers through the
different soil strata. The model is run using several different hammer sizes and
types. The results are presented in a report that shows how the different hammers
will drive piles through the different soil strata. This analysis also offers the
designer the opportunity to change pile types, sizes or thicknesses should the
drive analysis show that pile driving will be difficult.

Hammer Acceptance Study. The Hammer Acceptance Studies are done after the
contract is bid or awarded. Current contracts require the contractor to submit
information on the actual driving system proposed for the project. This
information is used by the Foundation Testing Branch to perform a wave equation
analysis. Some of the more current contracts require the contractor to perform
their own wave equation analysis. Essentially a driveability study is performed
using the actual hammer information instead of assumed values. From this
information, the Engineer can decide if the proposed hammer will drive the pile to
the specified tip elevation and reach the nominal resistance without overstressing
the pile during driving. The results of the study might also show that the chosen
hammer is not efficient. Either way the results of the driveability study are used
as a basis for accepting or rejecting the hammer submittal.

Acceptance Curve Study. The studies outlined above use theoretical or empirical
information to develop a model that gives a pretty accurate indication of what will
be encountered in the field. Gathering additional information while driving an
actual pile can refine this model. Pile Dynamic Analysis (PDA) equipment can be
used to record and process information gathered from stress and strain gauges

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attached directly to the pile. The information can be recorded during initial
driving and during re-drives to determine increased capacities over time. The
information from the PDA can be analyzed using the Case Pile Wave Equation
Analysis Program (CAPWAP) to estimate capacity. On some larger projects with
complex soils, a static load test might also be performed to refine CAPWAP even
further. The pile capacity as determined by CAPWAP is used to refine the
original WAVE model.

Acceptance curves are developed from outputs of the refined models. The curves
correlate pile capacity to blow counts and hammer energy/driving rate. They are
site specific and may even be foundation specific. The Engineer uses the curves
in the field to determine the nominal resistance of a driven pile. The curves are
used in place of the acceptance criteria outlined in the Standard Specifications
(Section 49-1.08). The curves may also be used to provide criteria for field
revisions to the specified tip elevation when compression controls the design.
Refer to Appendix E for samples of acceptance curves.

Another situation where acceptance curves are useful is in situations where the
ground conditions during driving are not what control the design. Examples of
this are foundations that require the installation of driven piles in scour sensitive
areas, through liquefiable soils or through large layers of re-moldable clays. In
these instances, piles need to be driven through materials that will provide skin
friction resistance during driving but not under the extreme event or in the case of
re-moldable clays where skin friction is lost during the driving operation and
returns over time.

Pile load tests, WAVE analysis and CAPWAP runs have been performed in the
design phase and the construction phase to provide additional information and
confidence to the designer and geoprofessional. These types of analysis are
normally done on large projects but in recent years have been done on projects
that use large diameter piles. The correlation of nominal resistance to pile driving
formulas is not very effective for large diameter piles so these additional measures
are needed.

Piles driven in re-moldable clays, such as Bay Mud found in the San Francisco
Bay Area, lose virtually all their skin friction during driving. The skin friction
returns with time as the pour water pressures are redistributed. The driven pile
will actually achieve greater a capacity over time as the skin friction returns. As
such, piles driven to specified tip on the day of driving might not achieve nominal
resistance but may do so days and sometimes hours later. Acceptance curves
provide new criteria for the piles thereby eliminating the need to perform
expensive and time consuming re-drives.

During the process to develop acceptance curves it may become apparent that
there is a need or opportunity to revise the specified tip elevations shown on the

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plans. When this is done during construction the special provisions will outline
administrative process to be followed. Often the Special provisions prohibit the
procurement of piles until pile load tests are completed and revised tip elevations
are provided. That way piles and rebar cages can be fabricated to the correct
length and any required splices kept to a minimum.

Manufacturer’s Energy Ratings

Generally each manufacturer publishes a catalog or brochure for their hammers.

It outlines operating specifications, including any specific equipment that is
required for the safe operation of the hammer. Manufacturer’s specifications such
as ram weight, stroke, blows per minute and the minimum required steam or air
pressure are important as they all relate to the energy that the hammer is capable
of delivering under ideal conditions. Manufacturers calculate hammer energy
differently. Some use ram weight multiplied by the stroke. At one time, Delmag
calculated a hammer’s energy as a function of the amount of fuel injected but now
use the weight of the hammer times the stroke. Other manufacturers include the
effects of additional parameters such as fuel ignited and the effect of the bounce
chamber. In any case, a hammer’s rated maximum energy is the rating when the
pile hammer is operating at or near refusal. It does not consider losses and is
essentially the amount of potential energy, in foot-pounds, capable of being
delivered by any one blow.

Engineers and inspectors use the manufacturer’s maximum rated energy as an

indication of the driving capability of the hammer. It is used in the Gates formula
as required by the Standard Specifications. It is important to know that the
manufacturer’s given energy rating should not be used “blindly”. The actual
potential energy needs to be verified by measuring the stroke of single acting
diesel hammers and by comparing the operations of the hammer with the
manufacturer’s operating specifications for other hammer types. Just because a
hammer is operating properly doesn’t mean that it is operating at maximum
efficiency.

As stated previously, manufacturers rate their hammers by determining the

amount of energy that can potentially be transferred to the pile. They do not
specify the amount of kinetic energy that is actually delivered by a hammer at the
head of the pile after undergoing losses. These losses occur in the transfer of
energy through the driving system and can vary from hammer to hammer and
from job to job. The ratio of the maximum rated energy provided by the
manufacturer to the actual energy delivered to the pile is the hammer’s efficiency.
An accurate determination of the actual available energy of any given hammer is
difficult as there are many things that can have an effect on the efficiency of the
system. Factors such as wear and tear, age and type of cushion, improper
adjustment of valve gear, poor lubrication, unusually long hoses, minor hose

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leaks, binding in guides, and minor drops in steam or air pressure can all affect
the performance of a hammer.

It is necessary to have a working knowledge of hammer operations. The Engineer

must ensure that the accepted hammer on the job is operating properly and is
capable of producing the manufacturer’s “rated energy” (or potential energy, at
the top of its stroke). Material presented in this manual and material found in
other technical publications will supplement this knowledge. However, there is
no substitute for field experience. The Engineer is advised to look into the
mechanical aspects of the pile driving operation when the Contractor starts
assembling the equipment and driving begins.

Battered Piles

When battered piles are driven, an adjustment to the hammer energy needs to be
made since the path of the ram is not plumb. The hammer path will follow the
slope of the battered pile so the stroke used to compute delivered energy must be
adjusted to reflect the change in vertical fall of the ram. This is simple to
determine for single acting air, steam or diesel hammers. For example, a 140 Ton
pile driven with a Delmag 30 hammer will require 28 blows per foot using the
Gates Formula. If the pile were driven on a 1:3 batter the minimum blow count
would be increased to 30 blows per foot ((3.162/3) X 28 = 30). Refer to
Appendix E for an example of this.

A similar adjustment must be made for double acting and differential hammers.
However, in determining the change in energy due to the batter, compensate only
for that portion of the energy attributed to the free fall of the ram as energy
delivered by differential action or pressure imparted on the downward stroke
should remain constant.

Preparing to Drive Piles

Pile driving techniques (including solutions to problems) are normally developed
with time and experience. It is the intent of this section to provide some insight
into the areas where problems can develop, so that as many of them as possible
can be eliminated or resolved before they occur.

The following material is essentially a checklist of what the Engineer should look
for both before pile driving begins and while pile driving is underway. This list is
by no means complete, as new and different construction challenges will develop
with each and every project.

Advance preparation to begin well before mobilization of pile driving equipment:

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NO. ITEM DESCRIPTION

1 Review the Plans, Special provisions, Standard Specifications and Foundation Report
for requirements on pile type, required bearing and penetration, predrilling depths
(critical with tension piles as well as compression piles), tip protection or pile lugs
and limitations on hammer types or other specific limitations or requirements.
2 Check for Form TL-29, “Release of Materials.”
3 Check Welding Quality Control Plan (WQCP) and welder certification requirements.
4 Prepare the pile layout sheet. Form DH-OS C80 in the CR&P Manual
5 Prepare the pile log forms. Form DH-OS C79 in the CR&P Manual
6 Advance preparation of a chart, table or graph that correlates the blow count, stroke,
blow rate, etc., to the bearing value is suggested for each hammer. An example is
included in Appendix E. Verify the hammer is an approved hammer in accordance
with the requirements of Bridge Construction Memo 130-2.0 and is able to develop
sufficient energy to drive the piles at a penetration rate of not less than 1/8-inch per
blow at the required bearing value. Refer to the “Verification of Hammer Energy”
section later in this chapter.
7 Review the mechanics of the hammer type to be used for further verification of
components in the field.
8 Obtain the necessary safety equipment (Refer to the “Safety” section later in this
chapter) and inspection tools (tape measure, paint, stop watch, etc.)

Once out in the field, prior to start up of pile driving:

NO. ITEM DESCRIPTION

1 Confirm pile layout and batter requirements. The Contractor is to locate the position
of the piles in the footing. The Engineer is to check the layout only. Do not layout
piles for the Contractor.
2 Confirm pile materials, tips and lugs. Refer to the “Materials Checklist” later in this
chapter.
3 Confirm the hammer type. If the hammer has a variable energy setting, check the
setting to ensure the proper energy will be obtained. Some of the newer diesel
hammers have four settings giving a range of 46% to 100% maximum energy.
4 Verify the reference elevation.
5 Layout and mark piles for logging. Mark additional reference points near the
anticipated tip elevations so that monitoring can take place at smaller increments.
6 Locate a good place to inspect operations. Notify the pile foreman of location and
signals to be used.

When pile driving starts:

NO. ITEM DESCRIPTION

1 Verify the pile location at the start of driving.
2 Verify plumbness or batter of the pile at the start of and during driving.
3 Monitor and log the blow count, stroke and penetration (Refer to the “Logging of
Piles” section later in this chapter).
4 Stop driving at proper bearing and penetration.

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After completion of driving piles:

NO. ITEM DESCRIPTION

1 Verify proper pile cutoff.
2 Prepare copies of pile logs to be sent to the Office of Structure Construction in
Sacramento in accordance with Bridge Construction Memo 3-7.0.

Verification of Hammer Energy

Several verification methods are available to field staff determine the amount of
hammer energy that a hammer delivers to a pile in any one blow or over a short
period of time. For single acting diesel, steam or air hammers, the simplest
method is to measure the stroke of the hammer and multiply this by the weight of
the ram. While this method may underestimate the complexities of pile driving
and energy transfer, it is the simplest method available for use in the field. To
determine the stroke for diesel hammers, measure the depth of ram below the top
of the cylinder before driving and add that to the height the top of the ram rises
above the cylinder during driving. To determine this height, paint is often applied
in one-foot intervals on the trip carriage above the cylinder. However, some
hammers have rams with identifiable rings that are visible during driving. The
location of the rings normally is shown on the manufacturer’s brochure.

The maximum rated stroke for maximum rated energy for many hammers is given
in Bridge Construction Memo 130-3.0.

Another method of determining the actual ram stroke of an open-end diesel

hammer is accomplished by measuring the ram stroke from the blow rate. The
equation involved with this method is sometimes called the Saximeter equation.
Saximeter is a trade name for a device used for remote measuring of the stroke of
an open-end diesel hammer or the measurement of the hammer speed. An
example is also available in Appendix E.

For Air and Steam hammers, check the boiler or air capacity of the outside energy
sources. This should be equal to or greater than that specified by the hammer
manufacturer. Gages that indicate steam and air pressures are required by the
Standard Specifications. Verify the system is using the proper hose size
recommended for the particular steam and air hammers. The hoses should
comply with the manufacturer’s specifications. All hoses should be in good
condition (no leaks).

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Materials Checklist

Precast Concrete Piles

CHECK CHECK DESCRIPTION

ITEM
1 Check for damage, cracks, chips, etc. Check the date the pile was cast. This date
is written, along with the release number, directly on the surface of the pile.
Section 49-1.07 of the Standard Specifications requires that piles be at least 14
days old before driving.
2 Lifting anchors for Class C piles are to be removed to a depth of one inch and the
hole filled with epoxy. Piles without Class C designation shall have the anchors
removed along the portion of pile above the final ground line. Section 49-3.01 of
the Standard Specifications covers this subject..

Discuss with the Contractor the type and method of rigging planned to lift the
precast/prestressed concrete piles. The Contractor is to provide the necessary
equipment so as to avoid appreciable bending of the pile or cracking of the
concrete. If the Contractor materially damages the pile, the pile must be replaced
at the Contractor’s expense (Refer to Section 49-3.03 of the Standard
Specifications).

Check the lifting procedure to ensure that the pile is not overstressed at anytime
during picking. The maximum permissible allowable stress is as follows:

Allowable Stress = 5 fc′ PSI tension

Measure piles and paint the necessary one-foot marks so blow counts can be
determined. Check the ends of the piles. Prestressing steel should be flush with
the pile head and cover with zinc primer. The head of the pile should be square.

When driving concrete piles, make sure that the cushion blocks are maintained in
good condition. Failure to do so may increase the risk of damaging the piles
during driving. If the driving is hard, the cushions may need to be changed once
or twice per pile.

Steel Piles

If the piles are to be spliced, the Contractor must have welder(s) qualified prior to
performing the welds. They must be qualified in accordance with the “Welding”
and “Piles” sections of the Special provisions, usually in accordance with a
Welding Quality Control Plan and the AWS D1.1, Structural Welding Code.
Assistance may be obtained by calling the Office of Materials Engineering and
Testing Services (METS).

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Some welders will have qualification tests that were performed by a private
testing laboratory. Prequalification can be accomplished in this instance by
forwarding a copy of the test reports to the nearest Transportation Laboratory
office where they will verify the welder’s qualifications.

It is obvious that all of the aforementioned takes time. Hence, it is extremely

important that determination of welder qualification be made as early as possible.
Keep in mind that just because a person holds a welding certification, it does not
mean you do not have to inspect the welding work.

Early contact with METS representatives in Los Angeles, Vallejo, or Sacramento

is encouraged, as they can be very helpful. Reference should also be made to
Section 180 of the Bridge Construction Records and Procedures Manual.

CHECK CHECK DESCRIPTION

ITEM
1 Check for proper diameter and shell thickness. Paint one-foot marks and lengths
on the piles. The Contractor may assist in this.
2 Check welded joints for any sign of improper welding. When piles are to be
spliced, a Welding Quality Control Plan will be required. Refer to the Special
provisions for information pertaining to this plan. Refer to Section 49-5.02 of the
Standard Specifications for additional information on types of welds allowed in
splices.

Timber Piles

Check the butt and tip diameters to ensure compliance with Section 49-2.01 of the
Standard Specifications. Treated timber piles shall be driven within 6 months
after treatment.

Piles shall have protective steel straps at 10-foot centers. Three additional straps
are placed at the tip and two at the butt. Straps are to be approximately 1-1/4
inches wide and 0.3 inch in nominal thickness per Section 49-2.03 of the Standard
Specifications.

The Contractor is also required to restrain the pile during driving from lateral
movement at intervals not exceeding 20 feet measured between the head and the
ground surface. Make sure the Contractor is equipped for this.

Logging of Piles

It is Office of Structure Construction policy to log at least one pile, in it’s entirety,
per footing. There are advantages to doing a more comprehensive logging of the
piles. One situation is when, during easy driving, the piles are not achieving the
necessary blow counts at specified tip. The Contractor will request to retap them

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later. A good log of the piles within the footing will help the Engineer to
determine how many piles might require a restrike/retap to prove bearing. If all
the piles drove in a similar manner, it might be possible to restrike/retap as few as
10% of the piles that did not originally achieve bearing. If the piles all drove
differently, a restrike/retap of all of the piles may be required. The following is a
discussion of factors affecting pile log data.

Typically when pile driving begins, the driving resistance of the pile is very low.
The stroke of the hammer will be proportional to this pile resistance (low
resistance equals low rebound energy). As a result, the energy delivered to the
pile will be different from the Manufacturer’s rated energy value. Keeping
careful track of blows per foot and actual stroke is necessary. If this difference is
not taken into account, the log will be misleading when the values are put in the
Gates Formula and bearing values are computed at various depths of driving.
This procedure should be followed all the way to the final tip penetration.

With double acting steam or air hammers, check the gages for proper pressure
during the driving operation. In addition to measuring the actual stroke, it is
important that the blow rate be verified.

Underwater and “closed” system hammers are difficult to inspect and can be
throttled by the operator. The full open position should be used to obtain
maximum energy. Be sure to pick a fixed reference point as close to the pile as
practical when logging piles or determining final blow count. This can be
accomplished several ways: (1) Mark the pile with one foot marks and note the
blows passing a fixed point near the pile (leads, reference point, lath driven near
the pile, water surface or other), or (2) Mark the lower part of the leads with one
foot marks and observe passage of a fixed point of the pile. Site conditions often
dictate how this is done, so improvise as necessary. Modifications must also be
made to obtain blow counts over smaller increments.

If a precast pile is undergoing hard driving and suddenly experiences a sudden

drop or movement, this could indicate a fracture of the pile below ground.
Driving should stop and an investigation of the soundness of the pile should be
made. Piles that are damaged should be extracted. However, this is not always
possible. Frequently, driving a “replacement” pile next to the rejected one can
solve this problem. However, the effect of this change could impact the footing
design so the project Engineer should be consulted when this option is used.

Be aware of the water level in the pile when driving hollow pipe piles in water. A
phenomenon known as a water hammer can develop during driving. The increase
in pressure from the water hammer could split the pile. To prevent this, the pile
may need to be pumped free of water after seating and before driving.

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Another problem that can occur with pipe piles has to do with what is called a soil
plug. When driving hollow piles, there is a tendency for the soil to plug within
the pile as it is being driven. This is common in cohesive materials. When this
does occur the pile will drive as if it is a displacement (closed-end) pile. There
are many implications if this happens. Among the possibilities include the
possible overstressing of a pile as well as misleading blow counts. Center relief
drilling may be needed to remove the plug so that the specified tip elevation can
be reached.

Driving Challenges
Problems with driving can vary in nature and cause. In general there are three
categories of problems: (1) hard driving, (2) easy driving, and (3) pile alignment.
The causes typically are the soil is too hard or soft, the type of hammer used is
inappropriate for the soils encountered, or the pile type being used is
inappropriate. The following is an outline of various driving problems that can be
encountered. The types of problems described are, by no means, a complete
listing of all possible problems.

Difficult or Hard Driving

Hard driving is a term used to describe piles that have achieved nominal
resistance but have difficulty reaching the specified tip elevation. This may
happen when the soils are dense or when the hammer size or type cannot
penetrate a particular soil lens or is inappropriate for the work in general. A
review of the Special provisions, Foundation Report and Log of Test Borings
should give an indication as to whether or not hard driving is to be expected. The
pile placement plan should address the means and methods proposed to address
hard driving.

The Standard Specifications and Special provisions discuss what can be done to
address this condition. For example, Section 49-1.05 of the Standard
Specifications states: “When necessary to obtain the specified penetration and
when authorized by the Engineer, the Contractor may supply and operate one or
more water jets and pumps, or furnish the necessary drilling apparatus and drill
holes not greater than the least dimension of the piles to the proper depth and
drive the piles therein.” For driven piles, shells or casings, the Standard
Specifications also require the use of special driving tips, heavier pile sections, or
other measures as approved by the Engineer, to assist in driving or prevent
damage to a pile through a hard layer of material.

The special provision should address the job specific requirements or limitations
for jetting or predrilling. If not, the Engineer should consult with Geotechnical
Services and Structure Design if hard driving is anticipated and the Contractor is

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considering jetting or predrilling to address it. While these methods may be used,
there is the potential for these methods to impact the capacity of the pile.
Therefore, there may need to be limitations, such as depth or diameter of
predrilling, on the use of these procedures.

Hard driving and pile refusal are often interrelated as refusal can be considered
the ultimate form of hard driving. Unfortunately, there are many definitions for
the term “refusal”. Some popular interpretations range from: (1) twice the
required blow count, (2) 10 or more blows per inch, or (3) no penetration of the
pile under maximum driving energy. Regardless of any specific definition,
refusal is essentially the point where additional measures are needed to advance
the pile to the specified tip elevation. These measures can be as simple as
verifying the efficient operation of the hammer or more time-consuming like
predrilling or jetting.

The size and type of hammer used to drive the pile play a part in having and/or
resolving a hard driving issue. One should keep in mind that proper hammer
sizing is not accomplished simply by meeting the minimum energy requirement
given in the Standard Specifications. It is important to be aware that the hammer
needs to overcome the anticipated soil resistance and impedance to achieve the
specified tip elevation. Other issues such as the dynamic response of soils and the
relative weights of the hammer and the pile if not properly considered may be the
root cause of hard driving. A Wave Equation Analysis can capture many of these
parameters and is often required on projects driving high capacity piles.

Hard driving is not always a permanent condition and can also be the result of a
pressure bulb that has developed near the pile tip. This can occur in saturated
sandy materials when pore water pressures build up during driving but can
dissipate over a relatively short period of time. Driving these types of piles in
stages may remedy this situation.

Sometimes the means and methods of construction may increase the likelihood of
experiencing hard driving. Soil densification/consolidation can occur when
driving displacement piles in a cluster for a building or bridge footing or
abutment. A revised driving sequence will often alleviate this problem. This can
often be a trial and error process. Driving from one side of the footing in a
uniform heading helps as does driving from the center in a uniform outward
pattern. Both of these procedures should mitigate the issue and increase the
likelihood of driving piles without issues.

Sometimes other construction methodologies are required to address hard driving.

These methods include predrilling and jetting. These methods are typically used
when economics dictate this to be the best solution or when larger hammers
cannot be utilized because they will overstress the pile.

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“Jetting” uses water pressure to remove soils and has the potential to impact the
capacity or alignment of a pile; as such care must be exercised when used. Two
methods are generally employed: (1) pre-jetting, and (2) side jetting. In terms of
controlling pile alignment pre-jetting is best. A pilot hole is simply jetted to the
desired depth. After the jet pipe is withdrawn the pile is immediately inserted in
the hole and driven. With side jetting the jet pipe is inserted into the ground
adjacent to the pile and the jetting and driving take place concurrently. Care must
be taken when this is done with a single jet, as the pile tip will tend to move off
line in the direction of the jetted side. Larger piles are frequently side jetted with
multiple pipe systems. These systems can be located outside the pile or within the
annular space of hollow piles. In addition, the pipe arrangement of multiple pipe
systems is usually symmetrical, thus enabling better control of pile alignment.
Jetting uses water to facilitate driving and the end result is a volume of muddy
water that must be addressed in the Storm Water Pollution Prevention Plan or
Water Pollution Control Program.

Drilling a “starter hole” to facilitate the advancement of a driven pile is known as

predrilling. As per Section 49-1.05 of the Standard Specifications, the hole
drilled shall not be larger than the least dimension of the pile to be driven. This
method has the potential to impact pile capacity particularly for those that utilize
skin friction. Often the amount or depth of predrilling is limited to address this.
There should be information in the Contract Plans, the Foundation Report or the
Special Provisions that outlines these restrictions.

Driving tips strengthen the tip/toe of the pile so that it can penetrate through
obstructions and dense lenses. Cutting shoes are another form of driving tip that
allows piles with thinner wall thicknesses to be driven through dense lenses.
Closed ended steel pile may require a conical tip to facilitate driving and mitigate
damage to the pile.

Spudding is another method used to assist the penetration of piles through dense
lenses of material. It involves the use of a heavy or stout section to drive, break
or cut through a lens of hard material. The spud is removed after this is achieved
and the production pile driven in its place to the specified tip elevation.

Except for timber piles, the term “hard driving” or “difficult driving” may be
subject to individual interpretation as there is no language in the specifications
that define it. Steel or concrete piles have no measures specified to mitigate hard
driving at predetermined blow count levels. However, the Contractor is required
to employ the measures described above to obtain the required penetration and is
also required to use equipment that will not result in damage to the pile.

Section 49-1.07 outlines what to do when hard driving is encountered in timber

piles. When the blow count for timber piles exceeds either 2 times the blow count
required in one foot, or 3 times the blow count required in 3 inches for the

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nominal resistance, additional means are required to achieve the specified tip
elevation. These may include predrilling, jetting or changing hammers to one
with a heavy ram striking at a low velocity.

Physical damage to the pile, even when it is below ground, is fairly easy to
determine. Impending damage and/or high driving stresses are not as easy to
pinpoint. In situations of high driving resistance, the Engineer is advised to
investigate pile stresses. This can be done with Pile Driving Analysis (PDA)
equipment.

Because of the many variables involved, each hard driving issue must be
evaluated on its own merit. There is no substitute for engineering judgment in
this area. It should also be remembered that these issues are somewhat common
and there is a broad base of experience within the Office of Structure
Construction.

Piles typically are designed to meet several different design criteria (Tension,
Compression, Lateral, etc.) When compression controls the design the Engineer
has the flexibility to raise tip elevations to address hard driving. However these
tips should only be revised to the elevation of the next controlling criteria.
Chapter 3 of this Manual discusses this issue in detail.

While it may be important to make a distinction between hard driving that was
anticipated and what was not, it is in the best interest of all parties to work toward
resolution of the issue quickly and efficiently in order to mitigate impacts to the
project. There have been occasions where pile penetration to the specified tip
elevation cannot be accomplished, despite everyone’s best efforts. When this
situation occurs, the Engineer needs to be proactive in finding an alternative
solution. This includes conversation and meetings with Structure Design and
Geotechnical Services to find an alternative tip elevation, method or design to
address the challenge.

Soft Piles and Re-Drive

The Standard Specifications require the Contractor to satisfy requirements for

minimum nominal resistance and specified tip elevation. A pile that drove “soft”
is a pile that has been driven to the specified tip elevation but has not obtained the
minimum nominal resistance. There are several options that can be explored
when this occurs:

• Continue driving until the minimal nominal penetration can be

achieved.
• Install pile lugs on H-Piles as discussed in Bridge Construction
Memo 130-5.0

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• The pile can be “re-driven” several days after initial driving with the
expectation that the pile has “set up” over time.

There are advantages and disadvantages to selecting any of these options. The
first two options require field welding of steel piles so a welding quality control
plan will most likely need to be created or revised for this work. Another issue is
that the locations of field splices in piles may be limited to certain zones along the
pile. Some pile designs have a no-splice zone or a no-field splice zone in the
upper portion of the pile. This is because the loads and subsequent risks of plastic
hinging are high. As such, the contract plans or special provisions may not allow
field welding an extension on to a pile as the splice may fall within this zone.

The third option is a “re-drive” or “re-strike” of the pile. To do this, pile driving
is stopped when the pile is a certain distance above the specified tip elevation (a
few to several inches). The pile is then driven the remaining distance at a later
date. This allows the soil the time to “set-up” around the pile. The time required
for “set-up” depends on the soil and is anywhere from a day to a week. This
option is effective in cohesive soils but not so much in submerged and saturated
sands and gravels as there is little cohesion in these soil.

The Gates formula is still used for pile acceptance during re-strikes. However, it
is important to note that the formula uses the number of hammer blows it takes to
drive the last foot to determine nominal pile resistance. Since the distance driven
in a re-strike is less than one foot, the number of blows per foot will need to be
extrapolated from the field results based on the length of re-drive. The
extrapolated value will be used to determine nominal resistance in the Gates
formula.

Following are some ground conditions and the expected outcome after re-driving
to address soft piles:

CONDITION DESCRIPTION
1 Loose submerged fine uniform sand. Driving temporarily produces a quick
condition. Re-drive will probably not indicate any change in capacity.
2 Cohesive soil. Driving temporarily breaks down the soil structure, causing it
to lose a part of its compressive strength and shear value. Re-drive should
indicate increased capacity.
3 Saturated coarse-grained pervious material. May display high driving
resistance, but on re-drive will lose capacity as compared to the initial
driving. This could be due to changes in pore water pressure within the soil
mass.

On contracts where soft driving in clay materials is anticipated, specific re-drive

guidelines are frequently given in the Special provisions. The period is usually
set at a minimum of 12 hours. In addition, only a fixed percentage of the piles are

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re-driven (10% or a minimum of 2 per footing). However, when re-drive

requirements are not listed in the Special provisions, the Engineer can still utilize
this methodology.

Re-driving is a tool that the Engineer can use in an attempt to obtain an acceptable
pile even though the Standard Specifications may not discuss re-drives or specify
elapsed time before attempting a re-drive. Trial and error methods may have to
be employed to figure out the appropriate time to wait before re-driving. It is the
Engineer’s responsibility to determine what criteria will be used to determine pile
acceptability. At times piles will not attain minimum bearing at specified tip,
even when re-driven. When this happens the only option is to splice on additional
length and continue driving to a point where the nominal penetration is achieved.

Issues with soft piles frequently occur in steel “H” piles. When overdriving is
excessive, lugs or “stoppers” can be welded on the pile to mitigate the problem.
If lugs are not required by the contract, they can be added by change order.
Bridge Construction Memo 130-5.0 covers this in detail.

Alignment of Piles

The Engineer needs to verify that each pile is placed in the correct location and
that the alignment is plumb or at the required batter. This should occur often
during the first part of the drilling or driving of each pile and periodically
thereafter. This is extremely important when swinging leads are used for pile
driving as these leads lack the guides that fixed leads have. Alignment
corrections should be made if the pile begins to move out of line. In certain
instances, driving may need to be stopped during driving so that the pile can be
pulled and re-driven correctly.

While the Standard Specifications state “piles materially out of line will be
rejected”, there’s no tolerance provided in the specification that define when a
pile truly is or isn’t “materially out of line”. Some contracts have specific
tolerances outlined in the Special provisions that defines the criteria for
acceptable alignment and/or plumbness of the piles. This is usually due to special
considerations in the design of the structure and to clarify the designer’s intent.
Each situation should be analyzed separately and “engineering judgment” used in
making final determination as to the acceptability of any misaligned piles.

Overdriving

Occasionally the Contractor will want to overdrive prefabricated piles to avoid

cutting piles to grade. This can be allowed in most circumstances. However, no
payment is allowed for the additional length driven below the specified tip
elevation unless it is part of an ordered change to the specified tip elevation. This
subject is discussed in Bridge Construction Memo 130-6.0.

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Safety
The potential for accidents to occur during pile driving operations may be greater
than for any other construction operation. The pile-driving crane rigged with a set
of heavy leads and a hammer is unwieldy enough; add to it a long pile and a high
potential for danger exists. These risks increase when the hammer is in operation
as all the parts are moving and support equipment such as a steam or high-
pressure line are at capacity.

The following are some of the items that individuals inspecting piles should be
aware of, especially personnel new to construction:

ITEM NO. DESCRIPTION

1 Stand away from the pile when it is being picked and placed in the leads.
Sometimes the pile when dragged will move in a direction not anticipated.
2 Stand as far away from the operation as practical while still inspecting the
work.
3 Keep clear of any steam, air or hydraulic lines.
4 Watch the swing of the rig so as not to be hit by the counterweight.
5 Wear safety glasses. There is a high incident of flying debris during the
driving operation (dirt from piles, concrete from piles and steel chips).
6 Keep an eye on the operation in progress. Look out for falling tools and
materials from the pile butts. Watch the rig in case the leads start to fall or the
rig starts to tip.
7 Hearing protection is required due to high noise levels.
8 Have a planned route for rapid escape. If required to move quickly there will
not be time to look around first.
9 Wear old clothes. Park your car and stand upwind when possible. Diesel oil
does not wash out of clothes!
10 Look where you are walking. The protective covers may not be securely in
place over the predrilled holes.
11 Welding must not be viewed with the naked eye. Shield eyes when in the
vicinity of a welding operation and wear appropriate shaded eye protection
when near this work.

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CHAPTER

8 Static Pile Load Testing and Pile

Dynamic Analysis

Introduction
Chapter 1 of this Manual explained how Geotechnical Services performs a
foundation investigation for all new structures, widenings, strengthenings or
seismic retrofits. Under normal circumstances, the Geoprofessional assigned to
perform the investigation is able to gather enough information to recommend a
pile type and tip elevation that is capable of supporting the required loads on the
recommended pile foundation. However, there are situations where subsurface
strata are variable, unproven or of such poor quality that additional information is
needed in order to make solid pile foundation recommendations. In these
situations, a Static Pile Load Testing and/or Pile Dynamic Analysis (PDA) will be
recommended. Information obtained from the testing and/or PDA will be used to
verify design assumptions or modify foundation recommendations.

Personnel from the Foundation Testing Branch, a subgroup of Geotechnical

Support in Geotechnical Services performs Static Load Testing and PDA on
Caltrans projects. Once the testing is completed, written reports summarizing the
findings are transmitted to the Engineer. Ideally, these tests would be performed
in the Design Phase however they are often done in the Construction Phase.

Reasons For Static Load Testing and Pile Dynamic Analysis (PDA)
Static Load Tests measure the response of a pile under an applied load and are the
most accurate method for determining pile capacities. They can determine the
ultimate failure load of a foundation pile and determine its capacity to support
load without excessive or continuous displacement. The purpose of such tests is
to verify that the load capacity in the constructed pile is greater than the nominal
resistance (Compression, Tension, Lateral, etc.) used in the design. The best
results occur when pile load tests are performed in conjunction with Pile Dynamic
Analysis (PDA). The tests give the Geoprofessionals the information needed to
allow the use of a more “rational” foundation design.

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Static load tests may be recommended when piles are installed in soils with
variable geologies or poor quality soils and can be used to validate design
assumptions or to provide sufficient information to modify the design tip
elevations. They are often recommended for Cast-In-Drilled-Hole (CIDH) piles
installed in unproven ground formations as there is no other means to determine
capacity; unlike driven piles. They provide more accurate information than can
be obtained from pile driving formulas and may demonstrate that driven piles can
be safely loaded beyond the capacities obtained from these formulas.

Pile load tests are expensive to perform but provide value to a structure. The
FHWA publication “Static Testing of Deep Foundations” provides the following
recommendations on when to perform a pile load test. They are as follows:

• When there is a potential for large cost savings. Typically on large

projects with similar strata and pile types.
• When the safe loading condition is in doubt, due to limitations of an
Engineer’s experience base, or unusual site or project conditions.
• When soil or rock conditions vary considerably from one portion of a
project to another.
• When the design load is significantly higher than typical design loads.
• When time-related soil capacity changes are anticipated (i.e. soil setup
& relaxation)
• Determining the length of pre-cast friction piles so as to avoid splices
• When new or unproven pile types or installation methods are to be
used.
• When existing piles will be used to support a new structure with
heavier loads.
• To obtain a reliable value for tensile and lateral pile resistance.
• When, during construction, the load carrying capacity of the pile
differs significantly from what was predicted from pile driving
formulas and PDA.

In lieu of doing a static load test, PDA can be used to establish criteria for pile
acceptance and to verify design assumptions. It can determine soil resistance,
hammer efficiency/performance and stresses in the pile during driving. PDA is
performed on all contracts that have piles that require capacities larger than those
of the piles in the Standard Plans.

The information obtained from the PDA can also be used by other programs to
determine the bearing capacity of the pile. Combining these results with those
from the pile load test increases the accuracy when determining the bearing
capacity.

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Static Pile Load Tests

The static pile load test gives the most accurate indication of the capacity of the
in-place pile. It is performed using a reaction method. The test procedure
involves applying an axial load to the top of the test pile with one or more
hydraulic jacks. The reaction force is transferred to the anchor piles that go into
tension in the case of a static load test in compression; or into compression in the
case of a static load test in tension. Various forms of instrumentation are installed
onto the test and anchor piles so that an accurate measurement the test pile
displacement can be obtained. Redundant systems are used to ensure accuracy of
the various measurements.

A five-pile test group (four anchor piles and one test pile) is used for all static
load tests in compression and for most tension tests (Figure 8-1). Occasionally, a
three-pile test group (two anchor piles and one test pile) is used for static load
tests in tension. (Refer to Appendix F) Loads are applied in increments; typically
equal to 10% of the design load. Each increment of load is held for a
predetermined time interval. The load increments are applied until the pile starts
to “plunge”, or up to the point where the capacity of the testing system is reached.
The “plunge” point is where little or no additional load is needed to cause the pile
to displace. In general, a pile is considered to have failed when the total
displacement exceeds 1/2 inch under load. An acceptable pile is one that reaches
double the design load without exceeding this displacement.

FIGURE 8-1 Static pile load test (five-pile array)

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The Static Pile Load Test causes a failure along the soil/pile interface. This
failure generally occurs well before the ultimate structural capacity of the pile is
reached. Once the test is complete, the pile is returned to a no-load condition and
can be incorporated into the foundation of a structure. The only permanent effect
of a pile load test on a driven pile is the downward displacement of the test pile.
The same effect would be achieved if a pile hammer drove the pile the additional
distance. The previous statement, while true for driven piles, may not be the case
for Cast-in-Place piles and rock sockets in particular as these piles will not behave
the same once the bond between the concrete and the rock has been broken.

Once the pile load testing is completed, personnel from the Foundation Testing
Branch compile and review the load test data. The test data is used to produce a
plot of load versus pile displacement. The ultimate capacity of the test pile is
determined using graphical or analytical procedures. A summary report is then
forwarded to the Engineer, along with any recommended changes or
modifications to the design.

Static Pile Load Testing exceeds the standards set in the “Quick Load Method” of
ASTM D1143 for static load testing in compression, and ASTM D3689 for static
load testing in tension. Both the compression and tension load tests each take
approximately 4 to 8 hours to complete.

The Foundation Testing Branch has four static axial pile load test systems of
varying maximum load capacity:

• 4.5 Meganewton (1,000,000-pound) Load Test System

• 9 Meganewton (2,000,000-pound) Load Test System
• 17.5 Meganewton (4,000,000-pound) Load Test System
• 35 Meganewton (8,000,000-pound) Load Test System

Requests for Static Load Tests are made to the Foundation Testing Branch on the
Pile Load Test (PLT) Request Form. A copy of this form is included in Appendix
F and is available for download at:
http://www.dot.ca.gov/hq/esc/geotech/requests/plt.pdf

Pile Dynamic Analysis (PDA)

The dynamic analysis refers to the use of a device called the Pile Driving
Analyzer (PDA). The PDA consists of a portable computer that collects and
analyzes strains and accelerations measured by instrumentation attached to the
pile being driven.

The PDA operator inputs parameters related to the physical characteristics of the
pile before the pile analysis begins. Data to describe the surrounding soil and its

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damping resistance is also entered. The PDA is capable of analyzing the stress
wave produced along the length of the pile by each blow of the hammer during
the driving operation. By analyzing the shape of the wave trace, the PDA is able
to measure pile stresses generated during driving. During installation, damage to
a pile can often be detected by the PDA. The data retrieved during the analysis
can be used to determine the location or depth of a crack in a concrete pile and to
the point of buckling in a steel pile.

The PDA very accurately measures the energy delivered to the pile during
driving. This energy rating can be compared to the manufacturer’s rated value to
provide an indication of the hammer’s actual performance efficiencies. Low or
unusual delivery of energy to the pile may indicate issues such as a pre-ignition
problem within the hammer, inefficient hammer combustion, misalignment of the
follower or helmet, or the use of an inappropriate pile hammer cushion.

Pile Dynamic Analysis is believed to be very reliable for piles driven in granular
soils. For finer grained soils, such as silts and clays, this method may be less
reliable because these soils offer significantly larger damping resistance to the
piles during driving and may be difficult to model accurately.

Information retrieved by the PDA is also used to predict a pile’s static load
capacity. The dynamic analysis is performed on production piles as specified in
the Special Provisions and on the test and/or anchor piles used for a Static Load
Test if applicable. Piles monitored using the PDA are usually driven a
predetermined distance above the specified tip before the analysis begins. At that
time, the driving stops to allow personnel from the Foundation Testing Branch to
attach the necessary instrumentation to the pile. The instrumentation is attached
1-1/2 to 2 pile diameters from the top of the pile. Once installed, the Contractor
resumes driving the pile. The first few blows are done slowly to allow the PDA
Operator to ensure that the instrumentation is attached correctly and that the data
is transmitted to the PDA computer. Afterward, driving continues until the
specified tip elevation is reached. Is some soils, typically cohesive soils, the piles
may increase in capacity or “set-up” over time. When this is anticipated, the tip
of the pile is left approximately one-foot above the specified tip elevation.

After the “set-up” period has elapsed, the pile is ready for a restrike. The
timeframe for “set-up” is usually overnight but can be longer. Before the restrike,
PDA instrumentation is once again attached to the pile, and the last foot of the
pile marked in increments of one tenth of a foot. The pile is hit for a few blows to
make sure that the instrumentation is working properly. The pile is then driven
for several inches or the remainder of the one-foot length. The capacity of the
pile is determined from the PDA or through pile driving equations. The new
bearing capacity is compared to the one prior to “set-up” to determine the increase
in capacity over that period of time. The concept of pile capacities increasing
during a ”set-up” period is discussed fully in Chapter 7 of this Manual.

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Under normal circumstances, dynamic analysis is used in conjunction with static

load testing to determine the adequacy of foundation piles. As with Static Load
Testing, personnel from the Foundation Testing Branch are assigned the
responsibility for performing PDA on Caltrans projects. Requests for PDA are
submitted to the Foundation Testing Branch on the Pile Dynamic Analysis (PDA)
Test Request Form. A copy of this form is included in Appendix F and is
available for download at:
http://www.dot.ca.gov/hq/esc/geotech/requests/pda.pdf

Contract Administration of Static Pile Load Testing and Pile Dynamic

Analysis
At the beginning of any project requiring Static Pile Load Testing and/or Pile
Dynamic Analysis, the Engineer should do a thorough of review the project plans,
Special Provisions, Standard Specifications, and Bridge Construction Memo 130-
2.0 to make themselves aware of the contract requirements.

It is the Engineer’s responsibility to coordinate the Static Pile Load Testing and
Pile Dynamic Analysis with the Foundation Testing Branch. Early contact and
good communication with them is important, as it will ensure that the process
flows smoothly. The Contractor’s schedule for the installation of the piles should
be obtained as early as possible. This schedule should then be forwarded to the
Foundation Testing Branch. Details relating to the logistical needs of the testing
work crew should also be discussed with the Foundation Testing Branch and the
necessary information relayed to the Contractor.

Section 49-1.04 of the Standard Specifications states that the Contractor needs to
perform extra work to assist in the set-up and performance of the Static Pile Load
Testing. As such, a change order will need to be written to compensate these
expenses. This is not the case with Dynamic analysis as it is paid under the
contract item for piling or as indicated in the Contract Special Provisions. The
Contractor should be notified as early as possible of the specific equipment and
personnel assistance required by the Foundation Testing Branch in order to
complete the Static Pile Load Testing or PDA operations.

In general, for a Static Pile Load Test, the Contractor will need to provide a crane
and operator for the lifting and placement of the testing equipment from the State
transport trailers on to the pile array, and for returning the equipment to the trailer
once the testing is complete. The crane will need to be capable of lifting and
placing the appropriate load test beam atop the pile test groups. Occasionally, a
54,000-pound or larger beam is used for load testing. The actual beam size to be
used should be confirmed with the Foundation Testing Branch. The Foundation
Testing Branch will supply all necessary rigging. The Contractor will need to

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provide a welder, welding machine and cutting torches to assist in the installation
of the testing equipment. Specific logistical needs and project-specific issues
should be discussed with personnel from the Foundation Testing Branch to ensure
that efficient coordination of the test set-up is accomplished.

Section 49-1.04 of the Standard Specifications states that no piles may be drilled,
cast, cut to length or driven for a structure until the required Static Load Testing is
completed. In addition, the Engineer needs to ensure that the area of the Static
Load Testing and/or PDA is dry and free of debris. A safe working area should
be established around the test piles, and any of the Contractor’s operations that
conflict with the work of the testing work crews should be suspended until the
testing is complete.

Static Pile Load Testing on concrete piles cannot begin until the concrete reaches
a compressive strength of 2,000 Pounds per Square Inch (PSI), except for pre-cast
concrete piles, which cannot be driven until 14 days after casting. Additional
cement or Type III (high early) cement may be used at the Contractor’s expense.
The Standard Specifications state that the Engineer will not require more than 5
working days to perform each static load test unless otherwise provided in the
Special Provisions. This is important, in that the Department will be responsible
for any additional costs or delays to the schedule should the testing take longer or
should it not start on the day requested. As such, early and effective
communication with the Foundation Testing Branch is essential.

Inspection Requirements During Static Load Testing and PDA

As with production piles, it is very important that the Engineer ensure that all
piles to be used for Static Pile Load Testing and PDA are driven or constructed in
accordance with the contract plans and specifications. Since the Foundations
Testing Branch has several new testing devices, the Engineer should discuss and
confirm the load test pile array set-up well in advance of the work even if the
contract plans do adequately describe the test pile set-up.

Test piles must be installed plumb and to the specified tip elevation shown on the
plans. All the piles (anchor and test piles) in each test group need to be logged for
the full length of driving. For drilled piles, a soil classification record should be
kept for the full length of each. If any of the driven piles have a low bearing
value at the specified tip elevation (less than 50% of required), then the Engineer
should contact the Foundation Testing Branch, the Project Engineer and
Geoprofessional to see if a revision to the specified tip elevation is appropriate.
Changes to the specified tip elevation of test and/or anchor piles will necessitate a
contract change order.

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Additional work on the anchor and test piles is required to facilitate the test
apparatus. These details are included in the Standard Plans and may also be
shown on the contract plans. If the details are inappropriate for the piles or are
unclear, contact the Project Designer and/or the Foundation Testing Branch. The
reactions in the load test are substantial and proper bearing is essential. Therefore
the top of CIDH test piles must be level and troweled smooth to ensure full
contact/bearing of the load test reaction beam.

The contract plans or Special Provisions may require the anchor piles be
constructed to tip elevations lower than the test pile as an added precaution to
ensure that the piles don’t pull out during the test. This issue should be discussed
with the Foundation Testing Branch. Any changes to the lengths of the piles from
those shown on the plans will warrant a contract change order.

If a construction project includes Pile Dynamic Analysis, the Special Provisions

will state when the piles to be analyzed are to be made available for State
personnel so that the necessary preparations before these piles can be made before
they are driven. A technician from the Foundation Testing Branch will need
access to the piles to prepare them for the attachment of the necessary
instrumentation. The Engineer needs to ensure that the Contractor provides
assistance to the technician as necessary to maneuver the piles.

Once the load testing crew arrives on the jobsite, the Engineer will need to have
copies of the pile driving logs, soil classification record (for CIDH piles), Log of
Test Borings, and Foundation Plan available for their use. When the Static Pile
Load Testing and/or Pile Dynamic Analysis is completed, the Foundation Testing
Branch will provide a report that states whether or the testing confirmed design
assumptions or whether changes to the production piles will be necessary. These
changes are normally made without the need for additional load tests. If an
additional test is required, the Engineer should be sure to document any delays to
the Contractor’s operations. If additional testing is required, the State will be
responsible for additional costs incurred by the Contractor. Substantial pile
revisions (as a result of poor test results for example) could have a substantial
impact on administrative aspects of the contract. Changes could be such that item
prices for pile work are no longer valid and an item price adjustment may be
necessary.

Again, it is very important that Engineers set up a good line of communication

between themselves and the Foundation Testing Branch in the early stages of the
project. The goal should always be to have a clear understanding of what
coordination needs to be done in order to properly install the test piles and set up
the load testing equipment without significant delays to the project. Good
coordination is also important as it allows the static load testing work crews to
perform the tests efficiently and on schedule.

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CHAPTER

9 Slurry Displacement Piles

Introduction
A slurry displacement pile is a Cast-In-Drilled-Hole (CIDH) pile whose method
of construction differs from the usual CIDH pile in that a drilling fluid is
introduced into the excavation concurrently with the drilling operation. The
drilling fluid also referred to as slurry or drilling slurry, is used to prevent caving
of unstable ground formations and intrusion of groundwater into the drilled hole.
The drilling slurry remains in the drilled hole until it is displaced by concrete,
which is placed under the drilling slurry through a rigid delivery tube.

Because the slurry displacement method, also referred to as the wet method, is a
specific construction method for the construction of CIDH piles, the reader is
advised to review Chapter 6 of this manual as it contains information about
inspection duties and responsibilities of the Engineer for construction of all CIDH
piles. This chapter contains modifications to inspection duties and responsibilities
of the Engineer necessary for the construction of CIDH piles using the slurry
displacement method.

History
The use of drilling slurry is commonly associated with methods used by the oil
well drilling industry over the last 100 years, which naturally provided much of
the technical and practical knowledge concerning their use in drilled foundation
applications. Use of the slurry displacement method for constructing drilled shafts
began in Texas in the years following World War II. This early method involved
the use of soil-based drilling slurries to advance drilled holes deeper than they
could have without. After which a casing was used to stabilize the drilled hole for
shaft construction. In the 1960’s, processed clay mineral slurry was introduced as
a means of eliminating the need for casing to stabilize the drilled hole. However,
the properties of the mineral drilling slurries were not controlled. Initial
information on the properties of mineral drilling slurries was obtained from the

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Reese and Touma Research Report, which was a cooperative research program
conducted in 1972 by the University of Texas at Austin and the Texas Highway
Department. Due to the numerous failures that occurred, by the mid-1970’s, more
attention was paid to the physical properties of mineral drilling slurries and
appropriate methods of preparing and recirculating drilling slurries.

There are still many unknowns about the use of drilling slurries, among them the
effect of the drilling slurry on the ability of a pile shaft to develop skin friction.
Research done to date has given conflicting results; however most indicate that
pile capacities may be less than that of CIDH piles constructed without the use of
drilling slurry. However, the design method used by Caltrans for determining the
pile capacity adequately accounts for the potential loss of pile capacity when
drilling slurry is used. Research funded in part by the Federal Highway
Administration (FHWA) is ongoing at universities around the United States.
Caltrans has also conducted research on several contracts in recent years, which
has lead to the development of contract specifications for use of the slurry
displacement method of CIDH pile construction.

Processed clay mineral slurries are considered to be environmentally hazardous

and are difficult to dispose of. In the 1980’s, the drilled shaft industry began a
trend towards the use of synthetic drilling slurries. These drilling slurries are less
hazardous to the environment and are easier to dispose of.

Caltrans first used the slurry displacement method on a construction contract in

1984 and has increasingly used this method since then. A change in Caltrans
seismic design philosophy has resulted in the use of more and larger CIDH piles.
Because of this, ground conditions have become less of a factor in the pile type
selection process. Other factors such as lower construction costs and construction
in urban environments with restricted access and noise limitations have also led
towards the expanded use of CIDH piles. Because of these factors, Caltrans
started inserting the slurry displacement method specifications into all contracts
with CIDH piles in 1994.

Slurry Displacement Method

The slurry displacement method of construction is similar to that of ordinary
CIDH pile construction until groundwater or caving materials are encountered.
When groundwater or caving materials are encountered during the drilling
operation, the Contractor must decide whether to use a casing to stabilize the
drilled hole, dewater the drilled hole, or drill the hole and place concrete under
wet conditions using the slurry displacement method. In most cases, the site
conditions are known to be wet or unstable. These conditions should have been
shown on the Log of Test Borings or in the Foundation Report. Sometimes
experience on adjacent projects may also give an indication of the site conditions.

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FIGURE 9-1 Slurry displacement method

Drilling slurries are generally introduced into the drilled hole as soon as
groundwater or caving materials are encountered. As drilling continues to full
depth, the drilling slurry is maintained at a constant level until the tip elevation of
the drilled hole is reached (Figure 9-1(a)). Because the drilling operation mixes
soil cuttings with the drilling slurry, it is necessary to remove the soil cuttings
from the drilling slurry. Depending on the type of drilling slurry used, removing
the soil cuttings may be accomplished by physically cleaning the drilling slurry,
or by allowing a settlement period for the soil cuttings to settle out of the drilling
slurry (Figure 9-1(c)). If the drilling slurry is cleaned such that its physical
properties are within the specified limits for the particular type of drilling slurry,
the bottom of the drilled hole is cleaned of any settled materials using a cleanout
bucket (Figure 9-1(d)). Since the action of the cleanout bucket may cause soil
cuttings to recontaminate the drilling slurry, cleaning the bottom of the drilled
hole and the drilling slurry may take several iterations. Additional cleanings of
settled materials from the bottom of the drilled hole may be performed with a
cleanout bucket, pumps, or an airlift. After the final cleaning has been
accomplished, the drilling slurry is retested to make sure its properties are within
the specified limits. Once the drilling slurry is ready, the pile bar reinforcement
cage may be placed. The slurry is again retested immediately prior to concrete
placement. Once the slurry is within the specified limits, the concrete is placed;
either by a rigid tremie tube or by a rigid pump tube delivery system. Concrete is
placed through the tube(s), starting at the bottom of the drilled hole (Figure 9-
1(e)). The tip of the rigid delivery tube is maintained at least 10 feet below the

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rising head of concrete. As concrete is placed, the displaced drilling slurry is

pumped away from the hole and prepared for reuse or disposal. Concrete
placement continues until the head of concrete rises to the top of the pile and is
then wasted until all traces of settled material or drilling slurry contamination in
the concrete are no longer evident. Under circumstances where contaminated
concrete cannot be wasted from the top of the pile, such as having a pile
construction joint within a permanent casing below grade, pile concrete is placed
to a predetermined level above the planned concrete placement elevation, and the
contaminated concrete above the planned concrete placement elevation is either
mucked out immediately after placement or chipped out at a later time.

Principles of Slurry Usage

All slurries of whatever kind keep excavations open by the use of positive
hydrostatic pressure. In order to exert hydrostatic pressure against the walls of an
excavation, a pressure transfer medium must be present. With mineral slurries
(e.g. bentonite mud) the deposited filter cake of clay solids on permeable
formations is the pressure transfer mechanism (the thing against which the
hydrostatic pressure can push). In the case of properly formulated synthetic
slurries, the pressure transfer mechanism is the zone of viscous permeation that
surrounds the excavation. This zone is preferably permeated (and plugged) by
viscous polymer slurry. The depth of the zone around the excavation can be
inches or feet.

Positive hydrostatic pressure refers to the excess pressure exerted by a column of

fluid against the interstitial or pore pressure of a soil layer (Figure 9-2(a)). A
column of water 33 feet tall exerts a hydrostatic pressure of 1.0 atmosphere or
14.7 pounds per square inch. It has been determined by experience that a positive
hydrostatic pressure of about 6 to 7 feet of water head is normally sufficient to
keep an excavation open. This is equivalent to 0.2 atmospheres or about 3 pounds
per square inch. A more useful way to consider 3 pounds per square inch is that it
equals 432 pounds per square foot of excavation wall area. This is apparently
sufficient to keep most holes open when proper operating practices are in use.

“Positive hydrostatic pressure” also refers to hydrostatic pressure above and

beyond that exerted inward on an excavation by ground water (Figure 9-2(a) &
(b)). Thus if the static ground water table is at 15 feet below ground level, and if
we want to maintain a column of slurry 7 feet higher than that, we will need to
keep the slurry level at 8 feet below ground level. If excessive fluid loss is not a
concern, we may want to keep the hole full of fluid, but this is probably not
necessary in most cases. Excessive hydrostatic pressure can accelerate non-useful,
unwanted loss or permeation of slurry into granular permeable soil layers.

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FIGURE 9-2(a)(b) Positive hydrostatic pressure

As mentioned previously, the filter caking process created by mineral or solid-

laden slurries is called filtration. When drilling slurry is applying positive
hydrostatic pressure to the sides of the drilled hole, some of the drilling slurry and
soil cuttings may be forced out of the excavation and into the ground formation.
When this material enters the formation, particles of the drilling slurry may be
trapped or “filtered” by the individual soil grains of the formation. This results in
the development of filter cakes on the sides of the drilled hole. These filter cakes
are referred to as “mudcakes” and help to temporarily stabilize the sides of the
drilled hole.

The filtration process is dependent upon many variables. These include the nature
of the ground formation, the type of mineral drilling slurry used, the amount of
time the drilling slurry is in the drilled hole, the presence of contaminants or
groundwater in the ground formation, and the chemical additives used in the
drilling slurry, just to name a few. The nature of the ground formation and the

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amount of time the drilling slurry is in the drilled hole are the two important
variables.

The nature of the ground formation has an effect on the thickness of the filter cake
that mineral slurries or other solids-laden slurries develop on the sides of the
drilled hole. In general, thicker cakes will form on permeable granular ground
formations, such as sands. Since the pore spaces between the individual soil
grains are larger, drilling slurry with entrained soil particles can infiltrate further
into the ground formation driven by the same positive hydrostatic pressure.
(Figure 9-3(a)). Eventually, the infiltration slows as drilling slurry and particles
build up against and beyond the exposed faces of the permeable formations. In
tighter ground formations, such as dense sands and cohesive soils, the pore spaces
between the individual soil grains are much smaller. The drilling slurry particles
tend to fill in the pore spaces at the exposed wall face preventing further
infiltration (Figure 9-3(b)). Drilling slurry cannot be forced into the ground
formation by positive hydrostatic pressure. This causes the build-up of the filter
cake to cease; resulting in a thinner filter cake than would be observed in looser
ground formations.

FIGURE 9-3(a) Filtration – loose ground formation

The amount of time that the drilling slurry is in the drilled hole also has a direct
effect on the thickness of the filter cake that develops on the sides of the drilled
hole. As long as positive hydrostatic pressure is continuous, the build-up of filter
cake will continue so long as the infiltration continues. In general, the longer the
drilling slurry is present in the drilled hole, the more filter cake will accumulate
on the sides of the drilled hole. Sometimes this results in the presence of excess
filter cake buildup, which must be removed before concrete can be placed in the
drilled hole.

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FIGURE 9-3(b) Filtration – tight ground formation

The important thing to remember about filtration is that it mainly pertains to

mineral slurries or other solid-laden slurries and its filter cake helps to temporarily
stabilize the sides of the drilled hole before concrete is placed. Filter cake is not
meant to be left in place during concrete placement operations. If the filter cake is
thin enough, the rising column of concrete will scrape it off the sides of the drilled
hole. However, if the filter cake has excessive thickness, the rising column of
concrete may not scrape all of it off the sides of the drilled hole. The remaining
filter cake may act as a slip plane between the pile concrete and the sides of the
drilled hole, resulting in the reduced skin friction capability of the pile. Excess
filter cake must be removed prior to concrete placement.

In regards to synthetic slurries, these fluids permeate and exert hydrostatic

pressure against the walls of an excavation in order to keep the excavation open
during drilling or digging and concrete placement. These synthetic slurries that
consist of very long, chain-like hydrocarbon molecules (polymers) do not deposit
a conventional wall cake or filter cake as with mineral slurries because the fluids
are not laden with fine plate-shaped particles, such as bentonite.

Instead, a properly prepared synthetic polymer slurry permeates granular soils to a

relatively shallow penetration around an excavation with long, hair-shaped strands
of slurry molecules (Figure 9-3(c)). This permeation has a gluing effect and
stabilizes an excavation due to drag forces and cohesion formed from the binding
of the soil particles in the formation by the polymer strands that tend to keep the
soil particles in place.

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FIGURE 9-3(c) Stabilization with synthetic polymer slurry

The phrase “properly prepared” refers to slurry that is well-dispersed, lump-free

and viscous enough to impede filtration into granular formations. In some cases
partially-hydrated, dry synthetic polymer (viscous slurry full of “pearls” of
incompletely dissolved dry synthetic polymer product) may be useful in plugging
coarse granular soils and appears to be more effective than emulsion synthetic
polymers at controlling unwanted excessive fluid loss. These long chain
polymers also inhibit hydration, swelling and distortion of clay components or
layers in the soil formation.

Sampling and Testing Drilling Slurry

Sampling and testing of drilling slurry is an important quality control requirement.
Responsibility for testing and maintaining drilling slurry of high quality is placed
on the Contractor by the contract specifications. The Engineer is responsible for
performing quality assurance testing on the drilling slurry.

The apparatus used to sample drilling slurry must be capable of sampling the
drilling slurry at a given elevation in the drilled hole without being contaminated
by drilling slurry from a different elevation in the drilled hole. This is necessary
because the contract specifications require the drilling slurry to be sampled at
different levels in the drilled hole. The sampler must also be large enough to
contain enough drilling slurry to perform all the required tests. The apparatus
generally consists of a hollow tube with caps positioned above and below the tube
on a cable that is used to lower the sampler into the drilled hole (Figure 9-4).

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Once the sampler has been lowered to the desired level, the drilling slurry
contained in the hollow tube (at that level) is contained by activating the caps so
that the ends of the tube are sealed. The sampler is then removed from the drilled
hole and the drilling slurry contained is tested.

FIGURE 9-4 Slurry sampler schematic

One of the responsibilities of the Contractor is to verify that the sampler used
seals properly. The Engineer may require the Contractor to verify this before
allowing the construction of slurry displacement piles to commence.

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The primary engineering reason for testing drilling slurries is to make sure that no
suspended material in the drilling slurry settles out during concrete placement. A
secondary reason for testing drilling slurries is to control their properties during
the drilling of the hole. This helps to stabilize the drilled hole. Drilling slurries
that have physical properties within the parameters described in the contract
specifications should have negligible settlement of suspended materials during
concrete placement provided the pile’s bar reinforcement cage and concrete are
placed promptly.

The contract specifications set parameters for some of the physical properties of
drilling slurries. The four specified physical properties are density, sand content,
pH, and viscosity.

Density

Density, or unit weight, is a function of the amount of solids held in suspension

by the drilling slurry. Since mineral slurries will hold solids in suspension for long
periods, the allowable density value is higher than that permitted for synthetic
slurries and water, which do not hold solids in suspension as well. Its viscosity
may affect the density of the drilling slurry since a more viscous fluid will
suspend more solids. The reason for having an upper limit on the allowable
density value is that drilling slurries with higher densities are unstable with
respect to their ability to suspend solids. These solids could settle out during
concrete placement and cause pile defects.

FIGURE 9-5 Density test kit

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Density is tested using the test kit shown in Figure 9-5 in conformance with the
test method described in American Petroleum Institute (API) Recommended
Practice 13B-1, Section 1. This test method can be obtained by contacting the
Offices of Structure Construction in Sacramento or accessing its intranet website
at http://onramp.dot.ca.gov/hq/oscnet/.

Sand Content

Sand content is an important parameter to keep under control, particularly just

prior to concrete placement. Sand is defined as any material that will not pass
through a No. 200 sieve. Since mineral slurries will hold sand particles and other
solids in suspension, the allowable sand content value is higher than that
permitted for synthetic slurries and water, which do not hold these solids in
suspension as well. The primary reason for setting an upper limit on the sand
content value is to prevent significant amounts of sand from falling out of
suspension during concrete placement. A secondary reason for setting an upper
limit on the sand content value is that high sand content can increase the amount
of filter cake on the sides of the drilled hole in mineral slurries. This increased
filter cake might have to be physically removed before concrete could be placed
in the drilled hole. Allowing the filter cake to remain would decrease the skin
friction value of the pile, thereby reducing the pile capacity.

FIGURE 9-6 Sand content test kit

Sand content is tested using the test kit shown in Figure 9-6 in conformance with
the test method described in API Recommended Practice 13B-1, Section 5. This
test method can be obtained by contacting the Offices of Structure Construction in

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Sacramento or accessing its intranet website at

http://onramp.dot.ca.gov/hq/oscnet/.

pH Value

The pH value of drilling slurry is important to ensure as its value indicates

whether or not the drilling slurry is functioning properly. Mineral slurries that
have pH values outside the allowable range will not fully hydrate the clay mineral
and will not develop the expected viscosity. Synthetic slurries that are mixed in
water having pH values outside the allowable range may not become viscous at
all. Even though drilling slurries may be mixed in a controlled environment (such
as in a mixing tank), they will be affected by acids and organic material from the
groundwater or the soil once it is introduced into the hole. Mineral slurries may
flocculate and form a thick, soft filter cake if the slurry becomes too acidic or too
alkaline. Synthetic slurries may lose their viscosity and their ability to stabilize
the sides of the drilled hole if the slurry becomes too acidic or too alkaline.

The pH value of drilling slurry is tested using either a pH meter or pH paper.

Viscosity

Viscosity refers to the “thickness” of the drilling slurry. This property is measured
to determine whether the drilling slurry is too “thick”, allowing the suspension of
more solids than permitted, which would affect the density and sand content
values. On the other hand, some soils may require drilling slurry with a higher
viscosity during drilling to permit the formation of filter cake or to stabilize the
sides of the drilled hole in loose ground formations such as gravels. Thinner
drilling slurry tends to flow through a loose ground formation without building a
filter cake or providing stability. After the hole is drilled and a filter cake has
formed or the sides of the drilled hole have stabilized, the drilling slurry can be
thinned as required prior to concrete placement.

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FIGURE 9-7 Marsh funnel viscosity test kit

The viscosity of drilling slurry is tested using the test kit shown in Figure 9-7 in
conformance with the test method described in API Recommended Practice 13B-
1, Section 2.2. This test method can be obtained by contacting the Offices of
Structure Construction in Sacramento or accessing its intranet website at
http://onramp.dot.ca.gov/hq/oscnet/.

Types of Slurry
It is important to note that the type of drilling slurry to be used will depend on the
ground conditions encountered. Use of different types of drilling slurries may be
necessary to drill through different types of ground formations. It is conceivable
that different types of drilling slurries may need to be used on the same contract
because of varying ground conditions within the highway right-of-way. Some of
the factors that influence the decision of what type of drilling slurry to use include
economics, ground and groundwater contamination, ground temperature, air
temperature, and the type of ground formation being drilled through.

Ground conditions can also have an effect on drilling slurry behavior. Some of
these include acidity or alkalinity of groundwater, grain size of the soil, velocity
of groundwater flow through the ground formation, cementation and cohesion of
soil, and the presence of rock or clay structures in the ground formation. The
drilling slurry’s physical properties can be adjusted to account for some of these
conditions, or chemical additives may be necessary.

Because most drilling slurries are difficult and expensive to dispose, they are
often reused. Occasionally, drilling slurry is reused on another pile after

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completion of the previous pile. Sometimes, the drilling slurry is reused on or

from another contract.

The reuse of drilling slurries requires careful planning on the Contractor’s part.
Drilling slurries must be cleaned before they are reused. For mineral slurries, this
is accomplished through the use of desanding units and chemical additives. For
synthetic slurries, this is accomplished by allowing the contaminants to settle out.

The contract specifications do not prohibit the reuse of drilling slurry. However, it
still must meet the physical property requirements of the contract specifications.
Drilling slurries will degrade over time (usually measured in months). If a
Contractor proposes to reuse drilling slurry from a different contract, the Engineer
may want to have the physical properties of the drilling slurry tested prior to
placement in the drilled hole.

The types of drilling slurries that are permitted for use by Caltrans are detailed in
the following sections. Three types of drilling slurries are permitted: water,
mineral, and synthetic polymer.

Water

Water may be suitable as drilling slurry under the right conditions. Most drilling
contractors will try to use water as drilling slurry if the ground conditions are right
because it is inexpensive. However, use of water as drilling slurry is limited to
ground formations that are strong enough not to deform significantly during
drilling. The water level in the drilled hole must be maintained at least 6 to 7 feet
above the groundwater level in order to maintain positive effective stress on the
sides of the drilled hole. This is the only means of stabilization provided to the
sides of the drilled hole since water does not control filtration.

The contract specifications state that water may only be used as drilling slurry
when a temporary casing is used for the entire length of the drilled hole. Although
water has been allowed as drilling slurry in the past by the contract specifications,
history has shown that water was inappropriately chosen as drilling slurry for use
in holes drilled in unstable ground formations. This resulted in many defective
piles that required repair.

The question that may arise from this limitation is why the contract specifications
allow the use of water as drilling slurry at all. Retaining the limited use of water
as a drilling slurry allows a Contractor, who attempts to dewater a drilled hole
using a temporary casing and is unable to do so for whatever reason, to have the
option of using the water in the drilled hole as a drilling slurry to prevent unstable
conditions at the bottom of the drilled hole and to be able to place concrete.
Water may also be used as drilling slurry when a Rotator or Oscillator is used to
advance the drilled hole since the drilling casing acts as a temporary casing.

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The physical properties of water used as drilling slurry are not as critical as with
other types of drilling slurries. Water is capable of suspending sand and silt only
for short periods, usually less than 30 minutes. This allows soil cuttings to settle
to the bottom of the drilled hole fairly rapidly. Since the pH of water used as a
drilling slurry is not important and water will not become more viscous unless a
contaminant is introduced, the contract specifications set parameters for density
and sand content only. Testing these parameters verifies that most of the
suspended material has settled before final cleaning of the drilled hole and
concrete placement.

Water used as drilling slurry can be easily disposed of on site after settlement of
all suspended materials has occurred unless hazardous materials have
contaminated the water.

Mineral

Mineral slurries are processed from several different types of clay formations.
Although there are a number of different types of clay formations available, the
most commonly used consist of Bentonite and Attapulgite clay formations.

Bentonite is manufactured from a rock composed of clay minerals, named after

Fort Benton, Wyoming, where this particular type of rock was first found. Its
principal active constituent is the clay mineral montmorillonite, which hydrates in
water and provides suspension of sands and other solids.

Bentonite slurry is a mixture of powdered bentonite and water. Bentonite slurry

will flocculate (destabilize) in the presence of acids and ionized salts and is not
recommended for ground formations where salty water is present without the use
of chemical additives.

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FIGURE 9-8 Bentonite slurry

Attapulgite comes from a clay mineral that is native to Georgia. It is processed

from the clay mineral Palygorskite, and is similar in structure to bentonite.
However, it does not hydrate in water and will not flocculate in the presence of
acids and ionized salts and can be used in ground formations where salty water is
present. Slurries made from attapulgite do not control filtration well, and tend to
deposit thick filter cakes on the faces of permeable soils. Due to the transportation
expenses and rare usage of this type of slurry in California, its application in
Caltrans projects is unlikely.

Mineral slurries stabilize the sides of the drilled hole by positive hydrostatic
pressure and by filtration. Mineral slurries will penetrate deeper into more open
formations, such as gravels, and will form thicker filter cakes in these formations.
While filtration is desirable, a thick filter cake is not desirable because it is
necessary to remove it before concrete placement. Continuous agitation or
recirculation of the mineral slurry with removal of sand and other soil solids will
help reduce the thickness of the filter cake by reducing the amount of suspended
material in the mineral slurry.

The contract specifications require the removal of “caked slurry” from the sides
and bottom of the drilled hole before concrete is placed. “Caked slurry” is
considered to be an excessively thick filter cake that has formed on the sides or
bottom of the drilled hole. Because the amount of filter cake that forms on the
sides and bottom of the drilled hole depends on so many variables and because
research of the effect of filter cake on the ability of the pile to transfer load
through skin friction has not been completed, the Offices of Structure
Construction defines excessively thick filter cake as a filter cake that has formed

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in a drilled hole where mineral slurry has been continuously agitated or

recirculated in excess of 24 hours or a filter cake that has formed in a drilled hole
where mineral slurry has been unagitated in excess of 4 hours. Due to the fact that
each site is different, some engineering judgment should be exercised before
implementing this definition. There are other indicators that can be used to assist
the Engineer in making a judgment on the amount of filter cake present on the
sides and bottom of the drilled hole. One indicator is the level of mineral slurry in
the drilled hole. If the mineral slurry level is difficult to maintain at the required
level in the drilled hole, this is an indicator that the mineral slurry is continuously
being driven into the ground formation through the sides of the drilled hole. This
means that filter cake build-up is continuing and it is likely that the thickness of
the filter cake is excessive. However, if the mineral slurry level is stable in the
drilled hole, this is an indicator that the mineral slurry has clogged up the ground
formation on the sides of the drilled hole. This means that the filter cake buildup
would have ceased and it is likely that the thickness of the filter cake is not
excessive. Removal of excessively thick filter cake is accomplished by slightly
over boring the full length of the drilled hole.

The contract specifications require that mineral slurries be mixed and fully
hydrated in mixing tanks prior to placement in the drilled hole. Mixing and
hydration of mineral slurries usually requires several hours. One way to determine
that the mineral slurry is thoroughly hydrated is to take Marsh funnel viscosity
tests at different time intervals. In general, mineral slurries will achieve their
highest viscosity value when they have fully hydrated. Once the viscosity test
values have stabilized at their highest level, the mineral slurry can be assumed to
be fully mixed and fully hydrated, providing that the mineral slurry is smooth,
homogeneous and not flocculated or “clabbered”.

The physical properties of the mineral slurry should be carefully monitored while
the mineral slurry is in the drilled hole. The mineral slurry’s density, sand content,
and viscosity should be tested and the values maintained within the limits stated
in the contract specifications. This will prevent excessive suspended materials
and to keep the filter cake thickness on the sides of the drilled hole to a minimum.
The mineral slurry’s pH should be tested and maintained within the limits stated
in the contract specifications to prevent flocculation or destabilization. It should
be noted that it usually takes the Contractor some time to get the mineral slurry’s
properties within the limits stated in the contract specifications. The important
factor is to verify that the mineral slurry’s properties are within the limits stated in
the contract specifications prior to concrete placement.

While mineral slurries are present in the drilled hole, they must be agitated in
order to maintain their physical properties and to reduce the amount of filter cake
buildup on the sides of the drilled hole. In order to accomplish this, the contract
specifications require mineral slurries to be agitated by either of two methods: (1)
the mineral slurry is to be continuously agitated within the drilled hole, or (2) the

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mineral slurry is to be recirculated and cleaned. Either of these methods will

provide the necessary continuous agitation of the mineral slurry. The method that
is chosen will depend on the cleanliness of the mineral slurry in the drilled hole.
This is typically influenced by the ground conditions encountered.

Recirculation and cleaning of mineral slurries is accomplished by removing the

mineral slurry from the drilled hole, running it through specialized cleaning
equipment, and then placing the cleaned mineral slurry back in the drilled hole.
To meet all of the specification requirements, a slurry “plant”, which is
approximately the size of a railroad boxcar, must be located adjacent to the work
area (Figure 9-9). The slurry plant contains screens, shakers, desanding
centrifuges (Figure 9-10), and agitators, and is capable of mixing, storing, and
cleaning the mineral slurry. Figure 9-11 shows a typical recirculation and cleaning
process. It is very important to remove the mineral slurry from the bottom of the
drilled hole. This is because excessive amounts of suspended materials will
eventually settle to the bottom of it. These materials must be removed in order to
fully clean the mineral slurry. Typically, it will take several hours to completely
clean the mineral slurry of sand and other suspended materials.

FIGURE 9-9 Mineral slurry plant

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FIGURE 9-10 Desanding centrifuges

FIGURE 9-11 Recirculation and cleaning schematic

Usually, in order for the mineral slurry to meet the physical property requirements
of the contract specifications, the mineral slurry will require recirculation and
cleaning during and after the drilling operation. Occasionally without any action

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on the part of the Contractor, the mineral slurry will meet the physical property
requirements of the contract specifications during and after the drilling operation,
in which case continuous agitation of the mineral slurry in the drilled hole is
acceptable. However, the contract specifications also require that any mineral
slurry that is continuously agitated in the drilled hole and exceeds the physical
property requirements must be recirculated and cleaned.

Should the mineral slurry’s properties change dramatically during the drilling
operation, chemical additives are available that can reduce the filter cake
thickness, modify the mineral slurry’s pH, and increase the mineral slurry’s
viscosity. Additives that reduce the filter cake thickness and increase the mineral
slurry’s viscosity include organic colloids such as CMC or starch. Additives that
lower the mineral slurry’s pH include pyrophosphate acid (“SAPP”). Additives
such as soda ash and caustic soda (sodium hydroxide) can increase the slurry’s pH
and reduce water hardness. Additives that decrease the mineral slurry’s viscosity,
reduce gelatin and improve filter cake quality include tannins, polyphosphates,
lignosulfonates and acrylates. Caltrans has little experience with chemical
additives and their use should be discussed with the Offices of Structure
Construction in Sacramento before approval is given for their use.

Mineral slurries may be used in most types of ground formations. They work best
in cohesionless sands and open gravels. Caution must be taken when using
mineral slurries in cohesive materials because they may contain clays that can be
incorporated into the mineral slurry and rapidly change the mineral slurry’s
physical properties. In addition, these cohesive materials can reduce filtration and
filter cakes may not form.

Disposal of mineral slurries can be difficult. Due to their particulate nature, they
are hazardous to aquatic life and cannot be disposed of on site or at locations
where they can enter State waters. The contract specifications require that any
materials resulting from the placement of piles under mineral slurry be disposed
of outside the highway right-of-way in accordance with Section 7-1.13 of the
Standard Specifications. Because they often contain chemical additives, mineral
slurries can be considered to be hazardous materials that must be disposed of in
landfills. This can be very expensive and can defeat the economic advantage of
using the slurry displacement method over other means of construction of CIDH
piles.

Synthetic

Since the 1980’s, synthetic drilling slurries have gained wide acceptance in the
construction industry. The main advantage of synthetic slurries is that they are
easier and cheaper to dispose of than mineral slurries and do not require slurry
plants to physically clean the slurry. Synthetic slurries are grouped into three

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groups: (1) naturally occurring polymers, (2) semi-synthetic polymers, and (3)
synthetic polymers. Synthetic polymers are either dry or emulsified.

The synthetic products that are approved by Caltrans at the present time are
synthetic polymers mixed with water to prepare viscous slurries for CIDH piles
and other foundation elements. These slurries have been shown to have no
deleterious effects on concrete-to-rebar bonding, concrete compressive strength
and other aspects of foundation construction processes. The contract
specifications currently allow the use of four brands of synthetic slurries. These
are: Super Mud, manufactured by PDSCo, Inc.; SlurryPro CDP™, manufactured
by KB International LLC; Shore Pac®, manufactured by CETCO Construction
Drilling Products; and Novagel™, manufactured by Geo-Tech Services, LLC.

Super Mud is an emulsified (water-in-oil, liquid form) synthetic polymer product.

A liquid form of SuperMud is currently approved for use on Caltrans projects. No
other form is approved. (Figure 9-12)

FIGURE 9-12 SuperMud container

SlurryPro CDP™ is a dry form synthetic polymer slurry product. A dry granular
form of SlurryPro CDP™ is currently approved for use on Caltrans projects. No
other form is approved. (Figure 9-13)

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FIGURE 9-13 SlurryPro CDP container

Shore Pac® is a dry form synthetic polymer slurry product. A dry granular form
of Shore Pac® is currently approved for use on Caltrans projects. No other form
is approved. (Figure 9-14)

FIGURE 9-14 ShorePac container

Novagel™ is a dry form synthetic polymer slurry product. A dry granular form of
Novagel™ is currently approved for use on Caltrans projects. No other form is
approved. (Figure 9-15)

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FIGURE 9-15 Novagel container

Synthetic slurries must be thoroughly mixed but do not require additional time to
hydrate. This is because these slurries can achieve effectively complete hydration
in a short time. Water used to mix with the synthetic polymer should have a pH in
the range of 8 to 11 in order to properly disperse the polymer. A more acidic pH
will retard hydration of the slurry, causing poor performance. A mixing tank is
usually required in order to regulate the water. The manufacturers of the approved
synthetic slurries recommend tank mixing, but mixing directly into the drilled
hole by introducing these products into the flow of water is also acceptable to the
manufacturers.
The physical properties of synthetic slurries should be carefully monitored during
drilling of the hole and before concrete placement. Because these slurries in
general do not suspend particles, the permissible density and sand content values
are much lower than those allowed for mineral slurries. The density and sand
content values should be tested and the values maintained within the limits stated
in the contract specifications to allow for quick settlement of suspended materials.
The synthetic slurry’s pH value should be tested and maintained within the limits
stated in the contract specifications to prevent destabilization of the slurry. The
allowable limits described in the contract specifications for density, sand content,
and pH vary between Super Mud, SlurryPro CDP™, Shore Pac® and Novagel™
due to the extensive research that had been done by the manufacturers during the
Caltrans approval process.

The synthetic slurry’s viscosity value has a higher level of importance than that of
mineral slurry. The viscosity value should be tested and maintained within the
limits stated in the contract specifications to prevent destabilization of the sides of
the drilled hole. However, synthetic slurries at high viscosities may be capable of
suspending sand particles for longer than expected periods, causing the density
and sand content values to increase above their allowable limits. For this reason,
caution must be practiced when using synthetic slurries at high viscosities so that
particulate settlement on the head of concrete during concrete placement can be

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prevented. The allowable limits described in the contract specifications for

viscosity vary dramatically between Super Mud, Shore Pac®, Novagel™ and
SlurryPro CDP™. This is due to the extensive research that had been done by the
manufacturers during the Caltrans approval process. SlurryPro CDPTM and
Novagel™ are approved for very high viscosity values (>70 sec/quart) during
drilling operations to further ensure stability of the drilled hole. Only one
synthetic slurry, Novagel™, with a very high viscosity value up to 110 sec/quart
is approved for use during concrete placement.

In general, synthetic slurries will break down when they come in contact with
concrete. This is advantageous as long as the synthetic slurry is clean and the
rising head of concrete is the only concrete in contact with the synthetic slurry.
However, if concrete is allowed to intermingle with the synthetic slurry, the
synthetic slurry may break down and cause the sides of the drilled hole to
destabilize.

The contract specifications also require the presence of a manufacturer’s

representative to provide technical assistance and advice on the use of their
product before the synthetic slurry is introduced into the drilled hole. The
Engineer must approve the manufacturer’s representative. Assistance on approval
of a manufacturer’s representative may be obtained from the Offices of Structure
Construction in Sacramento. The manufacturer’s representative can provide
assistance with slurry property testing, can test the water to be used for
contaminants that may adversely affect the properties of the synthetic slurry and
the stability of the drilled hole, and can give advice in the proper disposal of the
slurry.

The manufacturer’s representative may also recommend the use of chemical

additives to adjust the synthetic slurry to the existing ground conditions. Caltrans
has little experience with chemical additives and their use should be discussed
with the Office of Structure Construction in Sacramento before approval is given
for their use.

The contract specifications also require the manufacturer representative to be

present until the Engineer is confident that the Contractor has a good working
knowledge of how to use the product. Once this occurs, the manufacturer’s
representative can be released. This can usually be accomplished within the
completion of one pile.

Synthetic drilling slurries can be used in most types of ground formations.

However, the contract specifications state that synthetic slurries shall not be used
in soils classified as “soft” or “very soft” cohesive soils. There are two reasons for
this. First, synthetic slurries will encapsulate and cause settlement of clay particles
from the soil cuttings. These encapsulated clay particles are similar in appearance
and size as sand particles and will cause excessively high false readings of the

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sand content test value. This problem may also occur in soils that are only slightly
cohesive. To overcome this problem, the Contractor should use a dilute bleach
solution or dilute acid solution instead of water to dilute the slurry sample and
wash the fines through the #200 mesh screen during the sand content test. This
will avoid agglomeration of clay particles so they will wash through the #200
mesh screen. Second, the synthetic slurry manufacturers have not completed the
research necessary to show that their products function properly in soils defined
as “soft” or “very soft” cohesive soils. If this research is successfully completed,
the contract specifications may be amended to remove this limitation.

Disposal of synthetic slurries is somewhat easier than disposal of mineral slurries.

The manufacturers of the approved synthetic slurries are attempting to get
approval for different disposal techniques. However, until they do so, the contract
specifications require all material resulting from the placement of piles, including
drilling slurry, shall be disposed of outside of the highway right-of-way as
described in Section 7-1.13 of the Standard Specifications unless otherwise
permitted by the Engineer. The Engineer may allow disposal by other means if the
proper permits are secured or permission is obtained from the appropriate
regulatory agency. Other means of disposal include placing the synthetic slurry in
a lined drying pit and allowing it to evaporate. The dried solids then can be
disposed of in a similar fashion as other jobsite spoils. Synthetic slurries can also
be broken down to the viscosity of plain water with chemical additives, allow
time for solids to settle out, and then be disposed of as clarified waste water.
Permission must be obtained from the responsible authority, usually the
California Regional Water Quality Control Board or the local sanitation district,
for this type of disposal. The dried solids can be disposed of as mentioned above.

Equipment
The equipment used to construct CIDH piles by the slurry displacement method
are not much different than that used to construct CIDH piles by ordinary means.
However, there are some differences in the drilling tools, drilling techniques,
cleaning techniques, and use of casings.

The primary reason that modified drilling tools and drilling techniques are used
has to do with the way drilling slurries work. The drilling contractor must be
careful not to do anything that would disturb the positive hydrostatic pressure
provided by the drilling slurry on the sides of the drilled hole. The drilling tool
can produce rapid pressure changes above and below it, similar to the effect of a
piston, if it is lifted or lowered too quickly. When these pressure changes are
produced, the drilled hole can collapse (Figure 9-16). This problem can be
remedied through the use of drilling tools that allow the drilling slurry to pass
through or around the tool during lifting and lowering. For augers, special steel
teeth are added to over bore the drilled hole so the diameter of the drilled hole is

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larger than the diameter of the auger. For drilling buckets and cleanout buckets,
special steel teeth are added to over bore the drilled hole, or the bucket itself may
be vented. Even with these modifications, the drilling technique must be modified
so that the drilling tool is not lowered or raised too rapidly through the drilling
slurry.

For reverse-circulation-drills rapid pressure changes due to raising or lowering the

drill head are reduced considerably, because the drill stem acts as an airlift that
removes drill cuttings from the bottom of the hole as it is being excavated. This
allows the drill to remain in the hole and, barring malfunctions, eliminates the
need to raise or lower it until the excavation is complete.

FIGURE 9-16 Hole collapse induced by pressure changes

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The techniques used to clean the bottom of the drilled hole are also modified for
use in drilling slurries. The initial cleaning of the bottom of the drilled hole is
done with a cleanout bucket so that the bottom of the drilled hole has a hard flat
surface (Figure 9-17). However, as sand particles settle out of suspension in the
drilling slurry, additional cleanings may be required. These additional cleanings
can be accomplished with a cleanout bucket, the combined use of a cleanout
bucket and pumps, or with a device known as an airlift (Figure 9-18). The airlift
device operates with air that is supplied to the bottom of the drilled hole by an air
compressor. This causes the settled sand particles to be lifted off the bottom of the
drilled hole and vented.

FIGURE 9-17 Cleanout bucket

For projects that utilize reverse circulation drills, typically the drill head is left at
the specified tip and allowed to spin for a certain amount of time. This allows the
airlift built into the drill stem to remove all large and small particles from the
bottom of the drilled hole. Once the drill stem and drill head are removed from the
hole, it may be necessary to remove more fine particles that may have settled out
of the slurry during removal of the drilling equipment. For these settled particles
a separate, smaller airlift or pump is typically used.

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FIGURE 9-18 Airlift schematic

The use of temporary casing may be appropriate in certain situations when the
slurry displacement method is used. Temporary casing may be necessary if a dry
loose material stratum or a loose material stratum with flowing groundwater is
encountered during drilling (Figure 9-19). Even drilling slurries with viscosity
values at the allowable maximum limit may not be able to stabilize a drilled hole
in these situations. It may be necessary to place temporary casing only where the
dry loose material strata or the loose material strata with flowing groundwater is
located and use mineral or synthetic drilling slurries to stabilize the remainder of
the drilled hole. Another option is to place – full-length – a temporary casing in
the drilled hole and use the water as the drilling slurry in order to avoid a quick
condition at the bottom of the drilled hole.

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FIGURE 9-19 Use of casing

Specifications
Because of the nature of slurry displacement construction, visual inspection of the
drilled shaft is not possible for much of the time. Most of the drilling and concrete
placement is done “in the blind”. As a result, the contract specifications for this
work are quite stringent in an attempt to minimize the risks and to ensure that the
pile has structural and geotechnical integrity. Some of the more critical
requirements of the contract specifications are discussed in the following sections.

Minimum Pile Diameter Requirements

Only piles 24 inches in diameter or greater may be constructed by the slurry

displacement method. This is because a pile with a lesser diameter does not

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contain enough room for the pile bar reinforcement cage, inspection tubes, and the
large concrete delivery tubes. If a contract specifies the use of piles with a
diameter of less than 24 inches, the Contractor may propose to increase the
diameter of the pile to at least 24 inches by the provisions described in Section
49-4.03 of the Standard Specifications if use of the slurry displacement method of
construction is desired. However, the diameter of the pile bar reinforcement cage
would have to be increased from the original size in order to accommodate the
items mentioned above.

Concrete Compressive Strength and Consistency Requirements

Before any pile construction work using the slurry displacement method can
begin, the Contractor shall demonstrate the concrete mix design can meet the
required compressive strength requirements and consistency requirements. This is
accomplished by producing a concrete test batch. The concrete test batch must
demonstrate the proposed concrete mix design achieves the specified nominal
penetration at the time of placement. For piles where the concrete placement
operation is expected to be 2 hours or less, the test batch shall demonstrate that
the proposed concrete mix design achieves either a penetration of at least 2 inches
or a slump of at least 5 inches after twice the time of the proposed concrete
placement operation. For piles where the concrete placement operation is
expected to be longer than 2 hours, the test batch shall demonstrate that the
proposed concrete mix design achieves either a penetration of at least 2 inches or
a slump of at least 5 inches after the time plus 2 hours of the proposed concrete
placement operation. The intent of this specification is to make sure the first load
of concrete placed in the drilled hole will remain sufficiently fluid as it rises to the
top of the pile. The concrete must also have a high fluidity in order to flow
through the pile bar reinforcement cage, compact and consolidate under its own
weight without the use of vibration, and to deliver high lateral stresses on the
sides of the drilled hole in order to keep the drilled hole from collapsing as the
drilling slurry is displaced and the filter cake (in the case of mineral slurries) is
scoured from the sides of the drilled hole by the rising column of concrete. The
concrete test batch and compressive strength requirement give the Engineer and
the Contractor the opportunity to observe how the concrete mix will behave
before it is used.

Slurry Testing and Cleaning Requirements

During pile construction work, the contract specifications require the Contractor
to sample and test the drilling slurry in order to control its physical properties.
The contract specifications also require that each type of drilling slurry be
sampled and tested at different intervals and locations.

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Mineral
For mineral slurries, samples shall be taken from the mixing tank for testing prior
to the mineral slurry’s introduction into the drilled hole. Once the mineral slurry
has been introduced into the drilled hole, the contract specifications require the
mineral slurry to undergo either recirculation or continuous agitation in the drilled
hole. The Contractor must address which method of agitation will be used in the
pile placement plan.

If the recirculation method is used, the contract specifications require the mineral
slurry to be cleaned as it is recirculated. This is done using a slurry plant, which
stores, recirculates, and cleans the mineral slurry. Samples for testing shall be
taken from the slurry plant storage tank and the bottom of the drilled hole. As the
mineral slurry is recirculated and cleaned, samples shall be taken every two hours
for testing until the test values for the samples taken at the two testing locations
are consistent. Once the test samples have consistent test values, the sampling and
testing frequency may be reduced to twice per work shift. As the recirculation and
cleaning process continues, the properties of the mineral slurry will eventually
conform to the specification parameters. Once the test samples have properties
within the specification parameters, the bottom of the drilled hole can be cleaned.

If the continuous agitation in the drilled hole method is used, the contract
specifications do not require the mineral slurry to be physically cleaned. Samples
for testing shall be taken at the mid-height and at the bottom of the drilled hole.
As the mineral slurry is continuously agitated, samples shall be taken every two
hours for testing. If the samples at the two locations do not have consistent test
values, the mineral slurry shall be recirculated. This means that the continuous
agitation in the drilled hole method is failing to keep the suspended particles in
the mineral slurry from settling. This is also an indication that the mineral slurry
is not clean enough to meet the specification parameters. Therefore, the
Contractor is required to abandon this method and use the recirculation method.
However, if the test samples do have consistent test properties within the
specification parameters, the bottom of the drilled hole can be cleaned.

Once the bottom of the drilled hole has been initially cleaned, recirculation or
continuous agitation in the drilled hole may be required to maintain the specified
properties of the mineral slurry. Usually the initial cleaning will stir up the settled
materials at the bottom of the drilled hole, thus requiring the mineral slurry to be
recleaned so it meets the requirements of the contract specifications. Several
iterations may be required before both the mineral slurry and the bottom of the
drilled hole are clean. To verify the cleanliness of the mineral slurry, the contract
specifications require additional samples to be taken for testing. Samples shall be
taken at the mid-height and at the bottom of the drilled hole. Once the test
samples show the mineral slurry’s properties to be within the specification
parameters and there is no settled material on the bottom of the drilled hole, the
last cleaning of the bottom of the drilled hole can be considered to be the final

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cleaning. At this point, the pile bar reinforcement cage can be placed. The
contract specifications require that samples for testing be taken just prior to
concrete placement to verify the properties of the mineral slurry. Samples shall be
taken at the mid-height and at the bottom of the drilled hole. If the test samples
have consistent test properties within the specification parameters, concrete may
be placed. Otherwise, additional cleaning of the mineral slurry and removal of
settled materials from the bottom of the drilled hole may be required.

The reason for testing mineral slurries at different levels is to make sure the
mineral slurries are well mixed and have consistent physical properties throughout
the length of the drilled hole. The mineral slurry’s physical properties should be
the same at both locations. This indicates that the mineral slurry is completely
mixed and that any sand or particles contained are in suspension.

Synthetic
For synthetic slurries, sampling for testing shall be conducted before, during, and
after the drilling operation, and as necessary to verify and control the physical
properties of the slurry. Samples shall be taken at the mid-height and at the
bottom of the drilled hole. Once the drilling operation has been completed,
additional samples for testing shall be taken. When the synthetic slurry’s physical
properties are consistent at the two sampling locations and meet the requirements
of the contract specifications, the bottom of the drilled hole can be cleaned.

Synthetic slurries are cleaned by allowing for an unagitated settlement period,

usually of about 30 minutes in length. Because synthetic slurries in general will
not suspend sands, the sands will settle to the bottom of the drilled hole during the
settlement period.

Once the bottom of the drilled hole has been initially cleaned, further settlement
periods may be required. Usually, the initial cleaning will stir up the settled
materials at the bottom of the drilled hole, thus requiring the synthetic slurry to be
recleaned so it meets the requirements of the contract specifications. Several
iterations may be required before both the synthetic slurry and the bottom of the
drilled hole are clean. To verify the cleanliness of the synthetic slurry, the contract
specifications require additional samples to be taken for testing. Samples shall be
taken at the mid-height and at the bottom of the drilled hole. Once the test
samples show the synthetic slurry’s properties to be within the specification
parameters and there is no settled material on the bottom of the drilled hole, the
last cleaning of the bottom of the drilled hole can be considered to be the final
cleaning. At this point, the pile bar reinforcement cage can be placed. The
contract specifications require that samples for testing be taken just prior to
concrete placement to verify the properties of the synthetic slurry. Samples shall
be taken at the mid-height and at the bottom of the drilled hole. If the test samples
have consistent test properties within the specification parameters, concrete may

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be placed. Otherwise, additional settlement periods and removal of settled

materials from the bottom of the drilled hole may be required.

The reason for testing synthetic slurries at different levels is to make sure the
synthetic slurries are well mixed and have consistent physical properties
throughout the length of the drilled hole.

The intent of these specifications is to ensure that the drilling slurry is properly
mixed in order to provide stability to the drilled hole and to control the amount of
suspended materials in the drilling slurry that may settle during placement of the
pile bar reinforcement cage and concrete.

Pile Acceptance Testing Access Requirements

During pile construction work, the contract specifications require the installation
of inspection tubes at specific intervals around the perimeter of the pile bar
reinforcement cage. This is necessary to provide access for acceptance testing.

Pile Concrete Placement Requirements

During pile construction work, the contract specifications require that concrete
shall be placed through rigid tremie tubes with a minimum diameter of 10 inches
or through rigid pump tubes. The tubes are required to be capped or plugged with
watertight plugs that will disengage once the tubes are charged with concrete. The
tip of the concrete placement tube is required to be located a minimum of 10 feet
below the rising head of concrete.

The concrete placement operation for a CIDH pile constructed under drilling
slurry is an operation that requires much preplanning. Before the work begins, the
contract specifications require the concrete mix design to meet the trial batch
requirements for compressive strength concrete. These requirements are described
in the contract special provisions. The concrete mix must contain at least 675
pounds of cementitious material per cubic yard. It is also important to compare
the maximum aggregate size in the concrete mix design to the bar reinforcement
spacing. The bar spacing should be no less than five (5) times the maximum
aggregate size and preferably larger than five (5) inches. The Project Designer
should be contacted if this is not the case. A concrete test batch is also required to
show the concrete mix design meets the consistency requirements of the contract
specifications. The concrete consistency requirements are to ensure that the
concrete will remain fluid throughout the length of the pour. The Engineer shall
not allow the Contractor to exceed the maximum allowable water requirement to
achieve this goal. Chemical admixtures will most likely be necessary. It is also
important for the concrete mix to be properly proportioned to prevent excess
bleed water due to the high fluidity of the concrete.

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The method of concrete placement should not permit the intermingling of

concrete and drilling slurry. The contract specifications allow placement of
concrete through rigid tremie tubes, or through rigid tubes connected directly to a
concrete pump. In order to prevent intermingling of concrete and drilling slurry,
the concrete placement tubes must be capped with a watertight cap or plugged
such that the concrete will not come into contact with the drilling slurry within the
concrete placement tube. The cap or plug should be designed to release when the
placement tube is charged with concrete. Charging the placement tube with
concrete shall not begin until the capped or plugged tip of the placement tube is
resting on the bottom of the drilled hole. Once the placement tube has been
charged, the pour is initiated by lifting the tip of the placement tube 6 inches
above the bottom of the drilled hole. This allows the concrete in the placement
tube to force the cap or plug out of the placement tube and discharge.

Once the pour has started, it is important to place the concrete at a high rate until
the tip of the placement tube is embedded in the concrete. If concrete placement
operations slow or stop before the tip of the placement tube is embedded in
concrete, there is nothing to prevent the intrusion of drilling slurry into the
placement tube. If this happens, the likely result will be a defect at the tip of the
pile.

When concrete placement begins, the tip of the concrete placement tube shall not
be raised from 6 inches above the bottom of the drilled hole until a minimum of
10 feet of concrete has been placed in the pile. After this level is reached, the tip
of the concrete placement tube shall be maintained at a minimum of 10 feet below
the rising head of concrete. The best way to verify that the tip of the concrete
placement tube is being maintained at this is for the Contractor to mark intervals
of known distance on the placement tube and to measure the distance from the top
of the pile to the rising head of concrete with a weighted tape measure.

If for some reason concrete placement is interrupted such that the placement tube
must be removed from the concrete, the placement tube should be cleaned,
capped, and pushed at least 10 feet into the concrete head before restarting
concrete placement. Concrete placement continues in this manner until the rising
head of concrete reaches the top of the pile. Concrete is then wasted until all
traces of particle settlement and drilling slurry contamination are no longer
evident.

Vibration of the pile concrete is not necessary because concrete with high fluidity
self-consolidates under the high hydrostatic pressure provided.

The intent of these specifications is to prevent the concrete from intermingling

with the drilling slurry during concrete placement.

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Inspection and Contract Administration

The reader is advised to review this section in Chapter 6 of this manual. All
inspection and contract administration information listed therein, with the
exception of items that are precluded by the presence of slurry in the drilled hole,
are applicable to CIDH piles constructed using the slurry displacement method.
This section outlines the additional requirements for CIDH piles constructed using
the slurry displacement method.

The specifications require the Contractor to submit to the Engineer a Pile

Placement Plan for review and approval. The Pile Placement Plan should provide
sufficient detail for the Engineer to grasp the means, methods and materials the
Contractor plans to use to successfully complete pile placement. Typical
requirements include those listed in Chapter 6 of this manual, as well as additional
requirements including the following:

ITEM PILE PLACEMENT PLAN REQUIREMENT & REASONING

1 Concrete batching, delivery, and placing systems, including time schedules and
capacities. Time schedules shall include the time required for each concrete
placing operation at each pile.
Reasoning: This gives the Engineer advance knowledge of how, when,
and how long it will take for the Contractor to place concrete in each pile
and whether the proposal is appropriate. Time schedules are also
necessary to determine the amount of time required for the concrete test
batch.
2 Concrete placing rate calculations. When requested by the Engineer, calculations
shall be based on the initial pump pressures or static head on the concrete and
losses throughout the placing system, including anticipated head of slurry and
concrete to be displaced.
Reasoning: This gives the Engineer additional knowledge of how the
Contractor proposes to place concrete in each CIDH pile and is considered
supplementary information for Item 1. This information is especially
important for large deep piles as it will be used to verify whether the
proposed concrete delivery system has enough pressure to displace the
anticipated head of slurry and the fluid concrete placed in the pile.
3 Suppliers’ test reports on the physical and chemical properties of the slurry and any
proposed slurry chemical additives, including Material Safety Data Sheet.
Reasoning: This gives the Engineer advance knowledge of the slurry and
any chemical additives that the Contractor proposes to use and whether the
proposal is appropriate for each pile.
4 Slurry testing equipment and procedures.
Reasoning: This gives the Engineer advance knowledge of the slurry
testing equipment and procedures to verify that they are in accordance
with the requirements of the specifications.
5 Methods of removal and disposal of excavation, slurry, and contaminated concrete,
including removal rates.
Reasoning: This gives the Engineer advance knowledge of the means the
Contractor proposes to use for disposal of spoils from CIDH pile
construction and whether the proposal is appropriate and in conformance

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ITEM PILE PLACEMENT PLAN REQUIREMENT & REASONING

with Section 7-1.13 of the Standard Specifications.
6 Methods and equipment for slurry agitating, recirculating, and cleaning.
Reasoning: This gives the Engineer advance knowledge of the means the
Contractor proposes to use for mixing, circulating, cleaning and reusing
the slurry. This is especially important if the Contractor proposes to use
mineral slurry.

In order to facilitate pile testing, the contract specifications require the installation
of inspection tubes (Figure 9-20). Before the cage is placed in the drilled hole,
the Engineer should verify that these tubes are installed inside the spiral or hoop
reinforcement and are at least 3 inches away from the vertical reinforcement of
the pile bar reinforcement cage. Figure 9-21 shows a typical inspection tube
layout and spacing pattern within the pile bar reinforcement cage. These tubes
must be placed in a straight alignment, securely fastened in place, and be
watertight. These tubes permit the insertion of a Gamma-Gamma Logging test
probe that measures the density of the pile concrete. The most commonly used
test probe is 1.25 inches in diameter and 54 inches in length. If the inspection
tubes are not placed in a straight alignment or are not securely fastened, the test
probe will not fit in the inspection tube. One way of testing the tube would be to
try to deflect it by hand. If it can be deflected by hand, it may be deflected by the
placement of concrete. It is also recommended that the Contractor install a rigid
rod in each inspection tube prior to concrete placement to ensure that the
inspection tubes remain straight during and after concrete placement. . Inspection
tubes need to be filled with water prior to the start of concrete placement. The
reason for this is to prevent the inspection tube from separating from the pile
concrete (debonding) or overheating during the curing process. This helps keep
the inspection tube intact so that it can be used for crosshole sonic logging at a
later point if necessary. Once the inspection tube has separated or had airspace
created between it and the pile concrete, crosshole sonic logging can no longer be
performed because the airspace registers as an anomaly.

The specifications also require the Contractor to log the locations of any
inspection tube couplers and submit the log to the Engineer. This is necessary
because inspection tube couplers show up as areas of lower density when a
gamma ray scattering test is performed. Testing personnel can ignore these areas
if they are aware of the coupler locations.

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FIGURE 9-20 Inspection tubes

FIGURE 9-21 Location of inspection tubes within the pile

The Engineer shall notify the Foundation Testing Branch, Office of Geotechnical
Support and Geotechnical Services as soon as the proposed pile concrete
placement date is known, in accordance with the provisions of Bridge

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 __________________________________________November 2008_

Construction Memo 130-1.0. This places the Foundation Testing Branch on

notice that acceptance testing will be required and approximately when it will be
needed.

The Engineer should be present when the slurry manufacturer’s representative is

on site to verify the slurry is mixed, placed, tested, and disposed of or cleaned in
accordance with the provisions of the approved Pile Placement Plan and the
contract specifications. The Engineer should also perform side-by-side slurry
tests with the Contractor or manufacturer’s representative at least once per job.
Slurry testing equipment is available from the Bridge Construction Engineer.

During drilling operations, the Engineer should monitor the height of the slurry in
the drilled hole to verify that positive hydrostatic pressure is being maintained on
the sides of the drilled hole.

Prior to placement of concrete, the Engineer should verify the properties of the
slurry are within the specification requirements and that the bottom of the drilled
hole is clean in accordance with the provisions of the approved Pile Placement
Plan. This is very important because settled materials left at the bottom of the pile
cause over 50% of all pile defects.

Concrete placement warrants continuous inspection. Engineers should verify that

all equipment needed to measure the height of the concrete placed in the pile, the
depth of the concrete placement tube within the head of concrete, and the volume
of concrete placed in the pile in accordance with the provisions of the Pile
Placement Plan are on site and ready for use. During concrete placement
operations, the Engineer should verify that the concrete placement tube is always
at least 10 feet below the free surface of the in-place concrete. The specifications
require the Contractor to maintain a log of concrete placement for each pile and to
deliver the completed log to the Engineer after completion of concrete placement
in each pile. This log is used to pinpoint any potential problem zones within the
pile that may have occurred during concrete placement. Potential problem zones
are denoted on the log by marked differences between the actual amount of
concrete placed and the theoretical amount of concrete that should have been
placed at the same elevation within the pile.

Pile Acceptance Testing

After concrete placement and before acceptance testing is performed, the
inspection tubes shall be checked by the Contractor for blockages and straightness
with a dummy probe that is the same size and shape as the gamma ray scattering
test probe in accordance with the contract specifications. The contract
specifications allow the Contractor to use two different sized dummy probes to
test the inspection tubes for blockages and straightness because there are currently

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two different sized Gamma-Gamma Logging (GGL) test probes in use.

Inspection tubes that cannot accept either of the dummy probes shall immediately
be refilled with water. They must also be replaced with a 2-inch diameter cored
hole the full length of the pile. The Engineer should discuss this requirement with
members of the DES CIDH Pile Committee before any coring is performed. The
reason the inspection tubes must be refilled with water is as discussed in the
previous Section it is essential to keep the PVC tubes filled with water during the
entire curing process to reduce debonding problems.

FIGURE 9-22 Gamma-gamma logging test schematic

Determining the soundness of slurry displacement piles is of understandable

concern. There are a number of methods that may be used to test the soundness of
these piles. One method is the use of external vibration, which measures stress
wave propagations in the pile using either internal or external receivers. This
requires a variety of expensive electronic gear and skilled operators, as well as the
placement of instrumentation on the pile bar reinforcement cage prior to concrete

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placement. Another method uses an acoustical technique, which is commonly

referred to as crosshole sonic logging. This involves lowering sender and receiver
probes into the inspection tubes to measure the velocity of sonic waves through
the concrete. Defective concrete is registered by the increased amount of time it
takes for the sonic wave to be received by the receiver probe, as opposed to the
shorter amount of time it takes for the sonic wave to be received across a solid
medium (sound concrete). A third method would be to core the pile and recover
the physical cores for inspection. This method may be the most conclusive, but is
very time consuming and is destructive. A fourth method uses a radiographic
technique called Gamma-Gamma Logging (GGL) (Figure 9-22).

The contract specifications state that the Gamma-Gamma Logging (GGL) method
of testing piles constructed using the slurry displacement method will be used to
determine acceptance of the pile, in accordance with the provisions of California
Test Method 233.

In Gamma-Gamma Logging (GGL) testing, scatter counts are taken and

compared to counts taken on a standard containing the same material being tested.
By this means, relative densities can be ascertained. In general, the lower the
scatter count, the more dense the material. The nuclear probe used in these tests
contains a source which is relatively weak - a plus, considering the precautions
that would otherwise have to be taken - and its effective range of sensitivity is
limited to a 3 inch radius of concrete around the inspection tube. Because of the
nature of the data acquired, proper assessment or determination of the existence of
defective concrete or voids is subject to interpretation of the results. Typical
testing consists of continuous counts taken as the test probe is raised from the tip
of the pile at 10 to 12 feet per minute. This procedure requires about 2 hours to
log all of the inspection tubes for a 100-foot length pile.

The contract specifications also state that crosshole sonic logging or other means
of inspection may be used to perform acceptance testing. Typically, crosshole
sonic logging or other means of inspection are used to complement the results of
the Gamma-Gamma Logging (GGL) test and are only performed after gamma ray
scattering testing has been performed and the pile has been rejected.

All test methods used to accept CIDH piles constructed under slurry are
performed by Caltrans personnel from the Foundation Testing Branch, Office of
Geotechnical Support, Geotechnical Services, or by consultant personnel under the
auspices of the Foundation Testing Branch. The results of such testing, which
include a recommendation of acceptance or rejection of the pile, are reported to
the Engineer in writing. An example of these results can be found in Appendix G.

Further information on pile acceptance testing may be found at the Foundation

Testing Branch web page, located at
http://www.dot.ca.gov/hq/esc/geotech/ft/gamma.htm

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The Engineer has the responsibility for accepting or rejecting a pile based on the
recommendations of the Foundation Testing Branch. If the pile is accepted, the
inspection tubes may be cleaned and grouted, and the pile is complete.

Defective Piles
What causes piles constructed by the slurry displacement method to be defective?
One of the primary reasons for pile defects is a problem caused by the presence of
settled materials at the bottom of the drilled hole. These are materials that were
held in suspension by the drilling slurry that settled out of suspension either
before or during the concrete placement operation. These materials can also be the
result of improper cleaning of the base of the drilled hole. These materials can be
trapped at the bottom of the pile by concrete placement as shown in Figure 9-
23(a) or they can be enveloped and lifted by the fluid concrete only to become
caught by the pile bar reinforcement cage or against the sides of the drilled hole
and not be displaced by the fluid concrete as shown on Figure 9-23(b). These
materials can also fall out of suspension and settle onto the head of concrete
during concrete placement, become enveloped by the concrete, and attach to the
pile bar reinforcement cage or the sides of the drilled hole as previously
described. These deposits will register on the pile testing results as areas of lower
density than that of sound concrete. Excessive amounts of settled materials can
occur in mineral slurries that were not properly cleaned or agitated and carry
inordinate amounts of suspended materials. Excessive amounts of settled
materials can occur in synthetic slurries when not enough time is allowed for the
materials to settle out before the final cleaning of the bottom of the drilled hole or
if the synthetic slurry becomes contaminated from clay-particle encapsulation.

Another reason for pile defects is due to improper drilling slurry handling. If
mineral slurries are not properly mixed and are not allowed to properly hydrate,
they can form balls or clumps that can become attached to the pile bar
reinforcement cage and not be removed by concrete placement as is shown in
Figure 9-24. Mineral slurries that remain in the drilled hole for too long can form
a filter cake that is too thick for the fluid concrete to scour off the sides of the
drilled hole as is shown in Figure 9-25. Mineral and synthetic slurries that carry
an excessive load of suspended materials can be subject to precipitation if an
unexpected chemical reaction takes place. This is possible if the concrete is
dropped through the drilling slurry.

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FIGURE 9-23 (a) (b) Defects from settled materials

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FIGURE 9-24 FIGURE 9-25

Defect from improperly mixed Defect from excess filter cake buildup
mineral slurry

A third reason for pile defects is concrete mix design and placement problems.
The most common defect of this type occurs when an insufficient amount of
slurry-contaminated concrete is wasted from the top of the pile during concrete
placement, resulting in a defective pile top. To avoid this type of defect, it is
recommended that the volume of concrete to a depth of one pile diameter within
the pile be wasted. A less common defect can occur when the seal between the
head of concrete and the drilling slurry is lost. This is because entrapment of
drilling slurry within the concrete is almost inevitable under this circumstance
(Figure 9-26). If the concrete placement tube loses its seal and allows concrete
from the placement tube to drop through the drilling slurry onto the head of
concrete, the drilling slurry and any settled material on the head of concrete could
be trapped between the concrete layers, causing a pile defect. Typically this
occurs when the concrete placement tube is removed too rapidly and pulled out of
the concrete head. Another less common defect can occur if the concrete head
begins to set, resulting in the concrete “folding” over as it rises through the pile
bar reinforcement cage and entrapping drilling slurry and any settled materials as
previously described. Yet another type of pile defect can result due to concrete
mix design problems. The Engineer should not permit the use of excess water in
the concrete mix design or allow additional water to be mixed with the concrete at
the jobsite to provide the necessary fluidity. This may result in severe bleed water

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from the concrete after placement, which could indicate segregation and
subsidence of the pile concrete. This may cause the entire pile to be defective. If
excess free water in the concrete is present when synthetic slurries are used, the
excess free water will attract the polymer chains from the drilling slurry into the
concrete and produce a material contaminant known as oatmeal at the concrete-
slurry interface. This material can potentially be caught on the pile bar
reinforcement cage and cause pile defects.

FIGURE 9-26 Defect from concrete placement problems

These types of problems can be avoided if the Contractor and the Engineer
closely follow the parameters specified in the contract specifications. These
specifications help to ensure the proper mixing and properties of drilling slurries,
the proper qualities of the concrete mix design, and the proper methods of
concrete placement.

If the Foundation Testing Branch recommends rejection of the pile and the
Engineer rejects the pile, the Contractor shall be informed in writing that the pile
is rejected and given a copy of the test results. The contract specifications also
require that the placement of concrete under drilling slurry be suspended until
written modifications to the method of pile construction are submitted to and
approved by the Engineer. This is to prevent additional failures due to the method
of pile construction.

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Pile Mitigation and Acceptance

What Happens When a Pile is Rejected

Once a pile has been rejected, the Contractor has several options. The defect can
be accessed and repaired, the pile can be supplemented, the pile can be replaced,
or the Contractor may propose a solution that allows the pile to remain in place.
The Contractor’s proposal is submitted to the Engineer in the form of a Pile
Mitigation Plan. For whatever solution the Contractor proposes, additional
investigation will be necessary to determine the nature and extent of the defect.

When a pile has been rejected, the Engineer should confer with the Foundation
Testing Branch and decide if the Foundation Testing Branch will perform
crosshole sonic logging on the rejected pile. Crosshole sonic logging is used to
further delineate the nature of the defective area within the rejected pile.
Generally, this test method is used to determine whether the defective area is
within the core of the pile or at the perimeter surrounding the bar reinforcement
cage. If crosshole sonic logging is performed, the results of this test should be
made available to the Contractor to aid in the preparation of their Pile Mitigation
Plan.

The Contractor may also perform an investigation on the rejected pile. They may
perform their own non-destructive testing or may core the pile to further
determine the nature of the defective area of the rejected pile. The Contractor
should submit the results of their investigation to the Engineer and use the results
of their investigation in preparation of their Pile Mitigation Plan.

Pile Mitigation Methods – Repairs, Replace, Supplement

There are several ways to mitigate a pile once it has been determined to have
anomalies and been rejected. The pile can be repaired, replaced or supplemented
in some way. The following sub-sections address how to take corrective action
on a rejected pile.

REPAIRS

Basic Repair

Basic repair is simply the mechanical removal and replacement of any

concrete within the defective zone of the pile, as defined by the pile
acceptance test results. When a basic repair is performed within 5 feet of the
top of the pile, it is known as a Simple repair, as defined in Bridge
Construction Memo 130-11.0. Typically, a basic repair is used to mitigate

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pile defects caused by not wasting enough concrete from the top of the pile
during concrete placement. However, basic repairs can be performed deeper
down the length of the pile, provided shoring is in place to permit access to
the defect. Should the Contractor propose a basic repair below 5 feet from the
top of the pile, the Engineer shall consult with the Project Geotechnical
Professional to assess the effect of accessing the defect upon the skin friction
capacity of the pile.

Grouting Repair

Grouting repairs are used to mitigate defective concrete within the pile. These
repairs can be performed at any location within the pile, but are generally not
performed within 5 feet of the top of the pile, since it is more effective to use a
basic repair at this location. Grouting repairs are performed using three types
of grouting procedures: (1) permeation grouting, (2) replacement grouting, or
(3) compaction grouting.

Several operations are common to permeation and replacement grouting

repairs. First, the Contractor must access the defective area. This is usually
done through the existing inspection tubes. Generally, the inspection tube is
removed at the defective area using a high-pressure water jet, which cuts the
inspection tube into small pieces that are then flushed out through the top of
the inspection tube. Once the inspection tube has been removed at the
defective area, the Contractor will wash the defective area using high-pressure
water jets and observe the discharge for soil, fragmented concrete, or other
contaminants. After the initial washing operation is complete, the Contractor
will evaluate the defective area using water flow testing.

Water flow testing is used to assess the nature of the defective area and
determine whether permeation or replacement grouting is appropriate. If
water can be injected into a defective area at low pressure and relatively high
volume, then permeation grouting may be the appropriate grouting repair
technique. If the defective area is large enough and permeable,
communication with other inspection tubes may be observed, meaning the
water injected into one inspection tube may return to the ground surface
through adjacent inspection tubes. Water may also flow into the soil
formation if the defective area extends to the edge of the pile concrete.
However, if water cannot be injected into a defective area, replacement
grouting may be the appropriate grouting repair technique. This is an
indicator that the defective area is contained within the pile concrete and the
concrete surrounding the defective area is sound.

Once water flow testing has been conducted, the Contractor will typically
flush the defective area using low pressure flowing water to remove any

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remaining loose material. The Contractor may then use a down-hole camera
or other means to verify loose materials were adequately removed from the
defective area.

Up to this point, these operations are occasionally performed before submittal

of a Pile Mitigation Plan to give the Contractor information on the assessment
of the nature of the defective area and which repair methods are appropriate.
However, if the Pile Mitigation Plan is broad enough in scope to handle
multiple grouting repair scenarios, these operations can be performed during
the actual pile mitigation work.

Permeation Grouting. Typically used to repair a “soft tip” within the pile
concrete, to increase frictional resistance along the side of the pile, or to
address corrosion issues at the side of the pile. Usually, permeation grouting
is used to repair defects caused by excessive settled materials not removed
from the bottom of the drilled hole prior to concrete placement. First, the
inspection tube is removed at the location of the defective area. Then the area
is washed with high-pressure water jets to remove any contaminants and loose
materials. The discharge from the washing operation is evaluated. Generally,
permeation grouting is recommended only if soil is present in the washing
discharge or water flow testing verifies the permeability of defective area.
High-pressure grout injection is performed, usually through one of the
inspection tubes, with the grout permeating the soil or concrete formation,
displacing any pore water that may be present, resulting in a solid matrix of
cement grout and defective concrete or soil. Permeation grouting is only
successful if the pore water present in the formation can be forced out by the
grout, meaning that the pore water must be able to escape into the adjacent
soil or through an adjacent inspection tube. For this reason, permeation
grouting is not recommended for repair of defects completely within the pile.

Replacement Grouting. Typically used to repair a void area or an area of

unconsolidated concrete within the pile. Typically, replacement grouting is
used to repair defects caused by concrete placement problems. As with
permeation grouting, access to the defective area is usually provided through
the existing inspection tubes. First, the inspection tube is removed at the
location of the defective area. Then the area is washed with high-pressure
water jets to remove any contaminants and loose materials. This generally
results in the creation of a void within the pile concrete. The discharge from
the washing operation is evaluated. Generally, replacement grouting is
recommended only if soil is not present in the discharge or water flow testing
indicates the defective area is impermeable. All water resulting from the
washing operation must be removed from the void prior to placement of grout.
This is typically done with compressed air. Grout is then pumped into the
void, in effect, “replacing” the voided area with grout. Replacement grouting
cannot be used if the grout has a means of escaping the void area. If a side of

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the void area includes the side or bottom of the drilled hole, replacement
grouting generally cannot be used to repair the pile defect.

Compaction Grouting. Typically used to enhance the load-bearing capacity of

the soil at the tip of the pile. Because of the inherent difficulty of employing
grouting methods below the tip of a pile, compaction grouting is only used
when the pile defect consists of a “soft tip” and end bearing is required in the
design. Access to the defective area is usually provided through the existing
inspection tubes. Generally, only the bottom of the inspection tube is
removed and the area below the inspection tube is not washed or flushed.
Grout is then pumped at high pressure into the loose soil formation at the tip
of the pile, resulting in a “bulb” of soil-grout matrix at the tip of the pile. In
order to be successful, compaction grouting must be performed through each
inspection tube.

Depending on the nature and number of defective areas within the pile, one or
more of the grouting procedures described above may be required.

Supplemental and Replacement Piles

Occasionally, piles can be so riddled with defects that repair of the pile is not
feasible. In this case, supplemental piles or pile replacement may be required. If
space exists, the Contractor may propose to place supplemental piles to enhance
the load-bearing capacity of the defective pile. If there is no space available for
supplemental piles, the Contractor may be required to remove the defective pile
and replace it.

Pile Mitigation Plan Development and Approval Procedures

Once a pile is rejected, the contract specifications require the Contractor to submit
a Pile Mitigation Plan for review and approval. A Pile Mitigation Plan is required
for any type of repair proposed by the Contractor, or when supplemental or
replacement piling is necessary.

Development and review of the Pile Mitigation Plan is a shared responsibility

between the Engineer, the Contractor, and the Division of Engineering Services
(DES) Pile Mitigation Plan Review Committee.

Responsibilities of the Engineer

The Engineer is responsible for the following:

ITEM RESPONSIBILITY
1 Arranging for acceptance testing with the Foundation Testing Branch. Based on the
results of acceptance testing, accept or reject the pile and notify the Contractor in

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ITEM RESPONSIBILITY
writing and supply the Contractor with a copy of the test results.
2 Once the pile has been rejected, determine in consultation with the Foundation
Testing Branch whether additional acceptance testing will be performed. If
additional acceptance testing is performed, notify the Contractor in writing and
supply the Contractor with a copy of the test results.
3a Discuss whether the pile requires mitigation for structural, geotechnical, or corrosion
reasons with the Project Designer, the Project Geotechnical Professional, or the
Corrosion Engineer. If the pile requires mitigation, use the Pile Design Data form
provided with the test results to collect design information on what the capacity of
the repaired pile needs to be. If the pile requires mitigation, discuss with the Project
Designer, the Project Geotechnical Professional, and the Corrosion Engineer and
come to a consensus on whether the pile can be repaired or must be supplemented or
replaced.
3b If the results of the discussion described in Item 3a determine that mitigation is not
required, notify the Contractor in writing that mitigation is not required. Per the
contract specifications, the Contractor can either mitigate the pile or accept an
administrative deduction for the pile as described in the contract specifications.
4 If the pile requires mitigation, schedule and conduct a Repair Feasibility meeting
with the Contractor as described in the contract specifications.
5 Upon receipt of the Contractor’s Pile Mitigation Plan, review the plan to ensure that
it includes all of the requirements listed in the contract specifications. If the plan
does not include all of the requirements, return the plan to the Contractor for
resubmittal. Once the Contractor submits a Pile Mitigation Plan that includes all of
the requirements listed in the contract specifications, send the plan to the DES Pile
Mitigation Plan Review Committee for technical review.
6 Upon the recommendation of the DES Pile Mitigation Plan Review Committee,
either return the Pile Mitigation Plan to the Contractor for resubmittal or approve the
Pile Mitigation Plan.

Responsibilities of the Contractor

The Contractor is responsible for developing and submitting the Pile Mitigation
Plan to the Engineer for review and approval. The Contractor develops the plan
using the acceptance testing results and the Pile Design Data forms provided by
the Engineer, and in accordance with the outcome of the Repair Feasibility
Meeting. Pile Mitigation Plans must contain the following information:

ITEM REQUIREMENT & REASONING

1 The designation and location of the pile addressed by the mitigation plan.
Reason: Self-explanatory.
2 A review of the structural, geotechnical, and corrosion design requirements of the
rejected pile.
Reason: This information is provided to the Contractor by the Engineer
via the Pile Design Data form. Requiring the Contractor to address the
pile design requirements in the Pile Mitigation Plan ensures that the
Contractor understands why the pile requires mitigation and that the
proposed mitigation addresses the deficiencies in the pile to meet the
design requirements.
3 Step-by-step descriptions of the mitigation work to be performed, including

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ITEM REQUIREMENT & REASONING

drawings if necessary.
Reason: This gives the Engineer advance knowledge of the means and
methods the Contractor proposes to employ to mitigate the pile and to
assess whether the proposed means and methods are sufficient to mitigate
the deficiencies in the pile to meet the design requirements.
4 An assessment of how the proposed mitigation work will address the structural,
geotechnical, and corrosion design requirements of the rejected pile.
Reason: This is an expansion on Item 2 above. Requiring the
Contractor to address the pile design requirements in the Pile Mitigation
Plan ensures that the Contractor understands why the pile requires
mitigation and that the proposed mitigation addresses the deficiencies in
the pile to meet the design requirements.
5 Methods for preservation or restoration of existing earthen materials.
Reason: Some mitigation methods, such as Basic Repair, may disturb
the soil around the pile. Disturbance of the soil may affect the skin
friction load carrying capacity of the pile. This requirement ensures that
the Contractor considers the effect of the proposed mitigation upon the
skin friction load carrying capacity of the pile.
6 A list of affected facilities, if any, with methods and equipment for protection of
these facilities during mitigation.
Reason: There may be existing facilities, such as utilities, around or
above the pile. This requirement ensures that the Contractor takes these
facilities into account when developing the proposed mitigation.
7 The State assigned contract number, bridge number, full name of the structure as
shown on the contract plans, District-County-Route-Postmile Post, and the
Contractor’s (and Subcontractor’s if applicable) name on each sheet.
Reason: This requirement ensures that the Pile Mitigation Plan is
developed specifically for the rejected pile in question and that all sheets
of the plan can be identified and referenced for that specific pile.
8 A list of materials, with quantity estimates, and personnel, with qualifications, to
be used to perform the mitigation work.
Reason: This requirement ensures that the Contractor is aware of how
much material to have on site when the mitigation work is performed. It
also ensures that the Contractor uses personnel who have done mitigation
work in the past and are familiar with the mitigation procedures proposed
in the Pile Mitigation Plan.
9 The seal and signature of an engineer who is licensed as a Civil Engineer by the
State of California.
Reason: This ensures that the Pile Mitigation Plan is developed or at
least reviewed by an engineer. This is necessary to ensure that the
structural, geotechnical, and corrosion design requirements of the
rejected pile are met.
10 For piles to be repaired, an assessment of the nature and size of the anomalies in
the rejected pile.
Reason: Using the information provided in the acceptance test report,
the log of concrete placement and other available information, the
Contractor should be able to assess the nature of the anomalies in the
rejected pile. This is necessary to determine what type of repair method
is appropriate. The size of the anomaly may determine whether a basic
or grout repair is appropriate. The nature of the anomaly, be it an area of
unconsolidated concrete within the pile or a soil inclusion at the side of
the pile, may determine whether a basic or grout repair is appropriate.

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ITEM REQUIREMENT & REASONING

11 For piles to be repaired, provisions for access for additional pile testing if required
by the Engineer.
Reason: Generally, pile mitigation methods utilize the existing
inspection tubes for accessing the defective zone. This is almost always
the case for grout repairs. The repair generally renders the inspection
tube unusable for the purposes of additional acceptance testing. Should
the pile require additional acceptance testing after mitigation work has
been performed; the Contractor must address how to preserve the
existing inspection tubes or provide new access, usually new-cored holes.
12 For piles to be replaced or supplemented, the proposed location and size of
additional piling.
Reason: When rejected piles have to be supplemented or replaced, the
Contractor is responsible for the design of these additional piles. The
Engineer has to evaluate the design impact of the location and size of
additional piling on the structure being constructed and any existing
facilities or new facilities to be constructed during the life of the contract.
13 For piles to be replaced or supplemented, structural details and calculations for
any modification to the structure to accommodate the replacement or
supplemental piling.
Reason: See Item 12 above.

The Association of Drilled Shaft Contractors (ADSC), which is an industry group

composed of member drilling contractors, has developed several Standard CIDH
Pile Anomaly Mitigation plans. These plans are intended to address the most
common types of pile anomalies encountered, which generally consist of 80-90%
of all pile anomalies. These plans encompass Basic Repair, Permeation Grouting
and Replacement Grouting repair methods. Caltrans has approved these plans for
statewide use. Engineers should expect to receive a Standard CIDH Pile
Anomaly Mitigation plan if the drilling contractor is an ADSC member. The plan
will require a cover letter to address the pile-specific Pile Mitigation Plan
requirements of the contract specifications. The intent of the Standard CIDH Pile
Anomaly Mitigation plans is to reduce the amount of time needed for the
Contractor to develop the Pile Mitigation Plan and for the Engineer and DES Pile
Mitigation Plan Review Committee to review and approve the Pile Mitigation
Plan.

To aid the Engineer, a copy of these Caltrans approved, standard mitigation plans
can be obtained by contacting the Offices of Structure Construction in
Sacramento or accessing its intranet website at
http://onramp.dot.ca.gov/hq/oscnet/.

Responsibilities of the DES Pile Mitigation Plan Review Committee

The DES Pile Mitigation Plan Review Committee is responsible for the
following:

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ITEM RESPONSIBILITY
1 Provide advice to the Engineer, Project Designer, Project Geotechnical
Professional, and the Corrosion Engineer regarding pile mitigation procedures
and methods.
2 Provide a technical review of the Pile Mitigation Plan submitted by the Engineer.
Advise the Engineer in writing whether the Pile Mitigation Plan should be
approved or needs to be returned to the Contractor for correction and resubmittal.

Once all responsibilities of completion and review of the Pile Mitigation Plan
have been completed, the Engineer approves the Pile Mitigation Plan.

Pile Mitigation Field Procedures and Pile Acceptance

After approval of the Pile Mitigation Plan, the Contractor can proceed with the
work of mitigating the pile in the field.

What to Expect in the Field During Pile Mitigation

Personnel involved with the pile mitigation work and inspection of the pile
mitigation work should be thoroughly familiar with the details of the approved
Pile Mitigation Plan. Evaluation of the acceptability of the pile mitigation work is
dependent upon whether the procedures described in the approved Pile Mitigation
Plan were followed.

A good Pile Mitigation Plan will allow for alternatives should the initial
procedure not work. For example, if it is determined during the pile mitigation
work that replacement grouting is no longer appropriate because soil was
encountered in the flushing discharge, the Pile Mitigation Plan should allow an
alternative for permeation grouting. Occasionally, actual conditions in the field
determine that grouting repair is no longer appropriate and the whole mitigation
effort may have to be abandoned and a revised Pile Mitigation Plan submitted for
approval.

For grouting repairs, the Contractor should monitor and record observations of
inspection tube removal, the nature of the discharge from the washing operation,
the pressure and flow rate of water flow testing, photos or video from the down-
hole camera, and the volumes and pressures of grout placement.

For grouting repairs, the Engineer should be present to monitor the results of
inspection tube removal, assessment of the defective area of the pile, all flushing
operations, and any grouting repair work performed.

For Basic repairs, the Engineer should be present to verify the Contractor only
removes the soil for which removal has been approved in the Pile Mitigation Plan.
The Engineer should also verify the Contractor has removed all contaminated or
deleterious materials from the defective area of the pile. Finally, the Engineer

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should verify the Contractor replaces the soil around the repaired pile as
prescribed in the approved Pile Mitigation Plan.

Procedures For Approving the Pile Mitigation Work Performed in the Field
and Pile Acceptance

The approved Pile Mitigation Plan addresses how the pile mitigation work will be
accepted. Generally, the pile can be accepted if the mitigation work is performed
in accordance with the provisions of the approved Pile Mitigation Plan. However,
there are circumstances when the pile must be retested. Procedures for access for
retesting are provided in the approved Pile Mitigation Plan.

For all types of pile mitigation, once the mitigation work is complete, the
Contractor is required to submit a Mitigation Report to the Engineer for review
and approval. The Mitigation Report should contain information on the
Contractor’s observations recorded during the mitigation work, including grout
volumes and pressures if a grouting repair was performed. It is especially
important that any deviations from the approved Pile Mitigation Plan be included
in the Mitigation Report. This is necessary so the Engineer can determine
whether the deviations resulted in an effective repair. The results of any retesting
should also be included in the Mitigation Report.

Once the pile mitigation work is accepted, any remaining open inspection tubes
are grouted and the pile can be accepted.

Safety
Safety concerns to be considered during the construction of CIDH piles by the
slurry displacement method are similar to those to be considered when CIDH
piles are constructed by ordinary means. For specific information, refer to Chapter
6 of this manual. However, there is one additional item that requires further
attention; and that is the drilling slurry itself.

Some of the components of drilling slurries, especially chemical additives, are

considered to be hazardous materials. It is advisable to avoid skin contact and to
avoid breathing in vapors. The Construction Safety Orders require the Contractor
to provide Material Safety Data Sheets (MSDS) for all drilling slurries and
chemical additives. The Engineer should obtain these MSDS as part of the
submittal for the pile placement plan. During the tailgate safety meeting prior to
CIDH pile construction, be sure to discuss the contents of the MSDS and discuss
how Caltrans employees, the Contractor’s employees, and any manufacturer’s
representatives that may be present will adhere to the safety precautions.

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During construction, do not permit the use of drilling slurries or chemical

additives for which a MSDS has not been submitted.

For CIDH piles over 20 feet in depth and 30 inches in diameter, Cal-OSHA
Mining and Tunneling Safety Orders apply. Construction Procedure Directive
CPD 04-6 addresses this and is included in Appendix B.

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CHAPTER

10 Pier Columns

Description
Pier columns are an extension of the pier to a planned elevation in bedrock
material and are usually the same size, or slightly larger, than the pier. They are
ideally suited to canyons or hillside areas where there are limitations on the usual
footing foundations, i.e., the need for approximately level topography and level
underlying stratum. Footing foundations constructed in steep slopes are very
costly because of the tremendous amount of excavation required.

Pier columns are primarily a Cast-In-Drilled-Hole (CIDH) pile, except the means
of excavation is something other than the conventional drilling method. The
following is taken from Caltrans Memo to Designers, December 2000, Section 3-1
Deep Foundations, “Pier Columns” on page 6:

“Pier columns are utilized when the presence of rock precludes

conventional drilling equipment. Excavation by hand, blasting, and
mechanical/chemical splitting are some methods used in hard rock.”

Pier column excavation is considerably more expensive than conventional auger

drilling and the pay limits must be clearly defined. The pier column cutoff
elevation and tip elevation (upper and lower limits of the hard material) should be
shown in the Pile Data Table. The pay limits for Structure Excavation (Pier
Column) and Structure Concrete (Pier Column) shall be shown on the plans. See
Appendix D.

As mentioned above, pier columns are primarily CIDH piles, but pier columns
will have contract pay items for structure excavation and structure concrete. Pier
columns can also be referred to as pile shafts. Caltrans outlines the design of pier
columns in Bridge Design Aids (BDA), April 2005, “Pile Shaft Design” Chapter
12. Also, Federal Highway Administration (FHWA) has useful information on
drilled shafts.

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Specifications
The special provisions will contain a great deal of information regarding pier
columns and should be reviewed along with the contract plans and Standard
Specifications prior to the start of work. Construction of pier columns is an
excellent topic for the preconstruction conference, especially in regard to safety
and excavation plans.

Almost all pier columns will have neat line excavation limits specified on the
contract plans. Any excavation outside these neat lines shall be filled with
concrete. The Contractor should be reminded of this requirement prior to the start
of work. It should also be pointed out that care must be used in constructing the
access road and/or work area around the pier columns(s) so that these excavations
do not extend below the top of the neat line areas. The contract plans will also
specify no splice zones and ultimate splice zones for the main column
reinforcement and for the main pile reinforcement. It is very important that the
Contractor adheres to the rebar splice requirements.

Construction Methods
Methods and equipment used for construction of pier columns are dictated by
several major factors. Among them is access to the work area, which is
determined by the topography, and adjacent facilities such as existing structures,
roads, and streambeds, and also by the type of equipment required to do the work.
The cross sectional area of the pier shaft, depth of excavation, and the nature and
stability of the material to be excavated are other major factors affecting the
method and type of equipment to be used.

The above factors will vary significantly from project to project. Hence, there is a
wide variation in construction methods and equipment used by contractors on
different projects. Methods that have been used in the past include using a hoe-
ram, jackhammer, or Cryderman (“shaft mucker”). Others have used chemical
rock splitting. The most common method used is blasting with explosives.
Rotators and oscillators are somewhat new to the Department and may also be
used to perform this work. For additional information on these tools refer to
Chapter 6 of this Manual.

Excavation
One of the first orders of work, after access roads are constructed to the pier site,
is to establish survey control points. These points should be placed so that they
not only provide control during excavation operations, but also can also be used
for pier construction.

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After establishing survey control points, excavation operations begin. Usually,

soft material is excavated by conventional methods, such as a Gradall, flight
auger, clambucket and hand work. Hard material encountered in otherwise soft
material requires other means such as blasting. Since blasting is the most
commonly used excavation method, it merits further discussion.

Typically, the first phase of a pier column excavation operation with blasting
utilizes a line drill along the perimeter of the shaft to create holes along the neat
line dimensions of the excavation (the Contractor may elect to line drill slightly
outside the neat line dimensions). A line drill is an air-track compressor type drill
rig that uses 2-1/2 to 5 inch diameter drill bits in 20-foot lengths. The holes are
usually drilled on 12-inch centers with additional holes placed inside the
perimeter if needed. The holes are then blown out and filled with sand or pea
gravel to facilitate blasting at different levels. Next, blasting mats, tires, dirt, etc.
is placed to protect existing facilities from flyrock. A galvanometer should be
used to check for shorts in the wiring prior to blasting. After the blasting is
completed, the Contractor removes the loose material. Blasting and excavation
usually occur in stages until reaching the bottom pier column elevation.
Handwork to some degree is required at the bottom of all pier columns.

Problem Areas
Because of the wide range of variables associated with pier columns, different
problems can be expected with each project. Listed below are items common to
most projects. All represent potential problems that must be addressed in order to
successfully install pier columns.

ITEM POTENTIAL PROBLEM

Alignment It can be difficult to maintain plumb drilled holes if extensive predrilling techniques
are used. Consequently, the Contractor may elect to predrill the outside shaft
dimensions.
Surveying Be prepared to improvise. Access to the site and methods employed by the
Contractor may require unique solutions. Work should be monitored as it
progresses.
Access The Contractor must provide safe access to the site and inside the pier. Depending
on excavation depth, this could vary from ladders to boatswain’s chairs to suspended
personnel cages to other means (review the Construction Safety Orders). Often this
work will fall under Cal-OSHA’s Division of Mines and Tunnels.
Blasting A thorough review of the Contractor’s blasting plan, if blasting is the option used to
remove the bedrock material, is advised. Blasting should only be done by a licensed
person with a Department of Industrial Safety (DIS) permit. This individual should
supervise placing, handling, blasting and storage of explosive materials. Provisions
must be made for handling traffic. Restrictions on the transportation of explosives
must be enforced. Protection must be provided for existing facilities, utilities, etc.
A galvanometer should be used to check for shorts in the wiring prior to blasting.
Blasting mats, tires, dirt, etc. should be used to prevent flyrock from being scattered

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ITEM POTENTIAL PROBLEM

beyond expected limits. Proper warning signs should be provided along highways
and roads near the blast site. No explosive material should be left in the area
overnight. If it cannot be avoided, leave a guard overnight in the area. During the
blast, guards should be placed at selected locations to prevent individuals from
entering the blast area. Beware of “misfires.” In general, this operation is not our
responsibility, it falls under the umbrella of Geotechnical Services who should be
consulted whenever blasting is contemplated. If you have any questions on the
responsibility of Caltrans in regards to blasting, contact the Caltrans Headquarters
Construction Safety Officer.
See Appendix D – for sample blasting specifications.
Crane Safety Lifting pier column rebar cages into the excavated hole may require more than one
crane. Proper lifting plans must be enforced. Lane closures may be required when
working next to traffic lanes. Additional safety precautions are required when
working near overhead electrical lines and in windy areas.
Shoring Shoring is required in all areas that are not solid rock. In almost all cases, special
designs are required in accordance with Section 5-1.02A of the Standard
Specifications. Shoring systems can consist of concrete lining, steel or concrete
casing, box-type shields, rock bolts, and steel or timber lagging. Refer to the
Caltrans Trenching and Shoring Manual for shoring design and details.
Geology Be prepared for unanticipated ground conditions, such as soil instability,
groundwater, fissures, or simply material of lesser quality than that assumed for
design purposes. Revisions may be necessary.
Concrete Common to all mined shafts is the requirement that concrete be placed against the
undisturbed sides of the excavation. The length of shaft contact could vary from a
planned length in the lower portion of the shaft to the entire length of the shaft. The
Special Provisions for these projects will usually require a minimum side contact
area (generally 50%) with certain allowances for shoring left in place or to allow for
concrete flow through stay-in-place casings. In other instances the shoring or
lagging has to be removed as the concrete is placed. These provisions tend to
complicate concrete placing operations and therefore care must be exercised to do
the job properly. Close inspection is mandatory.

Safety
Extreme caution is absolutely necessary in order to protect not only personnel
working in the area, but the general public as well, since the potential for serious
injury is ever present.

Safety railing and barriers must be erected near the shaft perimeter and adequate
protection must be provided for personnel working inside the shaft. Workers
must wear full body harness and be tied off when working adjacent to the shaft
perimeter. Crane lifting plans may be required when erecting rebar cages and
column forms. Guy wire plans will be required for supporting column forms and
column reinforcement. Material Safety Data Sheets (MSDS) are needed when
slurries are used. Also, traffic handling plans and lanes closures may be required
when constructing pier columns.

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CHAPTER

Tiebacks, Tiedowns,
11 & Soil Nails

Introduction
Chapter 2 “Type Selection” classifies tiebacks and tiedowns as special case
foundations. They are used for earth retaining structures where it is not feasible
to excavate and construct a footing foundation or pile cap for a conventional
retaining wall. Tiedowns, sometimes referred to as Tension Piles, are used
generally for seismic retrofitting or existing footings where uplift and overturning
must be prevented.

Tiebacks
Tiebacks are used in both temporary and permanent structures. The use of
tiebacks with sheet pile or soldier beam shoring permits taller walls and deeper
excavations than are possible with cantilever type construction—up to 35 feet or
so depending on soil properties versus 15 feet for cantilever construction. Walls
can be built much higher than 35 feet by using high strength sheet pile or soldier
beams with multiple rows, or tiers, of tiebacks.

Components

Tiebacks are constructed by drilling holes at a slight angle (15 degrees) off the
horizontal axis. Afterwards a special prestressing system is installed and the tip
portion, known as the bonded length, is grouted. The bonded length acts as an
anchorage by distributing the prestressing force to the surrounding soil. The
unbonded end is secured with an anchor head. Refer to Figure 11-1.

The following list describes various tieback components:

COMPONENT DESCRIPTION
Prestressing Steel – This transfers load from the wall reaction to the anchor zone and is
Support Member generally a prestress rod or strand.
Bond Length The portion of prestressing steel fixed in the primary grout bulb through
which load is transferred to the surrounding soil or rock. Also known as

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the anchor zone.

Unbonded Length The portion of the prestressing steel that is free to elongate elastically and
transmit the resisting force from the bond length to the wall face.
Anchorage This consists of a plate and anchor head or threaded nut and permits
stressing and lock-off of the prestressing steel.
Grout This provides corrosion protection as well as the medium to transfer load
from the prestressing steel to the soil or rock.

FIGURE 11-1 Tieback detail

In addition to enabling the construction of higher/taller walls and deeper

excavations, tiebacks serve another useful purpose. The system provides an open
unrestricted work area adjacent to the wall and inside the excavation since the
only part of the system that projects beyond the wall is the relatively small
anchorage device.

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For permanent structures, the Contractor is responsible for providing a tieback

system that has been pre-approved by the Department and conforms to the design
requirements shown on the plans and meets/exceeds the testing requirements
specified in the contract documents. The Contractor has the option of choosing
which system will be installed. Tieback shoring designs are often proprietary and
require sophisticated engineering techniques and the calculations submitted by
Contractors and Consultants. The designed bonded length is based onsite specific
soil parameters/mechanical properties. The tieback shop drawings and design
calculations are submitted to the Office of Structure Design, Documents Unit, in
Sacramento for distribution, review, and approval. The project engineer in
Structure Design, geoprofessional in Geotechnical Services, the staff specialist for
Earth Retaining Systems in Structure Design Services and Earthquake
Engineering in Sacramento, the DES Prestressing Committee and the Structure
Construction field personnel all review the shop drawings. The project engineer
approves the shop drawings based on the recommendations of the individual units
reviewing the drawings. These individuals and groups can be consulted for help
in answering any questions that may arise in the field during construction. In
addition, the Office of Structure Construction Substructure Committee is also
available to provide assistance.

Specifications for tieback anchors are generally found in the contract special
provisions. Tieback anchors shall be installed in accordance with the
manufacturer’s recommendations. In case of a conflict between the
manufacturer’s recommendations and the special provisions, the special
provisions shall prevail.

The record of readings from the Performance and Proof tests performed to verify
the adequacy of the system shall be documented by the Contractor and provided
to the Engineer. Structure Construction field personnel shall witness all
performance and proof testing of the tiebacks.

Sequence of Construction

Sequence of tieback construction is as follows:

SEQUENCE DESCRIPTION
1 Drill the holes to the required length and diameter.
2 Install the prestressing steel unit. (Strands or Bar)
3 Place primary grout.
4 Complete Performance and Proof Tests (refer to section on testing later in this
chapter).
5 Lock-off and stress.
6 Place secondary grout.

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Note: Each step must comply with the contract specifications before proceeding
to the next step.

Safety

Check the Contractor’s construction sequence against the approved plans. As

excavation proceeds from the top down, look for signs of failure in the lagging or
changes in the soil strata.

Tieback systems use powerful hydraulic rams to prestress or post tension the
system. The premise is the same as what is done to in prestressed bridges.
Structure Construction employees should not stand behind the hydraulic ram or
cross it while stressing is taking place. The Prestressing Manual and the OSC
Code of Safe Practices should be consulted for additional safety considerations.

Tiedowns
Tiedown anchors, or tiedowns, are similar to tiebacks although they act in the
vertical plane. They can be used where site conditions do not allow traditional
piles to achieve the necessary tensile capacity. For example, where rock exists
close to the ground surface (or scour elevation), piles driven to refusal may be too
short to develop sufficient skin friction to resist uplift or tensile loads required by
the design. Tiedowns are especially effective when combined with spread
footings sitting directly on rock, or as part of a seismic retrofit strategy to add
uplift capacity to a footing.

An example of a prestressing bar tiedown anchor is shown in Figure 11-2.

The Contractor is responsible for providing the tiedown anchor system that
conforms to the design requirements shown on the plans and the testing
requirements specified in the contract documents. The option of choosing which
system to be installed is left to the Contractor. After selecting a tiedown system,
the Contractor sends the shop drawings and calculations to the Office of Structure
Design, Documents Unit, in Sacramento for distribution, review, and approval
similar to the process outlined above for tiebacks.

The record of readings from the Performance and Proof tests shall be documented
by the Contractor and provided to the Engineer. Structure Construction field
personnel shall witness all performance and proof testing of the tiebacks.

Specifications for tiedown anchors are generally found in the contract Special
Provisions. Tiedown anchors shall be installed in accordance with the
manufacturer’s recommendations. In the case of a conflict between the

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manufacturer’s recommendations and the special provisions, the special

provisions shall prevail.

Sequence of Construction

Sequence of tiedown construction is as follows:

SEQUENCE DESCRIPTION
1 Drill the hole the required depth and diameter.
2 Install the prestressing strands or bar.
3 Place primary grout.
4 Complete Performance and Proof Tests (refer to section on testing later in
this chapter).
5 Lock-off and stress.
6 Place secondary grout.

Note: Each step must comply with the specifications before proceeding to the next
step.

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FIGURE 11-2 Tiedown anchor

Testing of Tieback and Tiedown Anchors

Both tiedowns and tiebacks require testing of the in-place anchors. Performance
tests are done on a predetermined number of anchors, and proof tests are required
on all of the anchors. If the test results indicate that the anchors are not achieving
capacity, additional monitoring and testing, as outlined in the contract special
provisions, will be required. If they do not pass at that point, a revision to the
original design will be required. The redesign should be discussed with the
project engineer. The specific requirements for testing will be provided in the
contract special provisions, the following is a general explanation of the required
tests.

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Performance Tests

A Performance test involves incremental loading and unloading of a production

anchor to accurately verify that the design loads will be safely carried by the
system, that there is sufficient free length to allow for elastic elongation, and that
the residual movement of the anchor after stressing is within tolerable limits. As
a minimum, the first two production anchors installed should be Performance
tested. Do not wait until many anchors have been installed before testing the first
two anchors as the purpose of these tests is to verify the installation procedure
selected by the Contractor. It is in the best interest of both parties to begin testing
early and before a large number of anchors is installed. Each load increment or
decrement shall be held constant for at least one minute or until measured
deflection is negligible. The maximum load should generally be held for one hour
to determine long-term creep susceptibility. As stated earlier, the contract plans
and/or special provisions will specify the testing and acceptance criteria for each
test and the number of Performance tests required at each location.

Proof Tests

A proof test involves incrementally loading a production anchor to verify that the
design capacity can be safely carried and that the free length is as specified. The
proof test is a single cycle test where the load is applied in increments until the
specified maximum load value (150% of the design load) is reached. Each load
shall be applied in less than one minute and held constant for at least one minute
but not more than two minutes.

General Acceptance Criteria – Proof & Performance Tests

CRITERIA PERMORMANCE TESTS

1 Achieve test results that indicate that the anchor is capable of supporting 150%
of the design force for the anchor shown on the plans.
2 The measured elastic movement exceeds 0.80 of the theoretical elongation of
the unbonded length plus the jacking length at the maximum test load.
3 The creep movement between one and 10 minutes is less than 0.04—inch.

CRITERIA PROOF TESTS

1 Achieve test results that indicate that the anchor is capable of supporting 150%
of the design force for the anchor shown on the plans.
2 The pattern of movements is similar to that of adjacent performance tested
tiebacks.
3 The creep movement between one and 10 minutes is less than 0.04—inch.

The special provisions outline an acceptance criteria for these tests, however a
performance tested or proof tested tieback which fails to meet the second criterion

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will be acceptable if the maximum load is held for 60 minutes and the creep curve
plotted from the movement data indicates a creep rate of less than 0.08—inch for
the last log cycle of time.

General Construction Control

ITEM DESCRIPTION
1 Mill certs should be provided for the steel tendons.
a) Check the steel for damage.
b) Ensure that grease completely fills the free length plastic tube.
c) Securely tape the bottom of the free length.
d) Compare the actual free length dimensions versus the dimension specified.
2 Double corrosion protection anchors should be completely fabricated before being
delivered to the job site. Bar anchors are installed full-length into the hole. Record
the actual free and bond length for each installed anchor.
3 Tendons shall be equipped with centralizers. These centralizer devices are
absolutely necessary to center the tendon in the hole and to prevent the tendon from
laying on the side of the hole where incomplete grout cover will cause loss of
capacity and future corrosion.
4 Grout tubes are frequently tied to the tendon before inserting in the hole. This helps
to ensure that there are no voids in the grout.
5 Testing – check to ensure the tendon is concentrically located in the center hole
jack and load cell before testing begins. Poor alignment of the testing apparatus
will cause eccentric loading on the load cell and jack, which will give erroneous
readings. Deflections at the anchor head should be measured with a dial gauge.

Soil Nails
Soil nailing is a technique used to reinforce and strengthen an existing
embankment (Figure 11-3). It can also be used to reinforce excavations to allow
steeper cuts and or deeper excavations. The fundamental concept is that soil can
be effectively reinforced by installing closely spaced grouted steel bars, or
“nails”, into a slope or excavation as construction proceeds from the original
ground to the bottom of the excavation or from the top down. Unlike tiebacks,
the soil nail bars are not tensioned when they are installed and are grouted along
the entire length of the nail. They are forced into tension as the ground deforms
laterally in response to the loss of support caused by the excavation. The grouted
nails increase the shear strength of the overall soil mass and limit displacement
during and after excavation. Soil nails are bonded along their full length and are
not constructed with a permanent unbonded length, as are tieback anchors. A
typical soil nail is shown in Figure 11-4.

Soil nailing is a cost-effective alternative to conventional retaining wall structures

for most soils. However they are not practical in loose materials or plastic soils.

Common soil nail wall applications include the following:

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APPLICATION DESCRIPTION
1 Temporary and permanent walls for building excavations.
2 Cut slope retention for roadway widening and depressed roadways.
3 Bridge abutments – addition of traffic lanes by removing end slopes from
in front of existing bridge abutments.
4 Slope stabilization.
5 Repair or reconstruction of existing structures.

Soil nail wall construction is sensitive to ground conditions, construction

methods, equipment, and excavation sequencing. For soil nail walls to be most
economical, they should be constructed in ground that can stand unsupported on a
vertical or steeply slope cut of 3 to 6 feet for at least one to two days, and can
maintain an open drilled hole for at least several hours.

Figure 11-3 Soil nail schematic

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FIGURE 11-4 Soil nail details

Sequence of Construction

Soil Nail Wall Construction Sequence is as follows:

SEQUENCE DESCRIPTION
1 Excavate a vertical cut to the elevation of the soil nails.
2 Drill the hole for the nail.
3 Install and grout the soil nail tendon.
4 Place the geocomposite drain strips, the initial shotcrete layer, and install the
bearing plates and nuts.
5 Repeat process to final grade.
6 Place the final facing (for permanent walls).

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Engineer’s Responsibility

The Structure Representative shall ensure that the soil nail wall is being built in
accordance with the contract documents. The Department is responsible for
reviewing and approving the shop drawings and construction details. The review
process is similar to that of tiebacks and tiedowns. One important difference
between tieback designs and those of soil nails is that of design responsibility.
Tiebacks have a grouted length that is designed or determined by the contractor
while soil nail walls do not; they are grouted full length.

Prior to construction, the planned alignment, depth, and layout of the soil nails
shall be checked in the field for any possible discrepancies. As with any work
involving soils or rock, good daily diaries and records must be maintained of all
field activities.

A good reference for field inspectors is the Soil Nailing Field Inspectors Manual -
Soil Nail Walls – Demonstration Project 103, Publication No. FHWA-SA-93-068,
Federal Highway Adminstration, U. S. Department of Transportation, 1994, by
James A. Porterfield, David M. Cotton, R. John Byrne.

Contractor’s Responsibility

The Contractor is responsible for constructing the soil nail wall in accordance
with the contract documents. The Contractor is also responsible for submitting
complete details of the materials, procedures, sequences, and proposed equipment
to be used for constructing the soil nail assemblies and for constructing and
testing the test soil nail assemblies. The Contractor shall furnish a complete test
result to the Engineer for each soil nail assembly tested.

Testing of Soil Nail Walls – Verification, Proof & Supplemental

The contract documents should be consulted for the specific test requirements for
your project. Testing involves stressing the nails to simulate design load
conditions. The following is a general description of the required tests.

Verification Nails

Verification nails, sometimes referred to as test nails, are not production nails and
are meant to be “sacrificial”. They are installed in the same manner as production
nails but have an area that is not grouted or bonded. Verification tests should be
performed before excavation is continued below the level of the test nail. Once
the test is performed, the remainder of the drilled hole is filled with grout. The

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location of test nails is determined by the Project Engineer and shown on the
plans. Refer to Figure 11-5 for a test nail detail.

Verification testing has two criteria the first is a creep test and the second is a
maximum load test. They involve incrementally loading the test soil nail
assembly to its design load, holding it for an hour and loading the nail to 150% of
the design load. Movement of the soil nail end shall be measured and recorded to
the nearest 0.001 inch at each increment of load, including the ending alignment
load, relative to an independent fixed reference point. The Special Provisions will
outline acceptance criteria for the verification nails. The nails need to fulfill these
criteria before moving forward with construction of the rest of the wall. Should
the nails not meet the criteria, additional tests may be necessary. The nails may
fail due to constructability issues or insufficient length. In any case, additional
performance tests will be required. The Contractor will need to provide a log of
test borings of the material removed from the holes for the additional performance
test nails. This information should be provided to the Project Engineer and
Geoprofessional to help resolve this issue.

Proof Testing

Proof testing is performed on production nails that are shown on the plans. In
addition the Special Provision will indicate a specific number of proof tests to be
performed at locations identified by the Engineer in the field. The testing means
and methods as well as the acceptance criteria for these tests are different than
those for performance tests and are outlined in the Special Provisions.

Supplemental Testing

Supplemental testing is done on a specified number of nails (up to one-half of the

production nails) and is completed immediately after the completion of creep
testing. The testing and acceptance criteria will be specified in the Special
Provisions.

Safety

The soil nail wall should be monitored during construction for movement and for
signs of failure. Occasionally, poor material will be encountered as the
excavation continues downward. This differing condition may require a change
to the plans or safety provisions in the construction method.

Personnel working around soil nail operations must wear the required Personal
Protection Equipment (PPE) to include eye protection and ear plugs.

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FIGURE 11-5 Verification/test nail detail

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CHAPTER

12 Cofferdams and Seal Courses

General
A cofferdam is a retaining structure, usually temporary in nature, which is used to
retain water and support the sides of excavations where water is present. These
structures generally consist of: (1) vertical sheet piling, (2) a bracing system
composed of wales, struts or tiebacks, and (3) a bottom seal course to keep water
from piping up into the excavation or to prevent heave in the soil. Cofferdams
differ from braced excavations or shoring in that they are designed to control the
intrusion of water from a waterway and/or the ground.

A seal course is a concrete slab poured under tremie to block the intrusion of
water into the bottom of an excavation. The limits of the cofferdam are the limits
of the seal course and the thickness is calculated to address engineering
considerations such as pressures from differential hydrostatic head at the bottom
of footing elevation.

Sheet Piles and Bracing

There are three basic materials used for the construction of sheet piles: wood,
concrete, and steel. Wood sheet piling can consist of a single line of boards or
“single-sheet piling” but it is suitable for only comparatively small excavations
where there is no serious ground water problem.

FIGURE 12-1 Single sheet piling

In saturated soils, particularly in sands and gravels, it is necessary to use a more

elaborate form of sheet piling which can be made reasonably watertight with
overlapping boards spiked or bolted together, such as the “lapped-sheet piling” or
“Wakefield” system.
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FIGURE 12-2 Lapped and wakefield sheet piling

“Tongue and groove” sheet piling is also used. This is made from a single piece
of timber that is cut at the mill with a tongue and groove shape.

FIGURE 12-3 Tongue and groove wood sheet piling

Precast concrete sheet piles are normally used in situations where these members
are going to be incorporated into the final structure or are going to remain in place
after they fulfill their purpose. The Department does not normally encounter pre-
cast concrete sheet piling in structure work. However, it is usually made in the
form of a tongue and groove section; they vary in width from 18 to 24 inches and
in thickness from 8 to 24 inches. They are reinforced with vertical reinforcing
steel bars and hoops in much the same way that is done with precast concrete
bearing piles. This type of sheeting is not perfectly watertight; however the
spaces between the piles can be grouted to try to address this.

FIGURE 12-4 Concrete sheet piling

In order to provide a more watertight precast concrete sheet pile, two halves of a
straight steel web sheet pile, which has been split in half longitudinally, are cast
into the concrete pile during fabrication.

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FIGURE 12-5 Concrete sheet piling with steel interlocks

Steel sheet piling is most commonly used in the field. It is available in a number
of different sizes and shapes. The shape provides bending strength and each end
is fabricated with an interlock (connection between sheets) that provides
alignment and interconnectivity between sheets. Each steel company that
manufactures sheet piling has its own shape and form of interlock. The simplest
shape is known as the “straight-web”. These are made in various widths ranging
from about 15 to 20 inches. The web thickness varies from about 3/8 to 1/2 inch.
The straight-web sheet piling is comparatively flexible and it requires a
considerable amount of bracing in deeper excavations where lateral loads from
waterways and soils are large.

FIGURE 12-6 Straight section steel sheet piling

In order to provide greater resistance to bending, the steel companies have

developed sheet piles in a variety of shapes. One type is known as the “arch-web”
section, where the center of the sheet is offset to provide a greater moment of
inertia in the cross section. A “deep-arch” section provides an even greater
stiffness. It is similar to the “arch-web” except that the offset in the web is
considerably larger. A third type, known as the Z- Section has a stiffness
considerably greater than that of the “deep-arch” and is used in deeper
excavations.

FIGURE 12-7 Arch-web steel sheet piling

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FIGURE 12-8 Deep-arch steel sheet piling

FIGURE 12-9 Z-section steel sheet piling

The choice of the type of steel sheet pile to be used on a given job depends largely
on the kind of service in which it will be used. The straight-web is comparatively
flexible so it requires a considerable amount of bracing to resist large lateral loads
in excavations. However, its cross section allows it be used in locations where
space is an issue and where a deep-arch or Z-Section will not fit in between the
excavation limits and an obstruction or Right-of-Way line.

The composition of the bracing system inside the cofferdam will depend upon the
forces that system must resist, the availability of materials, and the costs
connected with the system. Tiebacks, sometimes prestressed, can be used in large
land cofferdams where a system of cross bracing is impractical.

Excavation
Cofferdams in waterways are typically excavated with a submerged clamshell
bucket, with the excavation elevations being checked by sounding. In the case of
pile foundations, it is often advisable to over-excavate a predetermined amount to
compensate for possible heave of the foundation material caused by driving piles;

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 __________________________________________November 2008_

and closed-end (displacement) piles in particular. This is done to eliminate the

need for excavation after driving. If excavation is needed, care needs to be taken
so as not to damage any of the driven piles.

To ensure the stability of the excavation, a seal course is used to control the influx
of water into the excavation from the bottom due to hydrostatic head differentials.
The contract plans will show where seal courses are required. As in many other
areas of our work, there are times when engineering judgment should be used to
make decisions. Depending on the types of soils and the depth of the excavation
in relation to that of the water table, the cofferdam may be dewatered without
constructing a seal course while still allowing construction of the footing in the
dry. The decision to use a seal course that is shown on the plans, or to revise its
thickness, is the responsibility of the Engineer. Discussions about the need for a
seal course or revisions to thickness need to take place early so that design
considerations for the cofferdam can be addressed.

Seal courses for cofferdams may not be shown on the plans but may be needed to
facilitate construction and provide a quality product. If a seal course is not shown
on the contract plans and the Contractor elects to use one to control and remove
water from the excavation, the work shall be done in accordance with the
provisions of Section 19-3.04 of the Standard Specifications.

Seal Course
Section 51-1.10 “Concrete Deposited Under Water” states that a seal course
should be used when the Engineer determines that it is impossible or inadvisable
to dewater an excavation prior to pouring concrete. As the name implies, a seal
course seals the entire bottom of a cofferdam and prevents subsurface water from
entering the cofferdam. It also controls the expansion of soils that have a
tendency to expand or heave. Sealing the bottom of the cofferdam allows
cofferdams to be dewatered and permits the construction of footings, columns or
other facilities in the dry. The seal course is a concrete slab placed underwater by
the tremie placement method and is constructed thick enough so that its weight is
sufficient to resist uplift from hydrostatic forces. The friction bond between the
seal course concrete and the cofferdam, and piles if present, also helps resist
uplift. A seal course is a construction tool and in terms of importance to the
designed structure it has no structural significance.

Following the installation of the cofferdam and prior to dewatering, the soil is
excavated to the elevation of the bottom of the seal course and the piles are
driven. The seal course is poured under tremie and allowed to cure. The
cofferdam is dewatered after the seal course has cured. A small area of the seal
course can be left low for the placement of a pump to remove water that seeps
into the excavation prior to the placement of footing concrete.

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Information about seal courses for a project can be found in the contract plans.
Additional information may be found in the Foundation Report or RE Pending
File. As previously discussed, when seal courses are shown on the plans, the
decision about the need for the seal course and its thickness rests with the
Engineer. This decision is based on conditions encountered on the jobsite. The
Standard Specifications also contain provisions for adjusting excavation item
quantities if seal courses are adjusted or eliminated. Additional information about
seal courses can be found in Bridge Construction Memo 130-17.0. Bottom of
footing elevations should not be revised as a result of eliminating or revising seal
courses unless shown on the plans or addressed in the special provisions.

Concrete Deposited Underwater (Tremie Placement Method)

The Tremie Placement Method is a name given to the method of placing concrete
under water through a pipe or tube, known as a tremie, or with a concrete pump.
The tremie can either be rigid or flexible. The purpose of the tremie is to enable
continuous placement of concrete, monolithically, underwater without creating
turbulence. Essentially the water is displaced by a slowly moving concrete mass.

To accomplish this, it is imperative that the discharge end of the tremie be kept
embedded in the concrete. It is also imperative that the concrete have good flow
characteristics. Concrete placement can be accomplished by either a tremie
supported and maneuvered by a crane or the discharge end of a concrete pump.
Frequently contractors will use multiple-tremie systems with each hopper
supported by bracing or walkways in the cofferdam. In this case, tremie spacing
is controlled by the flow characteristics of the concrete.

Briefly described, a typical tremie operation begins with the tremie pipe being
lowered into position with a plug or other device fitted into the pipe as a physical
barrier between the water and concrete. Concrete is charged into the pipe to a
sufficient height to permit gravity flow. The flow itself is started by slightly
lifting the pipe. Once started, the concrete flow must be continuously maintained
through the pipe. The operation continues until completion. The tremie pipe
remains immersed in concrete during placement. Some factors that assure success
for this operation are:

FACTOR DESCRIPTION
1 Tremie concrete shall have a penetration of between 3 and 4 inches.
2 Concrete shall contain a minimum of 675 pounds of cementitious material per
cubic yard. (Standard Specifications - Section 90-1.01)
3 Concrete placement and the maneuvering of the tremie pipe must be done
smoothly and deliberately.
4 Concrete delivery must be adequate and timely.
5 The concrete mix design should be geared to good flow characteristics.

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Seal Course Inspection

In addition to the usual concrete placement requirements, such as access and
suitability or adequacy of equipment, sufficient soundings of the bottom of the
excavation should be taken to verify as-built elevations so that deficiencies can be
addressed. Particular care should be given to the perimeter of the cofferdam and
the pile locations, as excavation is somewhat difficult in these areas. If not
completely excavated, ground elevations in these areas will be higher than those
in easier to reach areas which will result in a thinner than anticipated seal course.
Soundings can be accomplished using a flat plate of suitable size and weight on
the end of a rod or rag tape.

Sounding devices can also be used to determine the nature of the material (soft or
firm). During the pour, soundings are again used to verify the elevation of the top
surface of concrete. Because of the type of operation, surface irregularities can be
expected, particularly in pile footings. The important thing is to check for proper
thicknesses throughout and to address any excessively low spots.

Of the various devices available to plug the end of the tremie, an inflated rubber
ball is about the most practical. A tip plug can cause long tremie pipes to float
and should be used with caution.

Thickness of Seal Course

A chart for determining the thickness of seal courses is included in Appendix I.
Certain safeguards or safety factors are built into this chart. For example, seal
courses in pile footings are constructed one foot thicker than required to allow for
surface irregularities and the bond friction between sheet piling and concrete is
disregarded. The bond friction between seal course concrete and foundation piles
is limited to 10 Pounds per Square Inch (PSI). Minimum thickness of seal course
concrete is 2 feet. This subject is also covered in Bridge Construction Memo 130-
17.0 and Bridge Design Aid “Seal Course” included in Appendix I.

Contractor’s Responsibility
Cofferdams fall under the category of temporary features or measures necessary
to construct the work. As such, the Contractor is responsible for the proper
design, construction, maintenance and removal of cofferdams. The Contractor is
required to submit working drawings and calculations to the Engineer for
approval in accordance with Sections 5-1.02 and 19-3.03 of the Standard
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 __________________________________________November 2008_

Specifications. The Contractor is also required to comply with the applicable

sections of the Construction Safety Orders (Sections 1539-1543) and the
provisions of Section 6705 of the California Labor Code. Refer to the Trenching
and Shoring Manual for additional information on braced or shored excavations.

The Contractor has the option of constructing a seal course to control water when
one is not shown on the contract plans. In these situations the contractor is
responsible for determining the thickness and the performance of the seal course.
In addition, Section 19-3.04 of the Standard Specifications states the following:
“If the contractor elects to use a concrete seal course … the provisions of the
fourth paragraph and the first 2 sentences of the fifth paragraph of Section
51-1.10, "Concrete Deposited Under Water," shall not apply for spread footings
and the entire Section 51-1.10 shall not apply to pile footings. The successful
performance of the seals, if used, shall be solely the responsibility of the
Contractor.”

Engineer’s Responsibility
The Engineer is responsible for performing an independent analysis, or check, of
the contractor’s cofferdam and for approving the Contractor’s drawings. In
situations where a seal course is shown on the plans, the Engineer is responsible
for making the decision as to whether, or not, a seal course is needed.

The Engineer should be familiar with the information in the following sections of
the Standard Specifications: 5-1.02, 19-3.03, 19-3.04, 19-3.07, 19-3.08, 51-1.10,
51-1.22; and the following Bridge Construction Memos: 2-9.0 and 130-17.0.

Dewatering
Section 51-1.10 of the Standard Specifications requires a minimum cure period of
5 days (at concrete temperatures of 45° F or more) before dewatering may begin.
Dewatering can present some anxious moments since the cofferdam and the seal
course will be put to the test.

Dewatering is sometimes conducted in stages particularly for a deeper cofferdam.

Intermediate bracing systems may need installed before proceeding deeper.
Depending on the particular design, these internal braces maintain the stability of
the system. Details of dewatering and internal bracing placement should be
included in the cofferdam plans. A review of contract provisions for water
pollution control should be made before dewatering operations start.

Sheet pilings are not watertight and minor leaks can be expected as the cofferdam
is dewatered. These leaks are ordinarily not a problem and occur along the joints

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 __________________________________________November 2008_

between adjacent sheets. Sawdust, cement, or other material can be used to plug
these types of leaks. Dropping the material into the water adjacent to the leaking
sheets usually corrects this as the flow through the leak carries the fine material to
the problem area and seals the crack or opening. A sump built into the surface of
the seal outside of the footing limits is also helpful in keeping the work area
reasonably dry.

Prior to proceeding with footing work, all high spots in the seal course have to be
removed. All scum, laitance, and sediment must also be removed from the top of
the seal. This work can be very time consuming and expensive. It can be reduced
significantly if care is taken during the placement of the seal course.

Safety
Cofferdam work presents safety problems similar to braced excavations. Among
them are limited access, limited work areas, damp or wet footing, and deep
excavations. Provisions must be made for safe access and egress in terms of
adequate walkways, rails, ladders, or stairs into and out of the lower levels. The
Trenching and Shoring Manual goes into those issues in depth and should be
consulted prior to working around cofferdams.

Additional considerations apply to cofferdams, as they tend to occur within a

waterway, in which case additional safety regulations may apply. These include
provisions for flotation devices, boats, warning signals, and suitable means for a
rapid exit. The Construction Safety Orders and job specific Code of Safe
Practices should be consulted for specific requirements.

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 _________________________________________November 2008_

CHAPTER

Alternative Piles and Special

13 Considerations

Introduction

Micropiles
The primary reference for this chapter is from Micropile Design and Construction
Guidelines Implementation Manual, Publication No. FHWA-SA-97-070, Federal
Highway Administration, U.S. Department of Transportation, June 2000, by Tom
Armour, Paul Groneck, James Keeley, and Sunil Sharma.

Micropile Definition and Description

A micropile is a small-diameter (typically less than 300mm), drilled and grouted

replacement pile that is typically reinforced. A micropile is constructed by
drilling a borehole, placing reinforcement, and grouting the hole. Micropile
construction uses similar equipment and techniques as tiebacks, tiedowns, and soil
nails (Chapter 11). Many contractors who specialize in drilling and grouting,
tiebacks, tiedowns, and soil nails also construct micropiles. Micropiles are also
known as root piles, pin piles, needle piles, and minipiles.

Micropiles can withstand axial (compression and tension) loads and some lateral
loads. Depending upon the design concept employed, micropiles may be a
substitute for conventional piles or as one component in a composite soil/pile
mass. Micropiles are installed by methods that cause minimal disturbance to
adjacent structures, soil, and the environment. They can be installed in access-
restrictive environments and in all soil types and ground conditions. Since there
is little lateral resistance provided by these types of piles their use has been
limited to retrofit work and for the construction of retaining and sound walls.

Since the installation procedure causes minimal vibration and noise and can be
used in conditions of low headroom, micropiles are often used to underpin
existing structures. Underpinning is the process of strengthening and stabilizing
the foundation of an existing structure and is accomplished by extending the
foundation in depth or in breadth so it either rests on a stronger soil stratum or
Caltrans ● Foundation Manual 13 - 1
 _________________________________________November 2008_

distributes its load across a greater area. Specialized drilling equipment is often
required to install the micropiles from within existing basement facilities or
through existing bridge footings.

Most of the applied load on conventional cast-in-place replacement piles is

structurally resisted by the reinforced concrete; increased structural capacity is
achieved by increased cross-sectional and surface areas. Micropile structural
capacities, by comparison, rely on high-capacity steel elements to resist most or
all of the applied load. The special drilling and grouting methods used in
micropile installation allow for high grout/ground bond values along the
grout/ground interface. The grout transfers the load through friction from the
reinforcement to the ground in the micropile bond zone in a manner similar to that
of ground anchors. Due to the small pile diameter, any end-bearing contribution
in micropiles is generally neglected. The grout/ground bond strength achieved is
influenced primarily by the ground type and grouting method used, i.e., pressure
grouting or gravity feed. The role of the drilling method is also influential,
although less well quantified.

Applications

Micropiles are currently used in two general applications, (1) structural support
and (2) in-situ reinforcement.

In-situ Reinforcement includes:

• Slope Stabilization and Earth Retention
• Ground Strengthening and Protection
• Settlement Reduction
• Structural Stability

Structural Support includes:

• Earth Retention
• Foundations for New Structures
• Seismic Retrofitting
• Underpinning of Existing Foundations

Micropiles were originally developed for underpinning existing structures. The

underpinning of existing structures may be performed for many purposes:
• To arrest and prevent structural movement.
• To upgrade load-bearing capacity of existing structures.
• To repair/replace deteriorating or inadequate foundations.
• To add scour protection for erosion-sensitive foundations.
• To raise settled foundations to their original elevation.
• To transfer loads to a deeper strata.

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 _________________________________________November 2008_

Caltrans Applications

AASHTO will be adding a section on micropiles in the future. But while the rest
of the country sees the value, Caltrans will limit the use of micropiles due to the
lateral demand requirements. The lateral load capacity of micropiles is small as
their size is too small to develop any real bending moments. Micropiles can resist
lateral load, but not that much. A large quantity of micropiles would be required,
too many.

Caltrans is currently using micropiles for seismic retrofits, earth retention, and
foundations for new structures (retaining/sound walls).

Seismic Retrofit

Caltrans has used micropiles for seismic retrofitting of existing highway bridge
structures. The existing bridge foundations are retrofitted to increase the capacity
so as to resist tension/uplift forces resulting from a seismic event.

A somewhat recent Caltrans retrofit project using micropiles was at the Richmond
San Rafael Bridge located in the San Francisco Bay Area. (Bridge No. 28-0100,
Contract EA 04-0438U4, 04-Mrn-580-PM 6.22). The micropiles were completed
in 2005. See Appendix x.

Micropiles may be economically feasible for bridge foundation retrofits having

one or more of the following constraints:
• Restrictions on footing enlargements.
• Vibration and noise restrictions.
• Low headroom clearances.
• Difficult access.
• High axial load demands in both tension and compression.
• Difficult drilling/driving conditions.
• Hazardous soil sites.

Because of their high slenderness ratio (length/diameter), micropiles may not be

acceptable for conventional seismic retrofitting applications in areas where
liquefaction may occur, given the current standards and assumptions on support
required for long slender elements. However, the ground improvement that can
be induced by micropiles may ultimately yield an improved earthquake mitigation
foundation system.

Earth Retention

The ability of micropiles to be installed on an incline provides designers an option

for achieving the required lateral capacity.
Caltrans ● Foundation Manual 13 - 3
 _________________________________________November 2008_

Near the town of Duncan Mills in Sonoma County in the San Francisco Bay Area,
a micropile retaining wall was constructed in 2007 to stabilize the soil and
roadway. The wall has two rows of micropiles. The front row was vertical using
steel pipe as reinforcement and the interior row was at an angle/incline using two
#36 epoxy coated bundled rebar. See Appendix x.

Foundations for New Structures (Retaining Walls)

In 2007, construction started on a retaining wall on Rte 74 in District 12, Orange

County. Micropiles support the retaining wall, concrete barrier slab, and concrete
barrier. Tiebacks are also used to support the retaining wall.
See Appendix x.

Also, on Rte 1, San Mateo County near the city of Pacifica in the San Francisco
Bay Area, construction began in 2007 on a retaining wall supported by
micropiles. The retaining wall (with barrier and chain link fence) is on a steep
cliff facing the Pacific Ocean. A pedestrian sidewalk runs parallel to the barrier
and chain link fence. On one portion of the wall, the micropiles are battered in
opposite directions providing lateral support.
See Appendix x

Construction and Contract Administration

The Contract Special Provisions will outline all the submittal requirements and
construction requirements for micropiles. Depending on the project location, the
design, and the contractor, different drilling and grouting techniques may be used.
Per the special provisions, the contractor is required to submit to Caltrans for
review and approval all micropile working drawings and a step-by-step procedure
describing all aspects of pile installation. The Caltrans Structure Representative
will coordinate with the Foundation Testing Branch (FTB) for any Caltrans
required load tests. The special provisions may require performance tests to be
performed and recorded by the contractor. The grouting operation can be very
messy so the storm water pollution prevention plan (SWPPP) must be enforced
and all best management practices (BMPs) implemented.

Measurement and Payment

Per the Contract Special Provisions, micropiles will be measured and paid for by
the meter. The contract price paid per meter for micropile shall include full
compensation for furnishing all labor, materials, tools, equipment, and incidentals,
and for doing all the work involved in constructing micropiles, including
protecting and monitoring existing culverts, drilling, providing temporary casings,
double extra strong steel pipe, grout, grout socks, cutting tips, drill bits, pile
anchorage, and disposing of materials resulting from pile installation, complete in

Caltrans ● Foundation Manual 13 - 4

 _________________________________________November 2008_

place, as shown on the plans, as specified in the Standard Specifications and

special provisions, and as directed by the Engineer.

No payment will be made for micropiles that are damaged either during
installation or after the micropiles are complete in place. No payment will be
made for additional excavation, backfill, concrete, reinforcement, nor other costs
incurred from footing enlargement resulting from replacing rejected micropiles.

Safety

All personnel must wear the proper personal protection equipment (PPE) during
drilling and grouting operations to include eye protection, earplugs, and hardhat.
Life vests are required when working near water. Safe access must be provided
by the contractor when working on slopes or within trenches. Be cautious and
avoid slipping or falling when working near slopes. Caltrans field engineers
should not stand too close to the work when the pile reinforcement and steel pipe
is hoisted into place.

Changeable Message Signs

Changeable message signs (CMS) are typically large diameter Cast-In-Drilled-
Hole (CIDH) pile foundations. Figure xx shows a 5-ft diameter pile with a
minimum depth of 22-ft for CMS Model 500. Construction of CMS foundations
is made difficult when groundwater is encountered. If there is groundwater, then
the slurry displacement method is usually required (Chapter 9). The contract
special provisions will outline all the requirements. Small-sized, inexperienced
contractors may have difficulty meeting “wet method spec” submittal
requirements and construction requirements. Structure Representatives need to
thoroughly communicate all the requirements. The preconstruction meeting is a
good forum to initially discuss slurry displacement requirements.

A Log of Test Borings (LOTB) might not be included in small CMS projects
making it difficult to anticipate the presence of groundwater. A proactive
Structure Representative can obtain LOTB as-builts from the nearest bridge
structure location. The proactive Structure Representative should review the
LOTB as-builts and share the information with the contractor. As-builts are
available at District Headquarters and on-line on the intranet (Bridge Inspection
Records Information System (BIRIS) and Document Retrieving System (DRS)).

Personnel safety must be enforced during drilling and excavating operations. Full
body harness should be used when working near open holes. Personnel not
directly involved in the construction operation should not stand next to an open
hole to avoid falling in or if the edge collapses.

Caltrans ● Foundation Manual 13 - 5

 _________________________________________November 2008_

FIGURE 13-1 CMS details from 2006 Standard Plan S116

Caltrans ● Foundation Manual 13 - 6

 _________________________________________ References
November 2008

References
1. API Recommended Practice 13B-1 (RP13B-1). © American Petroleum Institute,
1st edition, 1990.

2. Bridge Construction Records and Procedures Manual. State of California,

Department of Transportation, 1990 (with revisions).

3. Bridge Design Aids Manual. State of California, Department of Transportation,

1986 (with revisions).

4. Bridge Memos to Designers. Memo 3-1, State of California, Department of

Transportation, 1986 (with revisions).

5. Michael W. O’Neill. Construction Practices and Defects in Drilled Shafts.

Transportation Research Record 1331, 1992, pp. 6-14.

6. Construction Safety Orders. State of California Administrative Code, Title 8,

Subchapter 4, 1989 (with revisions).

7. DFI Publication. © Deep Foundations Institute, 1981.

8. Design Manual Soil Mechanics, Foundations, and Earth Structures. NAVFAC

DM-7, U.S. Department of the Navy, 1971.

9. Drilled Shaft Inspector’s Manual. The Joint Caisson – Drilled Shaft Committee of
the Association of Drilled Shaft Contractors: The International Association of
Foundation Drilling and DFI: Deep Foundations Institute, 1989.

10. L. C. Reese and M. W. O’Neill. Drilled Shafts: Construction Procedures and

Design Methods. Publication No. FHWA-HI-88-042, FHWA, U.S. Department of
Transportation, 1988.

11. R. E. Majano and M. W. O’Neill. Effect of Mineral and Polymer Slurries on

Perimeter Load Transfer in Drilled Shafts. Report No. UHCE 93-1, University of
Houston, Department of Civil and Environmental Engineering, 1993.

12. R. E. Majano and M. W. O’Neill. Effects of Mineral and Polymer Slurries on Side
Load Transfer in Drilled Shafts – Part 1, Baseline Laboratory Studies. University
of Houston, Department of Civil and Environmental Engineering, 1992.

Caltrans ● Foundation Manual References-1

 _________________________________________ References
November 2008

13. Arthur Miller. “Figure used for Figure 7-1”. State of California, Department of
Transportation, District 02 Reprographics.

14. Joseph E. Bowles. Foundation Analysis and Design. 4th edition, McGraw-Hill,
1988.

15. Wayne C. Teng. Foundation Design. Prentice-Hall, Inc., 1962.

16. Handbook of Engineering Geology. State of California, Department of Public

Works, 1958.

17. G. B. Sowers and G. F. Sowers. Introductory Soil Mechanics and Foundations.

3rd edition, Macmillan, 1970.

18. Suneel N. Vanikar. Manual on Design and Construction of Driven Pile

Foundations. Publication No. FHWA-DP-66-1, FHWA, U. S. Department of
Transportation, 1986.

19. K. Terzaghi and R. B. Peck. Soil Mechanics in Engineering Practice. 2nd edition,
John Wiley & Sons, 1967.

20. James A. Porterfield, David M. Cotton, R. John Byrne. Soil Nailing Field
Inspectors Manual - Soil Nail Walls. Publication No. FHWA-SA-93-068, FHWA,
U. S. Department of Transportation, 1994.

21. Cheng Liu and Jack B. Evett. Soils and Foundations. Prentice-Hall, Inc., 1981.

22. Standard Specifications. State of California, Department of Transportation, 1992.

23. Standard Test Methods. State of California, Department of Transportation, 1978

(with revisions).

24. Steel Sheet Piling Design Manual. © U. S. Steel Corporation, 1984.

25. Trenching and Shoring Manual. State of California, Department of

Transportation, 1990 (with revisions).

26. Max Holmes, "The Driller’s Guide to Slurry Drilling"(copyright), Geo-Tech

Services, LLC, 2003-2008

27. Michael W. O'Neil & Lymon C. Reese, Drilled Shafts: Construction Procedures
and Design Methods. Publication No. FHWA-IF-99-025, FHWA, U.S.
Department of Transportation, 1999.

Caltrans ● Foundation Manual References-2

 _________________________________________ References
November 2008

28. Tom Armour, Paul Groneck, James Keeley, and Sunil Sharma, Micropile Design
and Construction Guidelines Implementation Manual, Publication No. FHWA-
SA-97-070, Federal Highway Administration, U.S. Department of Transportation,
June 2000

Caltrans ● Foundation Manual References-3

 _______________________Appendix A – Foundation Investigations
November 2008

APPENDIX

A Foundation Investigations

Table of Contents

Caltrans Soil & Rock Logging, Classification and Logging Manual A-2

Caltrans ● Foundation Manual A-1

 _______________________Appendix A – Foundation Investigations
November 2008

This 93-page document is available on the DES-

Geotechnical Services website:
http://www.dot.ca.gov/hq/esc/geotech/requests/logging_manual/logging_
manual.html

Caltrans ● Foundation Manual A-2

State of California
Department of Transportation
Division of Engineering Services
Geotechnical Services

Soil and Rock

Logging,
Classification, and
Presentation Manual

June 2007

© 2007 Department of Transportation

(This page left intentionally blank)
Preface
Detailed soil and rock descriptions and classifications are an essential part of the information
developed to support Caltrans’ design and construction processes. Subsurface information for
any given area is, and can be, generated and accumulated over a prolonged period of time by
various geotechnical practitioners for different projects and purposes. It is imperative that
geotechnical practitioners working on Caltrans projects use standardized terminology and
procedures to maintain consistency in borehole logging and reporting practices. Geotechnical
Services in the Division of Engineering Services, has published this Manual to ensure the
Department’s investment in maintaining consistent logging practices.
This Manual, “Soil and Rock Logging, Classification, and Presentation Manual”, improves
upon the original version of the manual, “Soil and Rock Logging Classification Manual (Field
Guide)”, published in 1996, by addressing the following:
• Serves as a comprehensive reference for Departmental staff, consultants, and contractors
• Provides standardized soil description and identification procedures utilizing field data
• Provides standardized soil classification procedures utilizing laboratory data
• Provides standardized rock description and identification procedures utilizing field and
laboratory data
• Serves as a basis for Departmental products and tools, such as:
– Boring Log presentation formats,
– Log of Test Boring (LOTB) legend sheets,
– Descriptive terminology presented in geotechnical reports, and
– Geotechnical Data Management System
The information presented in this Manual is based predominantly on American Standards for
Testing Materials (ASTM) and other publications. These references provide standardized
methods for identifying, describing, or classifying soil and rock; however, they do not provide
adequate descriptive terminology and criteria for identifying soil and rock for engineering
purposes. Consequently, this manual extends, and in some cases modifies these standards to
include additional descriptive terms and criteria.
In addition to soil and rock identification, description, or classification, this Manual contains
instructions that present Departmental standards for borehole and sample identification,
minimum material requirements for various laboratory tests, and boring log presentation
formats.
Geotechnical Services staff and any other organization providing geotechnical reports or
records of geotechnical investigations for the Department shall use the procedures presented in
this Manual.

James E. Davis
Deputy Division Chief, Geotechnical Services

i
Acknowledgements
Geotechnical Services wishes to thank the following team members for
preparing this Manual.
Roy Bibbens, Geotechnical Services
Mark Desalvatore, Geotechnical Services
Mark Hagy, Geotechnical Services
Craig Hannenian, Geotechnical Services
Deh-Jeng Jang, Geotechnical Services
Robert Price, Geotechnical Services
Loren Turner, Research & Innovation
Hector Valencia, Geotechnical Services
Thomas Whitman, Geotechnical Services
The team wishes to extend its appreciation to the following people and/or
organizations for their contributions to the content of this Manual.
Bruce Hilton, Kleinfelder Inc.
Mike Kennedy, Anderson Drilling Inc., Association of Drilled Shaft
Contractors
Mildred Macaranas, Geotechnical Services
Alan Macnab, Condon-Johnson & Associates, Association of Drilled
Shaft Contractors
Steve Mahnke, CA Dept. of Water Resources
Heinrich Majewski, Malcolm Drilling Co. Inc., Association of
Drilled Shaft Contractors
Rick and Dot Nelson, Dot.Dat.Inc
Parsons Brinckerhoff
Ron Richman, Geotechnical Services
Barry Siel, Federal Highway Administration
Sarah Skeen, Federal Highway Administration
URS Corp.
Will Smith, Case Pacific, Association of Drilled Shaft Contractors
(Names have been listed alphabetically.)

ii
Table of Contents
SECTION 1: INTRODUCTION .......................................................................................................1
1.1 Intent of this Manual...............................................................................................................1
1.2 Limitations ..............................................................................................................................1
1.3 Exceptions to Policy ...............................................................................................................1
1.4 Revisions to the Manual.........................................................................................................1
1.5 Organization of this Manual ...................................................................................................2
1.6 Overview of the Logging Process and Presentation Formats ................................................2

SECTION 2: FIELD PROCEDURES FOR SOIL AND ROCK LOGGING, DESCRIPTION, AND
IDENTIFICATION .............................................................................................................................5
2.1 Introduction ............................................................................................................................5
2.2 General Project and Hole Information ....................................................................................5
2.3 Assignment of Hole Identification ...........................................................................................7
2.4 Soil Description and Identification Procedures .......................................................................7
2.4.1 Soil Description and Identification ............................................................................................................8
2.4.2 Group Name and Group Symbol..............................................................................................................9
2.4.3 Consistency (Cohesive Soils).................................................................................................................13
2.4.4 Apparent Density (Cohesionless Soils) ..................................................................................................15
2.4.5 Color .......................................................................................................................................................15
2.4.6 Moisture..................................................................................................................................................15
2.4.7 Percent of Cobbles or Boulders .............................................................................................................15
2.4.8 Percent or Proportion of Soils ................................................................................................................16
2.4.9 Particle Size............................................................................................................................................16
2.4.10 Particle Angularity...................................................................................................................................17
2.4.11 Particle Shape .......................................................................................................................................17
2.4.12 Plasticity (for Fine-Grained Soils)..........................................................................................................17
2.4.13 Dry Strength (for Fine-Grained Soils).....................................................................................................18
2.4.14 Dilatancy (for Fine-Grained Soils) .........................................................................................................18
2.4.15 Toughness (for Fine-Grained Soils) ......................................................................................................18
2.4.16 Structure .................................................................................................................................................18
2.4.17 Cementation ...........................................................................................................................................18
2.4.18 Description of Cobbles and Boulders ....................................................................................................19
2.4.19 Additional Comments .............................................................................................................................19
2.4.20 Other Drilling Observations ....................................................................................................................19
2.5 Rock Identification Procedures for Borehole Cores..............................................................20
2.5.1 Rock Identification and Descriptive Sequence for Borehole Cores .......................................................20
2.5.2 Rock Name.............................................................................................................................................21
2.5.3 Rock Grain-size descriptors ...................................................................................................................23
2.5.4 Bedding Spacing Descriptors .................................................................................................................25
2.5.5 Rock Colors ............................................................................................................................................25
2.5.6 Textural Descriptors ...............................................................................................................................25
2.5.7 Weathering Descriptors for Intact Rock..................................................................................................26
2.5.8 Rock Hardness .......................................................................................................................................27
iii
 2.5.9 Fracture Density .....................................................................................................................................27
2.5.10 Discontinuity Type ..................................................................................................................................28
2.5.11 Discontinuity Condition (Weathering, Infilling and Healing) ...................................................................29
2.5.12 Discontinuity Dip Magnitude...................................................................................................................30
2.5.13 Rate of Slaking .......................................................................................................................................30
2.5.14 Odor........................................................................................................................................................30
2.5.15 Additional Comments .............................................................................................................................31
2.5.16 Other Drilling Observations ....................................................................................................................31
2.6 Sample Preparation and Identification for Laboratory Testing and Storage .........................32
2.6.1 Sample Preparation and Identification for Laboratory Testing and Storage ..........................................32
2.6.2 Identification of Large Soil Samples .......................................................................................................34
2.6.3 Core Box Layout.....................................................................................................................................37
2.7 Quality Check of Field Observations and Samples ..............................................................38

SECTION 3: PROCEDURES FOR SOIL AND ROCK DESCRIPTION AND/OR

CLASSIFICATION USING LABORATORY TEST RESULTS .......................................................39
3.1 Introduction ..........................................................................................................................39
3.2 Revising Soil Descriptions and Assigning Soil Classification Using Laboratory Test Results
.............................................................................................................................................39
3.2.1 Soil Classification and Description Descriptive Sequence .....................................................................40
3.2.2 Group Name and Group Symbol............................................................................................................41
3.2.3 Consistency (Cohesive Soils).................................................................................................................46
3.2.4 Percent or Proportion of Soils ................................................................................................................46
3.2.5 Particle Size............................................................................................................................................46
3.2.6 Plasticity (for Fine-Grained Soils)...........................................................................................................46
3.3 Revising Rock Identification and Description for Borehole Cores Using Laboratory Test
Results .................................................................................................................................47
3.3.1 Strength of Intact Rock ...........................................................................................................................47

SECTION 4: METHODS OF PRESENTATION OF SUBSURFACE INFORMATION ..................49

4.1 Introduction ..........................................................................................................................49
4.2 Factual vs. Interpretive Subsurface Data .............................................................................49
4.3 Incorporating Laboratory Data, Refining Descriptions, and Classifying Soil.........................50
4.3.1 Subsurface Data Presentation Method ..................................................................................................50
4.3.2 General Rules and Considerations ........................................................................................................50
4.3.3 Example..................................................................................................................................................51

SECTION 5: BORING LOG AND LEGEND PRESENTATION FORMATS .................................53

5.1 Introduction ..........................................................................................................................53
5.2 Log of Test Boring................................................................................................................53
5.2.1 Contents and Characteristics of the LOTB............................................................................................54
5.2.2 Notes on the LOTB.................................................................................................................................54
5.2.3 LOTB Sheet Formatting..........................................................................................................................54
5.2.4 As-Built LOTB Sheet Formatting ............................................................................................................56
5.2.5 The LOTB Legend Sheets......................................................................................................................57

iv
5.3 Boring Records ....................................................................................................................64
5.3.1 Content and Characteristics of the BR ...................................................................................................67
5.3.2 Notes on the BR .....................................................................................................................................67
5.3.3 The Boring Record Legend Sheets ........................................................................................................67

REFERENCES ...............................................................................................................................71

APPENDIX A: FIELD TEST PROCEDURES ...............................................................................73

A.1 Pocket Penetrometer ...........................................................................................................73
A.2 Torvane................................................................................................................................73
A.3 Dry Strength .........................................................................................................................73
A.4 Dilatancy ..............................................................................................................................73
A.5 Toughness ...........................................................................................................................73
A.6 Jar Slake Index Test ............................................................................................................74
A.7 Calcium Carbonate ..............................................................................................................74
A.8 Standard Penetration Test ...................................................................................................74
A.9 Core Recovery (REC) ..........................................................................................................75
A.10 Rock Quality Designation (RQD)..........................................................................................75

APPENDIX B: FIELD LOGGING AIDS ........................................................................................77

B.1 Field Sample Logging Forms ...............................................................................................77

APPENDIX C: PROCEDURAL DOCUMENTS ............................................................................81

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vi
Section 1:
Introduction
1.1 Intent of this Manual 1.2 Limitations
The intent of this Manual is to define the Although this manual may be used to train new
Department’s practices and procedures for soil and employees, this is not its primary intent.
rock description, identification, classification, and This manual does not replace education or
preparation of boring logs. experience and shall be used in conjunction with
Standardized terminology and consistent professional judgment. Not all aspects of this
presentation procedures for projects statewide manual may be applicable in all circumstances and
benefit the Department’s staff, engineering should be applied with consideration of a project’s
consultants, bidders, and contractors. Geotechnical many unique aspects.
Services staff as well as any other organization This manual does not purport to address all of the
providing geotechnical reports or records of safety problems, if any, associated with its use. It is
geotechnical investigations to the Department shall the responsibility of the user of this standard to
follow the procedures presented in this Manual. establish, or adhere to, appropriate safety and
The following terms, as defined below, are used health practices and determine the applicability of
throughout this Manual to convey the regulatory limitations prior to use. The reader shall
Department’s policy: follow at a minimum, the Caltrans Code of Safe
Drilling Practices.
Term Definition
Shall, Mandatory Standard. The 1.3 Exceptions to Policy
Required associated provisions must be
used. There is no acceptable Exceptions to the policy and procedures set forth in
alternative. this Manual require prior approval by the
Geotechnical Services Deputy Division Chief.
Should Advisory Standard. The Staff shall use the procedure for obtaining approval
associated provisions are preferred for an exception, as documented in a memorandum
practices.
to all staff dated June 15, 2007, included in
May, Permissive Standard. Use or
Appendix C.
Optional application of the associated
provisions is left to the discretion of
the Geoprofessional. 1.4 Revisions to the Manual
Staff who wish to propose changes to the Manual
shall do so in accordance with the Soil and Rock
Logging, Classification, and Presentation Manual
Committee Charter and Standard Procedures,
included in Appendix C.

Soil and Rock Logging, Classification, and Presentation Manual, Section 1 1

1.5 Organization of this Manual typically associated with an earthwork facility and
is attached to a Geotechnical Report.
The Manual is divided into five sections, as
described below:
Section 1 The process of creating boring logs, i.e., Log of
– Explains the intent and organization of this Test Boring (LOTB) and Boring Record (BR) can
Manual and the process for requesting be summarized in four steps:
exceptions and proposing changes to the • Field sampling and descriptions (Section 2)
Manual • Quality check of field descriptions (Section 2)
– Presents an overview of the logging process • Refinement of descriptions, and classification
and acceptable presentation formats of soil, based on laboratory test results, if
Section 2 performed (Section 3)
– Presents the Department’s field description and • Preparation of the boring logs (Sections 4
indentification procedures for soil and rock, and 5)
without the benefit of laboratory testing
(See Figure 1-1.)
– Explains procedures for handling and labeling
of samples Prior to the field investigation, the geoprofessional
– Explains how to perform a quality check of should have general understanding of the local
borehole logs and soil and rock samples soils and geologic information, and know the
Section 3 parameters and the basic descriptors required for
– Describes the Department’s classification the planned analyses. Specific laboratory tests,
procedures for soil and rock samples for which such as strength, consolidation, or permeability
the data was refined by appropriate laboratory may govern the type of drilling and sampling used.
tests Recovering and labeling, and accurately describing
Section 4 and classifying samples is a detailed process that
– Presents the process for developing and typically necessitates a thorough check of field
presenting geotechnical information on a Log notes and samples in the office before requesting
of Test Boring (LOTB) or a Boring Record laboratory tests. In some cases, the geoprofessional
(BR). may use only field observations. (See Section 2.)
In other cases, it may be the judgment of the
Section 5
geoprofessional that a combination of field
– Specifies presentation content and formats for observations and laboratory test results are needed
Log of Test Boring (LOTB) and Boring Record to describe or classify the soil or rock samples, and
(BR). generate appropriate layer descriptions for LOTB
or BR. (See Sections 2
and 3.)
1.6 Overview of the Logging
Process and Presentation
Formats
The Department uses the following formats to
present subsurface information:
• Log of Test Boring (LOTB), and/or
• Boring Record (BR).
An LOTB is typically associated with a structure
facility and is attached to Project Plans. A BR is
Soil and Rock Logging, Classification, and Presentation Manual, Section 1 2
If the results of laboratory tests change the Figure 1-1
description of the sample generated by field Logging and Presentation Process
observation, the classification and/or description
resulting from the laboratory tests shall be used on
the LOTB and/or the BR, and in the geotechnical Field
Sampling
report. Disclosure of the tests on the LOTB and/or and
the BR makes it clear whether the sample or layer Descriptions
(Sec. 2)
descriptor was based on visual observation or on
laboratory test results. (See Sections 4 and 5.)

Quality
Check of
Field
Observations
(Sec. 2)

Laboratory
Tests?

YES NO

Incorporate
Laboratory Data,
Refine
Descriptions, and
Classify (Sec. 3)

Prepare
Boring Logs
(Sec. 4 & 5)

Soil and Rock Logging, Classification, and Presentation Manual, Section 1 3

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Soil and Rock Logging, Classification, and Presentation Manual, Section 1 4

Section 2:
Field Procedures for Soil and Rock Logging, Description,
and Identification
2.1 Introduction
This section presents the procedures for logging, The identifications and descriptions in the field
describing, and identifying soil and rock samples logs may be corrected, calibrated, or verified later
in the field based on visual and manual procedures. based on laboratory test results of selected soil
The information presented in this section is samples to develop the final boring logs, as
predominantly based on: described in Section 3.
• American Society for Testing and Materials The process of correction, calibration, and
(ASTM) D 2488-06, Standard Practice for verification in developing the updated logs based
Description and Identification of Soils (Visual- on laboratory test results can effectively serve the
Manual Procedure), and purpose of self-training and self-calibration for
future field identification and description of soil
• The Engineering Geology Field Manual samples.
published by the Bureau of Reclamation.
In addition to soil and rock identification and
Although ASTM D 2488-06 provides a description, this section contains instructions that
standardized method for indentification of soils, it describe proper hole and sample identification
does not provide adequate descriptive terminology practices, and minimum material requirements for
and criteria for identifying soils for engineering various laboratory tests.
purposes. Section 17 of ASTM D 2488-06 states,
“this practice provides qualitative information 2.2 General Project and Hole
only,” and Note 4 adds, “The ability to describe
Information
and identify soils correctly … may also be
acquired systematically by comparing numerical One of the most important aspects of field work is
laboratory test results for typical soils of each type properly identifying the location of the project site,
with their visual and manual characteristics.” drilling tools and methods used, and the personnel
involved in the field work. Figure 2-1 presents the
This Manual extends, and in some cases modifies, information that is required to be recorded for
the ASTM standard to include additional every hole.
descriptive terms and criteria. It is not our intent to
replace the ASTM standards but to build on them,
and make them better understood.

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 5

Figure 2-1
Information Required for Borehole

Item Description

1 Date(s) of work
2 Hole Identification
3 Project and Site Information:
• District
• Project Name
• County
• Structure/Bridge Name and Number (if available)
• Route
• Project Number (Charge District - Expenditure
Authorization, 8-digits) • Postmile, range and prefix

4 Borehole Location and Elevation:

• Location (at least one of the following):
o Station and offset
o Latitude and longitude, horizontal datum
o Northing and Easting, local coordinate reference system
Note: In the absence of accurate coordinate data, a suitable and verifiable field description may be
temporarily used. (e.g., postmile and centerline offset, distance to fixed object or benchmark, etc.)
• Elevation, vertical datum, benchmark description
• Survey method(s) used, approximate accuracy
5 Personnel:
• Logger/Geoprofessional
• Drillers
6 Drilling and Sampling Equipment (verify with Driller):
• Drill rig (manufacturer and model, and Caltrans Equipment Identification number)
• Drilling method (mud rotary, air rotary, solid auger, hollow stem auger. etc.)
• Drill rod description (type, diameter)
• Drill bit description
• Casing (type, diameter) and installation depth
• SPT Hammer Type: Safety/Automatic Hammer, etc.
o Lifting mechanism (for safety hammer)
o Manufacturer & model
o Caltrans Equipment Identification number
o Measured SPT energy efficiency ratio (if available)
• Type of sampler(s) and size(s)
o Undisturbed Shelby tube
o Undisturbed Piston
o Split spoon (e.g. SPT, Cal Mod, etc.)
o Core (both rock and soil)
o Disturbed (include auger cuttings)
o Other
7 Groundwater
• Method (observed while drilling, measured in hole, etc.)
• Date, time, and depth of each reading
8 Hole Completion
• Cause of termination (e.g., drilled to depth, refusal, early termination of traffic control, etc.)
• Abandonment (e.g., grout, soil cuttings, dry bentonite chips, piezometers installed, slope inclinometer
installed, TDR, instrumentation, etc.)

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 6

2.3 Assignment of Hole 2.4 Soil Description and
Identification Identification Procedures
Holes shall be identified using the following This section presents the method for identification
convention: and description of soil based on ASTM D 2488-06
and USBR (2001). The detail of description
HHH – YY – NNN
provided for a particular soil should be dictated by
Where: the complexity and objectives of the project.
HHH: The Hole Type or Sounding Codes Optional descriptors should be considered by the
defined in Figure 2-2, which generally geoprofessional on a project by project basis.
follow ASTM D 6453-99
YY: 2-digit year
NNN: 3-digit number (001-199)
The numbers 001–099 are reserved for holes
used to produce a foundation report; numbers
101–199 are reserved for holes used to produce
a geotechnical design report.
The YY-NNN component of the hole identification
is unique and matched to a Caltrans project
expenditure authorization number (EA), not to a
site, structure, or bridge number. If two drilling
methods are used, such as auger boring followed
by rotary drilled boring, the prominent tool governs
the selection of Hole Type Code (HHH).
Figure 2-2
Hole Type Code and Description
Hole Type
Description
Code
Auger boring (hollow or solid stem,
A
bucket)
Rotary drilled boring (both conventional
R
and wire-line)
P Rotary percussion boring (Air)
HD Hand driven (1-inch soil tube)
HA Hand auger
D Driven (dynamic cone penetrometer)
CPT Cone Penetration Test
O Other

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 7

2.4.1 Soil Description and Identification Example of a complete descriptive sequence for a
sample using required and optional components:
When describing and identifying soil in the field,
the geoprofessional shall record the field data Well-graded SAND with GRAVEL (SW),
following the sequence presented in Figure 2-3 medium dense, brown to light gray, wet, about
below. Items marked “required” shall be used, 20% coarse subrounded to rounded flat and
when applicable, to describe the soil sample to elongated GRAVEL, about 75% coarse to fine
ensure complete descriptive coverage. For rounded SAND, about 5% fines, weak
example, percent cobbles and/or boulders is only cementation.
required if cobbles and/or boulders are encountered.
Figure 2-3 Example of a complete descriptive sequence for a
soil sample using only required components:
Identification and Description Sequence
Well-graded SAND with GRAVEL (SW),
Refer to Section
medium dense, brown to light gray, wet, little
coarse GRAVEL, mostly coarse to fine SAND,
Sequence

Required few fines, weak cementation.

Identification Optional Example of a complete descriptive sequence that
Components omits the percent or proportion of the primary soil
1 Group Name 2.4.2 J constituent, which may be used when the
2 Group Symbol 2.4.2 J percentage or proportion of the primary soil
Description constituent can be clearly inferred:
Components Well-graded SAND with GRAVEL (SW),
Consistency medium dense, brown to light gray, wet, little
3 2.4.3 J
(for cohesive soils) coarse GRAVEL, few fines, weak cementation.
Apparent Density
4 2.4.4 J
(for cohesionless soils)
5 Color (in moist condition) 2.4.5 J
6 Moisture 2.4.6 J 2.4.1.1 Soil Description for Intensely
Percent of cobbles or Weathered or Decomposed Rock
7 2.4.7 J
boulders
8 Percent or proportion of soils 2.4.8 J
Intensely weathered or decomposed rock that is
9 Particle Size Range 2.4.9 J friable and that can be reduced to gravel size or
10 Particle Angularity 2.4.10 E smaller by normal hand pressure shall be identified
11 Particle Shape 2.4.11 E and described as rock followed by the soil
12
Plasticity
2.4.12 J identification or classification, and description in
(for fine-grained soils) parenthesis (per Section 2.5).
Dry Strength
13 2.4.13 E
(for fine-grained soils)
Dilatency
14 2.4.14 E
(for fine-grained soils)
Toughness
15 2.4.15 E
(for fine-grained soils)
16 Structure 2.4.16 E
17 Cementation 2.4.17 J
Description of Cobbles and
18 2.4.18 J
Boulders
19 Additional Comments 2.4.19 E

Below are some examples that illustrate the

application of the descriptive sequence based on
field procedures.

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 8

2.4.2 Group Name and Group Symbol • The soil could be well graded or poorly graded,
Using visual examination and simple manual tests, e.g., GW/GP, SW/SP.
this section provides standardized criteria and • The soil could either be a silt or a clay, e.g.,
procedures for describing and identifying soil in CL/ML, CH/MH, SC/SM.
the field per ASTM D 2488-06. The soil is to be
identified by assigning a group name and symbol. • A fine-grained soil has properties that indicate
The Figures in this section are to be used for the that it is at the boundary between a soil of low
identification of both fine and coarse-grained soil plasticity and a soil of high plasticity, e.g.,
and to determine the appropriate group symbol(s) CL/CH, MH/ML.
and name(s) to be used. The order of the borderline symbols shall reflect
The ASTM procedure for identifying and similarity to surrounding or adjacent soils. For
describing fine-grained and coarse-grained soils is example, soils in a borrow area have been
only applicable to material passing the 3-inch sieve. identified as CH, and one sample is considered to
If the presence of cobbles or boulders or both is have a borderline symbol of CL and CH. To show
identified during the site exploration, the similarity, the borderline symbol shall be CH/CL.
percentage of cobbles and boulders shall be The group name for a soil with a borderline symbol
estimated and reported per Section 2.4.7. shall be the group name for the first symbol, except
Borderline Symbol – Because ASTM D 2488-06 is for:
based on estimates of particle size distribution and • CL/CH lean to fat clay,
plasticity characteristics, it may be difficult to • ML/CL clayey silt, and
clearly identify the soil as belonging to one
• CL/ML silty clay
category. To indicate that the soil may fall into one
of two possible basic groups, a borderline symbol Borderline symbols should not be used
shall be used with the two symbols separated by a indiscriminately. Use of a single group symbol is
slash. For example: SC/CL or CL/CH. preferable.
A borderline symbol shall be used when: Dual Symbol – A dual symbol is two symbols
separated by a hyphen, e.g., GP-GM, SW-SC, CL-
• The percentage of fines is estimated to be ML. They are used to indicate that the soil has been
between 45 and 55%. One symbol shall be for a identified as having the properties of a
coarse-grained soil with fines; the other for a classification in accordance with ASTM Test
fine-grained soil, e.g., GM/ML or CL/SC. Method D 2487-06 requiring dual symbols, i.e.,
• The percentage of sand and the percentage of when the soil has between 5 and 12% fines, or
gravel are estimated to be about the same, e.g., when the liquid limit and plasticity index values
GP/SP, SC/GC, GM/SM. plot in the CL-ML area of the plasticity chart.

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 9

2.4.2.1 Fine Grained Soils
A soil is considered to be fine-grained if it contains 50% or more fines. Particles that pass through a Number
200 sieve are defined as fine-grained. Fine-grained soils shall be assigned the Group Name and Symbol
according to Figure 2-4, below.
Figure 2-4
Flow chart for fine-grained soils (from ASTM D 2488-06)
Symbol
Group

Fines Coarseness Sand or Gravel Group Name

<15% plus No.200 Lean CLAY
<30% plus No.200 % sand > % gravel Lean CLAY with SAND
15-25% plus No.200
% sand < % gravel Lean CLAY with GRAVEL
CL < 15% gravel SANDY lean CLAY
% sand > % gravel
> 15% gravel SANDY lean CLAY with GRAVEL
>30% plus No.200
< 15% sand GRAVELLY lean CLAY
% sand < % gravel
> 15% sand GRAVELLY lean CLAY with SAND
<15% plus No.200 SILT
<30% plus No.200 % sand > % gravel SILT with SAND
15-25% plus No.200
% sand < % gravel SILT with GRAVEL
ML < 15% gravel SANDY SILT
% sand > % gravel
> 15% gravel SANDY SILT with GRAVEL
>30% plus No.200
< 15% sand GRAVELLY SILT
% sand < % gravel
> 15% sand GRAVELLY SILT with SAND
<15% plus No.200 Fat CLAY
<30% plus No.200 % sand > % gravel Fat CLAY with SAND
15-25% plus No.200
% sand < % gravel Fat CLAY with GRAVEL
CH < 15% gravel SANDY fat CLAY
% sand > % gravel
> 15% gravel SANDY fat CLAY with GRAVEL
>30% plus No.200
< 15% sand GRAVELLY fat CLAY
% sand < % gravel
> 15% sand GRAVELLY fat CLAY with SAND
<15% plus No.200 Elastic SILT
<30% plus No.200 % sand > % gravel Elastic SILT with SAND
15-25% plus No.200
% sand < % gravel Elastic SILT with GRAVEL
MH < 15% gravel SANDY elastic SILT
% sand > % gravel
> 15% gravel SANDY elastic SILT with GRAVEL
>30% plus No.200
< 15% sand GRAVELLY elastic SILT
% sand < % gravel
> 15% sand GRAVELLY elastic SILT with SAND
<15% plus No.200 ORGANIC SOIL
<30% plus No.200 % sand > % gravel ORGANIC SOIL with SAND
15-25% plus No.200
% sand < % gravel ORGANIC SOIL with GRAVEL
OL/ < 15% gravel SANDY ORGANIC SOIL
OH % sand > % gravel SANDY ORGANIC SOIL with
> 15% gravel
GRAVEL
>30% plus No.200
< 15% sand GRAVELLY ORGANIC SOIL
% sand < % gravel GRAVELLY ORGANIC SOIL with
> 15% sand
SAND

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 10

Clay and Silt – Identify the soil as a Lean CLAY (CL), a Fat CLAY (CH), a SILT (ML), or an Elastic SILT
(MH), using the criteria in Figure 2-5:
Figure 2-5
Identification of clayey and silty soils
Group Symbol Dry Strength Dilatancy Toughness

ML None to low Slow to rapid Low or thread cannot be formed

CL Medium to high None to slow Medium

MH Low to medium None to slow Low to medium

CH High to very high None High

Organic Soil – Identify the soil as organic, OL/OH, if the soil contains enough organic particles to influence
the soil properties. Organic soils usually have a dark brown to black color and may have an organic odor.
Often, organic soils will change color, for example, black to brown, when exposed to the air. Some organic
soils will lighten in color significantly when air-dried. Organic soils normally will not have a high toughness
or plasticity. The thread for the toughness test will be spongy.
Identification of Peat – A sample composed primarily of vegetable tissue in various stages of decomposition
that has a fibrous to amorphous texture, usually a dark brown to black color, and an organic odor, shall be
designated as a highly organic soil and shall be identified with the Group Name and Symbol, PEAT (PT),
and not subjected to the identification procedures described hereafter.

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 11

2.4.2.2 Coarse-Grained Soil
A soil is considered coarse-grained if it contains fewer than 50% fines. (Coarse-grain particles will not pass
through a Number 200 sieve.) Soil is identified as gravel if the percentage of gravel is estimated to be greater
than the percentage of sand. Soil is identified as sand if the percentage of gravel is estimated to be equal to or
less than the percentage of sand.

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 12

Figure 2-7
Flow chart for coarse-grained soils (from ASTM D-2488-06)
Type of Group
Fines Grade Fines Symbol Sand/Gravel Group Name
< 15% sand Well-graded GRAVEL
Well GW
> 15% sand Well-graded GRAVEL with SAND
< 5%
< 15% sand Poorly graded GRAVEL
Poorly GP
> 15% sand Poorly graded GRAVEL with SAND
< 15% sand Well-graded GRAVEL with SILT
ML or MH GW-GM
> 15% sand Well-graded GRAVEL with SILT and SAND
Well
< 15% sand Well-graded GRAVEL with CLAY
CL or CH GW-GC
Gravel

> 15% sand Well-graded GRAVEL with CLAY and SAND

10%
< 15% sand Poorly graded GRAVEL with SILT
ML or MH GP-GM
> 15% sand Poorly graded GRAVEL with SILT and SAND
Poorly
< 15% sand Poorly graded GRAVEL with CLAY
CL or CH GP-GC
> 15% sand Poorly graded GRAVEL with CLAY and SAND
< 15% sand SILTY GRAVEL
ML or MH GM
> 15% sand SILTY GRAVEL with SAND
> 15%
< 15% sand CLAYEY GRAVEL
CL or CH GC
> 15% sand CLAYEY GRAVEL with SAND
< 15% gravel Well-graded SAND
Well SW
> 15% gravel Well-graded SAND with GRAVEL
< 5%
< 15% gravel Poorly graded SAND
Poorly SP
> 15% gravel Poorly graded SAND with GRAVEL
< 15% gravel Well-graded SAND with SILT
ML or MH SW-SM
> 15% gravel Well-graded SAND with SILT and GRAVEL
Well
< 15% gravel Well-graded SAND with CLAY
CL or CH SW-SC
> 15% gravel Well-graded SAND with CLAY and GRAVEL
Sand

10%
< 15% gravel Poorly graded SAND with SILT
ML or MH SP-SM
> 15% gravel Poorly graded SAND with SILT and GRAVEL
Poorly
< 15% gravel Poorly graded SAND with CLAY
CL or CH SP-SC
> 15% gravel Poorly graded SAND with CLAY and GRAVEL
< 15% gravel SILTY SAND
ML or MH SM
> 15% gravel SILTY SAND with GRAVEL
> 15%
< 15% gravel CLAYEY SAND
CL or CH SC
> 15% gravel CLAYEY SAND with GRAVEL

2.4.3 Consistency (Cohesive Soils)

The preferred procedure for the determination of consistency of cohesive soils is to obtain relatively
undisturbed samples and perform field tests with a pocket penetrometer or torvane. (See Appendix A for
details on the test procedures.)

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 13

Use the terms and criteria indicated in Figure 2-8 below to describe the consistency of cohesive soils. These
terms generally follow, with some modifications, AASHTO (1988) and Bureau of Reclamation (2001)
standards.
Figure 2-8
Descriptors for Consistency of Cohesive Soils
Pocket
Torvane
Description Penetrometer Field Approximation
Measurement (tsf)
Measurement (tsf)

Very Soft < 0.25 < 0.12 Easily penetrated several inches by fist

Soft 0.25 to 0.50 0.12 to 0.25 Easily penetrated several inches by thumb

Medium Stiff 0.50 to 1.0 0.25 to 0.50 Can be penetrated several inches by thumb
with moderate effort

Stiff 1 to 2 0.50 to 1.0 Readily indented by thumb but penetrated only

with great effort

Very Stiff 2 to 4 1.0 to 2.0 Readily indented by thumbnail

Hard > 4.0 > 2.0 Indented by thumbnail with difficulty

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 14

2.4.4 Apparent Density (Cohesionless 2.4.6 Moisture
Soils) Use the ASTM D 2488-06 standard to describe the
Use the AASHTO (1988) standards to describe the moisture condition, as indicated in
apparent density of cohesionless soils, as indicated Figure 2-10 below.
in Figure 2-9 below. Figure 2-10
Figure 2-9 Descriptors for Moisture
Descriptors for Apparent Density
Description Criteria
of Cohesionless Soils
Dry Absence of moisture, dusty,
Description SPT N60 (blows/ft) dry to the touch
Moist Damp but no visible water
Very loose 0–4
Wet Visible free water, usually soil
Loose 5 – 10 is below water table

Medium dense 11 – 30
Dense 31 – 50 2.4.7 Percent of Cobbles or Boulders
Very dense >50 When particles greater than 3 inches in diameter
are encountered, they shall be identified and
Apparent density of a coarse-grained (cohesionless) described as “COBBLES,” or “BOULDERS,” or
soil is based on a corrected Standard Penetration “COBBLES and BOULDERS” as defined in
Test (SPT) N60 value as described in Appendix A Section 2.4.9. Cobbles and boulders reported as
and provided here: present within a matrix shall be estimated, by
volume, and reported by percentage of total
N60 = Nmeasured X (ERi /60) volume.

where, Estimation of volume of cobbles and/or boulders is

ERi = Hammer energy ratio based upon recovered intersected lengths, drilling
chatter, and observations and experience of the
N values are highly dependent on the energy driller and/or geoprofessional.
efficiency of the SPT method. Inconsistency in the
N values across a site may be attributed to A subset of rock descriptors shall be used to
variations in energy efficiency between different describe cobbles and boulders as explained in
drill rigs and crews. Section 2.4.18. Isolated boulders may be treated as
individual units and described as such.
For example, if it is estimated that 40% by volume
2.4.5 Color of the material is cobbles, describe the sample in
Color is an important property in identifying this way:
organic soils, and it may also be useful in Well-graded SAND with GRAVEL and
identifying materials of similar geologic origin COBBLES (SW), medium dense, brown to light
within a given locality. Use the color name from gray, wet, about 40% COBBLES, about 20%
the Munsell Color System to describe the color of a coarse subrounded to rounded flat and
moist soil sample at the time of drilling and elongated GRAVEL, about 75% coarse to fine
sampling. If the sample contains layers or patches rounded SAND, about 5% fines, weak
of varying colors, record this information and cementation; COBBLES consist of sandstone,
describe all observed colors. For example: fresh, hard, intersecting lengths from 8 to 10
Brown to light yellowish brown inches.
For additional information, see ASTM D 1535-06, Note, the percentages of constituents in the
Standard Practice for Specifying Color by the example do not add up to 100%., as cobbles are
Munsell System. estimated by total volume, whereas gravel, sand,
Soil and Rock Logging, Classification, and Presentation Manual, Section 2 15
and fines, are estimated by weight of the total removed if the percentage was revised based on
sample excluding the cobbles and boulders, per laboratory particle size analysis results.)
Section 2.4.8
2.4.9 Particle Size
If the sample or layer is estimated to be more than
50% cobbles and/or boulders by volume, the layer Use the ASTM D 2488-06 standard to describe the
shall be described as “COBBLES” or size of particles, as shown in Figure 2-12, below.
“BOULDERS” or “COBBLES and BOULDERS” Figure 2-12
with the soil matrix description following. Note, Descriptors for Particle Size
this is a departure from the descriptive sequence in
Familiar
Section 2.4.1. For example, if it is estimated that Description Size
Example
60% by volume of the material was cobbles,
Boulder >12 in. Larger than a
describe the layer as: basketball
COBBLES with some well-graded SAND with Cobble 3 to 12 in. Larger than a
GRAVEL, about 60% COBBLES (sandstone, grapefruit or
orange
fresh, hard, intersecting lengths from 8 to 10
Coarse 3/4 to 3 in. Larger than a
inches), matrix consists of medium dense, Gravel walnut or grape
brown to light gray, wet, about 20% coarse Fine Gravel No. 4 to 3/4 in.Larger than a pea
subrounded to rounded flat and elongated Coarse Sand No. 10 to No. 4 Larger than rock
GRAVEL, about 75% coarse to fine rounded salt grain
SAND, about 5% fines, weak cementation. Medium Sand No. 40 to No. 10 Larger than
openings of a
Note that the Group Symbol is not used in the last window screen
example, because the cobbles and boulders were Fine Sand No. 200 to No. 40 Larger than a
the predominant material. sugar grain

2.4.8 Percent or Proportion of Soils

Use the ASTM D 2488-06 standard to describe the
estimated percentage (to the nearest 5%) or
proportion of gravel, sand, and fines, by weight of
the total sample excluding the cobbles and boulders,
as shown in Figure 2-11, below.
Figure 2-11
Descriptors for percent or proportion of soils
Description Criteria
Trace Particles are present but
estimated to be less than 5%
Few 5 to 10%
Little 15 to 25%
Some 30 to 45%
Mostly 50 to 100%

The percentages of gravel, sand, and fines must

add up to 100 %. The term “about” shall be used if
the percentage or proportion of constituents is
estimated in the field. (The word “about” shall be

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 16

2.4.10 Particle Angularity Figure 2-14
Descriptors for Particle Shape
Use the ASTM D 2488-06 standard to describe the
angularity of the sand (coarse sizes only), gravel, Description Criteria
cobbles, and boulders, as indicated in Figure 2-13 Flat Particles with width/thickness > 3
below. Elongated Particles with length/width > 3
Figure 2-13 Flat and Particles meet criteria for both flat
Descriptors for particle angularity Elongated and elongated

Description Criteria

Angular Particles have sharp edges and 2.4.12 Plasticity (for Fine-Grained Soils)
relatively plane sides with
unpolished surfaces Use the ASTM D 2488-06 standard to describe the
Subangular Particles are similar to angular plasticity of the material based on observations
description, but have rounded made during the toughness test, as indicated in
edges Figure 2-15 below.
Subrounded Particles have nearly plane sides,
Figure 2-15
but have well-rounded corners and
edges Descriptors for Plasticity
Rounded Particles have smoothly curved Description Criteria
sides and no edges
Nonplastic A 1⁄8-in. thread cannot be rolled at
any water content.
Low The thread can barely be rolled and
the lump cannot be formed when
drier than the plastic limit.
Medium The thread is easy to roll and not
much time is required to reach the
plastic limit. The thread cannot be
Rounded Angular rerolled after reaching the plastic
limit. The lump crumbles when drier
than the plastic limit.
High It takes considerable time rolling
and kneading to reach the plastic
Subrounded Subangular
limit. The thread can be rerolled
several times after reaching the
plastic limit. The lump can be formed
without crumbling when drier than the
2.4.11 Particle Shape
plastic limit.
Use the ASTM D 2488-06 standard to describe the
shape of the gravel, cobbles, and boulders if they
meet any of the criteria in Figure 2-14.
The particle shape shall be described as follows
where length, width, and thickness refer to the
greatest, intermediate, and least dimensions of a
particle, respectively.

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 17

2.4.13 Dry Strength (for Fine-Grained Soils) Figure 2-18
Use the ASTM D 2488-06 standard to determine Descriptors for toughness
dry strength, as indicated in Figure 2-16 below. Description Criteria
(See Appendix A for details on field test Low Only slight pressure is required to roll
procedures.) the thread near the plastic limit. The
thread and the lump are weak and soft.
Figure 2-16
Descriptors for Dry Strength Medium Medium pressure is required to roll the
thread to near the plastic limit. The
Description Criteria thread and the lump have medium
stiffness.
None The dry specimen crumbles into
powder with mere pressure of handling. High Considerable pressure is required to
roll the thread to near the plastic limit.
Low The dry specimen crumbles into The thread and the lump have very
powder with some finger pressure. high stiffness
Medium The dry specimen breaks into pieces or
crumbles with considerable finger
pressure 2.4.16 Structure
High The dry specimen cannot be broken Use the ASTM D 2488-06 standard to describe the
with finger pressure. Specimen will structure of intact soils, as indicated in Figure 2-19
break into pieces between thumb and a below.
hard surface.
Very High The dry specimen cannot be broken
Figure 2-19
between the thumb and a hard surface. Descriptors for structure
Description Criteria
2.4.14 Dilatancy (for Fine-Grained Soils) Stratified Alternating layers of varying
material or color with layers at least
Use the ASTM D 2488-06 standard to determine ¼ in. thick; note thickness.
dilatancy, as indicated in Figure 2-17 below. (See
Laminated Alternating layers of varying
Appendix A for details on field test procedures.) material or color with the layers less
Figure 2-17 than ¼ in. thick; note thickness.
Descriptors for dilatancy Fissured Breaks along definite planes of
fracture with little resistance to
Description Criteria
fracturing.
None No visible change in the specimen Slickensided Fracture planes appear polished or
Slow Water appears slowly on the surface glossy, sometimes striated.
of the specimen during shaking and Blocky Cohesive soil that can be broken
does not disappear or disappears down into small angular lumps
slowly upon squeezing which resist further breakdown.
Rapid Water appears quickly on the surface Lensed Inclusion of small pockets of
of the specimen during shaking and different soils, such as small lenses
disappears quickly upon squeezing of sand scattered through a mass of
clay; note thickness.
2.4.15 Toughness (for Fine-Grained Soils) Homogeneous Same color and appearance
throughout.
Use the ASTM D 2488-06 standard to determine
toughness, as indicated in Figure 2-18 below. (See
Appendix A for details on field test procedures.) 2.4.17 Cementation
Use the ASTM D 2488-06 standard to describe the
cementation of intact coarse-grained soils, as
indicated in Figure 2-20 below.

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 18

Figure 2-20 brick, clay pipe, dimensioned lumber, concrete
Descriptors for cementation debris, in-place pavement sections, asphalt debris,
metal, plastics, plaster, etc. Other items that may
Description Criteria
suggest fill include buried vegetation mats, tree
Weak Crumbles or breaks with handling or limbs, stumps, etc.
little finger pressure.
Moderate Crumbles or breaks with
The size and distribution of fill indicators shall be
considerable finger pressure. noted. The limits (depth range) of fill material shall
Strong Will not crumble or break with finger
be determined and identified at each exploration
pressure. location.
2.4.20 Other Drilling Observations
2.4.18 Description of Cobbles Other observations, not included in the descriptive
and Boulders sequence, may include:
Use the descriptive sequence for rock in Section • Caving or sloughing of borehole or trench sides
2.5. of this Manual to describe cobbles and • Difficulty in drilling or excavating, etc.
boulders. The description shall include, at
minimum, the following information: • Generic name (e.g., hard pan, fault gouge, etc.)
• Rock identification • Ground water inflow, elevation(s), and
estimated rate(s)
• Weathering
• Loss of drill fluid circulation
• Rock hardness
• Range of intersected lengths of core (An
“intersected length” is the length of the intact
core. This is not necessarily the size of the
cobble or boulder.)

2.4.19 Additional Comments

Additional constituents and soil characteristics not
included in the previous categories may be noted.
Observations may include:
• Presence of roots or root holes
• Presence of mica, gypsum, etc.
• Presence of voids
• Surface coatings on coarse-grained particles
• Oxide staining
• Cementing agents (e.g. calcium carbonate – see
Appendix A.7)
• Odor
• Depositional history (i.e. Alluvium, Colluvium,
Aeolian, Lacustrine, Fill)
• Geologic formation name or soil survey unit
name
All soils shall be examined to see if they contain
materials indicative of man-made fills. Man-made
fill items shall be listed in each of the soil
descriptions. Common fill indicators include glass,
Soil and Rock Logging, Classification, and Presentation Manual, Section 2 19
2.5 Rock Identification Procedures 2.5.1 Rock Identification and Descriptive
for Borehole Cores Sequence for Borehole Cores

Rock identification procedures presented in this Use the descriptors and the descriptive sequence,
section are based on a hybrid of the International shown in Figure 2-21, when identifying rock
Society of Rock Mechanics (ISRM) (1981) specimens collected from exploratory boreholes.
standards and the Bureau of Reclamation (2001)
standards. The detail of description provided for a
Figure 2-21
particular material shall be dictated by the
complexity and objectives of the project. Optional Rock Identification and Descriptive Sequence
descriptors should be considered by the

Refer to Section
geoprofessional on a project by project basis.
Intensely weathered or decomposed rock that is

Sequence

Required
friable and that can be reduced to gravel size or

Optional
smaller by normal hand pressure shall also be Identification
classified as a soil. The material shall be identified Components
and described as rock followed by the soil
1 Rock Name 2.5.2 J
identification or classification, and description in
parenthesis. Description
Components
For example: 2 Rock Grain-size 2.5.3 E
IGNEOUS ROCK (GRANITE), massive, light 3 Bedding Spacing 2.5.4 J
gray to light yellowish brown, intensely 4 Color 2.5.5 J
weathered, soft, unfractured, (Lean CLAY with
5 Texture 2.5.6 E
SAND (CL), medium stiff, moist, mostly clay,
Weathering Descriptors for
little coarse SAND, medium plasticity). 6 2.5.7 J
Intact Rock
Note, color is not repeated in the descriptive 7 Rock Hardness 2.5.8 J
sequence for soil. 8 Fracture Density 2.5.9 J
Although not included in the descriptive sequence, 9 Discontinuity Type 2.5.10 E
Core Recovery (REC) and Rock Quality Discontinuity Condition
Designation (RQD) shall be recorded and 10 (Weathering, Infilling and 2.5.11 E
presented on the boring logs. Core Recovery shall Healing)
be reported for all rock coring operations as 11 Discontinuity Dip Magnitude 2.5.12 E
described in Appendix A.9. RQD shall be Rate of Slaking
12 2.5.13 E
recorded and presented on the boring logs in (Jar Slake Test)
accordance with Appendix A.10. 13 Odor 2.5.14 E
14 Additional Comments 2.5.15 E

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 20

2.5.2 Rock Name
Rock name based on field identification in this section is taken from those presented by Zumberge et al.
(2003). As a general practice, a staff geologist should be consulted if there are questions of the correct
lithology. Rock name shall be reported using a combination of the family name (e.g. sedimentary, igneous,
metamorphic), followed by the rock identification. The identification can be approximated using Figures 2-
22, 2-23, or 2-24, or specifically identified by a qualified geologist.

Figure 2-22
Field identification of Igneous rock
Felsic Intermediate Mafic
Ultramafic
(Light Colored) (Intermediate-Colored) (Dark-Colored)

90%
Quartz
80%

70%
Percent by Volume

60% Plagioclase
50%

40% K-feldspar

30%
Olivine
20% Pyroxene
Biotite (Augite)
10% Amphibole
Muscovite (Hornblende)

Texture Rock Identification

Phaneritic Granite Diorite Gabbro Peridotite

Phaneritic with Gabbro Peridotite

Granite Porphyry Diorite Porphyry
Phenocrysts Porphyry Porphyry

Aphanitic Rhyolite Andesite Basalt

Aphanitic with Basalt

Rhyolite Porphyry Andesite Porphyry
Phenocrysts Porphyry

Vesicular Pumice, Scoria

Glassy Obsidian

Non-vesicular Agglomerate, Breccia, Tuff

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 21

Figure 2-23
Field identification of Sedimentary rock
Textural Features and Rock
Origin Composition Diagnostic Features Color
Particle Size Identification
Clastic (Boulders, Gravels, Angular rock or mineral Sedimentary
Pebbles and granules fragments Breccia
embedded in a matrix of Rounded rock or mineral
cemented sand grains Conglomerate
fragments
angular fragments of
Clastic (Coarse sand and
feldspar mixed with quartz K-feldspar common Arkose
Inorganic Detrital Materials

granules)
and other mineral grains
Rounded to subrounded white, buff, pink,
Quartz Sandstone
Clastic (Sand size quartz grains brown, tan
particles) Calcite and/or dolomite effervesces freely with
light-colored Calcarenite
grains cold dilute HCl
Clastic (Sand size
Quartz and other mineral dark gray to gray- Wacke (Lithic
particles mixed with clay
grains mixed with clay green Arenite)
size particles)
Mineral constituents may
be identifiable with a hand usually well stratified varies Siltstone
lens
Clastic (Silt and clay size fissile, may be scratched
Mineral constituents not
particles) with fingernail, usually well varies Shale
identifiable
stratified
Mineral constituents not massive (earthy), may be
varies Claystone
identifiable scratched with a fingernail
effervesces freely with
Dense (Crystalline or cold dilute HCl, may
Calcium Carbonate white, gray, black Limestone
Oolitic) contain fossils, generally
Inorganic Chemical

lacks stratification
powder effervesces
Precipitates

weakly with cold dilute

Calcium Magnesium varies, but similar
Dense or Crystalline HCl, may contain fossils, Dolomite
Carbonate to Limestone
generally lacks
stratification
conchoidal fracture, black, white, gray,
Dense (Porous) Silica Chert
scratches glass red
commonly can be varies, commonly
Dense (Amorphous) Hydrous Calcium Sulfate Rock Gypsum
scratched with a fingernail pink, buff, white
Crystalline Sodium Chloride crystalline, salty taste white to gray Rock Salt
effervesces freely with
Calcium Carbonate cold dilute HCl, easily white Chalk
Earthy (Bioclastic) scratched with a fingernail
does not react with HCl,
Silica gray to white Diatomite
soft, commonly stratified
Organic Detrital Materials

effervesces freely with

cold dilute HCl, shell Fossiliferous
Calcium Carbonate
fragments in a massive or Limestone
crystallne matrix
Bioclastic
effervesces freely with
cold dilute HCl, shell
Calcium Carbonate Coquina
fragments cemented with
little or no matrix material
soft, porous, low specific
Fibrous (Bioclastic) Plant fibers brown Peat
gravity
Mineral free carbonaceous
harder than peat, moist brownish to black Lignite
plant matter
Dense (Bioclastic) harder than lignite, dull
Mineral free carbonaceous
luster, smudges fingers black Bituminous Coal
plant matter
when handled

The names of rocks derived from inorganic detrital materials may be appended to indicate the cementing
agent, e.g., arkose with calcite cement.

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 22

Figure 2-24
Field identification of Metamorphic rock
Rock
Texture Diagnostic Features Composition Color
Identification
slaty texture with slaty cleavage, variable, black and
Slate
dense, microscopic grains dark gray common
phyllitic texture, fine grained to dense,
micaceous minerals are dominant Phyllite
"shiny" appearance
schistose texture, medium to fine chlorite, biotite, muscovite, garnet and
Foliated

grained, "sparkling" appearance, dark elongate silicate minerals, talc, Schist

porphyroblasts common feldspar commonly absent
gneissic texture, coarse grained, abundant quartz and feldspar in light
foliation present as macroscopic grains bands and hornblende, augite, garnet Gneiss
arranged in light and dark bands or biotite in dark bands
granulitic texture, medium to coarse
grained, even grained, foliation present Granulite
in quartzo-feldspathic rocks
Nonfoliated
Foliated or

mostly crystals of amphibole,

medium to coarse-grained Amphibolite
sometimes feldspar, mica and talc

color variable,
crystalline, scratches glass, breaks
quartz white, pink, buff, Quartzite
across grains as easily as around them
brown, red, purple
various shades of
dense, dark colored gray, gray-green, Hornfels
to nearly black
texture of conglomerate but breaks granules, pebbles or cobbles are
Nonfoliated

across coarse grains as easily as commonly granitic or jasper, chert, Metaconglomerate

around them quartz or quartzite
crystalline, scratches glass, breaks
across grains as easily as around calcite or dolomite white, pink, gray Marble
them, fossils in some
microcrystalline texture, usually with
serpentine, sometimes with crysotile shades of green Serpentinite
smooth wavy surfaces
granulitic texture, medium to coarse
grained, even grained, foliation lacking Granulite
in pyroxene-plagioclase bearing rocks
shiny luster, conchoidal fracture black Anthracite Coal

2.5.3 Rock Grain-size descriptors

The rock grain-size descriptors that follow are based on USBR (2001) standards.

Figure 2-25
Rock grain-size descriptors for Crystalline Igneous rock and Metamorphic rock
Description Average Crystal Diameter

Very coarse grained or pegmatitic > 3/8 in

Coarse-grained 3/16 – 3/8 in
Medium-grained 1/32 – 3/16 in
Fine-grained 0.04 – 1/32 in
Aphanitic <0.04 in

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 23

Figure 2-26
Rock grain-size descriptors for Sedimentary and Pyroclastic Igneous rock

Sedimentary (epiclastic)
USCS Rounded, subrounded, Volcanic (pyroclastic)
Size
(soils only) subangular
(inches)
Particle Size Particle or Lithified Lithified
Fragment
Fragment Product Product

Boulder Boulder Boulder Block Volcanic

Conglomerate (Angular) Breccia
12
10
Cobble Cobble Cobble
Conglomerate
Bomb Agglomerate
3 (Rounded)
Coarse Gravel 2.5
Pebble Pebble
Conglomerate
0.8
Fine Gravel Lapilli Lapilli
Tuff
0.19
0.16
Coarse Sand
Granule Granule
Conglomerate
0.08 Coarse Coarse
Very Coarse Sandstone Ash Tuff
Medium Sand 0.04 Sand (Very Coarse,
0.02 Coarse Sand Coarse,
Medium Sand Medium, Fine,
0.0165 or Very Fine)
Fine Sand 0.0098 Fine Sand
0.0049
0.0029 Very Fine Sand
Fines 0.0025
Non- Fine Fine
Silt Siltstone, Shale
plastic Ash Tuff
Silt 0.0002
Clay Claystone,
Shale
Plastic Clay

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 24

2.5.4 Bedding Spacing Descriptors 2.5.6 Textural Descriptors
Bedding planes are discontinuities along which Textural adjectives are employed to describe the
rock mass failure may occur. They also influence size and shape of voids within the rock mass that
the hydraulic conductivity and shear strength of the are visible to the unaided eye. These voids are
rock mass. relevant to the estimation of the hydraulic
The bedding thickness or spacing, modified from conductivity, unconfined compressive strength, and
USBR (2001), shall be used as indicated in Figure the weathering susceptibility of the intact rock.
2-27 below. Use the USBR (2001) standard to describe the size
Figure 2-27 and shape of voids, as indicated in
Figure 2-28 below.
Bedding Spacing Descriptors
Figure 2-28
Description Thickness/Spacing Textural Descriptors
Massive Greater than 10 ft. Description Criteria
Very thickly bedded 3 to 10 ft.
Pitted Pinhole to 3/8 in. openings.
Thickly bedded 1 to 3 ft.
Vuggy Small opening (usually lined with
Moderately bedded 3-5/8 in. to 1 ft. crystals) ranging in diameter from
3/8 in. to 4 in.
Thinly bedded 1-1/4 to 3-5/8 in.
Cavity An opening larger than 4 in., size
Very thinly bedded 3/8 to 1-1/4 in. descriptions are required, and
adjectives such as small, or large,
Laminated Less than 3/8 in.
may be used, if defined.
Honeycombed If numerous enough that only thin
2.5.5 Rock Colors walls separate individual pits or
vugs, this term further describes
Use the color name from the Munsell Rock Color the preceding nomenclature to
Chart, which is based on the National Bureau of indicate cell-like form.
Standards/Inter Society Color Council system, to Vesicular Small openings in volcanic rocks of
describe the rock at the time of sampling. If the variable shape formed by
sample contains layers or patches of varying colors, entrapped gas bubbles during
record that information and describe and all colors solidification.
observed.
For additional information, see ASTM D 1535-06,
Standard Practice for Specifying Color by the
Munsell System.

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 25

2.5.7 Weathering Descriptors for Intact Rock
Weathering increases the clay content of the intact rock and the amount of separation at grain boundaries.
Weathered rock masses have lower unconfined compressive strength, lower intact rock shear strength, lower
shear strength along discontinuities, higher hydraulic conductivity, and are more likely to fail through the
intact rock. Use USBR (2001) weathering descriptors, as indicated in Figure 2-29 below.
Figure 2-29
Weathering Descriptors for Intact Rock
Diagnostic Features
Chemical weathering-discoloration Mechanical Texture and
and/or oxidation weathering-grain solutioning
boundary conditions
(disaggregation)
primarily for granitics
Fracture and some coarse- General
Description Body of rock surfaces grained sediments Texture Solutioning characteristics
Fresh No discoloration, not No No separation, intact No change No solutioning Hammer rings when
oxidized discoloration (tight) crystalline rocks are
or oxidation struck.
Slightly
Weathered to
Fresh
Slightly Discoloration or oxidation Minor to No visible separation, Preserved Minor Hammer rings when
Weathered is limited to surface of, or complete intact (tight) leaching of crystalline rocks are
short distance from, discoloration some soluble stuck. Body of rock not
fractures; some feldspar or oxidation minerals may weakened.
crystals are dull of most be noted
surfaces
Moderately to
Slightly
Weathered
Moderately Discoloration or oxidation All fracture Partial separation of Generally Soluble Hammer does not ring
Weathered extends from fractures surfaces are boundaries visible preserved minerals may when rock is struck.
usually throughout; Fe- discolored or be mostly Body of rock is slightly
Mg minerals are “rusty,” oxidized leached weakened.
feldspar crystals are
“cloudy”
Intensely to
Moderately
Weathered
Intensely Discoloration or oxidation All fracture Partial separation, rock Texture altered Leaching of Dull sound when struck
Weathered throughout; all feldspars surfaces are is friable; in semiarid by chemical soluble with hammer, usually
and Fe-Mg minerals are discolored or conditions granitics are disintegration minerals may can be broken with
altered to clay to some oxidized, disaggregated (hydration, be complete moderate to heavy
extent; or chemical surfaces argillation) manual pressure or by
alteration produces in situ friable light hammer blow
disaggregation, see grain without reference to
boundary conditions planes of weakness
such as incipient or
hairline fractures, or
veinlets. Rock is
significantly weakened.
Very Intensely
Weathered
Decomposed Discolored or oxidized Complete separation of Resembles a soil, partial or Can be granulated by
throughout, but resistant grain boundaries complete remnant rock structure hand. Resistant minerals
minerals such as quartz (disaggregated) may be preserved; leaching of such as quartz may be
may be unaltered; all soluble minerals usually present as “stringers” or
feldspars and Fe-Mg complete “dikes.”
minerals are completely
altered to clay
NOTE: Combination descriptors (such as "slightly weathered to fresh") are permissible where equal distribution of both weathering characteristics is
present over significant intervals or where characteristics present are "in between" the diagnostic feature. However, combination descriptors shall
not be used where significant identifiable zones can be delineated. Only two adjacent descriptors shall be combined.

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 26

2.5.8 Rock Hardness 2.5.9 Fracture Density
Use the modified USBR (2001) descriptors to Fractures are defined in Section 2.5.10. The
describe the hardness of intact rock, as indicated in fracture density is based on the spacing of all of the
Figure 2-30 below. fractures observed in recovered core lengths from
Figure 2-30 boreholes. This measurement excludes mechanical
breaks and incipient joints/fractures. It also
Descriptors for Rock Hardness
excludes features not identified as fractures, such
Description Criteria as shears, faults, foliations, and bedding plane
separations, etc.
Extremely Hard Specimen cannot be scratched
with a pocket knife or sharp pick; Descriptive criteria presented below are based on
can only be chipped with borehole cores where lengths are measured along
repeated heavy hammer blows
the core axis. Use the USBR (2001) fracture
Very Hard Specimen cannot be scratched density standard, as indicated in Figure 2-31 below.
with a pocket knife or sharp pick.
Breaks with repeated heavy Figure 2-31
hammer blows. Descriptors for Fracture Density
Hard Specimen can be scratched with
a pocket knife or sharp pick with Description Observed Fracture Density
difficulty (heavy pressure). Heavy Unfractured No fractures.
Hammer blows required to break
Very slightly fractured Lengths greater than 3 ft.
specimen
Slightly to very slightly
Moderately Specimen can be scratched with
fractured
Hard a pocket knife or sharp pick with
light or moderate pressure. Core Slightly fractured Lengths from 1 to 3 ft. with
breaks with moderate hammer few lengths less than 1 ft. or
blows greater than 3 ft.
Moderately Specimen can be grooved 1/6 in. Moderately to slightly
Soft deep with a pocket knife or sharp fractured
pick with moderate or heavy Moderately fractured Lengths mostly in 4 in. to 1 ft.
pressure. Breaks with light range with most lengths about
hammer blow or heavy manual 8 in.
pressure.
Intensely to moderately
Soft Specimen can be grooved or fractured
gouged easily with a pocket knife
or sharp pick with light pressure, Intensely fractured Lengths average from 1 to 4
can be scratched with fingernail. in. with scattered fragmented
Breaks with light to moderate intervals with lengths less
manual pressure. than 4 in.
Very Soft Specimen can be readily Very intensely to
indented, grooved or gouged with intensely fractured
fingernail, or carved with a pocket Very intensely Mostly chips and fragments
knife. Breaks with light manual fractured with a few scattered short
pressure. core lengths.
NOTE: Combination descriptors (such as “very
intensely to intensely fractured”) are used where equal
distribution of both fracture density characteristics is
present over a significant interval or exposure, or where
characteristics are “in between” the descriptor
definitions. Only two adjacent descriptors may be
combined.

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 27

2.5.10 Discontinuity Type temperature) during shearing, brittleness of the
geo-materials, and the stress conditions.
A single description, or range of descriptors, shall
be used to describe the discontinuities observed
over the length of the reported fracture density. Figure 2-32
Discontinuity: A collective term used for all Descriptors for Discontinuity Type
planes including fractures, joints, faults, shears, Description Criteria
bedding planes and foliations. Contacts between
Joint (JT) A relatively planar fracture along
rock bodies of different lithologies may also be which there has been little or no
considered discontinuities. shearing displacement.

Fracture: A term used to describe any break in Foliation Joint A relatively planar fracture that is
geologic material, excluding shears and shear zones. (FJ) or parallel to foliation or bedding
Bedding Joint along which there has been little
Additional fracture terminology is provided in Figure (BJ) or no shearing displacement.
2-32, below.
Bedding Plane A separation along bedding after
Shear: A structural break where differential Separation extraction or exposure due to
movement has taken place along a surface, or zone stress relief or slaking.
of failure by a shear couplet, is termed a shear.
Shears are sometimes characterized by striations, Incipient Joint A joint or fracture that does not
slickensides, gouge, breccia, mylonite, or any (IJ) or continue through the specimen or
combination of these. Often direction, amount of Incipient is not seen with the naked eye.
Fracture (IF) However when the specimen is
displacement, and continuity may not be known wetted and then allowed to dry,
because of limited exposures or observations. the joint or fracture trace is
evident. When core is broken, it
Fault: A shear with significant continuity that can breaks along an existing plane.
be correlated between observations is a fault. Random A natural break (fracture) with a
Faults demonstrate high spatial continuity, and Fracture (RF) generally rough, very irregular,
non-planar surface which does
therefore occur over significant portions of given not belong to a joint set.
sites, foundation areas, or regions. The observed
fault feature may be a segment of a fault or fault Mechanical A break due to drilling, blasting,
Break (MB) or handling. Mechanical breaks
zone, as defined in the literature. The designation parallel to bedding or foliation are
of a shear as a fault or fault zone is a site-specific called Bedding Breaks (BB) or
determination. Foliation Breaks (FB),
respectively. Recognizing
Shear/Fault Zone: A shear or fault that exhibits mechanical breaks may be
significant width when measured perpendicular to difficult. The absence of
oxidation, staining, or mineral
the plane of the shear or fault. The zone may fillings, and often a hackly or
consist of gouge, breccia, or many related faults or irregular surface are clues for
shears together with fractured and crushed rock recognition.
Fracture Zone Numerous, very closely
between the shears or faults, or any combination of (FZ) intersecting fractures. Often
these. In the literature, many fault zones are fragmented core cannot be fitted
referred to as faults. together.

Shear/Fault Disturbed Zone: An associated zone

of fractures and/or folds adjacent to a shear or a
shear zone where the country rock has been
subjected to only minor cataclastic action and may
be mineralized. If adjacent to a fault or fault zone,
the term fault-disturbed zone is used. Occurrence,
orientation, and aerial extent of these phenomena
depend on the depth of burial (pressure and

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 28

2.5.11 Discontinuity Condition (Weathering, Figure 2-33
Infilling and Healing) Descriptors for Discontinuity Healing
Weathering: Descriptors for discontinuity Descriptor Criteria
weathering or alteration of fracture surfaces and Totally All fragments bonded, discontinuity is
fracture fillings (excluding soil materials) are the Healed completely healed or recemented to a
degree at least as hard as surrounding
same as those used for weathering and alteration of rock.
intact rock (per Section 2.5.7, Figure 2-29, third Moderately Greater than 50 percent of fractured or
column). Healed sheared material, discontinuity surface
Discontinuity Infilling: Descriptors for hardness of or filling is healed or recemented,
and/or strength of healing agent is less
fillings, gouges and/or fracture surfaces are the hard than surrounding rock.
same as those presented for intact rock or Partially Less than 50 percent of fractured or
consistency of soils. Healed sheared material, discontinuity surface
Discontinuity Healing: Discontinuities may be or filling is healed or recemented.
filled with air, water, soil, or a crystalline mineral Not Healed Discontinuity surface, fracture zone,
sheared material, or filling is not healed
material that provides a significant tensile and
or recemented. Rock fragments or
shear strength to the discontinuity. Discontinuity filling (if present) held in place by their
healing can be observed when there is a color own angularity and/or cohesiveness.
contrast with the bordering intact rock. Features
often referred to as veins are healed discontinuities.
In addition to an observation of the amount of the
discontinuity that has been healed, the healing
material should be observed and recorded. The
amount and material of the healing discontinuity is
relevant to the estimation of discontinuity shear
strength, discontinuity hydraulic conductivity, and
to the ease with which the rock can be excavated
(e.g., open excavation, tunnel, or borehole).
Use the USBR (2001) standard, as indicated below
in Figure 2-33 below, to describe the discontinuity
condition.

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 29

2.5.12 Discontinuity Dip Magnitude 2.5.13 Rate of Slaking
Observation of the magnitude of discontinuity dip Some rock types are subject to degradation when
made with non-oriented core is useful for exposed to weathering processes, particularly
anticipating difficulties that may arise from boring repeated wetting and drying cycles. Rocks that
piles or shafts in rock masses that contain exhibit slaking may disintegrate into gravel size
discontinuities that are oriented close to vertical. particles, or they may disaggregate completely to
the individual constituent particles: clay, silt, and
Use the USBR (2001) standard, as indicated below
sand.
in Figure 2-34 below, to describe the magnitude of
discontinuity dip. Rocks that are prone to slaking include: shale,
Figure 2-34 siltstone, claystone, weakly welded tuff, and highly
Discontinuity Dip Magnitude weathered crystalline igneous and metamorphic
rocks. Slaking behavior is relevant to the
Vertical performance of cut slopes and the stability of bored
Hole: piles/drilled shafts. See Appendix A for test
Apparent dip o
35 Dip procedures.
is measured
Figure 2-35
and reported.
Rate of Slaking
Jar Slake
Observed Behavior
Core Axis Index, IJ
1 Degrades to a pile of flakes or mud
2 Breaks rapidly and forms many chips
3 Breaks slowly and forms few chips
Breaks rapidly and develops several
4
fractures
Breaks slowly and develops few
5
Angle Hole: fractures
True dip is No change to condition of the rock
usually not 6
fragment
known, angle
is measured Core Axis
from core axis 2.5.14 Odor
and is called 45
o
Rocks containing significant amounts of organic
inclination. Inclination
material usually have a distinctive odor of decaying
vegetation. This is especially apparent in fresh
samples, but if the samples are dried, the odor often
may be revived by heating a moistened sample.
Petroleum products or other chemicals may also
influence the odor of the sample. Describe the odor,
if organic, and identify anything unusual, such as
odor of a petroleum product or other chemical.

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 30

2.5.15 Additional Comments
Additional rock characteristics not included in the
previous categories may be noted.
2.5.16 Other Drilling Observations
Other observations (not included in the descriptive
sequence) that may be presented on the LOTB or
BR as notes or remarks include:
• Time for core run
• Difficulty in drilling or excavating, etc.
• Generic name (e.g., hard pan, fault gouge, etc.)
• Ground water inflow, elevation(s), and
estimated rate(s)
• Loss of drill fluid circulation

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 31

2.6 Sample Preparation and 2.6.1 Sample Preparation and
Identification for Laboratory Identification for Laboratory Testing
and Storage
Testing and Storage
All samples shall be named according to the
Geoprofessionals who drill, sample, preserve, and
following convention:
transport soil samples play an important role in
ensuring the quality of the laboratory test results. Hole ID – SNN – T
When performing field investigations, the Where,
geoprofessional shall be familiar with the
procedures contained within the following ASTM Hole ID: Refer to Section 2.3
standards: S: The Sample Type Code, as defined in
• ASTM D 1586-99, “Test Method for Figure 2-36, which generally follow
Penetration Test and Split-Barrel Sampling of ASTM D 6453
Soils” NN: 2-digit sample number (01–99),
• ASTM D 1587-00, “Practice for Thin-Walled sequenced consecutively from the top
Tube Sampling of Soils” down.
• ASTM D 3550-01, “Practice for Ring-Lined T: 1-digit tube number, starting with the
Barrel Sampling of Soils” bottom tube numbered as 1.
• ASTM D 4220-00, “Standard Practices for For example:
Preserving and Transporting Soil Samples” A – 06 – 105 – U02 – 3
The information that follows explains the Figure 2-36
procedures and information required to submit soil
Sample Type Codes
samples and request testing services from the
Caltrans Geotechnical Laboratory, an AASHTO Code Description
Materials Reference Laboratory (AMRL) U Undisturbed Shelby tube
accredited facility located in Sacramento.
P Undisturbed Piston
S Split spoon (includes SPT and Cal Mod
Samplers)
B Block
C Core (both rock and soil)
D Disturbed (include auger cuttings)
R Reconstituted
O Other

Label Brass and Shelby Tubes as explained below

and shown in Figure 2-37, below:
• Use electrical tape to completely seal the end
caps onto the sample tubes.
• Clearly label samples with permanent marker
• Place the top of the label at the top end of the
tube to identify the proper orientation of the
sample as shown above.
• If the sample tube is only partially filled, use a
filler, such as newspaper, cloth rags, or sawdust

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 32

 to prevent movement of the sample in the tube Figure 2-37
during shipping and handling. Brass and Shelby Tube Label
• Whenever possible use a wax seal on the end of
the sample to prevent moisture exchange with
or contamination by the filler material. Top of Sample

Label bagged samples as explained below and

shown in Figure 2-38:
Sample ID: ______
• Identify the sample by writing directly on the Depth: __________
EA: ____________
plastic bag or attaching an adhesive label. Date: ___________
Sample Label
• Seal or tie the plastic bag properly to prevent Logger:
loss of moisture.
Bottom of Sample

Figure 2-38
Bagged Sample Label

Sample ID: ______

Depth: __________
EA: ____________
Date: ___________
Logger: _________
Sample Label

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 33

2.6.2 Identification of Large Soil Samples
In addition to the labeling requirements explained above, some soil samples must also be labeled with a
Sample Identification Card (Caltrans Form TL-101), including:
• Samples weighing more than 5 lbs.
• Samples to be tested by the Materials Engineering and Testing Services (METS), test names are followed
by “**” in Figure 2-39 below.
Place Form TL-101 inside a sealed plastic bag, then place it inside the large plastic or canvas bag that
contains the sample.
Figure 2-39
Minimum Material Requirements for Various Test Methods

Material TL-101
Test Method(s) Test Name Typical Sample Size/Type
Required Required
AASHTO T 265-93
(2004) Moisture Content 0.5 lb 1/2 Tube No
ASTM D 2216-05
ASTM D 4767-04 Unit Weight 1 lb 1 Tube No
AASHTO T 100-06 Specific Gravity 0.5 lb 1/2 Tube No
ASTM D 422-63
Particle-Size Analysis 1 lb 1 Tube No
(2002)
AASHTO T 89-02
Liquid Limit
AASHTO T 90-00 1 lb 1 Tube No
Plastic Limit, Plasticity Index
(2004)
Consolidation
Undisturbed
(2.0" Diameter) - 1 Tube No
ASTM D 2435-04
(2.5" Diameter) - 1 Tube No
Remolded
(2.0" Diameter) 80 lb 2 Full Canvas Bags Yes

Swell Potential
Undisturbed
(2.0" Diameter) - 1 Tube No
ASTM D 4546-03
(2.5" Diameter) - 1 Tube No
Remolded
(2.0" Diameter) 80 lb 2 Full Canvas Bags Yes

Collapse Potential
Undisturbed
(2.0" Diameter) - 1 Tube No
ASTM D 5333-03
(2.5" Diameter) - 1 Tube No
Remolded
(2.0" Diameter) 80 lb 2 Full Canvas Bags Yes

Direct Shear
ASTM D 3080-04 Undisturbed - 1 Tube No
Remolded 80 lb 2 Full Canvas Bags Yes
Relative Compaction
CTM 216 (Oct 2006) 80 lb 2 Full Canvas Bags Yes
(Compaction Curve Only)

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 34

 Material TL-101
Test Method(s) Test Name Typical Sample Size/Type
Required Required

Permeability
Undisturbed
CTM 220 (Nov Falling Head - 1 Tube No
2005) Remolded
Falling Head 80 lb 2 Full Canvas Bags Yes
Constant Head 80 lb 2 Full Canvas Bags Yes
ASTM D 2166-06
ASTM D 2938-95 Unconfined Compression - 1 Tube or Core No
(2002)
Triaxial CU (3 points)
Undisturbed No
(2.0" Diameter) - 3 Tubes - in series No
ASTM D 4767-02 (2.5" Diameter) - 3 Tubes - in series
Remolded Yes
(2.8" Diameter) 80 lb 2 Full Canvas Bags
Triaxial UU (1 point)
ASTM D 2850-03 Undisturbed No
(2.0" Diameter) - 1 Tube No
(2.5" Diameter) - 1 Tube
Remolded Yes
(2.8" Diameter) 80 lb 2 Full Canvas Bags

ASTM D 427-04 Shrinkage Limit 1 lb 1 Tube No

ASTM D 5731-05 Point Load - Rock Core No
ASTM D 4829-03 Expansion Index 40 lb 1 Full Canvas Bag Yes
CTM 217 (Nov
1999) Sand Equivalent** 10 lb 1/4 Full Canvas Bag Yes
AASHTO T 176-02
CTM 301 (Mar
2000) R-Value** 80 lb 2 Full Canvas Bags Yes
AASHTO T 190-02
CTM 643 (Nov
1999)
Corrosion**
CTM 417 (Nov
Sulfates** 10 lb 1/4 Full Canvas Bag Yes
2006)
Chlorides**
CTM 422 (Nov
2006)
Organic Content**
PH**
EPA 9081 10 lb 1/4 Full Canvas Bag Yes
Cation Exchange**

Notes:
1. ** Tests performed by Materials Engineering and Testing Services (METS)
2. A 12" by 24" canvas bag completely filled contains approximately 40 lb of material.
3. A 2" by 4" tube contains approximately 1 lb. of material.
4. Minimum material weights shown for remolded samples include sufficient material for the development of a
moisture density curve.

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 35

5. When calculating the number of triaxial samples that can be obtained from a Shelby tube, use a minimum sample
length equal to three times the sample diameter.

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 36

2.6.3 Core Box Layout
Core boxes shall be labeled as shown in Figure 2-40.

Figure 2-40
Core Box Layout and Label

Structure No.:_________ Date:__________

Engineer/Geologist Name
Geographic/Structure Name
Dist.-Co.-Rte.-PM
E.A.

Boring # Core Box #

Label on Side of Core Box

Structure No:___________ Structure Name:_________ EA:_____________
Boring No:__________ Core Box: _____ of ______
Depth Interval: ________ to _________
Engineer/Geologist Name: _____________ Date__________

Inside of Core Box

Use two blocks in

Use core blocks at beginning segments of no recovery
and end of each run

Labeling of Core Blocks

RUN# ______
Depth Interval
Depth = ___ _____To_____

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 37

2.7 Quality Check of Field Observations and Samples
The geoprofessional shall conduct a quality check of his/her field notes and observations once back in the
office. Sample descriptions and identifications shall be reviewed and revised as necessary to ensure that they
are in compliance with the procedures presented in this section.
Descriptors of sample properties that are subject to change due to time or environment, such as moisture or
RQD, shall not be revised. Samples that are to be stored for laboratory testing or other purposes shall be
inventoried to ensure correct labeling and accounting.

Soil and Rock Logging, Classification, and Presentation Manual, Section 2 38

Section 3:
Procedures for Soil and Rock Description and/or
Classification Using Laboratory Test Results
3.1 Introduction 3.2 Revising Soil Descriptions and
Section 2 describes the procedures for describing Assigning Soil Classification
and identifying soil and rock samples in the field Using Laboratory Test Results
using visual and manual methods and basic field Six of the 21 attributes in the identification and
testing tools. Most of these field procedures are descriptive sequence for soils, listed previously in
sufficient to generally identify and describe the soil section 2.4.1, may be revised with laboratory test
and rock in qualitative terms, and are appropriate results. They are:
for reporting in final boring records, as described
later in Sections 4 and 5. In many cases these • Group Name
descriptors can be correlated, to some degree, to • Group Symbol
engineering parameters for use in geotechnical • Consistency
designs. However, the geoprofessional may want to
• Percent or Proportion of Soils
more quantitatively and definitively characterize a
particular sample using laboratory test results. • Particle Size Range
This Section addresses how to apply the results of • Plasticity
specific laboratory tests to revise and supplement The Group Name and Group Symbol are estimated
the original field observations, identifications, and in the field using visual and manual procedures
descriptions. The information presented in this based on ASTM D 2488-06, Standard Practice for
Section is based largely on the American Society Description and Identification of Soils (Visual-
for Testing and Materials (ASTM) D 2487-06, Manual Procedure). The field method requires the
Standard Practice for Classification of Soils for user to make judgments on a number of
Engineering Purposes (Unified Soil Classification observations (e.g., percent of constituents by
System). weight, whether a soil is well or poorly graded, and
Laboratory test results can be used to whether the soil is a clay or silt or some
systematically refine field observations. The combination thereof).
process of correction, calibration, and verification Laboratory particle-size analysis, liquid limit, and
in developing an updated Log of Test Boring plasticity index provide a quantitative basis for
(LOTB) or Boring Record (BR) based on classification of the soil. Furthermore, the
laboratory test results can effectively serve the laboratory procedure employs a much more
purpose of self-training and self-calibration. This comprehensive listing of possible Group Names, as
process is described in more detail in Section 4 of compared to field methods.
this Manual.
Consistency is estimated in the field using one or
more of three methods (thumb test, Torvane, or
Pocket Penetrometer), with varying levels of
accuracy and repeatability. Laboratory triaxial,
direct shear, and unconfined compression tests
provide less subjective undrained shear strength
values that can be correlated to specific consistency
descriptors.

Soil and Rock Logging, Classification, and Presentation Manual, Section 3 39

Percent gravel, sand, and fines, and range of the plasticity is inherent in the Group Name and
particle sizes are estimated in the field using visual Group Symbol.
methods (e.g. jar test, visual approximation, etc.).
The laboratory particle-size analysis test provides a 3.2.1 Soil Classification and Description
quantitative distribution of particle sizes in Descriptive Sequence
proportion to the total sample weight. It is The descriptive sequence presented in the Figure 3-
important to recognize that the sample size is 1 below shall be used when classifying and
significant when dealing with gravel or larger sized describing soils. Items indicated by a check mark
soils. in the “Required” column shall be repeated to
Plasticity is estimated in the field in order to describe all the components of the subject soil to
determine Group Name and Group Symbol for provide complete descriptive coverage. To
fine-grained soils and to provide a plasticity incorporate laboratory test data in the classification
descriptor. The liquid limit and plasticity index and descriptive sequence, where applicable, refer
used in conjunction with ASTM D 2487-06 to the sections in this Manual as noted in Figure 3-
provide a Group Name and Group Symbol. The 1. (See “Lab” column below.)
field-based plasticity descriptor is eliminated, as

Figure 3-1
Classification and Description Sequence
Refer to Section
Sequence

Required

Optional
Field

Lab
Classification Components
1 Group Name 2.4.2 3.2.2 J
2 Group Symbol 2.4.2 3.2.2 J

Description Components
3 Consistency (for cohesive soils) 2.4.3 3.2.3 J
4 Apparent Density (for cohesionless soils) 2.4.4 J
5 Color (in moist condition) 2.4.5 J
6 Moisture 2.4.6 J
7 Percent of cobbles or boulders 2.4.7 J
8 Percent or proportion of soils 2.4.8 3.2.4 J
9 Particle Size Range 2.4.9 3.2.5 J
10 Particle Angularity 2.4.10 E
11 Particle Shape 2.4.11 E
12 Hardness (for coarse sand and larger particles) 2.4.12 E
13 Plasticity (for fine-grained soils)* 2.4.13 3.2.6 J
14 Dry Strength (for fine-grained soils) 2.4.14 E
15 Dilatency (for fine-grained soils) 2.4.15 E
16 Toughness (for fine-grained soils) 2.4.16 E
17 Calcium Carbonate (Reaction with HCl) 2.4.17 E
18 Structure 2.4.18 E
19 Cementation 2.4.19 J
20 Description of Cobbles and Boulders 2.4.20 J
21 Additional Comments 2.4.21 E

* This descriptive component is not reported for the primary soil type if the liquid limit and plasticity index are
available. (See Section 3.2.7)

Soil and Rock Logging, Classification, and Presentation Manual, Section 3 40

3.2.2 Group Name and Group Symbol limit and plasticity index in Figures 3-2 and 3-3,
below.
This section presents a procedure for classifying
soils for engineering purposes based on laboratory Classify the soil as fine-grained:
determination of particle-size characteristics, liquid
• In cases where the liquid limit exceeds 110, or
limit, and plasticity index. It shall be used when
the plasticity index exceeds 60, the plasticity
precise classification is required. This method is
chart may be expanded by maintaining the same
based on the ASTM version of the Unified Soil
scale on both axes and extending the “A” line at
Classification System (USCS).
the indicated slope.
The ASTM procedure for classifying and • The soil is organic if organic matter is present
describing fine-grained and coarse-grained soils is in sufficient amounts to influence the liquid
only applicable to material passing the 3-inch sieve. limit. Typically, organic soils have a dark color
If the presence of cobbles or boulders or both is and an organic odor when moist and warm, and
identified during the site exploration, the may contain visible organic matter. If the
percentage of cobbles and boulders shall be geoprofessional suspects there is sufficient
reported per Section 2.4.7. organic matter to influence the soil’s
classification, consult with the Caltrans
Geotechnical Laboratory about additional
3.2.2.1 Procedure for Classification of
laboratory testing.
Fine-Grained Soils
If 50% or more by dry weight of the test specimen
passes the No. 200 sieve, the soil is fine-grained.
Fine-grained soils are classified using the liquid

Figure 3-2
Classification of Fine-Grained Soils

Soil and Rock Logging, Classification, and Presentation Manual, Section 3 41

Figure 3-3
Flow chart for fine-grained soils

Plasticity
Organic
Liquid

Index
Limit

Group
Symbol Fines Coarseness Group Name
<15% plus
Lean CLAY
<30% plus No. 200
PI>7 and plots on or

No. 200 15-29% plus % sand > % gravel Lean CLAY with SAND
No. 200 % sand < % gravel Lean CLAY with GRAVEL
CL
above “A”-line

% sand > < 15% gravel SANDY lean CLAY

>30% plus % gravel > 15% gravel SANDY lean CLAY with GRAVEL
No. 200 % sand < < 15% sand GRAVELLY lean CLAY
% gravel > 15% sand GRAVELLY lean CLAY with SAND
<15% plus
SILTY CLAY
<30% plus No. 200
4<PI<7 and plots on

No. 200 15-29% plus % sand > % gravel SILTY CLAY with SAND
Inorganic

No. 200
or above “A”-line

% sand < % gravel SILTY CLAY with GRAVEL

CL-ML
% sand > < 15% gravel SANDY SILTY CLAY
>30% plus % gravel > 15% gravel SANDY SILTY CLAY with GRAVEL
No. 200 % sand < < 15% sand GRAVELLY SILTY CLAY
% gravel > 15% sand GRAVELLY SILTY CLAY with SAND
<15% plus
SILT
PI<4 or plots below “A”-

<30% plus No. 200

No. 200 15-29% plus % sand > % gravel SILT with SAND
No. 200 % sand < % gravel SILT with GRAVEL
LL<50

ML
% sand > < 15% gravel SANDY SILT
>30% plus % gravel > 15% gravel SANDY SILT with GRAVEL
No. 200 % sand < < 15% sand GRAVELLY SILT
line

% gravel > 15% sand GRAVELLY SILT with SAND

<15% plus
ORGANIC CLAY
<30% plus No. 200
PI>4 and plots on or

No. 200 15-29% plus % sand > % gravel ORGANIC CLAY with SAND
No. 200 % sand < % gravel ORGANIC CLAY with GRAVEL
above “A”-line

% sand > < 15% gravel SANDY ORGANIC CLAY

>30% plus % gravel > 15% gravel SANDY ORGANIC CLAY with GRAVEL
No. 200 % sand < < 15% sand GRAVELLY ORGANIC CLAY
Organic

% gravel > 15% sand GRAVELLY ORGANIC CLAY with SAND

OL
<15% plus
ORGANIC SILT
PI<4 or plots below “A”-

<30% plus No. 200

No. 200 15-29% plus % sand > % gravel ORGANIC SILT with SAND
No. 200 % sand < % gravel ORGANIC SILT with GRAVEL
% sand > < 15% gravel SANDY ORGANIC SILT
>30% plus % gravel > 15% gravel SANDY ORGANIC SILT with GRAVEL
No. 200 % sand < < 15% sand GRAVELLY ORGANIC SILT
line

% gravel > 15% sand GRAVELLY ORGANIC SILT with SAND

Soil and Rock Logging, Classification, and Presentation Manual, Section 3 42

Figure 3-3, continued
Liquid Limit

Plasticity
Organic

Index
Group
Symbol Fines Coarseness Group Name
<15% plus
Fat CLAY
Plots on or above “A”-line

No. 200
<30% plus
No. 200 15-29% plus % sand > % gravel Fat CLAY with SAND
No. 200 % sand < % gravel Fat CLAY with GRAVEL
CH
% sand > % < 15% gravel SANDY fat CLAY
gravel > 15% gravel SANDY fat CLAY with GRAVEL
>30% plus
No. 200 % sand < % < 15% sand GRAVELLY fat CLAY
Inorganic

gravel > 15% sand GRAVELLY fat CLAY with SAND

<15% plus
Elastic SILT
<30% plus No. 200
No. 200 15-29% plus % sand > % gravel Elastic SILT with SAND
Plots below “A”-line

No. 200 % sand < % gravel Elastic SILT with GRAVEL

MH
% sand > % < 15% gravel SANDY elastic SILT
gravel > 15% gravel SANDY elastic SILT with GRAVEL
>30% plus
No. 200 % sand < % < 15% sand GRAVELLY elastic SILT
gravel > 15% sand GRAVELLY elastic SILT with SAND
LL>50

<15% plus
ORGANIC CLAY
Plots on or above “A”-line

No. 200
<30% plus
No. 200 15-29% plus % sand > % gravel ORGANIC CLAY with SAND
No. 200 % sand < % gravel ORGANIC CLAY with GRAVEL
% sand > % < 15% gravel SANDY ORGANIC CLAY
gravel > 15% gravel SANDY ORGANIC CLAY with GRAVEL
>30% plus
No. 200 % sand < % < 15% sand GRAVELLY ORGANIC CLAY
Organic

gravel > 15% sand GRAVELLY ORGANIC CLAY with SAND

OH
<15% plus
ORGANIC SILT
No. 200
<30% plus
No. 200 15-29% plus % sand > % gravel ORGANIC SILT with SAND
Plots below “A”-line

No. 200 % sand < % gravel ORGANIC SILT with GRAVEL

% sand > % < 15% gravel SANDY ORGANIC SILT
gravel > 15% gravel SANDY ORGANIC SILT with GRAVEL
>30% plus
No. 200 % sand < % < 15% sand GRAVELLY ORGANIC SILT
gravel > 15% sand GRAVELLY ORGANIC SILT with SAND

Soil and Rock Logging, Classification, and Presentation Manual, Section 3 43

3.2.2.2 Procedure for Classification of
Coarse-Grained Soils
If 50% or more by dry weight of the test specimen
is retained on the No. 200 sieve the soil is coarse-
grained. Coarse-grained soils are classified using
the following procedure:
• Classify the soil as gravel if more than 50% of
the coarse fraction (plus No. 200 sieve) is
retained on the No. 4 sieve.
• Classify the soil as sand if 50% or more of the
coarse fraction (plus No. 200 sieve) passes
through the No. 4 sieve.
• If 12% or less of the test specimen passes
through the No. 200 sieve, plot the cumulative
particle-size distribution and compute the
coefficient of uniformity, Cu, and coefficient of
curvature, Cc, as given in Equations 1
and 2.
Equation 1 D60
Cu =
D10

Equation 2 (D30 )2
Cc =
(D10 × D60 )
Where D10, D30, and D60 are the particle-size
diameters corresponding to 10, 30, and 60
percentiles passing on the cumulative particle-
size distribution curve. It may be necessary to
extrapolate the curve to obtain the D10 diameter.
Use the above results to determine the
classification according to Figure 3-4 on the
following page.

Soil and Rock Logging, Classification, and Presentation Manual, Section 3 44

Figure 3-4
Flow chart for coarse-grained soils
Group
Fines Grade Type of Fines Sand/ Gravel Group Name
Symbol
Cu>4 < 15% sand Well-graded GRAVEL
GW
1<Cc<3 > 15% sand Well-graded GRAVEL with SAND
< 5%
Cu<4 < 15% sand Poorly graded GRAVEL
GP
1>Cc>3 > 15% sand Poorly graded GRAVEL with SAND
< 15% sand Well-graded GRAVEL with SILT
ML or MH GW-GM
> 15% sand Well-graded GRAVEL with SILT and SAND
Cu>4 Well-graded GRAVEL with CLAY (or SILTY
1<Cc<3 < 15% sand
CLAY)
CL, CH or CL-ML GW-GC
Well-graded GRAVEL with CLAY and SAND (or
> 15% sand
SILTY CLAY and SAND)
5-12%
Gravel

< 15% sand Poorly graded GRAVEL with SILT

ML or MH GP-GM
> 15% sand Poorly graded GRAVEL with SILT and SAND
Cu<4 Poorly graded GRAVEL with CLAY (or SILTY
1>Cc>3 < 15% sand
CLAY)
CL, CH or CL-ML GP-GC
Poorly graded GRAVEL with CLAY and SAND
> 15% sand
(or SILTY CLAY and SAND)
< 15% sand SILTY GRAVEL
ML or MH GM
> 15% sand SILTY GRAVEL with SAND
< 15% sand CLAYEY GRAVEL
> 12% CL or CH GC
> 15% sand CLAYEY GRAVEL with SAND
< 15% sand SILTY, CLAYEY GRAVEL
CL-ML GC-GM
> 15% sand SILTY, CLAYEY GRAVEL with SAND
Cu>6 < 15% gravel Well-graded SAND
SW
1<Cc<3 > 15% gravel Well-graded SAND with GRAVEL
< 5%
Cu<6 < 15% gravel Poorly graded SAND
SP
1>Cc>3 > 15% gravel Poorly graded SAND with GRAVEL
< 15% gravel Well-graded SAND with SILT
ML or MH SW-SM
Cu>6 > 15% gravel Well-graded SAND with SILT and GRAVEL
1<Cc<3 < 15% gravel Well-graded SAND with CLAY
CL, CH or CL-ML SW-SC
> 15% gravel Well-graded SAND with CLAY and GRAVEL
5-12%
< 15% gravel Poorly graded SAND with SILT
Sand

ML or MH SP-SM
Cu<6 > 15% gravel Poorly graded SAND with SILT and GRAVEL
1>Cc>3 < 15% gravel Poorly graded SAND with CLAY
CL, CH or CL-ML SP-SC
> 15% gravel Poorly graded SAND with CLAY and GRAVEL
< 15% gravel SILTY SAND
ML or MH SM
> 15% gravel SILTY SAND with GRAVEL
< 15% gravel CLAYEY SAND
> 12% CL or CH SC
> 15% gravel CLAYEY SAND with GRAVEL
< 15% gravel SILTY, CLAYEY SAND
CL-ML SC-SM
> 15% gravel SILTY, CLAYEY SAND with GRAVEL

Soil and Rock Logging, Classification, and Presentation Manual, Section 3 45

3.2.3 Consistency (Cohesive Soils) some, etc.) shall not be used when gradation data is
available.
Cohesive soil consistency descriptors shall
conform to terminology and criteria established in Figure 3-6
Figure 3-5 below, generally after Das (1983) and Percent or proportion of soils
Bureau of Reclamation standards (2001). Note that
Descriptive Term Size
the terms to be used have been modified from those
contained in both references. Gravel 3 inch to No.4 Sieve
Sand No.4 to No. 200 Sieve
The preferred procedure for the determination of
Fines Passing No. 200 Sieve
consistency of cohesive soils is to obtain relatively
undisturbed samples and perform laboratory
triaxial, direct shear, or unconfined compression 3.2.5 Particle Size
tests. The results from these tests can be correlated
When laboratory particle size analyses are
to specific consistency descriptors as presented in
performed, the USCS soil descriptions shall be
Figure 3-5 below.
further refined using the results and the Figure 3-8
A triaxial unconsolidated-undrained (UU) test is below.
recommended for strength determination. This can
Figure 3-8
be converted to an equivalent unconfined
Particle size
compressive strength by multiplying the Undrained
Shear Strength value by 2. Description Size
Figure 3-5 Boulder >12 in
Consistency Cobble 3 to 12 in
Unconfined Compressive Coarse Gravel ¾ to 3 in
Description Fine Gravel No.4 to ¾ in
Strength (tsf)
Very Soft < 0.25 Coarse Sand No.10 to No.4
Soft 0.25 to 0.50 Medium Sand No.40 to No.10
Medium Stiff 0.50 to 1.0 Fine Sand No. 200 to No.40
Stiff 1 to 2 Clay and Silt Passing No. 200
Very Stiff 2 to 4
Hard > 4.0 3.2.6 Plasticity (for Fine-Grained Soils)
Field estimates of plasticity shall not be included in
3.2.4 Percent or Proportion of Soils the descriptive sequence when USCS
Percentages of gravel, sand, and fines shall be classifications are based on liquid limit and
reported as percentages based on gradation and plasticity index, since the plasticity is inherent in
particle-size analysis (ASTM D 422-63 (2002)). the group name and group symbol.
Qualitative proportional descriptors (e.g. trace,

Soil and Rock Logging, Classification, and Presentation Manual, Section 3 46

3.3 Revising Rock Identification and Description for Borehole Cores Using
Laboratory Test Results
One additional component, relative strength of intact rock, can be added to the descriptive sequence for rock.

Figure 3-9
Rock Identification and Descriptive Sequence
Refer to Section
Sequence

Required

Optional
Field

Lab
Identification Components
1 Rock Name 2.5.2 J

Description Components
2 Rock Grain-size 2.5.3 E
3 Bedding Spacing 2.5.4 J
4 Color 2.5.5 J
5 Texture 2.5.6 E
6 Weathering Descriptors for Intact Rock 2.5.7 J
7 Relative Strength of Intact Rock 3.3.1 J
8 Rock Hardness 2.5.8 J
9 Fracture Density 2.5.9 J
10 Discontinuity Type 2.5.10 E
11 Discontinuity Condition (Weathering, Infilling and Healing) 2.5.11 E
12 Discontinuity Dip Magnitude 2.5.12 E
13 Rate of Slaking (Jar Slake Test) 2.5.13 E
14 Odor 2.5.14 E
15 Additional Comments 2.5.15 E

3.3.1 Strength of Intact Rock

Absent discontinuities, the strength of intact rock is best determined using unconfined compression
laboratory testing.

Figure 3-10
Descriptors for Relative Strength of Intact Rock
Description Uniaxial Compressive Strength (psi)
Extremely Strong > 30,000
Very Strong 14,500 – 30,000
Strong 7,000 – 14,500
Medium Strong 3,500 – 7,000
Weak 700 – 3,500
Very Weak 150 – 700
Extremely Weak < 150

Soil and Rock Logging, Classification, and Presentation Manual, Section 3 47

 (This page left intentionally blank)

Soil and Rock Logging, Classification, and Presentation Manual, Section 3 48

Section 4:
Methods of Presentation of Subsurface Information
• Continuity of material types between discrete
sampling locations is sometimes difficult to
4.1 Introduction confirm.
The process of creating boring logs, i.e., Log of
Test Borings (LOTB) and Boring Records (BR) Figure 4-1
can be summarized in four steps:
• Field sampling and descriptions (Section 2) Field
• Quality check of field descriptions (Section 2) Sampling
and
• Refinement of descriptions, and classification Descriptions
(Sec. 2)
of soil, based on laboratory test results, if
performed (Section 3)
• Preparation of the boring logs (Sections 4
and 5)
Quality
This section provides details and guidance for Check of
Field
incorporating laboratory test data and preparing Observations
boring logs. Figure 4-1 is a schematic (Sec. 2)

representation of the process from obtaining

subsurface information to the creation of boring
logs.

Laboratory
4.2 Factual vs. Interpretive Tests?

Subsurface Data YES NO

FHWA guidelines state: “factual subsurface data

which is pertinent to the project subsurface
conditions should be presented in an easily
understood fashion on the contract documents.” Incorporate
Laboratory Data,
However, there is an inherent level of professional Refine
interpretation in describing subsurface conditions Descriptions, and
Classify (Sec. 3)
that cannot be avoided.
Some examples:
• Field description and identification procedures,
according to ASTM D 2488-06, require
estimation and interpretation. Prepare
Boring Logs
• Sampling may occur at discrete intervals, yet (Sec. 4 & 5)
layer boundaries may fall between sampling
locations. The boundaries may be identified
based on visual observations of cuttings during
boring advancement. There may be uncertainty
as to the depth at which a material change
occurs.

Soil and Rock Logging, Classification, and Presentation Manual, Section 4 49

4.3 Incorporating Laboratory Data, the boring log presentation format and provide
Refining Descriptions, and clarity, especially to prospective bidders.
Classifying Soil
When describing soil or rock, the geoprofessional 4.3.2 General Rules and Considerations
shall use the most reliable data available. Such data The following general rules apply to the layer
could be field-generated, or a combination of field- presentation method:
and laboratory-generated data. If laboratory tests
are performed, and in the opinion of the • A change in a soil’s Group Symbol or a rock
geoprofessional, those test results represent the type shall result in a new layer within the
actual conditions of the soil or rock, those test boring log.
results shall control the identification, description, • Reliable laboratory test results shall be used
or classification. when performed to determine the applicable
descriptors within the descriptive sequence (i.e.
Laboratory tests are usually not performed on
Group Name and Symbol, consistency,
every sample, especially on contiguous samples
gradation properties, plasticity, and rock
within a layer of similar material. Professional
strength).
judgment should be used to apply test results from
one sample to the descriptor of contiguous samples • Individual descriptors for contiguous samples
within a boring when the field observations were with the same descriptions and classifications
such that the geoprofessional considers that should be adjusted based on the test results of
particular attribute of the material to be consistent one or more representative samples. Use of
across the contiguous samples. more than one test sample is encouraged.
For example, three contiguous samples were • When specifying a descriptive range, the range
determined to be “medium stiff” using the thumb shall not span more than one step on the range
method. However, a triaxial test on one of those of descriptors. For example, “stiff to very stiff”
samples indicated that the material was in fact would be acceptable; but “soft to hard” would
“stiff.” In this example, the consistency descriptor not be acceptable because the range is too
for the entire layer should be “stiff.” broad to be useful.
Exception: Any range of colors is acceptable.
• The descriptive sequence used to describe a
4.3.1 Subsurface Data Presentation layer of soil or rock shall describe that layer in
Method its entirety. Where changes are noted at depths
A “layer presentation” method shall be used to within the layer, those changes shall replace the
present soil and rock descriptions on boring logs. preceding descriptor and shall apply from that
(See Figure 4-3.) This method presents a single depth to the bottom of the layer.
primary description for a layer spanning one or • The layer presentation of the boring log shall
more contiguous sample locations. However, the enable the reader to derive individual sample
layer description may vary with depth as descriptions based on the layer description and
observations and/or laboratory testing at sample sample information provided.
locations warrant. This method is used to simplify

Soil and Rock Logging, Classification, and Presentation Manual, Section 4 50

4.3.3 Example
The process for developing boring logs has been presented in detail throughout this Manual In general, field
sample descriptions are corrected and calibrated based on laboratory results, layer boundaries are determined
by grouping samples within the same group symbol, sample descriptions are consolidated into a single layer
description, and, finally, description changes are noted with depth within layers.
The following example demonstrates how a geoprofessional develops a layer presentation, based on field
descriptions and laboratory test results.
Figure 4-2
Lab Corrected Description
Depth Field Field Description and Lab Final Layer
Sample and Identification or
(ft.) Testing Identification Testing Presentation
Classification
3.5-5 R-07- SPT Well-graded SAND with Well-graded SAND with Well-graded SAND with
001-S01 GRAVEL and COBBLES GRAVEL and COBBLES (SW), GRAVEL and COBBLES
(SW), loose, yellowish loose, yellowish brown, moist, (SW), loose, yellowish
brown, moist, about 10% about 10% subrounded brown, moist, about 10%
subrounded COBBLES, COBBLES, about 15% coarse subrounded COBBLES,
about 15% coarse to fine to fine GRAVEL, about 80% about 15% coarse to fine
GRAVEL, about 80% coarse to fine SAND, about 5% GRAVEL, about 80%
coarse to fine SAND, about fines, (fill) coarse to fine SAND,
5% fines, (fill) about 5% fines, (fill)
8.5-10 R-07- SPT Well-graded SAND with PA Well-graded SAND with
becomes medium dense
001-S02 GRAVEL and COBBLES GRAVEL and COBBLES (SW),
(SW), medium dense, medium dense, yellowish
yellowish brown, moist, brown, moist, about 10%
about 10% subrounded subrounded COBBLES, about
COBBLES, about 95% 95% coarse to fine SAND,
coarse to fine SAND, about about 5% fines, (fill)
5% fines, (fill)
13.5-15 R-07- PP SANDY lean CLAY (CL), SANDY lean CLAY (CL), SANDY lean CLAY (CL),
001-U03 medium stiff, dark bluish medium stiff, dark bluish gray, medium stiff, dark bluish
gray, moist, about 35% moist, about 35% medium gray, moist, about 35%
medium SAND, about 65% SAND, about 65% fines, trace medium SAND, about
fines, trace shell fragments, shell fragments, (bay mud) 65% fines, trace shell
(bay mud) fragments, (bay mud)
18.5-20 R-07- PP SANDY lean CLAY (CL), UU, PA, PI SANDY lean CLAY (CL),
as above except no shell
001-U04 soft, dark bluish gray, medium stiff, dark bluish gray,
fragments
moist, about 35% medium moist, about 35% medium
SAND, about 65% fines, SAND, about 65% fines, (bay
(bay mud) mud)
23.5-25 R-07- PP SANDY lean CLAY (CL), UU, PA, PI SANDY lean CLAY (CL), stiff, becomes stiff, dark gray
001-U05 medium stiff, dark gray, dark gray, moist, about 35%
moist, about 35% medium medium SAND, about 65%
SAND, about 65% fines, fines, trace shell fragments,
trace shell fragments, (bay (bay mud)
mud)
28-29 R-07- SPT SEDIMENTARY ROCK SEDIMENTARY ROCK SEDIMENTARY ROCK
001-S06 (SHALE), dark bluish gray, (SHALE), dark bluish gray, (SHALE), dark bluish
intensely weathered, intensely weathered, gray, intensely
moderately soft, intensely moderately soft, intensely to weathered, moderately
to moderately fractured moderately fractured soft, intensely to
moderately fractured
29-34 R-07- SEDIMENTARY ROCK UC SEDIMENTARY ROCK
001-C07 (SHALE), dark bluish gray, (SHALE), dark bluish gray, becomes moderately to
moderately to slightly moderately to slightly slightly weathered,
weathered, moderately weathered, strong, moderately strong, moderately hard,
hard, moderately fractured hard, moderately fractured moderately fractured

34-39 R-07- SEDIMENTARY ROCK UC SEDIMENTARY ROCK

becomes slightly
001-C08 (SHALE), dark bluish gray, (SHALE), dark bluish gray,
fractured
moderately to slightly moderately to slightly
weathered, moderately weathered, strong, moderately
hard, slightly fractured hard, slightly fractured

Soil and Rock Logging, Classification, and Presentation Manual, Section 4 51

The LOTB for the preceding example would appear as follows:
Figure 4-3

Soil and Rock Logging, Classification, and Presentation Manual, Section 4 52

Section 5:
Boring Log and Legend Presentation Formats
5.1 Introduction
The Department uses the following formats to present subsurface information:
• Log of Test Boring (LOTB), and/or
• Boring Record (BR).
An LOTB is typically associated with a structure facility and is attached to Project Plans. A BR is typically
associated with an earthwork facility and is attached to a Geotechnical Report. If a subsurface exploration
was performed, there shall be at least one type of log presentation.

5.2 Log of Test Boring

Figure 5-1
Example of LOTB

Soil and Rock Logging, Classification, and Presentation Manual, Section 5 53

5.2.1 Contents and Characteristics Classification, and Presentation Manual (Date)
of the LOTB except as noted in (Section) of (Report Title) dated
The Log of Test Boring (LOTB) document is (Date)”
presented as an attachment to project plans and
Optional notes may include:
characterized by the following attributes:
• Changes in drilling equipment
• Presents the boring logs on an elevation scale.
• Site observations
• Presents a plan view showing the location of
each boring relative to an alignment and/or • Other drilling observations from Sections
existing or planned facility. 2.4.20 or 2.5.16.
• Presents the type of drilling methods used to
perform the investigation, the type of sampling 5.2.3 LOTB Sheet Formatting
performed, and how the sampler was advanced. LOTB sheets shall be prepared in accordance with
• Presents the location and description, both this manual and the Caltrans Plans Preparation
graphical and written, of the types of soil and Manual. The LOTB sheet border shall present the
rock encountered within the borehole. following:
• Presents the types of field and laboratory
testing performed. 5.2.3.1 Signature Block (Upper Right
Corner)
• Field and Laboratory test data, if presented,
appear at the end of the descriptive sequence. a) The State of California Registered Civil
Engineer, Certified Engineering Geologist,
• Optimized for printing on full-size plan sheets
or Registered Geologist seal with the
(24" x 36") and typically reproduced on
signature, date, license number, and
11" x 17" sized paper.
registration certificate expiration date of the
• Allows presentation of more than one boring engineer or geologist in responsible charge
log per plan sheet. of the LOTB sheet;
• Is accompanied by LOTB legend sheets. b) Caltrans District, County, and Route;
c) Name and address of consultant firm in
responsible charge of the LOTB sheet (if
5.2.2 Notes on the LOTB
applicable);
Each LOTB sheet shall contain a note section for d) Name and address of the lead local agency
the geoprofessional to present notes deemed to be (if applicable); and
of interest to the reader. Content of notes is left to e) A disclaimer stating "The State of
the discretion of the geoprofessional except that the California or its officers or agents shall not
one of the following two notes shall be placed on be responsible for the accuracy or
each LOTB sheet: completeness of electronic copies of this
If the procedures of this manual were followed plan sheet."
without exception, then the note shall read: (The Office Engineer will provide the Post
Miles Total Project, Sheet Number, Total
“This LOTB sheet was prepared in accordance Sheets, and Plans Approval Date.)
with the Caltrans Soil & Rock Logging,
Classification, and Presentation Manual (Date)”
5.2.3.2 Title Block (Bottom, from left to
right)
If an exception to the procedures of this manual has
been approved and implemented, then the note a) Notes stating "DIVISION OF
shall be modified to read: ENGINEERING SERVICES" and
"GEOTECHNICAL SERVICES." For
“This LOTB sheet was prepared in accordance consultant-prepared LOTB sheets, instead
with the Caltrans Soil & Rock Logging, of those notes, show the name of the Design
Soil and Rock Logging, Classification, and Presentation Manual, Section 5 54
 Oversight (i.e., OSFP/OSCM Senior the stationing of the control line (i.e.,
Liaison) Engineer and sign-off date. showing sheet No. 1 with the lowest
b) “FUNCTIONAL SUPERVISOR”: The stationing and the last sheet with the highest
name of the person in charge of the stationing).
functional unit responsible for providing c) A distinct Plan View of the project site that
oversight of the registered engineer or is independent of the Profile View shall be
geologist who developed the LOTB sheet. shown on the LOTB.
c) “DRAWN BY”: The name of the person d) Show the location, description, and
who prepared (drafted) the LOTB sheet elevation of the benchmark used for
d) “CHECKED BY”: The name of the person determining the top of boring elevations at
who performed the quality control check of the top left side of the Plan View under the
the LOTB sheet heading “BENCHMARK”. Identify the
e) “FIELD INVESTIGATION BY”: The vertical datum (National Geodetic Vertical
name(s) of the field investigator(s); Datum, U.S. Geological Survey, U.S. Coast
f) A note stating "STATE OF CALIFORNIA, & Geodetic Survey, District, etc.) used to
DEPARTMENT OF determine the benchmark elevations.
TRANSPORTATION" with a scale below e) Show the scale directly below the Plan
the sub-block and a label on the left side View label.
stating "ORIGINAL SCALE IN INCHES f) Show a North arrow.
FOR REDUCED PLANS." For consultant- g) Lines or control lines shown in the Plan
prepared LOTB sheets, the note shall state View shall be consistent with those shown
"PREPARED FOR THE STATE OF on the General Plan sheet.
CALIFORNIA, DEPARTMENT OF h) Show stationing and names for control lines.
TRANSPORTATION." Stationing shall increase from left to right.
g) A note stating "DIVISION OF Show a minimum of two stations on all
ENGINEERING SERVICES lines.
STRUCTURE DESIGN." For consultant- i) Show control line intersection stationing
prepared LOTB sheets, instead of this note, and bearings.
show the name of the Project Engineer; j) Show names and directions of nearest cities.
h) The Caltrans Contract Expenditure k) Show names and directions of stream flows
Authorization (CU and EA) numbers; when applicable.
i) The State-assigned Bridge (or Structure) l) Plot boring locations with symbols as
Number, Kilometer Post, and the State- shown in the legend to identify drilling
assigned Bridge (or Structure) Name; methods (e.g., auger hole, rotary hole, cone
j) The initial drawn by and subsequent penetration). The Hole Identification shall
revision dates; and be presented with each symbol.
k) A label stating "LOG OF TEST BORINGS m) Boring locations are to be identified by
_ OF _" (if applicable). reference line, station, and offset.
(The Office Engineer will provide the Sheet Coordinates, such as Northing and Easting,
Number and Total Sheets Number.) may also be shown on the LOTB sheets.

5.2.3.3 Plan View 5.2.3.4 Profile View

a) Plan View shall be shown at the top of the a) Show the control line, increasing from left
first LOTB sheet. When the site is to right, horizontally across the bottom of
sufficiently large or complex, the first the Profile View.
LOTB sheet should be used entirely for the b) Show the elevations and grid lines on both
Plan View. the left and right margins. Numerical
b) When multiple LOTB sheets are drafted, values shall be in multiples of 10 (i.e. 20,
they shall be numbered with reference to 10, 0, -10, -20).

Soil and Rock Logging, Classification, and Presentation Manual, Section 5 55

 c) Show the Hole Identification, top of hole 5.2.4 As-Built LOTB Sheet Formatting
elevation, stationing, and offset at the top of As-Built LOTB sheet(s) shall be prepared
each boring log.
according to the following standards.
d) Show types and diameters of each boring as
shown in the legend.
5.2.4.1 Obtaining and Reproducing the
e) Show the completion date of boring (m/d/y)
As-Built LOTB Sheet
at the bottom of each boring log.
f) Show “Terminated at EL. XX’” to indicate a) Reproducible copies of As-Built LOTB
the bottom of boring elevation. sheets may be obtained from the Microfilm
g) Show the SPT hammer energy ratio, Services Units in the Caltrans District
“Hammer Energy Ratio (ERi) = XX%,” at Offices. If the As-Built LOTB sheets
the bottom of each boring. provided to Local Agencies or consultants
h) Show date and elevation of groundwater by the Caltrans District Offices are not
measurement. legible, a full sized copy should be
i) Show results from field penetration tests at requested from Geotechnical Services.
relevant elevations along the boring log. b) As-Built LOTB sheets shall be size "D"
j) Show types of field and laboratory tests (24" by 36"). The As-Built LOTB title
with symbols as indicated in the legend, at block shall be sized to fit and placed over
relevant elevations along the right side of any open space (preferably toward the top)
the boring log. on the As-Built LOTB sheet.
k) Show the Profile scales (horizontal and c) Information on the As-Built LOTB sheet
vertical) under the heading “PROFILE”. shall be clear and legible. In order to
improve the legibility of the information, it
5.2.3.5 Additional information to be may be necessary to darken the line work
included and the notations.
a) Show standard note identifying the logging
5.2.4.2 Typical Modifications to As-Built
practice as follows:
LOTB Sheets
“This LOTB sheet was prepared in a) If As-Built LOTB sheets are shown in
accordance with the Caltrans Soil & Rock metric units, the offset and stationing
Logging, Classification, and Presentation location of each boring must be converted
Manual” to imperial units. A table shall be added
showing the dual dimensions (Metric and
When a LOTB presents information that English) of each boring. The table shall
deviates from the Caltrans Soil & Rock show the station and offset in relation to the
Logging, Classification, and Presentation new English line. The General Plan will
Manual standards, the standard note shall show the current English control line.
be modified to read as follows:
5.2.4.3 The As-Built LOTB Title Block
shall include the following
“This LOTB sheet was prepared in
information for the current
accordance with the Caltrans Soil & Rock
project
Logging, Classification, and Presentation
Manual except as noted in (section) of a) A note stating "GEOTECHNICAL
(Report Title) dated (Date)” SERVICES -- DIVISION OF
ENGINEERING SERVICES" (if
b) Descriptions of types of samplers used for applicable).
the field exploration. b) Caltrans District, County, Route, Post Miles
- Total Project, State-assigned Bridge (or
Structure) Number and Name, and
Expenditure Authorization (CU and EA)
Soil and Rock Logging, Classification, and Presentation Manual, Section 5 56
 numbers. The Office Engineer will provide e) A sub-box stating "LOG OF TEST
the Sheet Number and Total Sheets Number. BORINGS _ OF _" (if applicable).
c) The State of California Registered Civil e) A note stating "A COPY OF THIS LOG
Engineer or Registered Geologist seal with OF TEST BORINGS IS AVAILABLE AT
the signature, date, license number, and OFFICE OF STRUCTURE
registration certificate expiration date of the MAINTENANCE AND
engineer or geologist in responsible charge INVESTIGATIONS, SACRAMENTO,
of the LOTB sheet. CALIFORNIA" (if applicable).
d) A note stating, "As-Built Log of Test
Borings sheet is considered an
5.2.5 The LOTB Legend Sheets
informational document only. As such, the
State of California registration seal with The soil and rock legend sheets are standard forms
signature, license number and registration that provide convenient references for the required
certificate expiration date confirm that this soil and rock description, identification, and/or
is a true and accurate copy of the original classification components presented in this Manual.
document. It does not attest to the accuracy References for optional descriptors do not appear
or validity of the information contained in on the legend sheets; however, they are explained
the original document. This drawing is in this Manual. To correctly interpret the LOTB,
available and presented only for the the reader shall be familiar with this Manual.
convenience of any bidder, contractor or There are two legend sheets, one predominantly for
other interested party." soil and the other for rock, as shown in the Figures
5-2 and 5-3.
The legend sheets define the format for the
graphical presentation of a boring log and
differentiate among the various borehole and
sounding types. The legend sheets also present the
symbols used to identify laboratory tests.

GEOTECHNICAL SERVICES – DIVISION OF ENGINEERING SERVICES

As-Built Log of Test Borings sheet is considered an informational document only. As such, the State of
California registration seal with signature, license number and registration certificate expiration date
confirm that is this a true and accurate copy of the original document. It does not attest to the accuracy or
validity of the information contained in the original document. This drawing is available and presented only
for the convenience of any bidder, contractor or other interested party.
DIST. COUNTY ROUTE POST MILES – TOTAL PROJECT SHEET NO. TOTAL SHEETS

08 SBD 210 10.00-15.00 24 25

REGISTERED ENGINEER – CIVIL DATE

MAIN STREET OVERCROSSING

LOG OF TEST BORINGS 5 OF 6
NOTE: A COPY OF THIS LOG OF TEST BORINGS IS AVAILABLE AT
CU: 12 BRIDGE NO.
OFFICE OF STRUCTURE MAINTENANCE AND INVESTIGATIONS,
SACRAMENTO, CALIFORNIA EA: 432563 12-3456

Soil and Rock Logging, Classification, and Presentation Manual, Section 5 57

 (This page left intentionally blank)

Soil and Rock Logging, Classification, and Presentation Manual, Section 5 58

Figure 5-2

Soil and Rock Logging, Classification, and Presentation Manual, Section 5 59

Figure 5-3

Soil and Rock Logging, Classification, and Presentation Manual, Section 5 60

Four general hole-type formats are graphically Figure 5-6
presented as follows: Definitions for changes in material
5.2.5.1 Hand Boring Term Definition
Hand Driven (HD) (1-inch soil tube) and Hand Material Change Change in material is
Auger (HA) borings shall be presented using the observed in the sample
or core, and the location
following format: of change can be
Figure 5-4 accurately measured.
Estimated Material Change in material
Change cannot be accurately
located because either
the change is
gradational or because
of limitations in the
drilling/sampling
methods used.
Soil/Rock Boundary Material changes from
soil characteristics to
rock characteristics and
that change can be
measured or estimated.

5.2.5.3 Dynamic Cone Penetration

Sounding
The Dynamic Cone Penetration Sounding (D) shall
5.2.5.2 Rotary Boring
be presented using the following format:
Rotary Drilled Boring or Diamond Core (R),
Figure 5-7
Rotary Percussion Boring (Air) (P), Auger Boring
(A), shall be presented using the following format:
Figure 5-5

Notes:
If laboratory tests are not shown as being performed, the soil
descriptions presented in the LOTB are based solely on the
visual practices described in this Manual.

Changes in material with depth shall be noted

using the following terms:

Soil and Rock Logging, Classification, and Presentation Manual, Section 5 61

5.2.5.4 Cone Penetration Test (CPT) 5.2.5.5 Rock Coring
Sounding Rock coring logs shall be presented using the
A Cone Penetration Test (CPT) sounding shall be following format:
presented using the following format: Figure 5-9
Figure 5-8

5.2.5.6 Hole Type Symbols

Hole type is identified within the hole
identification numbering convention (see Section
2.3) and symbolized on the LOTB as follows:
Figure 5-10

Soil and Rock Logging, Classification, and Presentation Manual, Section 5 62

5.2.5.7 Graphical Representation of Material Types
Soil Group Name and Group Symbol and Rock Type are symbolized on the LOTB as follows:
Figure 5-11

Soil and Rock Logging, Classification, and Presentation Manual, Section 5 63

5.3 Boring Records
Figure 5-12

Soil and Rock Logging, Classification, and Presentation Manual, Section 5 64

Figure 5-12 (continued)

Soil and Rock Logging, Classification, and Presentation Manual, Section 5 65

Figure 5-13

Soil and Rock Logging, Classification, and Presentation Manual, Section 5 66

5.3.1 Content and Characteristics of the Classification, and Presentation Manual (Date)
BR except as noted in (Section) of (Report Title) dated
(Date)”
A Boring Record (BR) document is presented as an
attachment to a geotechnical report and is
characterized by the following attributes: Optional notes are left to the discretion of the
• Presents a single borehole record or CPT geoprofessional and, if are specific to an elevation
sounding. or depth, should be presented at the appropriate
location in the “Remarks” column. These notes
• Presents the borings to an elevation scale. may include:
• Presents the type of drilling method used to
• Changes in drilling equipment
perform the investigation, the type of sampling
performed, and how the sampler was advanced. • Other drilling observations from Sections
2.4.22 or 2.5.17.
• Presents the location and description, both
graphical and written, of the types of soil and Notes that are more general in content, such as a
rock encountered within the borehole. site observation, should be placed within the body
of the geotechnical report.
• Accommodates the presentation of select field
and laboratory test results.
5.3.3 The Boring Record Legend Sheets
• Optimized for printing on 8.5" x 11" sheets
The soil and rock legend sheets are standard forms
• Is accompanied by BR Legend Sheets.
that provide convenient references for the required
soil and rock description, identification, and/or
5.3.2 Notes on the BR classification components presented in this Manual.
References for optional descriptors do not appear
If the procedures of this manual were followed on the legend sheets; however, they are explained
without exception, then the following note shall in this Manual. To correctly interpret the BR, the
appear on the first page of the BR: reader shall be familiar with this Manual.
There are three legend sheets: one predominantly
“This Boring Record was prepared in accordance for soil and the other for rock, as shown in the
with the Caltrans Soil & Rock Logging, following figures.
Classification, and Presentation Manual (Date)”
The legend sheets define the format for the
graphical presentation of a boring log and
If an exception to the procedures of this manual has differentiate among the various borehole and
been approved and implemented, then the note sounding types. The legend sheets also present the
shall be modified to read: symbols used to identify laboratory tests.

“This Boring Record was prepared in accordance

with the Caltrans Soil & Rock Logging,

Soil and Rock Logging, Classification, and Presentation Manual, Section 5 67

Figure 5-14

Soil and Rock Logging, Classification, and Presentation Manual, Section 5 68

Figure 5-15

Soil and Rock Logging, Classification, and Presentation Manual, Section 5 69

Figure 5-16

Soil and Rock Logging, Classification, and Presentation Manual, Section 5 70

References
Association of State Highway and Transportation Officials (AASHTO) (1988), Manual on Subsurface
Investigations. Washington, D.C.
American Society for Testing and Materials (ASTM), Annual Book of ASTM Standards, 2007 Edition,
ASTM International, West Conshohocken, PA
Das, Braja M. (1997), Advanced Soil Mechanics,2nd Edition, Taylor & Francis Group
Departments of the Army And The Air Force (1983), Backfill For Subsurface Structures, 5-8184/AFM 85,
Chap. 5, Technical Manual Headquarters, No. 5-818-4, Air Force Manual No. 88-5, Chapter 5
Washington, Dc, 1 June 1983
International Society of Rock Mechanics (ISRM) (1981), Suggested Methods for the Quantitative
Description of Discontinuities in Rock Masses, ed. E. T. Brown
U.S. Department of the Interior, Bureau of Reclamation (2001), Engineering Geology Field Manual,
2nd Edition
U.S. Department of Transportation, Federal Highway Administration, Geotechnical Guideline No.15,
Differing Site Conditions, Geotechnical Engineering Notebook (1996)
Wyllie, D.C., Mah, C. M. (2004), Rock Slope Engineering: Civil and Mining, 4th Edition, Taylor & Francis
Zumberge, J. H., Rutford, R. H., Carter, J. L. (2003), Laboratory Manual For Physical Geology,
11th Edition

Soil and Rock Logging, Classification, Description, and Presentation Manual, References 71
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Soil and Rock Logging, Classification, Description, and Presentation Manual, References 72
Appendix A:
Field Test Procedures
A.1 Pocket Penetrometer material, make at least three test specimens. A test
specimen shall be a ball of material about 1⁄2 in.
The Pocket Penetrometer test is conducted using (12 mm) in diameter. Allow the test specimens to
the following general instructions: dry in air, or sun, or by artificial means, as long as
• To begin test, remove protective cap, push ring the temperature does not exceed 60°C. If the test
against body so that low side reads 0. specimen contains natural dry lumps, those that are
about 1⁄2 in. (12 mm) in diameter may be used in
• Slowly insert piston until engraved mark is place of the molded balls. Test the strength of the
level with soil. dry balls or lumps by crushing between the fingers.
• Observe the reading in TSF (KG/SQ CM) using Note the strength as none, low, medium, high, or
low side of ring, (side closest to the piston end): very high in accordance with the criteria in the
record reading and repeat. table in Section 2.4.14. If natural dry lumps are
used, do not use the results of any of the lumps that
• For weak soils, use 1” adapter foot, multiply are found to contain particles of coarse sand. The
reading by 0.0625. presence of high-strength water-soluble cementing
materials, such as calcium carbonate, may cause
exceptionally high dry strengths. The presence of
A.2 Torvane calcium carbonate can usually be detected from the
The Torvane test is conducted using the following intensity of the reaction with dilute hydrochloric
general instructions: acid.
• To start test, push indicator counter clockwise
to zero stop. A.4 Dilatancy
• Select reasonably flat surface at least 1 inch in From the specimen, select enough material to mold
diameter. into a ball about 1⁄2 in. (12 mm) in diameter. Mold
• Using midsize vane, one revolution equals 1 the material, adding water if necessary, until it has
TSF (1KG/SQ CM). a soft, but not sticky, consistency. Smooth the soil
ball in the palm of one hand with the blade of a
• One revolution using small and large vane knife or small spatula. Shake horizontally, striking
equals respectively 2.5 and 0.2 TSF (KG/SQ the side of the hand vigorously against the other
CM). hand several times. Note the reaction of water
• Press pocket vane shear tester into soil to depth appearing on the surface of the soil. Squeeze the
of blade; maintain constant vertical pressure sample by closing the hand or pinching the soil
while turning knob clockwise at rate to develop between the fingers, and note the reaction as none,
failure within 5 to 10 seconds. slow, or rapid in accordance with the criteria in the
table in Section 2.4.15. The reaction is the speed
• After failure develops, release remaining spring with which water appears while shaking, and
tension slowly. Pointer will indicate maximum disappears while squeezing.
shear value until manually reset.
A.3 Dry Strength
A.5 Toughness
From the specimen, select enough material to mold
into a ball about 1 in. (25 mm) in diameter. Mold Following the completion of the dilatancy test, the
the material until it has the consistency of putty, test specimen is shaped into an elongated pat and
adding water if necessary. From the molded rolled by hand on a smooth surface or between the
palms into a thread about 1⁄8 in. (3 mm) in
Soil and Rock Logging, Classification, Description, and Presentation Manual, Appendix 73
diameter. (If the sample is too wet to roll easily, it A.7 Calcium Carbonate
should be spread into a thin layer and allowed to
lose some water by evaporation.) Fold the sample Because calcium carbonate is a common cementing
threads and reroll repeatedly until the thread agent, it is important to report its presence, which
crumbles at a diameter of about 1⁄8 in. The thread is done on the basis of the reaction with dilute
will crumble at a diameter of 1⁄8 in. when the soil hydrochloric acid (HCl). Use the ASTM D 2488-
is near the plastic limit. Note the pressure required 06 standard to describe the reaction with HCl, as
to roll the thread near the plastic limit. Also, note indicated in Figure 2-19 below.
the strength of the thread. After the thread
crumbles, the pieces should be lumped together Figure 2-19
and kneaded until the lump crumbles. Note the Descriptors for calcium carbonate reaction
toughness of the material during kneading. Description Criteria
Describe the toughness of the thread and lump as
None No visible reaction.
low, medium, or high in accordance with the
criteria in the table in Section 2.4.16. Weak Some reaction, with bubbles forming
slowly.
Strong Violent reaction, with bubbles forming
immediately.
A.6 Jar Slake Index Test
Slaking behavior of intact rock specimens is
quantified as an index. A laboratory index test A.8 Standard Penetration Test
called the Slake Durability Test (ASTM D 4644-04) Standard Penetration Tests (SPT) shall be
is the most rigorous method of measuring this conducted according to the following test methods:
behavior. A simple, but less sensitive method can
• ASTM D 1586-99, Standard Test Method for
be employed in the field or in the office to screen
Penetration Test and Split-Barrel Sampling of
specimens of the Slake Durability test. The “Jar
Soils
Slake Test” method is presented here. A water
filled jar and a watch are all that are required to • ASTM D 6066-96, Standard Practice for
perform this simple test. The steps are as follows: Determining the Normalized Penetration
Resistance of Sands for Evaluation of
• A fragment of rock is immersed in enough
Liquefaction Potential
water to cover it by 15 mm. It is best if the rock
is oven dried. It has been reported that damp The following guidance is provided:
material is relatively insensitive to degradation • Blow counts shall be reported on the LOTB
in this test when compared with dry material. and BR as observed in the field, N, with no
• After immersion, the fragment is observed corrections.
continuously for the first 10 minutes and
Where,
carefully during the first 30 minutes. When a
reaction occurs, it is often during the first 30 N The sum of the hammer blows required
minutes. A final observation is made after 24 to drive the sampler over the test
hours. interval from 0.5 to 1.5 ft below the
• The condition of the piece is categorized cleanout depth.
(complete breakdown, partial breakdown, no • Hammer efficiency shall be noted on the LOTB
change), as shown in the table in Section 2.5.14 and BR to allow the reader to determine N60 or
(Air Force Manual 1983). (N1)60.
Where,
ERi Hammer energy ratio

Soil and Rock Logging, Classification, Description, and Presentation Manual, Appendix 74
 N60 Penetration resistance adjusted to a
60 % drill rod energy ratio per
ASTM D 6066-96: N60 = A.9 Core Recovery (REC)
Nmeasured X (ERi /60) The core recovery value (REC), with few
(N1)60 Penetration resistance adjusted for exceptions, provides an indication of the success of
energy and normalized to a 1 ton/ft2 the coring operation in recovering the cored rock.
stress level. Portions of the cored rock mass may not be
recovered because the fluid used in the drilling
• Blow counts for each of the 6 inch increments operations transports portions of the rock mass
shall be recorded in the field, but not during the coring operation or the rotation of the
necessarily reported on the LOTB and BR. The core barrel traps and grinds away portions of the
2nd and 3rd driving intervals shall be summed rock mass. Diminished core recovery can also be
and reported. attributed to voids within the rock mass. Core
For example: recovery is expressed as a percentage.
1st 6 in. interval: 10 blows
2nd 6 in. interval: 15 blows Σ (Length of the recovered
core pieces, inches)(100%)
3rd 6 in. interval: 18 blows REC =
Total length of the core run, inches
N reported as “33”

• For partial increments, the depth of penetration

shall be reported to the nearest 1 inch, in A.10 Rock Quality Designation (RQD)
addition to the number of blows.
Rock Quality Designation is an index that relates to
For example: the degree of fracturing in a rock mass as observed
1st 6 in. interval: 20 blows in a core specimen. A high value of RQD is
2nd 6 in. interval: 40 blows indicative of a less fractured rock mass or a rock
3rd 6 in. interval: 60 blows for 2 inches, mass having widely spaced fractures. RQD is valid
then refusal for core diameters from 1.4 to 3.35 inches. This
N reported as “100/8” RQD criteria is generally based on ASTM D 6032-
• If the seating interval (1st 6 in. interval) is not 02.
achieved, note refusal.
For example: Σ (Length of intact core pieces > 4
st inches)(100%)
1 6 in. interval: 50 blows for 2 inches, RQD =
Total length of the core run, inches
then refusal
N reported as “REF”

• If a substantial change in material is Used alone, RQD is not sufficient to provide an

encountered over the course of driving the adequate description of rock mass quality. The
sampler, the 2nd and 3rd driving intervals can be RQD does not account for joint orientation,
reported separately. tightness, continuity, and gouge material. The RQD
For example: shall be used in combination with other geological
and geotechnical input.
1st 6 in. interval: 10 blows
2nd 6 in. interval: 20 blows The RQD denotes the percentage of intact rock
3rd 6 in. interval: 60 blows for 3 inches, retrieved from a borehole of any orientation. All
then refusal pieces of intact rock core equal to or greater than 4
N reported as “20/6, 60/3” inches long are summed and divided by the total
length of the core run. An intact core is any
segment of core between two open, natural
discontinuities.

Soil and Rock Logging, Classification, Description, and Presentation Manual, Appendix 75
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Soil and Rock Logging, Classification, Description, and Presentation Manual, Appendix 76
Appendix B:
Field Logging Aids
B.1 Field Sample Logging Forms for soil samples, while the other used for rock
samples.
Forms are provided to assist the sample logging
process in the field. One form is used specifically

Soil and Rock Logging, Classification, Description, and Presentation Manual, Appendix 77
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Soil and Rock Logging, Classification, Description, and Presentation Manual, Appendix 78
 Soil Sample Field Description & Identification
Instructions:
• Field Description and Identification based upon Soil and Rock Logging, Classification, and Presentation Manual, dated July 1, 2007.
• Shaded fields are required, non-shaded fields are optional.
• Intensely weathered or decomposed rock that is friable and that can be reduced to gravel size or smaller by normal hand pressure shall be identified and described as rock followed by the soil
identification or classification, and description in parenthesis.

Project Logged by Date Hole ID

District County Route Postmile EA Sample Depth Sample ID

Drilling Method Sampler Type and Size

SPT Blow Counts Hammer energy ratio (ERi) Pocket Penetrometer Measurement

1st 6 in. interval

2nd 6 in. interval N60 = Nmeasured x (ERi /60) Torvane Measurement
Nmeasured =
3rd 6 in. interval

Group Name Group Symbol Color

Consistency Apparent Density Moisture Structure Cementation Additional Description

Very Soft Very loose Dry Stratified Weak
Soft Loose Moist Laminated Moderate
Medium Stiff Medium dense Wet Fissured Strong
Stiff Dense Slickensided
Very Stiff Very dense Blocky
Hard Lensed
Homogeneous

Rock Identification Weathering Rock Hardness Angularity Shape

Fresh Extremely Hard Angular Flat
Slightly Weathered to Fresh Very Hard Subangular Elongated
100% Total by Volume of entire sample
Boulders

Slightly Weathered Hard Subrounded Flat and Elongated

% Moderately to Slightly Weathered Moderately Hard Rounded
Intersected Lengths of Core Moderately Weathered Moderately Soft
Intensely to Moderately Weathered Soft
Percent (est.)

Intensely Weathered Very Soft

Very Intensely Weathered
Decomposed
Rock Identification Weathering Rock Hardness Angularity Shape
Fresh Extremely Hard Angular Flat
Slightly Weathered to Fresh Very Hard Subangular Elongated
Cobbles

Slightly Weathered Hard Subrounded Flat and Elongated

% Moderately to Slightly Weathered Moderately Hard Rounded
Intersected Lengths of Core Moderately Weathered Moderately Soft
Intensely to Moderately Weathered Soft
Intensely Weathered Very Soft
Very Intensely Weathered
Decomposed

(or) Proportion Size Angularity Shape

Trace Coarse Angular Flat
Gravel

100% Total by Weight of soils portion

% Few Fine Subangular Elongated

Little Subrounded Flat and Elongated
Some Rounded
Mostly
Percent (est.)

(or) Proportion Size Angularity

Trace Coarse (for coarse only)
Sand

% Few Medium Angular

Little Fine Subangular
Some Subrounded
Mostly Rounded
(or) Proportion Plasticity Dry Strength Dilatency Toughness
Trace Nonplastic None None Low
Fines

% Few Low Low Slow Medium

Little Medium Medium Rapid High
Some High High
Mostly Very High

Soil and Rock Logging, Classification, Description, and Presentation Manual, Appendix 79
 Rock Sample Field Description & Identification
Instructions:
• Field Description and Identification based upon Soil and Rock Logging, Classification, and Presentation Manual, dated July 1, 2007.
• Shaded fields are required, non-shaded fields are optional.
• Intensely weathered or decomposed rock that is friable and that can be reduced to gravel size or smaller by normal hand pressure shall be identified and described as rock followed by the soil
identification or classification, and description in parenthesis.

Project Logged by Date Hole ID

District County Route Postmile EA Sample Depth Sample ID

Drilling or Coring Method Sampler Type and Size

Length of Core Run Length of the recovered core pieces Length of intact core pieces > 4 inches

Recovery (REC) Rock Quality Designation (RQD)

Rock Identification Family Name Bedding Spacing Texture

Sedimentary Massive Pitted
Color Odor Igneous Very thickly bedded Vuggy
Metamorphic Thickly bedded Cavity
Moderately bedded Honeycombed
Additional Description Thinly bedded Vesicular
Very thinly bedded
Laminated

Rock Grain-Size Weathering Rock Hardness

(Crystalline Igneous and Metamorphic Rock) (Sedimentary Rock) (Pyroclastic Igneous Rock) Fresh Extremely Hard
Very coarse grained or pegmatitic Boulder, Boulder Conglomerate Block (Angular), Volcanic Breccia Slightly Weathered to Fresh Very Hard
Coarse-grained Cobble, Cobble Conglomerate Bomb (Rounded), Agglomerate Slightly Weathered Hard
Medium-grained Pebble, Pebble Conglomerate Lapilli, Lapilli Tuff Moderately to Slightly Weathered Moderately Hard
Fine-grained Granule, Granule Conglomerate Coarse Ash, Coarse Tuff Moderately Weathered Moderately Soft
Aphanitic Very Coarse Sand Fine Ash, Fine Tuff Intensely to Moderately Weathered Soft
Coarse Sand Very Soft
Medium Sand (Requires completion of Soil Sample
Fine Sand Field Description and Identification
Very Fine Sand form)
Silt, Siltstone, Shale Intensely Weathered
Clay, Claystone, Shale Very Intensely Weathered
Decomposed

Fracture Density Discontinuity Type Discontinuity Dip Magnitude Jar Slake Index, Ij
Unfractured Joint (JT) 1
Very slightly fractured Foliation Joint (FJ) or Bedding Joint (BJ) 2
Slightly to very slightly fractured Bedding Plane Separation 3
Slightly fractured Incipient Joint (IJ) or Incipient Fracture (IF) 4
Moderately to slightly fractured Random Fracture (RF) 5
Moderately fractured Mechanical Break (MB) 6
Intensely to moderately fractured Fracture Zone (FZ)
Intensely fractured
Very intensely to intensely fractured
Very intensely fractured
Discontinuity Weathering Discontinuity Healing Discontinuity Infilling
Fresh Totally Healed Rock: Soils:
Slightly Weathered to Fresh Moderately Healed Extremely Hard Very Soft
Slightly Weathered Partially Healed Very Hard Soft
Moderately to Slightly Weathered Not Healed Hard Medium Stiff
Moderately Weathered Moderately Hard Stiff
Intensely to Moderately Weathered Healing Material: Moderately Soft Very Stiff
Intensely Weathered Soft Hard
Very Intensely Weathered Very Soft
Decomposed

Soil and Rock Logging, Classification, Description, and Presentation Manual, Appendix 80
Appendix C:
Procedural Documents

Soil and Rock Logging, Classification, Description, and Presentation Manual, Appendix 81
Soil and Rock Logging, Classification, Description, and Presentation Manual, Appendix 82
Soil and Rock Logging, Classification, Description, and Presentation Manual, Appendix 83
Soil and Rock Logging, Classification, Description, and Presentation Manual, Appendix 84
Soil and Rock Logging, Classification, Description, and Presentation Manual, Appendix 85
 ________________________Appendix B – Contract Administration
November 2008

APPENDIX

B Contract Administration

Table of Contents

Clarifications to Differing Site Condition Specifications (CPD 00–05) B-2

Review of Differing Site Condition Disputes by a Management
Review Committee (CPD 01-12) B-4
Application of Tunnel Safety Orders B-6
California Mining and Tunneling Districts B-9

Caltrans ● Foundation Manual B-1

 ________________________Appendix B – Contract Administration
November 2008

Caltrans ● Foundation Manual B-2

 ________________________Appendix B – Contract Administration
November 2008

Caltrans ● Foundation Manual B-3

 ________________________Appendix B – Contract Administration
November 2008

Caltrans ● Foundation Manual B-4

 ________________________Appendix B – Contract Administration
November 2008

Caltrans ● Foundation Manual B-5

 ________________________Appendix B – Contract Administration
November 2008

Caltrans ● Foundation Manual B-6

 ________________________Appendix B – Contract Administration
November 2008

Caltrans ● Foundation Manual B-7

 ________________________Appendix B – Contract Administration
November 2008

Caltrans ● Foundation Manual B-8

 ________________________Appendix B – Contract Administration
November 2008

Caltrans ● Foundation Manual B-9

 _______________________Appendix C – Footing Foundations
November 2008

APPENDIX

C Footing Foundations

Table of Contents

Tables Relating Standard Penetration “N” Value to Various Soil Parameters C-2
Sample Spread Footing Letter to Contractor C-4
Method for Installation and Use of Embankment Settlement Devices C-5
Footing Retrofit Strategies C-6

Caltrans ● Foundation Manual C-1

 _______________________Appendix C – Footing Foundations
November 2008

Please note that these conversion tables are approximate. They can be used by
characterizing the soil as being either predominately granular or cohsesive. If possible,
the conversion of the Penetration Index (N value) should be checked by using is-situ or
laboratory tests.

Caltrans ● Foundation Manual C-2

 _______________________Appendix C – Footing Foundations
November 2008

Caltrans ● Foundation Manual C-3

 _______________________Appendix C – Footing Foundations
November 2008

Caltrans ● Foundation Manual C-4

 _______________________Appendix C – Footing Foundations
November 2008

This 19-page document is available on the DES-

Materials Engineering and Services website:
http://www.dot.ca.gov/hq/esc/ctms/pdf/CT_112.pdf

Caltrans ● Foundation Manual C-5

California Test 112
March 1998

pipe riser settlement device should be used 4. After embankment has been placed 1.0 to
only on those projects where the fluid level 1.5 m above the desired elevation for the
type of settlement device would be standpipe unit, prepare a pit and trench
impractical. in the embankment for the standpipe unit
and tubing. See Figure 4. The bottom of
PART 1. FLUID LEVEL SETTLEMENT the pit should normally be about 0.3 m
DEVICES above original ground. The trench should
be cut to the same depth at the pit and
SECTION 1 - VENTED STANDPIPE UNIT should have a slight downward slope to
the indicator unit location. Make sure
A. APPARATUS that the trench is clear of any future
construction, such as pile driving, ripping,
1. Vented standpipe unit (Figure 1) ditching, etc.

2. Indicator unit (Figure 2) 5. Upon completion of the excavation,

remove all rocks and large clods from the
3. Polyethylene tubing, 10-mm inside trench. Prepare a smooth, level area in
diameter the pit using fine embankment material.

4. Hand tools - shovel, bar, posthold auger, 6. Assemble the standpipe unit as shown in
hammer, adjustable wrenches, etc. Figure 1. Do not attach the pipe cap.
Firmly seat the standpipe unit on a
5. Water container (approximately 4-L prepared level area.
capacity)
7. Install the indicator unit post at the
B. INSTALLATION previously selected point for the
indicator unit. This post can be either a
1. Select a location for the standpipe unit on metal sign post or 4-by-4.
the ground after approximately 0.3 m of
fill has been placed above original 8. Using a hand level, attach the indicator
ground and generally within the area unit to the post so that the 0.7-m
where the maximum height of graduation on the indicator unit scale is
embankment will be placed. See Figure 4. approximately level with the top of the
spill tube on the standpipe unit.
2. Select a point outside of the toe of the
proposed embankment for the indicator 9. Push the 10-mm water line through the
unit. See Figure 4. Select this location so metal tube conduit in the center of the
that sufficient vertical distance will be vented standpipe unit until the end is
available for lowering the indicator unit approximately 5 mm above the top. Push
as the standpipe unit settles. A hand the 10-mm air vent line through the
level may be used to estimate the desired other conduit until approximately 20 mm
elevations for the indicator unit. extends out the top. See Figure 1.

3. Because of terrain, excessive anticipated 10. Unroll the water and air vent lines
settlement, or other causes, it may be loosely in the trench from the standpipe
necessary to place the standpipe unit in to the indicator unit. It might be
the embankment at varying elevations desirable to encase both lines in 19-mm
above the original ground. In these cases, flexible metal conduit for additional
record the vertical distance between the protection under rocky material.
base of the standpipe unit and original
ground to allow proper consideration for 11. Cut and attach the water and air lines to
embankment compression in the the indicator unit as shown in Figures 2
settlement analysis. and 3. Then fill the system by pouring

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 California Test 112
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water in the sight tube of the indicator the end of a 0.3-m length of 6-mm plastic
unit (Figure 2) until water comes out of tubing in the end of the air line and loop
the top of the spill tube of the standpipe the smaller tubing inside the indicator
unit with no air bubbles showing in the unit.
line. Generally, 4 L of water is more than
adequate for 100 m of tubing. When 13. Carefully backfill the trench and pit
filling, attempt to keep the water level with material that is free from large
in the sight tube near the 0.7-m rocks or sharp objects and compact by
graduation. Do not allow the water level hand for a depth of at least 0.3 m.
to drop below the bottom of the sight tube Special care must be taken around the
since this would allow air to enter the base of the standpipe unit to prevent
system. separating the base plate from the
plywood platform and to prevent
NOTE: It is helpful if someone can watch breaking or distorting the plastic tubing.
the overflow at the standpipe unit while
the system is being filled to look for 14. After hand backfilling and compacting
evidence of entrapped air and to signal for a depth of 0.3 m has been completed,
when the system is full. mechanical methods may be used to
finish the backfilling operation until the
If there is evidence of air bubbles trench is level with the existing fill
entrapped in the water line, continue height. In those cases when the
charging the system with water until the standpipe unit extends above the existing
air is purged through the standpipe unit. fill height, attach a marker post to the
After charging the system with water unit and mound fill material around it
and purging the water line of all air, until it is completely covered. In no case
attach the indicator unit on the post to should compaction equipment be allowed
provide an initial reading of directly over an installation until a
approximately 0.7 m. minimum of 0.3 m of compacted material
has been placed over the standpipe unit.
Adjacent to the bottom of the indicator
unit, place a reference nail in the post at SECTION 2 - SEALED STANDPIPE UNIT
the elevation of the 0.0-m graduation.
This provides a reference point for A. APPARATUS
surveys and relocation of the indicator
unit. Complete the assembly of the 1. Sealed standpipe unit (Figure 5)
standpipe unit by attaching the pipe cap
as shown in Figure 1. 2. Plastic drain tubing, 13-mm inside
diameter
12. Cut the air line at approximately the
0.7-m graduation of the indicator unit. 3. Vented standpipe unit (as described in
Then loop the air line inside of the Part 1, Section 1-A)
indicator unit over the lock hasp. See
Figure 2. The end of the air line should B. INSTALLATION
be pointing downward to prevent the
entrance of water or debris. This air line Installation is similar to that for the vented
must be free of water at all times since it standpipe unit with the following exceptions:
serves to equalize atmospheric pressure
at the standpipe unit and the indicator 1. Install the device as shown in Figure 6.
unit.
2. Follow the procedure in Part 1, Sections
During cold weather when the air line is B-1 through B-5.
too stiff to be looped, cut the air line at
the 0.3-m graduation mark. Then insert

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California Test 112
March 1998

3. Assemble the standpipe unit as shown in b. Pour sufficient water in the sight tube
Figure 5. Do not attach the outer to raise the water level
galvanized pipe. Firmly seat the approximately 50 mm.
standpipe unit on the prepared area in
the pit. c. Take a reading at 1 h. The water
level after adding the water should
4. Follow the procedure in Part 1, Sections drop to the first reading or slightly
B-7 and B-8. above it.

5. Attach the 10-mm water tube to the d. If little or no change is observed in

baseplate as shown in Figure 5. the water level, or if the water level
is below the 0.01-m graduation, refer
6. Unroll the water, air vent, and drain to Part 2, Section 3.
tubes loosely in the trench from the
standpipe to the indicator unit. 3. Record the data as indicated in Figure 7.
The form is normally used to record
7. Follow the procedure in Part 1, Sections chronological data from a single
B-10 and B-11. settlement unit installed to monitor
settlement. Instructions in filling out the
8. Complete the assembly of the sealed form follow:
standpipe unit by attaching the outer
galvanized pipe, other fittings, air vent, a. Settlement Data Report (Figure 7)
and drain tubes.
Column 1 - Enter the date of the
NOTE: It may be desirable in some cases reading.
to fill around the sealed units with sand
so that the tubes will be supported at Column 2 - Record the water level
their attachment points. reading from the graduated scale on
the indicator unit (after adding
9. Cut the drain tube near the base of the water, as indicated above).
indicator unit post. Position the drain
tube so that water flows out freely and Column 3 - Record the latest
intrusion of soil or debris is prevented. elevation of either the 0.0-m
graduation on the indicator unit, or
10. Follow the procedure in Part 1, Sections the nail reference as determined by
B-13 and B-14. the survey.

SECTION 3 - POST-INSTALLATION Columns 4 and 5 - These columns are

PROCEDURES not used.

A. COLLECTION OF DATA Column 6 - Enter the changes in

water level elevation and reference
1. As soon as possible after the settlement elevation since the last reading. This
device has been installed, determine the is the sum of the differences between
elevation of the reference to ±2 mm by the current and immediately previous
survey. This elevation should be checked entries in Columns 2 and 3.
periodically to correct settlement
readings for settlement of indicator unit. Column 7 - Enter the total settlement
as minus the elevation change since
2. Settlement Readings installation. This is obtained by
changing the sign of the current data
a. Note the height of water in the sight in Column 6 and adding this value to
tube. the previous entry in Column 7.

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 California Test 112
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Column 8 - Enter the height of the sight tube, then recharge the system
fill at the surface as determined by with clean water as necessary.
survey (optional).
b. If the device is still not operating
Column 9 - Enter the height of fill satisfactorily and the sealed
above original ground to the nearest standpipe unit is being used, plug the
0.1 m. top of the sight tube and attempt to
force compressed air through the air
Column 10 - Enter the number of line and out the drain line. Do not use
calendar days elapsed since the greater air pressure than necessary to
settlement device was installed. obtain a small flow through the
lines. Do not allow the water in the
Column 11 - Enter any information sight tube to overflow. Keep the top
that would be helpful in the analysis of the sight tube sealed during this
of data as shown. If it is necessary to operation.
lower the indicator unit on the post,
enter the date and the vertical c. If all other attempts to correct the
distance lowered; be sure to include malfunction fail, disconnect and drain
the corrected values in Columns 2, 3, the water line. Then apply
and 6. compressed air at low pressure to the
air line in an attempt to remove
B. MAINTENANCE debris from the water line. If the
sealed standpipe unit is used, plug
1. Most important to the continued the drain line during this operation.
functioning of fluid level settlement Occasionally, force air through the
devices is the use of as little water as water line to clear the lines if no
necessary when recharging the system return is observed when pressurizing
before reading. For this reason, use only the air line. If successful in clearing
enough water to raise the level in the obstructions from the water line in
sight tube approximately 50 mm. this manner, considerable care is
Continuous additions of greater quantities required while recharging the system
of water will probably cause flooding of with water to not use too much water
the standpipe unit. and to not introduce large voids in the
system. For this reason, recharging
2. If the water level in the sight tube does the unit should be performed only by
not drop after adding water, check the personnel experienced in this type of
unit over a period of several days. Do activity.
not, however, add an excessive amount of
water; just observe the system to see if the 3. If the water level in the sight tube is
unit is slow to respond. below the 0.01-m graduation or if there is
no water in the sight tube, look for leaks
a. If the unit is not operating properly, around the connection between the sight
remove the indicator box from the tube and the water line. If no leak is seen,
post and raise it up about 0.3 m. measure the vertical difference between
Disconnect the water line from the the 0.0-mm graduation on the indicator
sight tube and attach the line unit and the reference point. Remove the
upright on the post. Inspect the unit from the post and lower it
bottom of the sight tube and connector approximately 0.5 m or until water is
for debris. Remove any obstructions observed in the sight tube. If possible,
and reassemble the unit without and without adding water, adjust the
losing water from the water line. height of the indicator unit on the post so
After assembly, lower the indicator that the water level in the sight tube is
unit until water is observed in the approximately at the 0.7-m graduation.

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California Test 112
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Add a small quantity of water and check device. Prepare a firm, level area free of
the water level before attaching the large rocks or clods for the settlement
indicator unit to the post. After adjusting device at the bottom of the pit.
the height of the indicator unit, again
measure the vertical distance between 3. Assemble the settlement device as shown
the 0.0-m graduation on the indicator unit in Figure 8. Attach a 19-mm pipe floor
and the reference point, and record the flange to the center of the wood platform
correction on the settlement data form with bolts or lag screws. Then screw a
(Figure 7, Column 3). 1.8 m length of 19-mm pipe into the floor
flange. Place a pipe coupling on the top
4. Be sure to replace the cover on the of the 19-mm pipe and tighten all joints
indicator unit after each reading to in the assembly using a pipe wrench.
prevent excessive loss by evaporation and
contamination by debris. 4. Measure and record the distance from the
top of the pipe coupling to the top of the
5. Occasionally, it may be necessary to wood platform. Then slip the 38 mm by
protect the air and water lines from 1.5-m protective sleeve, which may be
rodents or pests. If such a problem exists, either rigid polyvinyl chloride (PVC) or
protect these lines in flexible conduit iron pipe, over the control pipe until it is
extending from the bottom of the about 0.5 m above the floor flange. Place
indicator unit to below the ground surface. a duct seal or other seal to hold the
Although this should be done during protective sleeve in place. See Figure 8.
installation, the conduit can be added Do not attach the protective sleeve to the
later if extreme care is taken not to lose wood platform or the control pipe. This
water continuity as described above. protective sleeve is used to absorb the
friction between the fill material and the
PART 2. PIPE RISER SETTLEMENT settlement unit and, therefore, must be
DEVICE free to move independently from the
wood platform and control pipe.
A. APPARATUS
5. Firmly seat the settlement device on the
1. Pipe riser settlement device (Figure 8) prepared area in the bottom of the pit.
Then fill and compact by hand using fine
2. Hand tools - shovel, bar, hammer, pipe embankment material free of large rocks
wrenches, etc. and clods around the settlement device to
a depth of 0.3 m.
B. INSTALLATION
6. Using a spirit level, check to make sure
1. It will usually be necessary to determine the control pipe is reasonably plumb,
the location for installing the settlement then carefully fill the pit with
device by survey. If settlement readings embankment material and compact in
are to be continued after completion of the place.
fill and removal of surcharge, it is
imperative that the unit be located 7. Attach a post to the top of the protective
directly beneath the median of divided sleeve to alert construction equipment
travel lanes or the shoulder of other operators of the obstruction.
roadways.
NOTE: It has been found that a 1.8-m
2. After approximately 1 m of embankment long 2-by-4 painted with alternate 0.3 m
material has been placed, excavate a pit wide stripes of red and white is
to a depth of approximately 0.5 m above satisfactory for this use. It is
original ground at the previously recommended that flagging be attached
determined location for the settlement to the top of this post. The post should be

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 California Test 112
March 1998

attached so that it can be easily removed d. Measure the added length of control
and reattached as additional pipe is pipe, including the coupling. If
added during embankment construction. possible, check this distance by
determining the elevation of the
C. COLLECTION OF DATA control pipe.

1. As soon as possible after the settlement e. Record the length of additional

device has been installed, determine the control pipe added under Column 5 on
elevation of the top of the 19-mm pipe the form shown in Figure 9. Be sure to
coupling attached to the control pipe. add this length to the previous value
Normally, the elevations required will shown in Column 4.
be obtained by a survey party.
f. Add and secure a 1.5-m length of
2. During embankment construction, the protective sleeve to the existing
elevation of the top of the control pipe sleeve and secure to the top of the
should be determined by survey post.
approximately twice weekly. After
embankment construction is completed, 4. Enter all data on the form shown in
the elevation should be determined Figure 9 as follows:
frequently enough to indicate significant
changes in the rate of settlement. Column 1 - Record the reading date.
Normally, the time between surveys will
be weekly immediately subsequent to Column 2 - This column is not used.
completion of the embankment, and the
interval between surveys will increase Column 3 - This column is not used.
with time.
Column 4 - Record the elevation to top of
3. During fill placement, it will be control pipe as determined by survey.
necessary to extend the lengths of the
control pipe and protective sleeve. When Column 5 - Record the length of the
extending the control pipe, use the control pipe.
following procedure:
Column 6 - Record the height of the riser
a. Determine the elevation to the top of above the original ground (Column 4
the existing control pipe coupling. minus Column 5).

b. Remove the protective post, attach a Column 7 - Record the total settlement to
coupling to the length of control pipe the nearest 0.002 m. This figure is
to be added, and tighten the joint obtained by subtracting the figure in
with pipe wrenches. Column 6 for the day being read from the
figure at the top of Column 6 (elevation
c. Insert the added length in the at the time of installation).
coupling on top of the existing control
pipe and tighten the joint by using one Column 8 - Record the elevation of the
pipe wrench on the existing coupling surface of the fill as determined by
and one pipe wrench on the added survey (that is optional).
length of control pipe. While
tightening the joint, do not allow the Column 9 - Record the height of the fill
coupling between the control pipe and above original ground to the nearest
the added length to turn. Turn only 0.1 m.
the added length of control pipe.

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California Test 112
March 1998

Column 10 - Record the number of measures must be taken to reduce the

calendar days elapsed since the rate of settlement.
settlement device was installed.
NOTE: This may include removing a
Column 11 - Record any information that portion of the embankment or
would be helpful in the analysis of data. constructing berms or struts. Such
Be sure to indicate in this column the date measures usually require a
and length added to the control pipe. comprehensive analysis and, for that
reason, the problem must be brought
PART 3. SETTLEMENT DATA ANALYSIS to the attention of the Project
SCOPE Engineer without delay.

The procedure for plotting and analyzing 3. After embankment construction has been
settlement data obtained from all types of completed, the rate of settlement will
settlement devices is described in this decrease with time, especially for soft
method. Comprehensive settlement analyses foundation soils. However, a marked
are complex and require extensive knowledge decrease in the rate of settlement may be
of soil mechanics and soil structure of the noticed until an appreciable amount of
area under study. Considerable information, time has elapsed since completion of the
however, can be obtained by the simplified embankment.
method described in this part.
a. Any significant increase in the rate of
1. Plot the data on a semi-logarithmic settlement after completion of the
chart as shown in Figure 10. Note that embankment is sufficient cause for
the scale for days is on the logarithmic immediate corrective action as
abscissa of the chart and both settlement described above.
and fill height are scaled arithmetically
on the ordinate. b. When the plotted data indicate that
the slope of the rate of settlement
2. Note that during construction, the rate of curve is essentially horizontal, the
settlement increases in approximate embankment surcharge may be
proportion to the fill load applied. This removed and/or permanent structure
is generally true in all cases where the construction may be started. For
rate of loading embankment is nearly example, from data shown in
constant. If embankment construction is Figure 10, a practical minimal rate of
suspended for an appreciable length of settlement was obtained at about
time, the negative slope indicating rate 360 days; at this time the
of settlement should become more embankment surcharge was removed
positive or flatter until embankment as shown.
construction resumes. In no case, however,
should the rate of settlement curve 4. Data should be collected throughout the
assume a positive slope. life of the contract. Longer data-
collection periods are necessary if
a. A sudden increase in the rate of significant rates of settlement are
settlement during construction is an measured.
indication of impending failure and
would dictate that fill loading be a. The time interval between readings
stopped immediately. may be increased as the indicated
rate of movement decreases.
b. If the rate of settlement remains
excessive after suspending fill b. Collection of data may be required for
operations, additional corrective several years on selected projects.
Long-term settlement data are

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 California Test 112
March 1998

frequently useful in the design of A, Section 5.0, Part B, Sections 5.0, 6.0 and 10.0
embankments where similar and Part C, Section 1.0 of Caltrans Laboratory
conditions are encountered. Safety Manual. Users of this method do so at
their own risk.
PART 4. SAFETY AND HEALTH
REFERENCES:
Prior to handling, testing or disposing of any None
waste materials, testers are required to read: Part
End of Text (California Test 112 contains 19 pages)

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California Test 112
March 1998

FIGURE 1 - VENTED STANDPIPE UNIT

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 California Test 112
March 1998

FIGURE 2 - INDICATOR UNIT

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California Test 112
March 1998

FIGURE 3 - DETAIL OF INDICATOR UNIT

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 California Test 112
March 1998

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California Test 112
March 1998

FIGURE 5 - SEALED STANDPIPE

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 California Test 112
March 1998

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California Test 112
March 1998

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 California Test 112
March 1998

FIGURE 8 - PIPE RISER SETTLEMENT DEVICE

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California Test 112
March 1998

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 California Test 112
March 1998

12
Fill Height (m)

8 AA A A A A A A AAAAA
A
A A A
A
A
4 A

Surcharge Complete

Surcharge Removed
A
A
A
0A A A
A
Settlement (m)

A
0.2 A
A
A
A
A
A A A
A A A A
0.4 AA A A

4/22/94

10/6/94
12/1/94

9/28/95
8/1/94

2/1/95
0.6
1 10 100 1000
Time (days)

Settlement Data
San Ramon Road OC Abutment 1 Bridge No. 49-193
05-039733 05-SLO-101-47.2/52.5
Station: 2.3 m Rt. 8+50 F-30 Line Installed: 3/3/94
1 m Vertical Loading per Week Waiting Period Not to Exceed 270 days

FIGURE 10 - SETTLEMENT DATA ANALYSIS

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 _______________________Appendix C – Footing Foundations
November 2008

Throughout the 1990’s the Department underwent a massive seismic retrofit program.
Retrofits of footings designed and built prior to 1973 were required to address
deficiencies. These retrofits required the installation of a top mat of reinforcing steel to
address tensile loads at the top of the footing due to seismic forces. In some cases footing
dimensions were increased and/or perimeter piles added. These additional piles provide
additional resistance to bending moment in the structure and provide additional restraint
against rotation. Typical spread footings seismic retrofits are shown in the Figures below.

Caltrans ● Foundation Manual C-6

 _________________________________Appendix D – Pier Columns
November 2008

APPENDIX

D Pier Column & Pile Shaft

Table of Contents

Pier Column D-2

Blasting Example & Sample Special Provisions D-3
Blasting Photos D-11
Pier Shaft (Type II) – Case Study D-12

Caltrans ● Foundation Manual D-1

 _________________________________Appendix D – Pier Columns
November 2008

Pier Column - Caltrans Bridge Design Details, page 7-20

Caltrans ● Foundation Manual D-2

 _________________________________Appendix D – Pier Columns
November 2008

Blasting – Example
What follows is an example of how the Department uses blasting in the construction of
bridge foundations. In the past, blasting has been performed to facilitate the construction
of spread footings and pier columns. The photograph below is an example of what can be
considered a hybrid of the two. Pier W2 of the San Francisco-Oakland Bay Bridge East
Span Construction project uses blasting to construct a foundation in rock. The foundation
is in excess of 60’ deep and 80’ square.

Pier W2, part of the E2-T1 project (EA 04-0120L4) is part of the new San Francisco
Oakland Bay Bridge. Blasting was used for structure excavation of these piers.
Construction of W2 structures was complete in Sept 2004 at a cost of $24.1 million.

Caltrans ● Foundation Manual D-3

 _________________________________Appendix D – Pier Columns
November 2008

Special Provisions – EA 04-0120C4

The following specification was taken from the Special Provisions of the above referenced
Contract. It is understood that projects of this type are unique and extreme in their
application of engineering principals but still utilize construction operations utilized on
projects throughout the State. Note that special provisions are unique to each contract; and
as such may vary from what is presented below. In some geologic regions blasting may be
the only option however Industry continues to implement new technologies. In some cases,
new tools such as the rotator and/or oscillator (refer to Chapter 6) may be more appropriate
and more environmentally considerate.

Special Provisions – EA 04-0120C4

BLASTING

Attention is directed to, "Project Information," and "Photo Survey of

Existing Facilities," of these special provisions, regarding the Blasting
Demonstration Report, and photo survey of the existing facilities.
Attention is directed to "Order of Work," of these special provisions
regarding transportation and use of explosives.
If the Contractor elects to use blasting for structure excavation (bridge) at
Piers W2 , project blasting shall conform to Sections 7-1.10, "Use of Explosives,"
and 19-2.03, "Blasting," of the Standard Specifications and these special
provisions.
The Contractor shall control project blasting effects (fly rock, ground
motion, and air noise levels) within the safe limits so as not to cause damage to
neighboring improvements.

Blasting Plan Submittal

The Contractor shall submit a blasting plan to the Engineer detailing how
he proposes to control fly rock, air noise level, and ground motion peak particle
velocity. No blasting operations, including drilling, shall start until the Engineer
has reviewed and approved the blasting plan.
The Contractor shall submit the blasting plan in accordance with the
provisions in "Working Drawings," of the special provisions not less than 30
working days before commencing blasting activity or at any time the Contractor
proposes to change the drilling and blasting methods. The Contractor shall
provide 10 working days for the Engineer to complete the review of the blasting
plan. In the event that additional blasting plans are required, the Contractor
shall provide 5 working days for the review of each additional plan.
The blasting plan shall provide for limiting ground motion to a maximum
peak particle of 100 mm/sec at the existing E1 Pier of the San Francisco Oakland
Bay Bridge (Bridge No. 33-0025), and 50 mm/sec at the Torpedo Building

Caltrans ● Foundation Manual D-4

 _________________________________Appendix D – Pier Columns
November 2008

(Building 262). Controlling fly rock, air noise levels, and ground motor peak
particle velocities as specified herein shall not relieve the Contractor of his
responsibility for assuring the complete safety of his operation.
The blasting plan shall indicate the type and method of instrumentation
proposed by the Contractor to determine air noise levels, and ground motion peak
particle velocity at the nearest improvements. The blasting plan shall also
provide for a pre-blast reconnaissance survey of all adjacent improvements.
Approval of the Contractor's blasting plan or blasting procedures shall
not relieve the Contractor of any of his responsibility under the contract for
assuring the complete safety of his operations with respect to neighboring
improvements, or for the successful completion of the work in conformance with
the requirements of the plans and specifications.
If the Engineer fails to complete the review within the time allowed, and if,
in the opinion of the Engineer, the Contractor's controlling operations are
delayed or interfered with by reason of the delay, an extension of time
commensurate with the delay will be granted as provided in Section 8-1.07,
"Liquidated Damages," of the Standard Specifications.

Qualifications
The blasting supervisors (blaster in charge) shall have a minimum of 10
years experience, directly related to the specific types of blasting they are
supervising.
All blasters and supervisors shall be properly qualified and licensed in
accordance with applicable federal, State, and local government regulations.
The Contractor shall retain the services of an experienced seismologist or
engineering consultant with at least 10 years experience in monitoring blasting
operations and interpreting ground vibration, air overpressure, and water
pressure amplitudes for similar construction projects.
The Contractor shall retain the services of an experienced specialist who
will conduct the pre-blast inspections of private properties as specified herein.
The specialist shall have performed similar pre-construction survey services on at
least three projects of similar scope and complexity.

Pre-Blast Condition Survey

The Contractor shall perform a pre-blast survey of specified buildings and
structures, and utilities within 100 meters or which may potentially be at risk from
blasting damage. The survey method used shall be acceptable to the Contractor's
insurance company. The Contractor shall perform the pre-blast survey within 30
working days in advance of the planned commencement or resumption of blasting
operations and pre-blast records shall be made available to the Engineer for
review. The Contractor prior to the beginning of the blast shall notify occupants
of the local buildings. The pre-blast survey shall, as a minimum, contain the
following:

A. The name of the person making the inspection.

Caltrans ● Foundation Manual D-5

 _________________________________Appendix D – Pier Columns
November 2008

B. The names of the property owner and occupants, the addresses of the property,
the date and time of the inspection.
C. A complete description of the structure(s) or other improvement(s) including
culverts and bridges.
D. A detailed interior inspection with each interior room (including attic and
basement spaces) designated and described. All existing conditions of the walls,
ceiling and floor such as cracks, holes and separations shall be noted.
E. A detailed exterior inspection fully describing the existing conditions of all
foundations, walls, roofs, doors, windows, and porches.
F. A detailed listing, inspection and documentation of existing conditions of garages,
outbuildings, sidewalks and driveways.
G. A detailed listing of highway signposts, light fixtures and overhead power lines.
H. A survey of any wells or other private water supplies including total depth and
existing water surface levels.

The Contractor shall perform a re-survey of all locations whenever

blasting operations are either terminated or suspended for a period in excess of
30 working days. The documentation may consist of either a written report, or
videotape with voice narration. The videotape, if used, must include date and
time displayed on the image. The Contractor shall provide copies of the pre-blast
inspection report or videotape documentation to the Engineer at the time that the
blasting plan is submitted.
The Contractor shall control project blasting so that vibration, flyrock,
ground and vibration motion, and air noise levels do not cause damage to nearby
structures including highway sign posts, light fixtures and parked vehicles, undue
annoyance to nearby residents, or danger to employees on the project. The
Contractor shall use controlled blasting techniques and designs and shall
coordinate the traffic control during blasting operation. The Contractor shall be
responsible for all damage resulting from blasting.

Vibration Control and Monitoring

When blasting within proximity of buildings, structures, or utilities that
may be subject to damage from blast-induced ground vibrations, the Contractor
shall control ground vibrations by the use of properly designed delay sequences
and allowable charge weights per delay. Allowable charge weights per delay
shall be based on vibration levels that will not cause damage. The Contractor
shall perform trial blasts to select allowable charge weights per delay by
measuring vibration levels. The Contractor shall select proper control method to
limit over break. The trial blasts shall be carried out in conformance with the
blasting test section requirements, modified as required to limit ground vibrations
to a level which will not cause damage. The blasting test section requirements
require that two seismographs be used, one placed on the end of the shot and one
placed at 90 degrees behind the shot to establish vibration levels and their
relation to the measurement location. The Contractor shall have full
responsibility to control over break.

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 _________________________________Appendix D – Pier Columns
November 2008

Whenever vibration damage to adjacent structures is possible, the

Contractor shall monitor each blast with an approved seismograph located, as
approved, between the blast area and the structures subject to the blast site. The
seismograph used shall be capable of recording particle velocities for three
mutually perpendicular components of vibration in the range generally found with
controlled blasting.
The Contractor shall employ a qualified vibration specialist to establish
safe vibration limits. The vibration specialist shall also interpret the seismograph
records to ensure that the seismograph data are utilized effectively in the control
of the blasting operations with respect to the existing structures. The vibration
specialist used shall be subject to the Engineer’s approval.
The Contractor shall provide vibration monitoring at the following
locations:

A. Existing E1 pier of San Francisco-Oakland Bay Bridge

B. Torpedo Building (Building 262)
C. Navy Building 1
D. Coast Guard Building 27

The measuring devices should be positioned at the closest face of structure

or body of water to the blast site.
Data recorded for each shot shall be furnished to the Engineer prior to the
next blast and shall include the following information:

A. Identification of instrument used.

B. Name of qualified observer and interpreter.
C. Distance and direction of recording station from blast area.
D. Type of ground at recording station and material on which instrument is sitting.
E. Maximum particle velocity in each component.
F. A dated and signed copy of seismograph readings record.

At the Contractor's option, shot designs may be based upon scaled

distance following the chart below. The scaled distance is the ratio of distance in
feet from the blast site to the site to be protected to the square root of the
maximum explosive weight used for each delay of 9 milliseconds or more.

Blast Design Table

Distance to site to Scaled distance factor
be protected
0 to 91 meters 22.57 m/kg1/2
91 to 1,524 meters 24.94 m/kg1/2
1,524 meters 29.4 m/kg1/2

Caltrans ● Foundation Manual D-7

 _________________________________Appendix D – Pier Columns
November 2008

Environment Protection
Sound Pressure Level (SPL) due to blasting shall not be greater than 180
dB (decibels) in the water at a distance of 10 meters from any point on the
shoreline at Yerba Buena Island. The Contractor shall design blasting plan to
meet SPL performance limitations and shall perform trial blasts to select
allowable charge weights per delay based on measured values of SPL. The
Engineer will conduct acoustical monitoring and marine mammal monitoring
during all blasting activities. The safe distance for marine mammals due to
blasting effects is herein referred to as the Marine Mammal Safety Zone (MMSZ).
The MMSZ will be established at a 50-meter radii from the shoreline adjacent to
the blasting area, and may be increased or decreased in size based on results of
acoustical monitoring. The purpose of the marine mammal monitoring is to
prohibit blasting activity if marine mammals are present within the MMSZ. In
addition, the Engineer will monitor for Pacific herring spawning event within a
200-meter distance from the shoreline adjacent to the blasting area. If spawning
is observed, blasting activity will be prohibited. Work shall not resume until the
Engineer notifies the Contractor, which is expected to be approximately 14
calendar days from the time of spawning.
The Contractor shall provide two working days advance notice to the
Engineer before each day he is planning to blast. The marine mammal
monitoring shall commence at least 15 minutes before blasting begins. The
Engineer will have the sole discretion to direct Contractor with approval to
proceed with blasting operation prior to each and every blast.
The Department will conduct surveys and monitoring of bird activity
before and during blasting activities as part of an agreement with the resource
agencies.

Air Blast and Noise Control

The Contractor shall install an air blast monitoring system between the
main blasting area and the nearest structure subject to blast damage or
annoyance. The equipment used to make the air blast measurements shall be the
type specifically manufactured for that purpose. Noise levels shall be held below
125 dbA at the nearest structure or designated location. The Contractor shall use
appropriate blast hole patterns, detonation systems, and stemming to prevent
venting of blasts and to minimize air blast and noise levels produced by the
blasting operations. The decibel level shall be lowered if it proves to be too high
based on damage or complaints. The Contractor shall furnish a permanent,
signed and dated record of the noise level measurement to the Engineer
immediately after each shot.

Flyrock Control
Before the firing of any blast in areas where flying rock may result in
personnel injury or unacceptable damage to property, parked vehicles or the
work, the Contractor shall cover the rock to be blasted with approved blasting
mats, soil, or other equally serviceable material, to prevent flyrock.

Caltrans ● Foundation Manual D-8

 _________________________________Appendix D – Pier Columns
November 2008

If flyrock leaves the construction site and lands on private property all
blasting operations will cease until a qualified consultant, hired by the
Contractor, reviews the site and determines the cause and solution to the flyrock
problem. Before blasting proceeds, a written report shall be submitted by the
Contractor to the Engineer for approval.

Video Recordings of Blasts

Videotape recordings will be taken of each blast. The tapes or sections of
tapes will be indexed in a manner to properly identify each blast. At the option of
the Engineer, copies of videotapes of blasts will be furnished on a weekly basis.
The Contractor shall keep accurate records of each blast. Blasting
records shall be made available to the Engineer at all times and shall contain the
following data as a minimum:

A. Blast Identification by numerical and chronological sequence.

B. Location (referenced to stationing), date and time of blast.
C. Type of material blasted.
D. Number of holes.
E. Diameter, depth and spacing of holes.
F. Height or length of stemming.
G. Types of explosives used.
H. Type of caps used and delay periods used.
I. Total amount of explosives used.
J. Maximum amount of explosives per delay period of 9 milliseconds or greater.
K. Powder factor (pounds of explosive per cubic yard of material blasted).
L. Method of firing type.
M. Weather conditions (including wind direction).
N. Direction and distance to nearest structure or structures of concern.
O. Type and method of instrumentation.
P. Location and placement of instruments.
Q. Instrumentation records and calculations for determination of ground motion
particle velocity or for charge size based on scaled distance.
R. Measures taken to limit air noise and fly rock.
S. Any unusual circumstances or occurrences during blast.
T. Measures to limit over break
U. Name of contractor.
V. Name and signature of responsible blaster.

Blasting Guards
The Contractor shall provide sufficient blasting guards and station them
around the blasting area during blasting to assure that people and structures are
not endangered. Traffic during blasting shall be controlled by the Contractor.
Blasting operations may be suspended by the Engineer for any of the
following:

Caltrans ● Foundation Manual D-9

 _________________________________Appendix D – Pier Columns
November 2008

A. Safety precautions, monitoring equipment and traffic control measures are

inadequate.
B. Ground motion particle velocity or air noise exceeds the limits specified.
C. Blasting control plan have not been approved.
D. Required records are not being kept.
E. Excessive outbreak as determined by the Engineer

Suspension of blasting operations shall in no way relieve the Contractor

of his responsibilities under the terms of this contract. Blasting operations shall
not resume until modifications have been made to correct the conditions that
resulted in the suspension.
Blasting complaints shall be accurately recorded by the Contractor as to
complainant, address, date, time, nature of the complaint, name of person
receiving the complaint, the complaint investigation conducted, and the
disposition of the complaint. The Contractor shall make the complaint available
to the Engineer as soon as practical, but no later than at the beginning of the
following day’s work shift.

PAYMENT
Full compensation for blasting including all the requirements as specified
herein, shall be considered as included in the contract price paid per cubic meter
for structure excavation (bridge) and no separate payment will be made therefor.

Caltrans ● Foundation Manual D-10

 _________________________________Appendix D – Pier Columns
November 2008

Caltrans ● Foundation Manual D-11

 _________________________________Appendix D – Pier Columns
November 2008

Pile Shaft (Type II) - Case Study

Contract No. 04-470804
04-SJ, Ala-205, 580-10.0/0.4 (near the City of Tracy)
580/205 Separation (Bridge No. 33-0693R)
Construction started in 2006.

Pile Shaft Project: Although this project has large diameter CIDH piles, this project is
not considered a pier column. It does not have contract pay items for structure
excavation (pier column) and structure concrete (pier column). Conventional methods
were used to drill the CIDH pile.

However, the pile shaft design was chosen because limited space constraints next to the
existing freeway and change of elevation differences between Abutment 1 to Abutment 8.
If a pile cap foundation was chosen, then the pile caps would have had to have been
excavated 10 to 20 feet beneath the existing freeway to account for the different column
stiffness. This excavation would have been problematic due to space constraints in the
middle of the existing freeway. Due to the limited space constraints, single column pile
shaft foundations were considered easier to construct than a conventional pile cap with
standard plan piles. Due to the different column lengths, isolation casing were required at
certain locations to account for the different stiffness of short and long columns. Also,
the claystone formation underlying the project site was conducive to drilled shaft
construction since caving issues would be reduced after using temporary casings to
stabilize softer/looser near surface soils (Comments by Tim Alderman, Caltrans
Geologist).

Description of Bridge Work: construct a 7-span cast-in-place prestressed concrete box

girder bridge approximately 373 meters in length and 12.6 meters in width.
Pile shaft diameter: 1980-mm for Bents 2, 3, & 4; 2280-mm for Bents 5, 6, & 7.
Pile shaft length: 26.75 meters (Bent 4) to 39.8 meters (Bent 2)
Column heights: 8.9 meters (Bent 4); 19.2 meters (Bent 7)
Isolation casings: Bents 2, 3 & 4.

Construction Issues:
Groundwater was anticipated and encountered. Two-cranes were needed to lift the pile
shaft column rebar into place. Windy conditions affected crane operations.

(Photos contributed by Gon Choi, Consultant Engineer.)

Caltrans ● Foundation Manual D-12

 _________________________________Appendix D – Pier Columns
November 2008

Bents 2 & 3 Column Details – 580/205 Separation, Contract No. 04-

470804

Caltrans ● Foundation Manual D-13

Appendix D-14
 CMP casing used to prevent cave-in during drilling of Contractor placing SlurryPro CDP with CMP casing
the CIDH concrete piles. used to prevent cave-in @ Bent 5 of the 580/205

Drilling at Bent 3 of the 580/205 Separation Bridge Drilling at Bent 7 with Steel casing to prevent cave-in.
using a 1.98m diameter auger.
PROJ/RTE/PM: 04/10-SJ/ALA-580/205 Date: 2006/2007
PROJECT NO. 04-470804 Photos contributed by Gon Choi, P.E., Consultant Engineer Photo Page D-15
Link Belt LS-518 Crane with Steven M Hain Co 450K, 2.13-m diameter Clean out bucket cleaning out Bent 7 of
Series 1 drill. the 580/205 Separation Bridge.

Cave-in at Bent 3 of the 580/205 Separation Bridge. Drilling at Bent 5.

PROJ/RTE/PM: 04/10-SJ/ALA-580/205 Date: 2006/2007
PROJECT NO. 04-470804 Photo Page D-16
 Iron Workers splicing the #43 rebar with BarGrip Iron Workers making rebar cage for Bent 4R
couplers. CIDH/COLUMN.

Rebar coupler splice equipment in use. Iron Workers making the rebar cage at Bent 5.

PROJ/RTE/PM: 04/10-SJ/ALA-580/205 Date: 2006/2007

PROJECT NO. 04-470804 Photo Page D-17
Critical lift safety meeting held just before the cage lift. Two cranes; Bent 7 – Cage 20 pick.

At the middle of the cage lift. Vertical rebar cage lifted in the air.
PROJ/RTE/PM: 04/10-SJ/ALA-580/205 Date: 2006/2007
PROJECT NO. 04-470804 Photo Page D-18
 Slurry storage and setting tanks. 4-inch tremie tubes.

CIDH pour with tremie tube in the middle of the pile and Column pour
slurry is being pump back to the tank.

PROJ/RTE/PM: 04/10-SJ/ALA-580/205 Date: 2006/2007

PROJECT NO. 04-470804 Photo Page D-19
Guy wire placed near the top & middle of the rebar cage. Guy wire on a short column.

Guy wire placed on the column forms. Guy wire in place during column pour.
PROJ/RTE/PM: 04/10-SJ/ALA-580/205 Date: 2006/2007
PROJECT NO. 04-470804 Photo Page D-20
 Bent 5: 180-ft long rebar cage with 3” gamma gamma Bent 7 cage; Bent 6 drilling.
PVC inspection tubes installed.

Bent 5 Column - After the forms were stripped. Bent 5 - side view of the column.

PROJ/RTE/PM: 04/10-SJ/ALA-580/205 Date: 2006/2007

PROJECT NO. 04-470804 Photo Page D-21
 __________________________________Appendix E – Driven Piles
November 2008

APPENDIX

E Driven Piles

Table of Contents

Gates Formula Commentary E-2

Pile Driving Formulas E-4
Comparison Of Formulas E-7
Example 1: Calculation Of Minimum Hammer Energy E-12
Example 2: Calculations For Establishing A Blow Count Chart E-13
Example 3: Battered Pile Blow Count Chart E-15
Example 4: Calculations For Piles With Downdrag E-17
Example 5: Estimate Hammer Stroke Of A Single Acting Hammer E-20
Example Battered Pile Blow Count Chart E-21
Example Wave Equation Field Acceptance Charts E-22

Caltrans ● Foundation Manual E-1

 __________________________________Appendix E – Driven Piles
November 2008

GATES FORMULA COMMENTARY

Projects with driven pile foundations specify the “Gates Formula” to determine nominal
resistance. No longer will contracts utilize the ENR formula. This change is
incorporated in the “Amendments To July 1999 Standard Specifications” (Section 49-
1.08) found in the front of the Special Provisions. The change is also discussed in Bridge
Construction Memo (BCM) 130-4.0 dated June 14, 2007.

Why change from ENR to Gates Formula?

• Factor of safety from ENR (Engineering News Record) varies from ½ to 20.
With low factor of safety, capacity of the pile is actually driven to be under the
factored design load. Lack of capacity has result in excessive settlement.
Extremely high factor of safety often cause damage to the pile and result in
contractor claims and also is a waste of time and energy.

• California was actually one of the last States using the ENR formula.

• ENR does not properly account for down drag or the overburden effects and
resistance associated with zones that may scour or liquefy.

Advantage of Gate’s Formula

• This formula predicts the static capacity of the pile significantly more accurately
than the ENR Formula because it provides a significantly lower coefficient of
variation.

Additionally, since the formula utilizes ultimate capacity and not an unfactored safe load,
the formula can account for the effects of downdrag, scour, and liquefaction.

The Gates formula (US Customary) is:

Ru = (1.83 ∗ ( Er ) 2 ∗ log10 (0.83 ∗ N )) − 124

1

Ru = Calculated nominal resistance/ultimate compressive capacity in kips

Er = Energy rating of hammer at observed field drop height in foot pounds
N = Number of blows in the last foot (maximum of 100)

Additional Notes:

Caltrans Memo To Designer 3-1 was updated in July 2008. During constructability
reviews, it is very important that the Structure Construction reviewer checks the pile data
table on the plan sheets for notes on downdrag and liquifaction.
Caltrans ● Foundation Manual E-2
 __________________________________Appendix E – Driven Piles
November 2008

A very good reference showing the differences in formulas (Gates, ENR, Haley, Janbu,
etc) is the “Comparison of Methods for Estimating Pile Capacity, Report No. WA-RD
163.1”, Final Report dated August 1988, by the Washington State Department of
Transportation. In lieu of that, examples of comparisons are shown below.

Caltrans ● Foundation Manual E-3

 __________________________________Appendix E – Driven Piles
November 2008

PILE DRIVING FORMULAS

GATES FORMULA

( )
P = (1.83 ∗ ( Er ) 2 ∗ log10 (0.83 ∗ N )) − 124 z
1

Where, P = safe load in kips

Er = energy of driving in foot pounds
N = number of hammer blows in the last foot
z = conversion factor for units and safety with this formula

ENGINEERING NEWS (ENR)

2E
P=
( s + 0.1)
Where, P = safe load in pounds
E = rated energy in foot-pounds
s = penetration per blow in inches
This formula was derived from the original Engineering News formula for drop hammers
on timber piles, which was:
WH
P=
( s + c)
Where, W = weight of ram in pounds
H = length of stroke in inches
c = elastic losses in the cap, pile, and soil in inches
It was modified to correct units and apply other factors to compensate for modern
equipment.

Caltrans ● Foundation Manual E-4

 __________________________________Appendix E – Driven Piles
November 2008

JANBU FORMULA

⎛ WH ⎞
P = ⎜⎜ ⎟⎟ z
⎝ ku s ⎠
Where, P = safe load in pounds
W = weight of ram in pounds
H = length of stroke in inches
s = penetration per blow in inches
ku = factor derived from the following,
[
ku = Cd 1 + 1 + (λ Cd )]
Cd = 0.75 + 0.15(W p W )
WHL
λ=
AEs 2
when, Wp = weight of pile in pounds
L = length of pile in inches
A = area of pile in square inches
E = modulus of elasticity of pile in pounds per square inch
z = conversion factor for units and safety with this formula

HILEY FORMULA

⎞⎛ W + n W p ⎞
2
⎛ e f WH
P = ⎜⎜ ⎟⎟⎜ ⎟z
⎜ ⎟
⎝ s + 2 (c1 + c2 + c3 ) ⎠⎝ W + W p
1
⎠

Where, P = safe load in pounds

ef = efficiency of hammer (%)
W = weight of ram in pounds
H = length of stroke in inches
s = penetration per blow in inches
c1 , c2 , c3 = temporary compression of pile cap and head, pile, and soil,
respectively in inches
n = coefficient of restitution
Wp = weight of pile in pounds
z = conversion factor for units and safety with this formula

Caltrans ● Foundation Manual E-5

 __________________________________Appendix E – Driven Piles
November 2008

PACIFIC COAST FORMULA

⎛ W + kW p ⎞
En ⎜ ⎟z
⎜ W +W ⎟
P= ⎝ ⎠
p

PL
s+
AE

Where, P = safe load in pounds

En = energy of driving in inch pounds
W = weight of ram in pounds
Wp = weight of pile in pounds
s = penetration per blow in inches
L = length of pile in inches
A = area of pile in square inches
E = modulus of elasticity of pile in pounds per square inch
k = 0.25 for steel piles
0.10 for other piles
z = conversion factor for units and safety with this formula

Caltrans ● Foundation Manual E-6

 __________________________________Appendix E – Driven Piles
November 2008

COMPARISON OF FORMULAS

Given Problem Conditions

Hammer Data: Delmag D36-32

Maximum Energy = 83,880 ft·lbs
Hammer/Ram Weight = 7,938 lbs
Maximum Stroke = 10.42 ft
Penetration or Set = 0.844 inches
Length of Pile = 80 feet - Assume hard driving -

Case 1: 12” PC/PS concrete pile

Case 2: 12 BP 53 Steel Piles

GATES FORMULA

For Case 1 & 2: (

P = (1.83 * ( Er ) 2 * log10 (0.83 * N )) − 124 z
1
)
= ((1.83 * (83,880) )
* log10 (0.83 * (12 / 0.844)) − 124 2 (2 kip1 )
1
2

ton

= ((1.83 * 289.62 * 1.072) − 124) 2 (2 kip )

1
ton

= (568.122 − 124) 2 (2 kip ) 1

ton

444.122 kips
= ≈ 111.0 tons
2(2 kip ton )

ENGINEERING NEWS (ENR) FORMULA

For Case 1 & 2: 2E

P=
( s + 0.1)
2(83,880.0 ft ⋅ lbs)
=
0.844 in + 0.1
= 177,712 lbs ≈ 70 tons

Caltrans ● Foundation Manual E-7

 __________________________________Appendix E – Driven Piles
November 2008

JANBU FORMULA

Case 1: ⎛ WH ⎞ ⎛ WH ⎞ cd = 0.75 + 0.15(W p / W )

P = ⎜⎜ ⎟⎟ z = ⎜⎜ ⎟⎟ 3(20001 lbs )
⎝ u ⎠ ⎝ u ⎠
k s k s ton
= 0.75 + 0.15(11,600 lbs 7,938 lbs)
⎛ 7,938 lbs(10.42 ft ×12 in ft ) ⎞ = 0.969
= ⎜⎜ ⎟⎟ 3( 20001 lbs )
⎝ 2.697(0.844 in ) ⎠
ton
λ=
WHL
⎛ 435,931 lbs ⎞
AEs 2
= ⎜⎜ ⎟⎟ ≈ 72.66 tons 7,938 lbs(10.42 ft × 12 in ft )(80 ft × 12 in ft )
⎝ 3(2000 lbs ton ) ⎠ =
(144 in 2 )(4.4 ×10 6 lbs in 2 )(0.844 in ) 2
= 2.111
[
ku = cd 1 + 1 + (λ cd ) ]
[
= 0.969 1 + 1 + (2.111 0.969) ]
= 2.697

Case 2: ⎛ WH ⎞ ⎛ WH ⎞ cd = 0.75 + 0.15(W p / W )

P = ⎜⎜ ⎟⎟ z = ⎜⎜ ⎟⎟ 3(20001 lbs )
⎝ u ⎠ ⎝ u ⎠
k s k s ton
= 0.75 + 0.15(4,240 lbs 7 ,938 lbs)
⎛ 7,938 lbs(10.42 ft ×12 in ft ) ⎞ = 0.830
= ⎜⎜ ⎟⎟ 3( 20001 lbs )
⎝ 2.581(0.844 in ) ⎠
ton
λ=
WHL
⎛ 455,578 lbs ⎞
AEs 2
= ⎜⎜ ⎟⎟ ≈ 75.93 tons 7,938 lbs(10.42 ft × 12 in ft )(80 ft × 12 in ft )
⎝ 3(2000 lbs ton ) ⎠ =
(15.58 in 2 )(30 ×10 6 lbs in 2 )(0.844 in ) 2
= 2.861
[
ku = cd 1 + 1 + (λ cd ) ]
[
= 0.830 1 + 1 + (2.861 0.830) ]
= 2.581

Caltrans ● Foundation Manual E-8

 __________________________________Appendix E – Driven Piles
November 2008

HILEY FORMULA

Case 1: ⎛ e f WH ⎞⎛ W + n W p ⎞
2

P = ⎜⎜ ⎟⎜ ⎟z
+ 1 (c + c + c ) ⎟⎜ W + W ⎟
⎝ s 2 1 2 3 ⎠⎝ p ⎠

⎞⎛ W + n W p ⎞
2
⎛ e f WH
= ⎜⎜ ⎟⎟⎜ ⎟ 2.75( 2000
1
⎜ ⎟
⎝ s + 2 (c1 + c2 + c3 ) ⎠⎝ W + W p ⎠
lbs
1 ton )

⎛ 1.00(7,938 lbs)(10.42 ft × 12 in ft ) ⎞⎛ 7,938 lbs + (0.252 )(11,600 lbs) ⎞

= ⎜⎜ ⎟⎟⎜⎜ ⎟⎟ 2.75( 2000
1

⎝ 0.844 in + 2 (0.37 in + 0.32 in + 0.10 in) ⎠⎝ 7,938 lbs + 11,600 lbs

lbs
1 ton )
⎠
355,090 lbs
= ≈ 64.6 tons
2.75(2000 lbs ton )

Case 2: ⎛ e f WH ⎞⎛ W + n 2W p ⎞
⎜
P=⎜ ⎟⎜ ⎟z
+ 1 (c + c + c ) ⎟⎜ W + W ⎟
⎝ s 2 1 2 3 ⎠⎝ p ⎠

⎛ e f WH ⎞⎛ W + n 2W p ⎞
= ⎜⎜ ⎟⎜ ⎟ 2.75( 2000
1
+ 1 (c + c + c ) ⎟⎜ W + W ⎟ lbs
ton )
⎝ s 2 1 2 3 ⎠⎝ p ⎠

⎛ 1.00(7,938 lbs)(10.42 ft × 12 in ft ) ⎞⎛ 7,938 lbs + (0.552 )(4,240 lbs) ⎞

= ⎜⎜ ⎟⎜ ⎟⎟ 2.75( 2000
1
+ 1 (0.0 in + 0.48 in + 0.10 in) ⎟⎜ +
lbs
ton )
⎝ 0.844 in 2 ⎠⎝ 7,938 lbs 4,240 lbs ⎠
662,508 lbs
= ≈ 120.5 tons
2.75(2000 lbs ton )

Caltrans ● Foundation Manual E-9

 __________________________________Appendix E – Driven Piles
November 2008

PACIFIC COAST FORMULA

Case 1: ⎛ W + kW p ⎞
En ⎜ ⎟z
⎜ W +W ⎟
P= ⎝
p ⎠

PL
s+
AE
⎛ W + kW p ⎞
En ⎜ ⎟
⎜ W +W ⎟ 1
= ⎝ p ⎠
×
s+
PL 4(2000 lbs ton )
AE
⎛ 7,938 lbs + 0.1(11,600 lbs) ⎞
83,880 ft ⋅ lbs(12 in lbs)⎜⎜ ⎟
⎝ 7,938 lbs + (11,600 lbs) ⎟⎠ 1
= ×
P (80 ft × 12 in ft ) 4(2000 lbs ton )
0.844 in +
(144 in )(4.4 × 10 )
2 6

468,711 in ⋅ lbs 1
= − 6 in
×
0.844 in + P (1.52 × 10 lbs) 4(2000 lbs ton )
343,511 lbs
= ≈ 42.94 tons
4(2000 lbs ton )

Case 2: ⎛ W + kW p ⎞
En ⎜ ⎟z
⎜ W +W ⎟
P= ⎝
p ⎠

PL
s+
AE
⎛ W + kW p ⎞
En ⎜ ⎟
⎜ W +W ⎟ 1
= ⎝ ⎠×
p

s+
PL 4(2000 lbs ton )
AE
⎛ 7,938 lbs + 0.25(4240 lbs) ⎞
83,880 ft ⋅ lbs(12 in lbs)⎜⎜ ⎟
⎝ 7,938 lbs + (4240 lbs) ⎟⎠ 1
= ×
P(80 ft × 12 ft )
in
4(2000 lbs ton )
0.844 in +
(15.58 in 2 )(30 × 106 )
743,720 in ⋅ lbs 1
= − 6 in
×
0.844 in + P (2.1×10 lbs) 4(2000 lbs ton )
430,395 lbs
= ≈ 53.8 tons
4(2000 lbs ton )

Caltrans ● Foundation Manual E - 10

 __________________________________Appendix E – Driven Piles
November 2008

TABLE WITH RESULTS OF FORMULA COMPARISON

CASE 1 CASE 2
Pile Formula 12" PC/PS Concrete Pile HP12x53 Steel Pile

Pile Length 80.0 ft 40.0 ft 80.0 ft 40.0 ft

GATES 111.0 tons 111.0 tons 111.0 tons 111.0 tons

ENR 88.9 tons 88.9 tons 88.9 tons 88.9 tons

JANBU 72.7 tons 91.5 tons 75.9 tons 92.7 tons

HILEY 64.6 tons 88.0 tons 120.5 tons 135.7 tons

PACIFIC COAST 42.9 tons 63.5 tons 53.8 tons 73.3 tons

Caltrans ● Foundation Manual E - 11

 __________________________________Appendix E – Driven Piles
November 2008

EXAMPLE 1: CALCULATION OF MINIMUM HAMMER ENERGY

Given:

Hammer Data: Delmag D36-32

Hammer/Ram Weight = 7938 lbs
Manufacturer’s Maximum Energy Rating = 83,880 ft·lbs

Nominal Resistance = 390 kips

CHECK: Hammer Energy per Standard Specification 49-1.05.

From the GATES Equation,

Ru = (1.83 ∗ ( Er ) 2 ∗ log10 (0.83 ∗ N )) − 124

1

⎛ Ru +124 ⎞
⎜⎜ ⎟
⎝ 1.83 Er ⎟⎠
10
Rearranging for N: N=
0.83

⎛ 390+124 ⎞
⎜⎜ ⎟
1.83 83,880 ⎟⎠
⎝
10
N=
0.83
(514 530 )
10
=
0.83
10 0.9698
=
0.83
= 11.23 ≈ 11 blows ft

s = penetration per blow in inches

= N −1 (12 in ft )
= (11.23 blows ft ) (12 in ft )
−1

= 1.07 in blow > 0.125 in blow

∴ Meets the energy requirements of S.S. 49 - 1.05.

Caltrans ● Foundation Manual E - 12

 __________________________________Appendix E – Driven Piles
November 2008

EXAMPLE 2: CALCULATIONS FOR ESTABLISHING A BLOW COUNT CHART

Given:

Hammer Data: Delmag 36-32

Hammer/Ram Weight = 7938 lbs
Maximum Stroke = 10.42 ft

Nominal Resistance = 390 kips

ASSUMPTION(S): Er = Ram Weight × Observed Field Drop Height

Observed Field Drop Height = 6 ft

From the GATES Equation,

Ru = (1.83 ∗ ( Er ) 2 ∗ log10 (0.83 ∗ N )) − 124

1

Rearranging to solve for N:

⎛ Ru +124 ⎞
⎜⎜ ⎟⎟
10 ⎝ 1.83 Er ⎠ Er = 6 ft (7938 lbs )
N=
0.83 = 47,628 ft ⋅ lbs

⎛ 390+124 ⎞
⎜⎜ ⎟
⎝ 1.83 47 , 628 ⎟⎠
10
N=
0.83
(514 399 )
10
=
0.83
101.287
=
0.83
= 23.33 ≈ 23 blows ft

Calculations for the chart data are completed by using the Excel
spreadsheet, PileEquation-Gates.xls (updated 7/26/2007), downloaded from
the OSC Intranet website. See next page for calculation results of the
spreadsheet.

Caltrans ● Foundation Manual E - 13

 __________________________________Appendix E – Driven Piles
November 2008

Caltrans ● Foundation Manual E - 14

 __________________________________Appendix E – Driven Piles
November 2008

EXAMPLE 3: BATTERED PILE BLOW COUNT CHART

Given:

Hammer Data: Delmag 36-32 Battered pile: 1:3

Hammer/Ram Weight = 7938 lbs
Maximum Stroke = 10.42 ft

Nominal Resistance = 390 kips

3.16
3

θ
1

ASSUMPTION(S): Er = Ram Weight × Observed Field Drop Height

Observed Field Drop Height = 9 ft
As in the previous example, rearranging the Gates Formula gives,

⎛ Ru +124 ⎞
⎜⎜ ⎟
1.83 E r ⎟⎠

N=
10 ⎝
θ = sin -1 ( 3 3.16 ) = 71.565°
0.83
Er = 7938 lbs(9 ft × sin 71.565°)
⎛ 390 +124 ⎞
⎜⎜ ⎟
1.83 67 , 775.8 ⎟⎠
⎝
10
= = 67,775.8 ft ⋅ lbs
0.83
(514 )
10 476
=
0.83
101.0798
=
0.83
= 14.48 ≈ 14 blows ft

Calculations for the chart data are completed by using a MODIFIED version of the Excel
spreadsheet, PileEquation-Gates.xls (updated 7/26/2007). See next page.

Caltrans ● Foundation Manual E - 15

 __________________________________Appendix E – Driven Piles
November 2008

Caltrans ● Foundation Manual E - 16

 __________________________________Appendix E – Driven Piles
November 2008

EXAMPLE 4: CALCULATIONS FOR PILES WITH DOWNDRAG

The following metric example has downdrag:

(Example submitted by Joy Cheung, P.E., and Anh Luu, P.E.)

Island Parkway Overcrossing – Rte 101/Ralston Interchange

EA 04-256804, Oversight Project

The Pile Data Table from the contract plans show:

Bent 2 Piles – Class 900C Alt “X” (Pile Data Table)
Nominal Resistance (Compression) = 1250 KN
Estimate Down Drag Load = 242 KN
Ultimate Pile Capacity = Ru = Nominal resistance + 2 x downdrag

Therefore:
Ru = Nominal resistance + 2 x downdrag
Ru = 1250 KN + (2 * 242KN) = 1734 KN

Contractor’s proposed hammer:

DELMAG D36-32

Pile Hammer Data - (per specs, Contractor provides data)

Also see BCM 130-3.0 dated June 14, 2007.
Internet: www.pileco.com, www.hmc-us.com, …etc;

Pile hammer data:

Max Energy Output = 83880 ft.lbs = 83880 * 1.3558 = 113724.5 Joules
Piston Weight/Ram Weight = mass = 7938 lbs = 3600.6 kg
Maximum obtainable stroke/Piston Drop = height = 10’5” = 3.18 m
Find:

Caltrans ● Foundation Manual E - 17

 __________________________________Appendix E – Driven Piles
November 2008

Er = Energy rating of hammer at observed field drop height in Joules

**It is generally accepted that the energy output of an open-end diesel hammer is
equal to the ram weight times the length of stroke.

Gravitational potential energy = mass × free-fall acceleration × height = m · g · H = Er

Er = 3600.6 kg · 9.81 · 3.18 = 112,323 Joules < 113,724 (Max Energy)

** For battered pile, E r = m ⋅ g (H ⋅ sinθ )

N = Number of blows per 300 millimeters (maximum of 100)

⎛ Ru + 550 ⎞
⎜⎜ ⎟⎟
⎝ 7 Er ⎠
10
N=
0.83

Set up table:
Hammer Type: Delmag D 36-32
Design Load: 625kN
Nominal Resistance: 1734kN
Max Energy 113724Joules
Piston Wt 3600.6Kg
Blows Per Last 300 mm.
PISTON DROP (ft) PISTON DROP (m)ENERGY (joules) GATES
10.417 3.18 112151 11
10 3.05 107661 12
9 2.74 96895 13
8 2.44 86129 16
7 2.13 75363 19
6 1.83 64597 23
5 1.52 53831 31
4 1.22 43064 45
3 0.91 32298 79

Set up graph:

Caltrans ● Foundation Manual E - 18

 __________________________________Appendix E – Driven Piles
November 2008

GATES
(Delmag D36-32, Design Load = 625 kN,
Nominal Resistance = 1734 kN)

35
30
BLOWS / FT

25
20
GATES
15
10
5
0
5 6 7 8 9 10 11
PISTON DROP (FT)

Meets Bearing Value

NOT GOOD

A very good spreadsheet (PileEquation-Gates.xls) used to calculate blows per foot using
the Gates equation can be found on the OSC Intranet Homepage under,
“Downloads/Forms”. This spreadsheet was updated on 7/26/07.
Continue calculations:
Standard Specifications - Section 49-1.05
--Impact Hammer Minimum Energy “not less 3mm/blow at the specified bearing
value…”

Use the Gates formula again…

Ru = (7 ∗ ( Er ) 2 ∗ log10 (0.83 ∗ N )) − 550
1

Find N.
Using Er = 3600.6 kg * 9.81 * 3.18 = 112,323 Joules
Ru = 1250 KN + (2 * 242KN) = 1734 KN
N = 11 blows/ 300 mm
s = Penetration per blow in millimeters
= 300 mm/11 blows
≈ 27.0 mm > 3 mm OK.

Note: An upper limit is not specified for the Contractor to furnish an approved hammer
having sufficient energy to drive piles at a penetration rate of not less than 1/8-inch per
blow at the required bearing value.

End of example.

Caltrans ● Foundation Manual E - 19

 __________________________________Appendix E – Driven Piles
November 2008

EXAMPLE 5: ESTIMATE HAMMER STROKE OF A SINGLE ACTING HAMMER

Given:

Hammer Data: Delmag 36-32

Hammer/Ram Weight = 7938 lbs
Maximum Stroke = 10.42 ft

From Field Observations: Ram Blows per Minute (bpm) = 43

From the SAXIMETER Formula,

2
H = 4.01⎛⎜ 60 ⎞⎟ − 0.3
⎝ bpm ⎠
H = hammer stroke in feet
bpm = field observation of hammer blows per minute

2
H = 4.01⎛⎜ 60 ⎞⎟ − 0.3
⎝ bpm ⎠
2
= 4.01⎛⎜ 60 ⎞⎟ − 0.3
⎝ 43 bpm ⎠
= 7.81 − 0.3
= 7.51 ≈ 7.5 ft

Caltrans ● Foundation Manual E - 20

 __________________________________Appendix E – Driven Piles
November 2008

Caltrans ● Foundation Manual E - 21

 __________________________________Appendix E – Driven Piles
November 2008

Caltrans ● Foundation Manual E - 22

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

APPENDIX

Static Pile Load Testing and

F Dynamic Monitoring

Table of Contents

Pile Load Test (PLT) Request Form F-2

Pile Dynamic Analysis (PDA) Request Form F-3
Five Pile Test Group Diagrams F-4
Three Pile Test Group Diagrams F-5
Sample Report of Static Pile Load Test Results F-6
Sample Report of Dynamic Pile Monitoring Results F-19

Caltrans ● Foundation Manual F-1

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F-2

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F-3

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F-4

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F-5

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F-6

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F-7

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F-8

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F-9

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 10

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 11

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 12

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 13

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 14

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 15

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 16

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 17

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 18

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 19

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 20

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 21

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 22

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 23

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 24

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 25

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 26

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 27

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 28

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 29

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 30

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 31

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 32

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 33

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 34

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 35

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 36

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 37

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 38

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 39

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 40

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 41

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 42

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 43

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 44

 ____Appendix F – Static Pile Load Testing and Dynamic Monitoring
November 2008

Caltrans ● Foundation Manual F - 45

 _______________________Appendix G – Slurry Displacement Piles
November 2008

APPENDIX

G Slurry Displacement Piles

Table of Contents

Sample Letter Regarding Gamma-Gamma Logging Testing Results G-2

Caltrans ● Foundation Manual G-1

 _______________________Appendix G – Slurry Displacement Piles
November 2008

Caltrans ● Foundation Manual G-2

 _______________________Appendix G – Slurry Displacement Piles
November 2008

Caltrans ● Foundation Manual G-3

 _______________________Appendix G – Slurry Displacement Piles
November 2008

Caltrans ● Foundation Manual G-4

 _______________________Appendix G – Slurry Displacement Piles
November 2008

Caltrans ● Foundation Manual G-5

 _______________________Appendix G – Slurry Displacement Piles
November 2008

Caltrans ● Foundation Manual G-6

 _______________________Appendix G – Slurry Displacement Piles
November 2008

Caltrans ● Foundation Manual G-7

 _______________________Appendix G – Slurry Displacement Piles
November 2008

Caltrans ● Foundation Manual G-8

 _______________________Appendix G – Slurry Displacement Piles
November 2008

Caltrans ● Foundation Manual G-9

 _______________________Appendix G – Slurry Displacement Piles
November 2008

Caltrans ● Foundation Manual G - 10

 _______________________Appendix G – Slurry Displacement Piles
November 2008

Caltrans ● Foundation Manual G - 11

 _______________________Appendix G – Slurry Displacement Piles
November 2008

Caltrans ● Foundation Manual G - 12

 _______________________Appendix G – Slurry Displacement Piles
November 2008

Caltrans ● Foundation Manual G - 13

 _______________________Appendix G – Slurry Displacement Piles
November 2008

Caltrans ● Foundation Manual G - 14

 _______________________Appendix G – Slurry Displacement Piles
November 2008

Caltrans ● Foundation Manual G - 15

 _______________________Appendix G – Slurry Displacement Piles
November 2008

Caltrans ● Foundation Manual G - 16

 _______________________Appendix G – Slurry Displacement Piles
November 2008

Caltrans ● Foundation Manual G - 17

 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

APPENDIX

Tiebacks, Tiedowns
H & Soil Nails

Table of Contents

Tieback Construction Checklist H-2

Soldier Pile Construction Checklist H-15
Soil Nail Wall Construction Checklist H-25

Caltrans ● Foundation Manual H-1

 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

Tieback Construction Checklist

GENERAL OVERVIEW

Tiebacks are utilized in both temporary and permanent structures. Tiebacks are normally
used to achieve higher walls or deeper excavations than can be achieved by cantilevered
construction alone. In temporary construction, if soil conditions and physical
development adjacent to the work area allows, tiebacks may be proposed by the
Contractor to avoid the use of struts and bracing that may obstruct the work area. In
temporary applications tiebacks are proposed and designed by the Contractor and
included within their shoring submittal to the Structures Representative. In permanent
applications tiebacks are normally utilized with soldier piling for timber lagged
cantilevered tieback wall construction. As such, this checklist should be integrated with
the “SOLDIER PILE CONSTRUCTION CHECKLIST”.

The following checklist is intended to append Bridge Construction Memo 145-10.0, and
serves as a stand-alone reference related solely to the installation of tiebacks. The
Structure Representative is encouraged to employ the following checklist for tieback
installations. If a problem or situation is encountered that is not addressed by this
checklist, you are encouraged to contact either your Senior Bridge Engineer or the Earth
Retaining Systems Specialist.

I. SOURCES OF TECHNICAL INFORMATION

A. Bridge Construction Records and Procedures Manual:

1. 145-10.0 - Tieback Wall Construction Checklist:
• Recent memo issued July 1, 2001.
2. BCM 160-6.0 – Prestressed Concrete Working Drawings and Microfilms.

B. Foundation Manual:
1. Chapter 11 – Tiebacks, Tiedowns, and Soil Nails
2. Appendix H – Tiebacks, Tiedowns, and Soil Nails
• Construction Checklist

C. Trenching and Shoring Manual:

• Chapter 9 – Tiebacks: General theory on tiebacks.

D. Prestress Manual:
• Focus on subjects including safety, prestress working drawings,
strands/rods, bearing plates, wedges, jacks, stressing, grouting, and
Appendices A through F.
Caltrans ● Foundation Manual H-2
 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

II. SOURCES OF PROJECT SPECIFIC INFORMATION

A. Structures Pending File:

1. Foundation Report:
Review recommended unbonded lengths for each tieback level beyond the
Retaining Wall Layout Line (RWLOL).
Note any comments concerning anticipated constructability problems:
• Caving, presence of boulders, groundwater problems.
• Structure Rep should verify Foundation Report comments regarding
specifications or design features are incorporated into the Contract
Documents.
2. Designer’s notes.

B. Information Handout:
• Local, Regional, State, and Federal regulatory and permit specific
requirements:
• Focus review on regulatory requirements/restrictions related to Structures
contract items.

III. CONTRACTURAL REQUIREMENTS

A. Contract Special Provisions:

1. Section 5. General:
• Section 5-1._ Local Agency/State Parks/DFG/RWQCB/USACOE
Requirements
Review requirements for all local, regional, State, and Federal regulatory
agencies having jurisdiction over the work and note potential impacts to
structures related work.
2. Section 8. Miscellaneous:
• Section 8-3. Welding Quality Control:
Note applicable shop and field welding for tieback related items:
Bearing plates.
Wedge plates – double pile systems.
3. Section 10. Construction Details:
• Water Pollution Control Program – WPCP.
• Tieback Anchors.

B. Contract Plans:
1. General Plan – Typical Section:
• Note tieback levels and angle on inclination of tiebacks.
2. Retaining Wall Elevation:
• Note varying tieback spacings for various tieback levels.

Caltrans ● Foundation Manual H-3

 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

3. Retaining Wall Details:

• General Notes:
Note Design Force, T, for various tiebacks/levels.
4. Tieback Anchor Details:
• Note differences between Alternative A & B Tiebacks.
• Note Tieback Minimum Unbonded Length for various tiebacks/levels.
5. Log of Test Borings – LOTB:
• Review LOTBs’ with respect to wall layout line and tieback
locations/elevations – the data provided may be extrapolated over the full
depth of the tiebacks extending into the hillside.

C. Standard Specifications:
1. Section 50 – Prestressing Concrete.

IV. JOB BOOKS SET-UP

A. Category 12 – Contractor’s Submittals:

NOTE: Contact Documents Unit ASAP!
e-mail Manjit Sandhu at the Documents Unit as soon as possible with your latest
office address/location and telephone number to avoid any unnecessary delays in
receiving submittals for review and comment back to the design engineer.
1. Tieback Working Drawing Submittals.

B. Category 20 – Contractor’s Water Pollution Control Program.

C. Category 37 – Initial Tests and Acceptance Tests:

1. Tieback Performance and Proof Testing.
2. Grout Tests.

D. Category 41 – Reports of Inspection of Material:

1. Tiebacks:
• Sheathing.
• Corrosion inhibiting grease.
• Anchor heads.
• Wedges.
• Bearing plate/trumpet assemblies.
• Grout caps – if required.

E. Category 42 – Welding Quality Control Program:

1. Contractor’s Welding Quality Control Program.
2. CWI Inspection Reports related to tieback fabrications.
F. Category 43 – Concrete and Reinforcing Steel:
1. Grout mix designs.

Caltrans ● Foundation Manual H-4

 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

V. PRE JOB DISCUSSION WITH DESIGN & GEOLOGY/GEOTECHNICAL

A. Establish contacts with Structures Design and Geotechnical Services:

1. Structures Design (SD) Contacts:
Specifications – Look for RCE Stamp at beginning of Specials.
Plans – Engineer of record on Plans.
2. Geotechnical Services Contact:
Name and phone number should be at bottom of Foundation Report.

B. Discuss/resolve any concerns developed either during review of project specific

information, or as a result of preliminary site investigations.

VI. PRE CONSTRUCTION MEETING WITH CONTRACTOR

A. Remind Contractor of his responsibility to submit tieback working drawings,

Welding Quality Control Program, Water Pollution Control Program measures
related to tieback installations, and grout mix designs in a timely manner to allow
sufficient time for review/comment/approval by the Structure Representative.

VII. SUBMITTAL REVIEWS

A. Tieback Working Drawings:

1. SD responsibility to approve with Structures review/comment.
NOTE: Memo to Designers 5-14, “Review of Working Drawings for Tieback
Anchors”:
“The responsibility for checking working drawings is shared by the
Designer and the Structure Representative”.
2. Verify:• Order of work defined in sufficient detail – see CONSTRUCTION.
• Stressing equipment calibrated by METS within 1 year of intended use on
the project.
• Contingencies should difficult drilling/tieback installation conditions
develop.
• Testing loads specified agree with Plans/Special Provisions requirements.
• Bearing plate dimensions provided do not result in overstress of concrete
in compression (11 Mpa), steel in bending (0.55 fy), or cast steel or iron
(0.36fy).
• Unbonded lengths meet or exceeds the minimum length specified upon the
Structures Construction Plans.
• Check calculations:
Lock-off shim thickness for varying design loads.
80% elongation at test load.

Caltrans ● Foundation Manual H-5

 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

• Upon receipt of TL-29s’ for strands – compare As’ & Es’ with values on
submitted working drawings.
• Corrosion inhibiting grease is specified over the unbonded, sheathed
portion of the strands.
• Centralizers and spacing are noted.

B. Contractor’s Water Pollution Control Program:

1. District responsibility to approve with Structures review/comment.
2. Verify regulatory/agency permit requirements w/in Section 5 of SPs’ are
addressed:
• Containment of groundwater pumped from tieback drilled holes.
• Containment of grout during grouting operations.

C. Welding Quality Control Program:

1. BCM 180-9.0.
2. Submitted WQCP forwarded to appropriate regional METS office for
review/approval.
3. Structures Representative’s responsibility to approve with METS
review/comment/input.
4. Assure all applicable requirements and submittals per Special Provisions
Section 8 are met:
• Separate QCP for each Item of work.

VIII. CONSTRUCTION

A. Construction Sequence:
1. Soldier piles installed, face of wall excavated, timber lagging installed
• Refer to the “SOLDIER PILE CONSTRUCTION CHECKLIST”.
2. Drilling, installation, and primary grouting of tiebacks.
3. Post grouting (i.e., pressure grouting) at Contractor’s discretion.
4. Concrete waler construction:
• Bearing plate/sleeve assembly installation during concrete waler
formwork construction.
• Pour concrete waler.
• Testing/stressing of tieback and lock-off to final service load.
• Perform secondary grouting.
• Install grout cap and complete third stage grouting.
4. Dual soldier pile construction:
• Welding of bearing bar to piles.
• Installation of wedge plate and bearing plate/sleeve assembly.
• Testing/stressing of tieback and lock-off to final service load.
• Perform secondary grouting.
• Perform third stage grouting.
• Form and pour concrete encasement over anchor assembly.

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 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

3. Prepare cut sheets for each pile:

• Cut to required pile tip.
• Cut to top of Class 3 Concrete (Backfill).
• Cut to top of pile cut-off.

B. Delivery/Storage of Materials:
1. Tiebacks:
• Perform thorough inspection of tiebacks for damage:
Refer to repair procedures submitted by contractor for damaged sheathing.
• Verify proper storage of tiebacks.
2. Bearing plate/sleeve (trumpet) assemblies:
• Inspect for damage to assemblies, particularly damaged galvanizing.
• Note different bearing plate dimensions for various tieback locations.

C. Equipment Mobilization:
1. Note and photograph all equipment mobilized to jobsite:
• Drill rig, augers, and casings.
• Grout plant, pumps, and compressors.
• Testing/stressing equipment.
• Settling tank, pumps, hoses – condition of hoses.
2. Verify all equipment mobilized conforms to Contractors tieback working
drawing submittal.

D. Materials Inspection, Sampling, & Testing:

1. Each shipment of tiebacks should include:
• TL-0624 Inspection Release Tags (orange).
• Corrosion inhibiting grease – Certificate of Compliance, laboratory
chemical analysis.
• Corrugated HDPE exterior sheathing – Certificate of Compliance.
• Smooth HDPE tendon sheathing – Certificate of Compliance.
2. Each shipment of steel fabrications should include:
• TL-0624 Inspection Release Tags (orange) .
• Certified Welding Inspection reports:
For steel fabricated items required by Section 8 Welding Quality Control
Program requirements.
• Certificates of Compliance for fabrication and galvanizing.
3. Prior to testing/stressing, each shipment of anchor heads and strand wedges
should include:
• Anchor heads - Certificate of Compliance, material certifications, lot/batch
numbers.
• Strand wedges – Certificate of Compliance, material certifications,
lot/batch numbers.

E. Drilling:
SAFTY CONCERNS:

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 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

• Review OSC Code of Safe Practices – Drilling Tiebacks and Soil Nails
• Stay away from rotating machinery.
• Maintain eye contact with drilling equipment operator.
1. Full Time Inspection Required:
• Drilled hole activity is highest potential for Differing Site Condition –
DSC to occur.
• Begin logging holes immediately – don’t wait for Contractor to file a
claim.
• Compare drill tailings (spoils) with information contained upon LOTBs’.
• Note productivity rates for drilling advancement, soil conditions, presence
of groundwater at given drilling depth/elevation.
• Use high powered spotlight or mirror to observe soil structure over full
depth of drilled hole.
• Note any potential problem soils areas:
Focus performance tests at tiebacks where questionable soil conditions are
encountered.
• Verify actual hole depth and actual drilled diameter:
To estimate grout volume to assure tiebacks are being fully grouted.
To determine maximum primary grout level outside of corrugated
sheathing.
Potential Problems:
Rocks or boulders are encountered within drilled holes:
• Contractor is contractually on notice within “Tieback Anchors” of the
Contract Special Provisions to anticipate and be prepared for difficult
drilling conditions.
• Submitted/approved tieback working drawings should address.
• Amend as necessary in writing prior to proceeding.
• For encountering rocks and boulders, down hole pneumatic hammer drill
rigs and drill bits should be employed.
Drilled holes caving:
Usually not detected until the tieback is attempted to be installed.
• Submitted/approved tieback working drawings should address.
• Amend as necessary in writing prior to proceeding.
Caving in dry holes:
• Casing system advancing with drilling.
Caving in wet holes:
• Casing system, or
• Tremie seal: 3-sack slurry & re-drill 24 hours later.
Tieback Installation:
1. Prior to installation:
• Re-inspect each assembly for damage.
• Verify bonded length:
Cut sheathing in vicinity of bonded/unbonded zone, verify, and patch.
• Ensure centralizers are installed:
Provide one at end of strand.

Caltrans ● Foundation Manual H-8

 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

Use even with casing advancing system.

2. Installation:
• Re-inspect hole for presence of caving.
• Do not allow Contractor to forcibly shove tiebacks down drilled hole.
• Assure tieback installed to required depth.

G. Tieback Grouting:
1. Within corrugated sheathing:
• Section 50-1.09 – 5 gals per sack of cement
2. Outside of corrugated sheathing:
• Where holes exceed 8 inches in diameter special provisions allow fine
aggregate added to grout mix.
• Cement content is not less than 500 kg per cubic meter.
3. Post grouting (pressure grouting):
• Section 50-1.09 requirements apply.
4. Grouting equipment:
• Check equipment for wear.
• Check plumbing for all required valves and gauges.
5. Water Pollution Control Program:
• Address WPCP/Regulatory permit requirements.
• Prevent run-off into drainage structures & natural courses.
6. Primary Grout Placement:
• Within sheathing:
Grout to end of sheathing.
Continue until all air is expelled.
• Outside of sheathing:
Grouting via exterior tube with one-way valve:
Two conditions:
Holes less than 6 inches in diameter:
Grout to within 6 inches of sleeve.
Holes greater than 6 inches in diameter:
Grout only the bonded length of the tieback.
Difficult to verify – error on high side.
7. Post Grouting:
• Involves pressure grouting in vicinity of bonded length.
• At Contractor’s discretion – not required by the Special Provisions.
• Typically provided for on Contractor’s tieback working drawings.
• Grout pressure injected until specified pressure is achieved:
Typically 300 to 500 psi.
• Volume of grout injected and pressure recorded by Contractor.
• Provides an indication as to the soil conditions within the bonded length.
8. Grout Volume Determinations:
• Per Special Provisions, Contractor must record all primary grout volumes
and furnish results to the Structures Representative – file within Category
41 for tiebacks.

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 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

• Have contractor pump one stroke of grout into a wheelbarrow or other

suitable container and measure. Note number of pump strokes per nail
grouted and compare with estimated volumes.

H. Bearing Plate/Trumpet Installation:

1. Concrete waler construction:
• Cast into waler structure.
• Assure face of bearing plate is flush with face form.
2. Dual piling system:
• Installed prior to stressing.

I. Testing/Stressing:
SAFETY:
• Static nature of testing/stressing belies danger of forces involved
• Hold a special safety meeting prior to testing including:
All assistants and District personnel who may be working in the area
• Topics to cover include:
“OSC Code of Safe Practices – “POST TENSIONING OPERATIONS
• Prestress Manual – “SAFETY”
• Emphasize avoiding path of forces being applied
• Inspect pumps and hoses for excessive wear
1. Testing/stressing normally conducted against the permanent structures.
2. Testing equipment:
• Shims of varying thickness.
• Hydraulic ram, pump, and pressure gauges:
Must be calibrated by METS annually.
• Device capable of measuring elastic/slip movement of strands to
0.025mm.
3. Permanent stressing Devices:
• Anchor head.
• Seating wedges.
4. Testing/stressing procedure:
•Testing conducted on all tiebacks.
• Threading anchor head onto strands:
Assure proper arrangement of strands to achieve uniform loading of
strands.
• Placement of shims between anchor head and bearing plate.
• Threading wedges onto strands and seating into anchor head.
• Threading strands through ram and installing lock wedges and loading
plate at upper end of ram.
• Aligning ram along axis of tieback.
• Apply alignment load to ram:
Check for uniform bearing of anchor head on bearing plate and alignment
of ram with strands.
• Commence with testing.

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 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

5. Performance vs. Proof tests:

• Performance testing:
Cyclic loading with incremental increase in maximum load for each cycle
up to 1.5*T.
• Proof testing:
Single cycle of loading to 1.5*T.
6. Performance Tests:
• Special Provisions specify a required minimum number or test.
• Locations per Structures Rep’s observations:
During plan review – highest design forces.
During preliminary site investigation.
During drilling operations.
During post grouting operations.
7. Loading:
• Each loading increment applied within 1 minute.
• Each loading increment held for no more than 2 minutes.
• Movement for each load increment is noted and recorded.
• Test load hold at 1.5*T:
Test load of 1.5*T held constant for 10 minutes.
8. Test acceptance criteria:
• Performance tests:
Elastic movement exceeds 80% of theoretical.
Movement at 1.5*T test load hold less than 1 mm.
• Proof tests:
Elastic movements similar to performance tests.
Movement at 1.5*T test load hold less than 1 mm.
9. Failed tests:
• Elastic movement does not exceed 80% of theoretical.
• Possible causes:
Unbonded length insufficient – should be checked by visually inspecting
prior to installation.
Insufficient loading is being applied to the strands by the testing
mechanism – verify accuracy of gauge pressure.
Check load path from ram to strands for losses – check that wedges are
properly seated within both the loading plate and permanent anchor head.
• Contact Designer and Geotechnical Services contact for further direction.
• Movement at test load hold exceeds 1 mm:
Tieback is rejected.
Test load held for additional 50 minutes.
Movement recorded at 5 minute intervals.
Deflection vs. time plotted & forwarded to Geotechnical Services.
10. Contractor’s responsibility to address failed tiebacks:
• Elastic movement does not exceed 80% of theoretical:
If applied loading and load path are satisfactory, reject and replace
tieback.

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 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

• Movement at test load hold exceeds 1 mm:

Contractor normally repeats post grouting operation and retests after
sufficient cure time.
11. File all testing results within Category 37 for tiebacks.

J. Lock-Off:
1. Lock-off results in relaxation of tieback force to 75% of Design Load.
• 75% of design load is specified to achieve residual capacity within the
tiebacks.
• Lock-off conducted upon successful testing of tieback:
Ram is backed off anchor head.
Stands stressed to relax anchor head off shims.
Shims between anchor head and bearing plate removed.
Anchor head returned to bearing plate.
Perform Lift-off test.
2. Lift-off test:
• Verifies force in tieback.
• Load re-applied to strands until anchor head lifts off of bearing plate.
• Pressure/load at lift-off noted:
Should be within 5% of required 75% of Design Force.
Record final force in tieback upon test sheets.
Potential Problems:
Actual lift-off force exceeds 75% of Design Load in excess of 5%
tolerance
• Shim thickness used too thin
Back strand wedges out of anchor head.
Install thicker shim - 3mm increments.
Re-stress to 1.5*T.
Repeat lock-off & lift-off test.
Actual lift-off force less than 75% of Design Load in excess of 5%
tolerance:
• Shim thickness used too thick.
Back anchor head off of bearing plate.
Install thinner shim - 3mm increments.
Re-stress to 1.5*T.
Repeat lock-off & lift-off.

K. Testing/Stressing Summary:
1. STRESSING/TESTING REQUIRES FULL-TIME, ATTENTIVE
INSPECTION.
2. ASSURE RESIDUAL FORCE IN EACH TIEBACK IS PER CONTRACT
DOCUMENTS WITHIN ALLOWED TOLERANCES.
3. BE SAFE AROUND TESTING/STRESSING OPERATIONS.

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 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

IX. PROJECT COMPLETION/AS-BUILTS

A. Bridge Construction Memo 9-4.0 applies:

Do not forward post tensioning test results – maintain within the job files.
B. Note/draw any modifications on the as-built drawings on the number or location
of tiebacks.

Caltrans ● Foundation Manual H - 13

 APPENDIX H-14

“Before”. Facing east. Survey stakes placed. Slope “Before”. Facing west. Survey stakes placed. Slope is
is eroding (on the left). 12/31/03 eroding. Existing drainage pipe and creek on right.

“After”. Facing east. Type 7 chain link fence. Type “After”. Facing west. Wall is complete. Two rows
27 modified concrete barrier on top of barrier slab. of concrete walers (with tieback anchors). Creek on
6/24/04 the right. 6/24/04

PROJ/RTE/PM: 04-SM-Rte 84-PM 10.2 Soldier Pile Wall with Tieback Anchors Date: 2003/2004
PROJECT NO. 04-1S2724 Photos by Dan Dait, P.E., Sr Br Engr Photo Page 1
 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

Soldier Pile Construction Checklist

GENERAL OVERVIEW

The following construction checklist for soldier piles has been developed to assist field
personnel in preparing documents and inspecting fieldwork to ensure compliance with
contract requirements for the placement of soldier piles. It is important that the Structure
Representative reviews the plans and specifications and conducts preconstruction
meetings with the Contractor to lay out the procedures, identify potential field problems
and solve those problems prior to the commencement of soldier pile installations.

Soldier piles are commonly used for temporary shoring and permanent timber lagged
maintenance walls, with or without tiebacks. In permanent applications, soldier piles are
simply CIDH piles with structural steel piling partially embedded within Class 3 concrete
with the balance of the drilled hole filled with a sacrificial lean concrete backfill. For
permanent soldier pile walls with tiebacks, this checklist should be integrated with the
“TIEBACK CONSTRUCTION CHECKLIST”.

The Structure Representative is encouraged to employ the following checklist for soldier
pile installations. If a problem or situation is encountered this checklist does not address,
you are encouraged to contact either your Senior Bridge Engineer or the Earth Retaining
Systems Specialist.

I. SOURCES OF TECHNICAL INFORMATION

A. Trenching & Shoring Manual

1. Chapter 10 – Soldier Piles

B. Foundation Manual:
1. Chapter 6 – Cast-In-Drilled-Hole-Piles
Foundation Manual does not currently address soldier piling
2. Chapter 11 – Tiebacks, Tiedowns, and Soil Nails
3. Appendix H – Tiebacks, Tiedowns, and Soil Nails
• Construction Checklist

II. SOURCES OF PROJECT SPECIFIC INFORMATION

A. Structures Pending File

1. Foundation Report
Review recommended depth for soldier piles.
Note any comments concerning anticipated constructability problems:

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 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

• Caving, presence of boulders, groundwater problems

• Structure Rep should verify Foundation Report comments regarding
specifications or design features are incorporated into the Contract
Documents.
2. Designer’s notes
3. Engineer’s Estimate quantity calculations for contract items related to Soldier
Piling installations.

B. Information Handout:
1. Local, Regional, State, and Federal regulatory and permit specific
requirements
• Focus review on regulatory requirements/restrictions related to Structures
contract items.

III. CONTRACTURAL REQUIREMENTS

A. Contract Special Provisions

1. Section 5. General
• Section 5-1. Local Agency/State Parks/DFG/RWQCB/USACOE
Requirements
Review requirements for all local, regional, State, and Federal regulatory
agencies having jurisdiction over the work and note potential impacts to
structures related work
2. Section 8. Miscellaneous
• Section 8-2. Concrete
Class 3 Concrete (Backfill) requirements
• Section 8-3. Welding Quality Control
Note applicable shop and field welding to piles:
Concrete anchors
Shim plates – double pile systems
3. Section 10. Construction Details
• Water Pollution Control Program - WPCP
• Soldier Pile Earthwork
• Piling
• Steel Soldier Piling
• Drilled Holes
• Clean and Paint Steel Soldier Piling

B. Contract Plans
1. General Plan – Structures
• Check curve data, profile grades and construction stationing for
conformity with road plans.
2. Retaining Wall Elevations

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 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

• Check Superelevation Diagram from road plans and spot-check specified

top of wall elevations within Pile Data Table.
• Note specified tip elevations & compare with LOTB for anticipated
drilling/placement conditions. Pay particular attention to locations where
caving may occur
• Note number of lagging at each pile location and determine top of Class 3
concrete elevations
3. Retaining Wall Sections
• Note pay limits for soldier pile, clean and paint soldier pile, Class 3
concrete backfill
4. Retaining Wall Details
• Note any required welding of/to soldier piling for Welding Quality
Control Program requirements
• Top of pile cut-off with respect to barrier rail slab
5. Log of Test Borings
• Note groundwater surface (GWS) elevations – note time of year borings
were taken – GWT level could seasonally fluctuate.
• Focus review on soil structure in vicinity of drilled holes for soldier piles –
be cognizant that plane of GWS could possibly tend uphill across varying
elevations of soldier piles due to original ground surfaces beneath existing
fills.

C. Standard Specifications
1. Section 19 – Earthwork
• Section 19-3.062 – Slurry Cement Backfill
2. Section 49 – Piling
• Section 49-4.03 Drilled Holes
• Section 49-5 Steel Piles
3. Section 57 – Timber Structures
4. Section 58 – Preservative Treatment of Lumber, Timber, and Piling
5. Section 59 – Painting
6. Section 90 – Portland Cement Concrete
7. Section 91 – Paint

IV. JOB BOOKS SET-UP

A. Category 8 – Surveys
1. Soldier Pile cut sheets

B. Category 12 – Contractor’s Submittals

NOTE: Contact Documents Unit ASAP!
e-mail Manjit Sandhu at the Documents Unit as soon as possible with your latest
office address/location and telephone number to avoid any unnecessary delays in
receiving submittals for review and comment back to the design engineer

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 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

1. Soldier Pile Earthwork Working Drawings

• Required per Special Provisions section “Soldier Pile Earthwork”
2. Soldier Pile Placement Plan
• Required per Section 49-1.01 of Standard Specifications

C. Category 20 – Contractor’s Water Pollution Control Program

1. Drilled hole dewatering plan

D. Category 37 – Initial Tests and Acceptance Tests

1. Class 3 Concrete aggregate gradation and SE tests

E. Category 41 – Reports of Inspection of Material

1. Soldier Piling
2. Clean and Paint Soldier Pile

F. Category 42 – Welding Quality Control Program

1. Contractor’s Welding Quality Control Program
2. CWI Inspection Reports

G. Category 43 – Concrete and Reinforcing Steel

1. Class 3 Concrete Mix Design
2. Lean Concrete Backfill Mix Design

V. PRE JOB DISCUSSION WITH DESIGN & GEOLOGY/GEOTECHNICAL

A. Establish contacts with Structures Design and Geotechnical Services, Foundations

Branch –
1. Structures Design Contacts:
Specifications – Look for RCE Stamp at beginning of Specials
Plans – Engineer of record on Plans
2. Foundations Contact:
Name and phone number should be at bottom of Foundation Report

B. Discuss/resolve any concerns developed either during review of project specific

information, or as a result of preliminary site investigations.

VI. PRE CONSTRUCTION MEETING WITH CONTRACTOR

A. Remind Contractor of his responsibility to submit soldier pile earthwork

drawings, soldier pile placement plans, Welding Quality Control Program, Water
Pollution Control Program measures related to Drilled Hole activity, concrete mix
designs, and proposed paint systems in a timely manner to allow sufficient time
for review/comment/approval by the Structure Representative.

Caltrans ● Foundation Manual H - 18

 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

VII. SUBMITTAL REVIEWS

A. Soldier Pile Earthwork Drawings

1. DSD responsibility to approve with Structures review/comment
2. Likely to contain additional construction including lagging, tiebacks, etc
3. Order of work should be defined in sufficient detail
4. Special Provisions special requirements should be re-iterated

B. Soldier Pile Placement Plans

1. DSD responsibility to approve with Structures review/comment
2. Order of work should be defined in sufficient detail
3. Proposed traffic control measures adhere to Special Provisions requirements
4. Method of installation of soldier piles:
• Proposed drilling equipment
• Proposed de-watering methods – WPCP
5. Contingency plans for difficult soil conditions
• Very important to avoid claims by contractor
• Casing methods
Steel pipe casing
Tremie seal:
Placement of 3-sack lean concrete backfill and re-drill following day
Drilling muds:
Only if permitted within Special Provisions section “Drilled Holes”

C. Contractor’s Water Pollution Control Program

1. District responsibility to approve with Structures review/comment
2. Verify regulatory/agency permit requirements w/in Section 5 of SPs’ are
addressed:
• Pumping, treatment, and disposal of groundwater removed from drilled
holes
• Handling and disposal of drilling muds or chemical stabilizers – if
permitted

D. Welding Quality Control Program

1. BCM 180-9.0
2. Submitted WQCP forwarded to appropriate regional METS office for
review/approval
3. Structures Representative’s responsibility to approve with METS
review/comment/input
4. Assure all applicable requirements and submittals per Special Provisions
Section 8 are met
• Separate QCP for each Item of work

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 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

E. Paint
1. Verify inorganic zinc primer on Department’s list of approved brands
2. Verify –finish coating systems are supplied by the same manufacturer of the
primer system and are compatible with the primer system

VIII. CONSTRUCTION

A. Surveys
1. Have Contractor submit staking request – review w/ Contractor prior to
submittal
2. Request surveys provide two points at stationing for each pile: one for grade
at 6 feet offset from RWLOL and one for line approximately 6 feet beyond.
3. Prepare cut sheets for each pile
• Cut to required pile tip
• Cut to top of Class 3 Concrete (Backfill)
• Cut to top of pile cut-off

B. Delivery/Storage of Materials
1. Assure piling is carefully handled when unloading and placed upon wooden
sleepers
2. Verify primer paint system has not been damaged due to shipment and
handling – notify contractor of any required repairs to primer paint system
3. Piece-mark each pile and field measure overall length for future reference
when determining tip elevation and required cut-off

C. Equipment Mobilization
1. Note and photograph all equipment mobilized to jobsite:
• Drill rig, augers, clean out buckets, and core barrels
• Hydraulic crane – check crane certifications
• Casings - in event caving conditions encountered
• Settling tank, pumps, hoses – condition of hoses
2. Verify all equipment mobilized conforms to Contractors pile earthwork and
placement submittals

D. Materials Inspection, Sampling, & Testing

1. Soldier Piling
• Locate and pull all TL-0624 (orange) inspection tags from each shipment
of piles
• Associate all TL-0624s’ with TL-29s’ transmitted from METS into
Category 41
2. Class 3 Concrete (Backfill)
• Strength tests not required
• Aggregate gradations, SE, & penetration daily

Caltrans ● Foundation Manual H - 20

 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

E. Drilling
SAFTY CONCERNS:
Stay away from perimeter of drilled hole
• unpredictable soil conditions at top of shaft
• could result in bank failure
• subsequent fall could result serious injury or death
Stay in visual contact with drill rig operator
• be constantly aware of operator’s blind spots and direction of drill rig swing
to clean auger of drill spoils
• when maneuvering around drill rig be aware of swing radius at back end of
drill rig
• place caution flagging to warn personnel of swing radius
1. Full Time Inspection Required:
• Drilled hole activity is highest potential for Differing Site Condition –
DSC to occur.
• Begin logging holes immediately – don’t wait for Contractor to file a
claim
• Compare drill tailings (spoils) with information contained upon LOTBs’
• Note productivity rates for drilling advancement, soil conditions, presence
of groundwater at given drilling depth/elevation
• Use high-powered spotlight or mirror to observe soil structure at face of
drilled hole
• Note depth ranges where changes in soil conditions occur, presence of
caving occurs, depth to groundwater, etc.
• Measure depth of hole with respect to 6 foot offset grade point to check
clearance between bottom of hole and tip of pile and to estimate Class 3
concrete backfill quantities for hole.
• Verify bottom of hole is cleaned of all loose drilling spoils prior to
placement of soldier pile
Potential Problems
Caving
• Contractor’s in driver’s seat – refer to Contractor’s Pile Placement Plan
for contingencies
• Possible solutions:
– Casing – difficult to retrieve during concrete placement with pile
placed and plumbed in center of drilled hole
– Tremie seal
The drilled hole is advanced beyond the depth of caving and backfilled
with typically a 3-sack slurry mix and allowed to set overnight. The
hole is then re-drilled the following day through the 3-sack slurry,
which essentially cases the hole. This procedure may need to be
repeated within the same hole to achieve the necessary pile tip
elevation.
– Suspend drilling until the Class 3 concrete backfill arrives. The final
drilling is then advanced, hole is cleaned, and the pile quickly placed,

Caltrans ● Foundation Manual H - 21

 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

plumbed, and secured, and then the hole is quickly backfilled with
Class 3 concrete before caving continues. If the caving proceeds
before the concrete can be placed, use of either a casing or a tremie
seal will be necessary.
High groundwater infiltration
• Again, Contractor is in driver’s seat
• Refer to Contractor’s Pile Placement Plan for contingencies
• Verify settling tank is of sufficient capacity to contain water pumped from
hole

F. Soldier Pile Installation

1. Lowering pile:
• Assure soldier pile is slowly lowered into drilled hole
• Prevent pile from hitting side of drilled hole causing caving
2. Setting pile:
• Verify tip elevation is achieved
• Verify pile clears bottom of drilled hole – 75 mm (3 inches) is adequate
• Verify web of pile is aligned with reference points
• Verify pile is centered on Retaining Wall Lay Out Line - RWLOL
3. Plumb pile:
• Once the pile is properly placed vertically, the contractor normally rests
two channels on the ground beside the drilled hole and clamps them to
each flange of the pile to suspend the pile in the drilled hole during
concrete placement

G. Class 3 Concrete (Backfill)

1. With pile set note top of pile elevation and determine cut to top of Class 3
Concrete (Backfill)
2. Verify solider piling remains plumb, aligned, and on RWLOL as concrete
backfill is placed.
3. Carefully monitor level of Class 3 concrete backfill to prevent over-filling
drilled hole beyond level required for bottom lagging course
NOPC WARNING!
Error on placing the Class 3 concrete backfill on the low side of the bottom
lagging course elevation
• Class 3 Concrete (Backfill) too high?
• Extra work required to chip out the concrete
• The prime contractor may file a NOPC
• Therefore keep the Class 3 concrete backfill on the low side

H. Lean Concrete Backfill

1. Completely fill balance of drilled hole to prevent a safety hazard.

I. Welding
SAFETY

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 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

Avoid eye contact during stud welding/field welding operations

1. Concrete anchors:
• Welder Qualification
- Assure Contractor’s personnel have been qualified by concrete
anchor/welding equipment supplier for horizontal position for concrete
anchor placement
• CWI inspection required
2. Double pile systems:
• Welding of shims takes place after placement and grouting of tiebacks.
• CWI inspection required
3. Welding Quality Control Program
• CWI need not be onsite during anchor placement, however must inspect
and accept anchors prior to commencement with reinforcing steel
placement
• Structure Representative or Assistant should follow-up CWI’s inspection –
even a CWI has been prone to overlook an unacceptable anchor.
• File all CWI inspection reports within Category 42

J. Painting
1. Shop Prime:
• Inspected by METS in fabricator’s facility
2. Finish Coats:
• Verify temperature and humidity are acceptable for paint application
- Refer to paint manufacturer’s technical data sheets
• Assure minimum dry film thickness will be achieved
- Spot check wet film thickness as paint is applied
• Application of second coat is delayed by over seven days:
- Contractor required to pressure wash surface prior to second finish
coat application

IX. PROJECT COMPLETION/ AS BUILTS

A. As-Built Drawings
1. Changes to pile tip elevations
2. Indicate upon log of test borings deviations from subsurface conditions
indicated including presence of groundwater

B. Completion of Report of Completion - Bridges DS-OS C3

1. Soldier piling source and supplier
2. Stud connectors source and supplier
3. Paint system, manufacturer and supplier.

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 _____________________________________________Appendix H
November 2008

APPENDIX

Case Study- Soldier Pile Wall

with Tieback Anchors
Contract No. 04-1S2724 04 - SM - Rte 84 - PM 10.2
Soldier Pile Wall with Tieback Anchors (7.7 km west of Rte 35).
Completed in June 2004. $850,000.00.
Hwy 84 runs through the Santa Cruz Mountains in San Mateo County. The forested hills
form a ridge that separates the Pacific Ocean from San Francisco Bay and from Santa
Clara Valley. Hwy 84, along with Hwy 1, 9, 17, and 35, are continuously being
improved because of unstable slopes and erosion.
Project 04-1S2724 specified a soldier pile wall with tieback anchors. The wall prevents
further erosion of the slope adjacent to a creek. The design specified 44 soldier piles with
timber lagging. Two rows of tieback anchors are connected to concrete walers. A
concrete barrier slab and concrete barrier with chain link fence is on top of the wall.

Soldier Pile Wall with Tieback Anchors within two concrete walers. Date: June 2004.
Fiber rolls placed along slope for erosion control. Photo by D. Dait, P.E., Sr Br Engr

Caltrans ● Foundation Manual Tieback Anchors - 1

APPENDIX H-24
 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

Soil Nail Construction Checklist

GENERAL OVERVIEW

Soil nails provide a means to reinforce and strengthen an existing soil structure in order
to achieve a slope face steeper than the natural angle of repose. Soil nails provide tensile
reinforcement for soils that typically exhibit low tensile strength. They are termed
“passive inclusions” as they are not pre-tensioned but rather simply grouted in place
along their full embedment into the ground. Tensile forces develop within soil nails as
active failure planes develop in the soil mass reinforced by the soil nails. The soil nails
are designed with sufficient embedment depths to adequately transfer the tensile stresses
developed by the active soil mass pressures back into stable soil structures behind the
active failure planes.

Common applications of soil nails include but are not limited to:
• Temporary shoring walls.
• Permanent walls into cut slopes and bridge abutment fill slopes for roadway
widenings.
• Slope stabilization measures.

Construction of soil nail walls commonly follow or closely follow the following
sequence:

Excavation by lifts from the top of slope, downward (i.e., “top-down” construction) to
depths generally limited by some dimension below the horizontal level of each row of
soil nails.

Drilling for, insertion of, and grouting of soil nails.

Placement of geocomposite drain material in between soil nails.

Placement of welded wire fabric across surface of excavated lift and continuous
reinforcing steel above and below row of soil nails and application of shotcrete to
construct a temporary shoring of the excavated embankment slope.

Embedment into the wet shotcrete of anchor plates upon soil nails to transfer lateral
active soil pressures from the shotcrete facing into soil nails.

Completion of sub-drainage system at base of soil nail wall.

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 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

Construction of a permanent cast-in-place wall facing affixed to anchor plates embedded

into the shotcrete temporary shoring.

I. SOURCES OF TECHNICAL INFORMATION

A. Foundation Manual:
1. Chapter 11 – Tiebacks, Tiedowns, and Soil Nails.
2. Appendix H – Tiebacks, Tiedowns, and Soil Nails.
• Construction Checklist

B. “Soil Nailing Field Inspectors Manual”:

Federal Highway Administration Publication No. FHWA-SA-93-068
Very extensive technical publication focusing on the inspection of soil nail wall
construction and the resolution of common problems encountered in the process.

II. SOURCES OF PROJECT SPECIFIC INFORMATION

A. Structures Pending File:

1. Foundation Report:
• Review recommended lengths for each soil nail level beyond the
Retaining Wall Layout Line - RWLOL.
• Note any comments concerning anticipated soil nail constructability
problems:
Caving, presence of boulders, groundwater problems.
• Structure Rep should verify Foundation Report comments regarding
specifications or design features are incorporated into the Contract
Documents.
2. Designer’s notes.

B. Information Handout:
1. Local, Regional, State, and Federal regulatory and permit specific
requirements:
• Focus review on regulatory requirements/restrictions related to Structures
contract items.

III. CONTRACTURAL REQUIREMENTS

A. Contract Special Provisions:

1. Section 5. General:
• Section 5-1._ Local Agency/State Parks/DFG/RWQCB/USACOE
Requirements:
Review requirements for all local, regional, State, and Federal regulatory
agencies having jurisdiction over the work and note potential impacts to
structures related work.
2. Section 8. Miscellaneous:

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 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

• Section 8-2. Concrete:

Shotcrete requirements – 375 kg/m3 cementious material– Class 1.5
concrete
3. Section 10. Construction Details:
• Water Pollution Control Program – WPCP.
• Designated Waste Handling – if applicable.
• Water Pollution Control.
• Designated Waste Handling – if applicable:
Of importance if potential for subsurface contaminated soils exists.
• Soil Nail Wall Earthwork.
• Soil Nail Assembly.
• Geocomposite Drain.
• Shotcrete.

B. Contract Plans:
1. General Plan & Elevation:
• Check stationing, grades, and bearings with District layout plans.
2. Typical Section:
• Note inclination angles for various soil nail levels.
• Note offset distances to RWLOL.
3. General Notes:
• Note Ultimate Bond Stress σb for pullout test load determination.
4. Structure Plans/Elevations:
• Note top and bottom wall elevations.
• Note/check dimensioning and stationing with General Plan.
• Check continuity of grades and stations at match lines between sheets.
5. Foundation Plans:
• Review against District layout, utility, and drainage plans.
• Check for conflicts and required coordination with other agencies.
6. Soil Nail Details:
• Note dimensions from RWLOL to face of shotcrete/wall excavation.
• Test soil nail assembly detail:
Note required embedment and bonded lengths.
• Production soil nail assembly detail:
Note required embedment lengths for various soil nail levels.
• Drainage Details:
Note geocomposite drain placement with respect to soil nail locations.
7. Soil Nail Layouts:
• Note soil nail spacings and dimensions from top and bottom of finished
wall.
Combine with Structure Plans/Elevations to develop cut sheets for soil nail
installations.
• Note test soil nail assembly locations.
8. Log of Test Borings – LOTB:
• Review LOTBs’ with respect to wall layout line and soil nail
locations/elevations – the data provided may be extrapolated over the full
depth of the soil nails extending into the hillside.

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 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

C. Standard Specifications:
1. Section 19: Earthwork:
• Section 19-3 Structure Excavation and Backfill.
2. Section 50: Prestressing Concrete:
• Section 50-1.09 Bonding and Grouting.
3. Section 52: Reinforcement.
4. Section 53: Shotcrete.
5. Section 88: Engineering Fabrics.

IV. JOB BOOKS SET-UP

A. Category 12 – Contractor’s Submittals:

NOTE: Contact Documents Unit ASAP!
e-mail Manjit Sandhu at the Documents Unit as soon as possible with your latest
office address/location and telephone number to avoid any unnecessary delays in
receiving submittals for review and comment back to the design engineer.
1. Soil Nail Earthwork Drawing Submittals.
2. Soil Nail Working Drawing Submittals.

B. Category 20 – Contractor’s Water Pollution Control Program.

C. Category 37 – Initial Tests and Acceptance Tests:

1. Refer to BCM 4-5.4.
2. Include:
• Test Soil Nail testing results.
• Grout tests.
• Shotcrete tests.

D. Category 41 – Reports of Inspection of Material:

1. Includes METS Source Inspections, Field Release of Materials, Certificates of
Compliance
2. Refer to BCM 4-5.6
3. Include:
• Soil Nails.
• Bearing plates, couplers, beveled washers.
• Geocomposite drain material.
• Sub-drainage piping materials.
• Welded wire fabric.
• Reinforcing steel.

E. Category 43 – Concrete and Reinforcing Steel

1. Include:
• Grout mix designs.
• Shotcrete mix designs.

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 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

V. PRE JOB DISCUSSION WITH DESIGN & GEOLOGY/GEOTECHNICAL

A. Establish contacts with Structures Design and Geotechnical Services:

1. Structures Design (SD) Contacts:
Specifications – Look for RCE Stamp at beginning of Specials
Plans – Engineer of record on Plans.
2. Geotechnical Services Contact:
Name and phone number should be at bottom of Foundation Report.

B. Discuss/resolve any concerns developed either during review of project specific

information, or as a result of preliminary site investigations.

VI. PRE CONSTRUCTION MEETING WITH CONTRACTOR

A. Remind Contractor of his responsibility to submit soil nail earthwork drawings,

soil nail working drawings, Water Pollution Control Program measures related to
soil nail installations, grout mix designs, and shotcrete mix designs in a timely
manner to allow sufficient time for review/comment/approval by the Structure
Representative.

VII. SUBMITTAL REVIEWS

A. Soil Nail Earthwork Drawings:

1. SD responsibility to approve with Structures review/comment.
2. Review with respect to soil nail installations.
3. Verify excavation restrictions are specified.

B. Soil Nail Working Drawings:

1. Memo to Designers 5-14, “Review of Working Drawings for Tieback
Anchors” applies for soil nails as well:
• “The responsibility for checking working drawings is shared by the
Designer and the Structure Representative”.
2. Verify:• Conformity with Construction Plan Soil Nail Details.
• Stressing equipment calibrated by METS within 1 year of intended use on
the project.
• Ram proposed for testing is properly sized:
Lower 10% of rated capacity not used for testing• Contingencies
specified should difficult drilling/soil nail installations develop.
• Testing loads specified agree with Plans/Special Provisions requirements.
• Embedment lengths for production and test soil nails meet minimum
lengths specified upon the Structures Soil Nail Details.
• Bonded lengths for test soil nails meet minimum lengths specified upon
the Structures Soil Nail Details.
• Repair procedures for damaged epoxy coatings.
• Centralizers and spacing are noted.

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 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

C. Grout Mix Designs:

1. Section 50-1.09 of Standard Specifications.

D. Shotcrete Mix Designs:

1. Section 53-1.02 of Standard specifications

E. Contractor’s Water Pollution Control Program:

1. District responsibility to approve with Structures review/comment.
2. Verify regulatory/agency permit requirements w/in Section 5 of SPs’ are
addressed:
• Containment of groundwater pumped from soil nail drilled holes.
• Containment of grout during soil nail grouting operations.

VIII. CONSTRUCTION

A. Construction Sequence:
1. Excavation by lifts from top of slope downward – i.e., “top-down”
construction.
2. Drilling, insertion, and grouting of production and test soil nails.
3. Placement of geocomposite drains between soil nails.
4. Placement of welded wire fabric over face of excavation.
5. Placement of continuous reinforcing bars along soil nail row.
6. Application of shotcrete for temporary shoring of slope.
7. Embedment of bearing plate over soil nails into shotcrete.
8. Testing of soil nails.9. Construction sequence repeats to bottom of wall.
10. Completion of sub-drain collection system from geocomposite drains.
11. Placement of permanent wall facing.

B. Layout:
1. Review staking request with Contractor prior to submittal.
2. Structures Representative responsible for initial line and grade for
embankment excavation and soil nail installations.
3. Establish additional references for horizontal and vertical as top-down
construction progresses using:
• Soil nails.
• Re-bar embedded into shotcrete.

C. Delivery/Storage of Materials:
1. Soil Nails:
• Check epoxy coating and encapsulation for any damage.
• Refer to repair procedure within the Contractor’s Soil Nail Working
Drawings.
2. Centralizers:

Caltrans ● Foundation Manual H - 30

 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

• Verify centralizers adequately support soil nail bar in center of drilled

hole.
• Verify centralizers for different drilled hole diameters are delivered if the
Contractor’s Soil Nail Working Drawings indicate a potential for different
sized holes.

D. Equipment Mobilization:
1. Note and photograph all equipment mobilized to jobsite:
• Drill rig, augers, and casings.
• Grout plant, pumps, and compressors.
• Testing equipment.
• Settling tank, pumps, hoses – condition of hoses.
2. Verify all equipment mobilized conforms to Contractors soil nail working
drawing submittal.

E. Materials Inspection, Sampling, & Testing:

1. Initial and acceptance tests – Category 37:
• Grout tests:
Verify <2% air per Ca Test 504.
Verify initially 90 mm penetration per Ca Test 533.
• Shotcrete tests:
Gradations and SE – daily production.
Compressive strength–Average of three cores:
Every 30 m2 of wall area placed.
2. Field Releases – Category 41:
• Field inspect and release on form DH-OS C53, the following materials:
Soil nails.
Bearing plate assemblies.
• Certificates of Compliance are required for the following items:
Soil nails, encapsulation PVC, epoxy coatings.
Bearing plate assemblies.
Couplers.
Beveled washers.
Geocomposite drain.
Sub-drain piping.
Re-bar, welded wire fabric.
Cement.
3. Materials Certifications – Category 41:
• Mill certs required for:
Soil nails.
Fabricated steel assemblies.
Couplers.
Beveled washers.
Re-bar and welded wire fabric.

Caltrans ● Foundation Manual H - 31

 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

F. Soil Excavations:SAFTY CONCERNS:

Review OSC Code of Safe Practices – Drilling Tiebacks and Soil Nails:
• Section IV – Excavations.
• Section XVII – Earthwork:
Stay away from vertical cut slopes.
• Note signs of soil distress.
• Note changes in soil structures.
• Maintain eye contact with excavation equipment operator.
1. Monitor embankment excavation noting:
• Potential unstable soils:
Cohesionless sands and gravels.
Saturated soils.
• Unstable soils may not remain stable over period of exposure prior to
shotcrete placement.
• Perched groundwater day lighting at face:
Could affect curing of shotcrete.
• Excavation limits below soil nail levels do not exceed depth permitted by
Special Provisions.
Potential Problems:
Embankment collapse:
• Caused by disturbed or poor soil conditions.
• Solutions differ by circumstances:
Flash excavated face with shotcrete:
Not always practical.
Segmental slot excavations.
Cut back bank to stable slope.
Groundwater day lighting at face of cut:
• Solutions include:
Place additional geocomposite drain material.
Embankment collapse behind wall above:
• Solutions differ by circumstances:
Shotcrete up into cavity
Not always practical
Erect plywood forms and apply shotcrete against plywood
Core shotcrete at cavity and pump controlled fill material

G. Drilling:
1. Requires full-time inspection:
• Begin logging holes immediately – don’t wait for Contractor to file a
claim.
• Compare drill tailings (spoils) with information contained upon LOTBs’.
• Note productivity rates for drilling advancement, soil conditions, presence
of groundwater at given drilling depth/elevation.
• Note locations exhibiting poor soils.
• Use high-powered spotlight or mirror to observe soil structure over full
depth of drilled hole.
• Note any potential problem soils areas.

Caltrans ● Foundation Manual H - 32

 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

• Verify actual hole depth and actual drilled diameter to estimate grout
volume to assure soil nails are being fully grouted.
2. Test Soil Nails:
• Adjust location shown on plans or require additional test soil nails if
necessary to test poor soil conditions.
• Measure actual diameter for test load determination.
• Verify adequate depth is achieved and hole is cleaned prior to soil nail
installation.
• Note hole depth and with actual drilled diameter, determine required
grout volume and cut-off of grout to assure the specified bonded length
for test nails is accurately achieved.
Potential Problems:
Rocks or boulders are encountered within drilled holes:
• Submitted/approved soil nail working drawings should address.
• Amend as necessary in writing prior to proceeding.
• Contractor is contractually on notice within “SOIL NAIL ASSEMBLY”
of the Contract Special Provisions:
On notice to anticipate and be prepared for difficult drilling conditions.
For encountering rocks and boulders, down hole pneumatic hammer drill
rigs and drill bits should be employed.
Drilled holes caving:
• Usually not detected until soil nail installation is attempted.
• Submitted/approved soil nail working drawings should address.
• Amend as necessary in writing prior to proceeding.
• Caving in dry holes:
Casing system advancing with drilling auger.
• Caving in wet holes:
Casing system, or tremie seal:
3-sack slurry & re-drill 24 hours later. Differing Site Condition – DSC:
• High potential for DSC during soil excavation and drilled hole activity.
• Contractor is contractually on notice to anticipate and be prepared for
difficult excavation and drilling conditions.
• Difficult conditions should be addressed within the submitted/approved
soil nail earthwork and working drawing submittals:
Amend as necessary in writing prior to proceeding

H. Soil Nail Installations:

1. Prior to installation:
• Verify drilled hole depth and cleanliness.
• Ensure centralizers are properly installed and secured to soil nails.
2. During installation:
• Verify centralizers do not gouge into soil.
Potential Problem:
Centralizers rut bottom of drilled hole.
• Results in bar not being centered in hole.
Solution:

Caltrans ● Foundation Manual H - 33

 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

• Use 150 mm length of CHPEP cut in half as a trough to slide nail down
hole – withdrawing trough cleans out remaining drilling spoils.

I. Soil Nail Grouting:

1. Where holes exceed 150 mm in diameter special provisions allow fine
aggregate added to grout mix:
• Cement content is not less than 600 kg per cubic meter.
2. Grout tests:
• 2% air per Ca Test 504.
• 90 mm penetration per Ca Test 533:
Only on initial trial batch
3. Grouting equipment:
• Check equipment for wear.
• Review Water Pollution Control Program for grouting operations:
Address WPCP/Regulatory permit requirements.
Prevent run-off into drainage structures & natural courses.
4. Requires full-time inspection:
• Verify grout tube is fully inserted into hole.
• Ensure grout tube remains embedded within advancing grout to avoid air
pockets.
Potential Problems:
Soil nails pushed into hole during grout tube insertion.
Soil nail bending at face of drilled hole.
Solution:
• Tie soil nail to welded wire fabric prior to grouting.
5. Test Soil Nails:
• Verify actual limits of grout placement to determine actual bonded length
for each individual test soil nail.
6. Grout Volume Determinations:
• Have contractor pump one stroke of grout into a wheelbarrow or other
suitable container and measure. Note number of pump strokes per nail
grouted and compare with estimated volumes.

J. Shotcrete Application:
1. Shotcrete functions as temporary shoring prior to final facing.
2. Method of application can affect performance:
• Apply in horizontal lifts along length of exposed cut to avoid sloughing.
3. “Wet set” bearing plate over soil nails to obtain flush bearing upon shotcrete.

K. Soil Nail Testing:

SAFETY:
• Static nature of testing/stressing belies danger of forces involved
• Hold a special safety meeting prior to testing including:
All assistants and District personnel who may be working in the area
• Topics to cover include:
“OSC Code of Safe Practices – “POST TENSIONING OPERATIONS.
• Prestress Manual – “SAFETY.”

Caltrans ● Foundation Manual H - 34

 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

• Emphasize avoiding path of forces being applied.

• Inspect pumps and hoses for excessive wear.
1. Testing is normally conducted against the shotcrete wall facing.
2. Testing equipment:
• Hydraulic ram, pump, and pressure gauges:
Must be calibrated by METS annually.
• Device capable of measuring movement of soil nail to 0.025mm. (English)
• Use temporary bearing yoke to avoid punching shear through shotcrete:
Verify bearing area will not distress shotcrete.
3. Test Loads:
• Pullout test loading is specified within the Special Provisions:
• Commonly specified as: M = k * σb * D where:
M = the maximum pullout test load.
k = a constant provided within the Specials.
σb = ultimate bond stress provided within the General Notes within the
Structures Construction Plans.
D = actual diameter of drilled hole for test nail, in meters.
• Verify the constant, k, agrees with the basic equation:
M = π * D * Lb * σb * F.S. where:
Lb = bonded length as specified upon the plans.
F.S. = factor of safety – typically 1.5 for pullout.
• NOTE:
Careful monitoring of the actual drilled hole diameter and embedment
length is essential to accurately verify successful testing of the soil/cement
bond. If a test soil nail embedment length is excessive, require of the
Contractor to apply a test load determined by the basic equation.
4. Testing procedure:
• Install temporary bearing yoke over nail against shotcrete
Verify uniform bearing against shotcrete.
• Place ram and loading plate over nail and install coupler and bring ram up
to alignment load.
• Ensure ram is aligned along axis of soil nail.
• Commence with loading sequence.
5. Loading sequence:
• Test load applied in 0.1 increments of M.
• Load at 0.7M held for 10 minutes.
• Each loading increment applied within 1 minute and held for no more than
2 minutes (except 0.7M loading).
• Movement for each load increment is noted and recorded on Contractor’s
supplied test data sheet.
6. 10 minute load hold at 0.7M:
• Movement recorded at 1,2,3,4,5,6, and 10 minutes.
• Total movement < 2 mm @ 10 minutes?:
Incremental test loading continues to M.
• Total movement > 2 mm @ 10 minutes?:
0.7M load maintained for additional 50 minutes.
Movement recorded at 15,20,25,30, 45, and 60 minutes.

Caltrans ● Foundation Manual H - 35

 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

Incremental test loading continues to M unless failure occurs.

7. Test acceptance criteria:
• Successful testing is achieved whenever the pullout test load M is
achieved without:
Continuous movement of test soil nail, and
Movement in excess of 50mm.
• Soil Nail Test Records:
Contractor to complete.
Forwards to Structures Representative.
File within Category 37.
Forward copy of results to Geotechnical Services – if requested to do so.
Potential Problems:
Test Soil Nail fails:
• Notify Geotechnical Services contact immediately, forwarding test results.
• Exhume test nail to asses cause of failure:
Bond length not fully grouted:
Install new test nail and re-test.
Solutions differ depending upon degree of failure:
• Design and Geotechnical Services should take lead on course of action.
• Augment wall with additional soil nails.
• Deepen existing nails:
Use couplers to utilize existing nails:
Not always practical – easement restrictions, poor soil conditions, etc.
• Perform a secondary fracture grouting around the existing bonded length:
An alternative when bond values are lower than those estimated.
Additional expense as extra work – requires a Contract Change Order.
Requires drilling and installing grout tubes to inject the grout.

L. Onward and Downward:

1. Next level of excavation cannot proceed until wall area directly above is
structurally complete:
• Structurally completeness:
Soil nail assemblies installed.
Shotcrete cover has set.
Testing has been satisfactorily completed and results have been
furnished to Structures Representative.
2. Maintain a minimum 3 meter spacing between wall areas not structurally
complete and subsequent lower level excavations:
• Normally not a concern as Contractor typically completes one continuous
level of wall at a time, returning to the opposite end of the wall for the
next subsequent lower level.

IX. PROJECT COMPLETION/AS-BUILTS

A. As-Built Drawings:

Caltrans ● Foundation Manual H - 36

 _________________Appendix H – Tiebacks, Tiedowns & Soil Nails
November 2008

• Indicate limits for any grout, controlled fill material, or shotcrete where
backfilled behind shotcrete walls at slip-out areas.
• Indicate locations of actual and any additional test soil nails installed.
• Indicate locations of any additional production nails installed.

Caltrans ● Foundation Manual H - 37

 Appendix IH– Soil Nail Wall
November 2008

APPENDIX

Case Study - Soil Nail Wall

Contract No. 04-1123C4
04-SM - Rte 1- KP 61.2/62.2
Soil Nail Wall (South Rock Cut) near Devil’s Slide.
Construction began in Spring 2005 and finished Spring 2006.

Description of Work:
The South Rock Cut Soil Nail Wall project, located in San Mateo County between the
City of Pacifica and town of Montara, is part of the overall Devil’s Slide Tunnel and
Bridge work.

The large “rock-cut” at the Tunnel’s south portal area is planned to align the highway and
to provide adequate site distance. The face of the large rock-cut is designed to match the
appearance of existing rock-cuts in the immediate view.

The South Rock Cut wall consists of a soil nail wall. The soil nail wall is composed of
two walls separated by a 25m concrete barrier. Total length of walls is 281m (RW No. 2
is 190m long, RW No. 1 is 91m long). The soil nail assembly pay item equals 18, 860
meters.

Retaining Wall #2. Shotcrete sculpting at northern end of wall.

Photo by Ann Meyer, P.E., Structure Representative. Photo Date: Feb.24, 2006.

Caltrans ● Foundation Manual South Rock Cut - 1

Appendix H-38
 Appendix H-39

Drilltech drilling top row of nails at Wall #2. Test Drilltech shooting next section of initial shotcrete at
nail installed between two nails. 8/09/05 Wall #1. 8/11/05

Soil nail getting ready to be installed in a drilled hole. Drilltech crew installed 12” geocomposite drain strips
Grouting lower nail w/1” PVC grout tube. 8/04/05 between nail columns.

PROJ/RTE/PM: 04-SM-Rte1-KP 61.2/62/2 South Rock Cut Soil Nail Wall Date: 2005/2006
PROJECT NO. 04-1123C4 Photos by Ann Meyer, P.E., Structure Representative Photo Page 1
 Appendix H-40

GNB installing tieback walers at temporary shoring GNB begins hand excavation at Wall #1. 7/01/05
wall at Wall #1. 6/28/05

Drilltech begins drilling at Wall #2. 8/04/05 Drilltech installing soil nails with forklift at top row of
Wall #2. 8/05/05

PROJ/RTE/PM: 04-SM-Rte1-KP 61.2/62/2 South Rock Cut Soil Nail Wall Date: 2005/2006
PROJECT NO. 04-1123C4 Photo Page 2
 Appendix H-41

Drilltech workers shotcreting at Wall #1. 8/04/05 Northern end of Wall #2, sculpted. 03/21/06

Southern end of Wall #1, after staining complete. Type 60D barrier being installed at Wall #2. 03/21/06
Matches existing geology and color well. 04/18/06

PROJ/RTE/PM: 04-SM-Rte1-KP 61.2/62/2 South Rock Cut Soil Nail Wall Date: 2005/2006
PROJECT NO. 04-1123C4 Photo Page 3
 _____________________Appendix I – Cofferdams and Seal Courses
November 2008

APPENDIX

I Cofferdams and Seal Courses

Table of Contents

Thickness of Seal Course I-2

Widths of Seal Course I-3
Example of Seal Course Thickness Calculation I-4

Caltrans ● Foundation Manual I-1

 _____________________Appendix I – Cofferdams and Seal Courses
November 2008

Caltrans ● Foundation Manual I-2

 _____________________Appendix I – Cofferdams and Seal Courses
November 2008

Caltrans ● Foundation Manual I-3

 _____________________Appendix I – Cofferdams and Seal Courses
November 2008

Caltrans ● Foundation Manual I-4

 __________________ Appendix J – Micropile/Alternative Pile
November 2008

APPENDIX

J Micropiles/Alternative Piles

Table of Contents

Nicholson Pin Pile J-2

Tubex Grout Unit J-3
GeoJet Foundation Unit J-4
Specification Example - Micropiles for Earth Retention J-5
Case Study – Micropile Retaining Wall Foundation J-13
Case Study - Micropile - Seismic Retrofit J-17
Case Study – Micropile Retaining Wall Foundation (Devil’s Slide) J-21

Caltrans ● Foundation Manual J-1

 __________________ Appendix J – Micropile/Alternative Pile
November 2008

Caltrans ● Foundation Manual J-2

 __________________ Appendix J – Micropile/Alternative Pile
November 2008

Caltrans ● Foundation Manual J-3

 __________________ Appendix J – Micropile/Alternative Pile
November 2008

Caltrans ● Foundation Manual J-4

 __________________ Appendix J – Micropile/Alternative Pile
November 2008

Specification Example - Micropiles

for Earth Retention
Contract No. 04-1S2804
04 - SON - Rte116, PM 3.2
Duncan’s Mills Retaining Wall
Construction completed in 2007.

Description of Work:
The micropile retaining wall was constructed along the eastbound shoulder of Highway
116 in Sonoma County and separates the roadway from the Russian River, which flows
west approximately 15-ft below the road surface. The wall consists of a reinforced
concrete cap beam and curtain wall supported on micropiles. The face of the curtain wall
has an architectural surface (textured shotcrete). Type ST-30 bridge rail (modified) is on
top of the wall. The length of the wall is approximately 300-ft long. The 100 micropiles
are 12-inch diameter with steel pipes installed to a depth of 50-ft and spaced 3-ft on
center with another set of 100 piles set at an angle to form a buttress to stabilize the soil
and the roadway. Inclinometers (slope indicators) were installed in six micropiles.

Construction Issues:
Pile production was slow at the western end of the wall due to the hard rock conditions.
At another location along the wall, a loose sand and ground water contributed to the
caving of the drilled hole during drilling and while waiting for the holes to be grouted.

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 __________________ Appendix J – Micropile/Alternative Pile
November 2008

Cap beam construction. Photo from Jim Cook, Sr Br Engr

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November 2008

Sample - CONTRACT SPECIAL PROVISIONS

10-1.32 PILING
GENERAL
Piling shall conform to the provisions in Section 49, "Piling," of the
Standard Specifications, and these special provisions.
Unless otherwise specified, welding of any work performed in
conformance with the provisions in Section 49, "Piling," of the Standard
Specifications, shall be in conformance with the requirements in
AWS D1.1.
Foundation recommendations are included in the "Information
Handout" available to the Contractor as provided for in Section 2-1.03,
"Examination of Plans, Specifications, Contract, and Site of Work," of the
Standard Specifications.
Attention is directed to "Welding" of these special provisions.
Difficult pile installation is anticipated due to the presence caving
soils, rocks, serpentine materials, tidal flow fluctuation, high ground
water, the requirement of pile embedment into rock, sound control and
traffic control.

MICROPILING
Micropiling consisting of steel pipe NPS 8 double extra strong and
epoxy coated bar reinforcing steel that is grouted in place shall conform
to the design requirements and layout shown on the plans and these
special provisions.

Materials
Double extra strong steel pipe shall conform to the requirements of
ASTM Designation: A53, Grade B. Galvanized pipe is not required.
The stud connectors shall conform to the provisions in Section 55,
"Steel Structures," of the Standard Specifications and these special
provisions.
Stud connectors shall be Type B as defined in AWS D1.5, Section 7.
Grout shall be non-shrink type. Grout shall conform to the provisions
in Section 50-1.09, "Bonding and Grouting," of the Standard
Specifications. Fine aggregate may be added to the grout mixture of
Portland cement and water used outside of the grouted sheathing in
drilled holes which are 200 mm or greater in diameter, but only to the
extent that the cement content of the grout is not less than 500 kg per
cubic meter of grout. Fine aggregate, if used, shall conform to the
provisions in Section 90-2, "Materials," and Section 90-3, "Aggregate
Gradings," of the Standard Specifications.
Epoxy-coated reinforcement shall conform to the provisions in Section
52, "Reinforcement," of the Standard Specifications.

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November 2008

Working Drawings
The Contractor shall submit complete project specific working
drawings for the micropile system to the Office of Structure Design (OSD)
in conformance with the provisions in Section 5-1.02, "Plans and Working
Drawings," of the Standard Specifications. Working drawings for
micropiling shall be 559 mm x 864 mm in size. For initial review, 10 sets
of drawings shall be submitted. After review, between 6 and 12 sets, as
requested by the Engineer, shall be submitted to (OSD) for final approval
and use during construction. Within 3 weeks after final approval of the
working drawings, one set of the corrected prints on 75-g/m sq.
(minimum) good quality bond paper, 559 mm x 864 mm in size, prepared
by the Contractor, shall be furnished to (OSD).
Working drawings for micropiling shall show the State assigned
designations for the contract number, bridge number, full name of the
structure as shown on the contract plans, and District-County-Route-
Kilometer Post on each drawing and calculation sheet. The pile vendor
company name, address, and phone number shall be shown on the
working drawings. Each sheet shall be numbered in the lower right
corner and shall contain a blank space in the upper right corner for future
contract sheet numbers.
Working drawings for micropiles shall contain all information
required for the construction and quality control of the piling, including
the following:

A. Information on space requirements for installation equipment that

verify that the proposed equipment can perform at the site.
B. Step-by-step procedure describing all aspects of pile installation
including personnel, testing, and equipment to assure quality
control. This step-by-step procedure shall be shown on the
working drawings in sufficient detail so that the Engineer can
monitor the construction and quality of these micropiles.
C. Details for drilling a plumb and battered hole.
D. Details of centralizers.
E. Grout mix designs.
F. Details and procedures involved in testing components, including
grout.
G. Pipe and reinforcement splice locations.
H. Details of equipment and operation for grouting. Details shall be
included for monitoring grout quality, volume installed, and
pressure during installation.
I. Information on the minimum cure time and strength requirements of the
pile system.
J. Proposed method for casing installation and removal when
necessary.

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A supplement to the working drawings shall include the following:

A. Construction details, structural details, and load test results from

at least 3 previous successful installations by the proposed
micropile vendor. The installations shall be from 3 separate test
sites. The installations shall be similar to those proposed for this
contract.
B. Methods of removal and disposal of excavation, slurry, and
contaminated water, including removal rates.

The working drawings and supplement shall be stamped and signed by

an engineer who is licensed as a Civil Engineer in the State of California.
The Engineer will notify the Contractor in writing when the submitted
working drawings and supplement have been determined to be complete.
The Contractor shall allow the Engineer 30 working days to review the
working drawing submittal after a complete set has been received.
No micropile shall be installed until the Engineer has approved, in
writing, the working drawing submittal for micropiling.
Should the Engineer fail to review the complete working drawing
submittal within the time specified, and if, in the opinion of the Engineer,
the Contractor's controlling operation is delayed or interfered with by
reason of the delay in reviewing the working drawing submittal, an
extension of time commensurate with the delay in completion of the work
thus caused will be granted in conformance with the provisions in Section
8-1.09, "Right of Way Delays," of the Standard Specifications.

Construction
Drill cuttings resulting from installing micropiling shall be disposed of
in conformance with the provisions in Section 19-2.06, "Surplus
Material," of the Standard Specifications. Material resulting from
grouting micropiles shall be disposed of in conformance with the
provisions in Section 7-1.13, "Disposal of Material Outside the Highway
Right of Way," of the Standard Specifications, unless otherwise permitted
in writing by the Engineer.
Drilling mud or chemical stabilizers shall not be used.
Foreign material dislodged or drawn into the hole during construction
of the micropiles shall be removed. Loose material existing at the bottom
of the hole after drilling operations are complete shall be removed prior to
placing grout.
Steel pipe NPS 8 double extra strong and epoxy coated bar reinforcing
steel shall be installed using centralizers as shown on the plans.
The pipe shall be placed vertically and grouted in place. Grout shall
be injected at the bottom of the pile and may be placed before or after
placing the steel pipe.

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 __________________ Appendix J – Micropile/Alternative Pile
November 2008

A positive means of support shall be provided for maintaining the

position of the steel pipe NPS 8 double extra strong and epoxy coated bar
reinforcing steel until the grout has set.

INCLINOMETER MONITORING SYSTEM

General
The Contractor shall furnish and install an inclinometer monitoring
system consisting of slope inclinometer casing at the location shown on
the plans. The Contractor shall use a specialist to design and oversee
installation of the instrumentation system.
The Contractor shall submit to the engineer working drawings and a
construction sequence for the proposed method of installation of the
micropile monitoring system construction for the site, at least 10 weeks
prior to the planned micropile installation. The drawings shall include all
product documentation and specifications for the proposed slope
inclinometer casings, strain gauges, wiring, conduit and data logging
system, including the name of the manufacturer’s design and oversight
specialist or representative. The drawings shall conform to the provisions
in Section 5-1.02, “Plans and Working Drawings,” of the Standard
Specifications. One set of the drawings, construction sequence, and
product specifications shall be furnished to the Engineer. The working
drawings and construction sequence shall include, but not be limited to,
defining order of work, traffic control, method of installation of
inclinometer casings, strain gauges and data logging system, method of
testing system prior to pile installation, and method of grouting the pile.
The Contractor shall allow six weeks after complete drawings and all
support data are submitted for the review and approval of the proposed
method of micropile wall construction.
Should the Engineer fail to complete the review and approval within
the time allowance and if, in the opinion of the Engineer, the Contractor’s
controlling operation is delayed or interfered with by reason of the delay
in working drawing and construction sequence plan review and approval
for the micropile wall, the delay will be considered a right of way delay in
conformance with the provisions in Section 8-1.09, "Right of Way Delays,"
of the Standard Specifications.

Inclinometer Casings
The Contractor shall furnish and install a total of 6 vertical slope
inclinometer casings complete with caps centered inside locations shown
on the plans. The inclinometer casings shall be non-metallic with an
outside diameter of approximately 70 millimeters. Centralizers shall be
used to position the casing along the center axis of each micropile. The
casing shall be installed prior to the grouting of the micropiles. The grout
shall conform to the requirements specified in "Micropiling" elsewhere in
these special provisions. At the Contractor’s option, inclinometer casings

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 __________________ Appendix J – Micropile/Alternative Pile
November 2008

may be of the type manufactured by either of the following companies or

equal:

Geokon, Inc. Roctest

48 Spencer Street P.O. Box 3556
Lebanon, NH 03766 Champlain, NY 2919-3568
(603) 448-1562 (877) 762-8378
www.geokon.com www.roctest.com

Durham Geo Slope Indicator

2175 West Park Court
Stone Mountain, GA 30087
(770) 465-7557

These inclinometers, once installed, shall be monitored and data

processed by the CalTrans Instrumentation unit.
The Contractor shall allow a maximum of 7 working days for the
Engineer to install the inclinometer system, in the location shown on the
plans, immediately prior to pouring concrete at the location.

MEASUREMENT AND PAYMENT (PILING)

Measurement and payment for the various types and classes of piles
shall conform to the provisions in Sections 49-6.01, "Measurement," and
49-6.02, "Payment," of the Standard Specifications and these special
provisions.
Micropiles will be measured and paid for by the meter.
The contract price paid per meter for micropile shall include full
compensation for furnishing all labor, materials, tools, equipment, and
incidentals, and for doing all the work involved in constructing micropiles,
including drilling, providing temporary casings, double extra strong pipe,
grout, epoxy coated bar reinforcement, cutting tips, drill bits, pile
anchorage, and disposing of materials resulting from pile installation,
complete in place, as shown on the plans, as specified in the Standard
Specifications and these special provisions, and as directed by the
Engineer.
No payment will be made for micropiles which are damaged either
during installation or after the micropiles are complete in place. No
payment will be made for additional excavation, backfill, concrete,
reinforcement, nor other costs incurred from footing enlargement
resulting from replacing rejected micropiles.
The contract lump sum price paid for the inclinometer monitoring
system, shall include full compensation for furnishing and installing slope
inclinometer casings, including drilling, grout, providing temporary
casings, installing studs, disposal of material, and any additional required
appurtenances; and for all labor, materials, tools, equipment, and

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 __________________ Appendix J – Micropile/Alternative Pile
November 2008

incidentals and for doing all the work involved in submitting the
construction sequence plans, as shown on the plans, as specified in the
Standard Specifications and these special provisions, and as directed by
the Engineer.

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November 2008

Case Study – Micropile

Retaining Wall Foundation
Contract No. 12-043214
12-ORA-74 PM 13.3/16.6
Route 74 Widening Project (Anchored Walls)
Construction began in 2007.

Description of Work:
The structure work to be done consists, in general, of constructing thirteen anchored
shotcrete retaining walls founded on micropiles. The anchored shotcrete walls are
founded on steel pipe micropiles and capped with concrete barrier slabs and concrete
barriers. Architectural treatment applied includes sculptured shotcrete at various walls
and stain application at all walls.

The project site is located on Route 74 (Ortega Highway), between the Orange/Riverside
county line and San Juan Creek Bridge. Route 74 is a two-lane highway cut into the side
of the Santa Ana Mountains along the San Juan Creek valley. The existing roadway
consists of substandard 3.05-meter (10-ft.) lanes and no shoulders.

The purpose of the project is to bring the lanes to the standard 3.66-meter (12-ft.) width
with 1.2-meter (4-ft.) shoulders on each side and to increase the sight distance for this 5.3
kilometers of roadway. Since the existing roadway is cut into the mountains, it is
necessary to cut further into the mountains, build viaducts, or add retaining walls on the
downhill (north) side of the road in many locations. A total of 20 structures (13 anchored
retaining walls, 3 sidehill viaducts, and 4 retaining walls) are planned throughout the
project limits. The anchor walls will be supported on micropiles.

Structure Representative Comments:

The drilling operation and drilling conditions are difficult, however, the drilling is being
completed rapidly. The solid rock is between 9,000 and 15,000 psi, the fractured rock is
even more difficult to drill because it has a tendency to cave in and jam the drill stem.
The time required to drill a 50-ft deep (6-inch) anchor is approximately 1 hour. The time
needed to drill a 21-ft deep, 12-inch diameter micropile is about 1.25 hrs.

There are several factors affecting the anchored wall (rock anchor and micropile) drilling
operation.

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 __________________ Appendix J – Micropile/Alternative Pile
November 2008

1) The experience of the drilling contractor.

2) The suitability of the equipment used.
3) The material characteristics of the earth at the site.

Drilling has been difficult. The "specialty" drilling subcontractor, required by the
Contract Special Provisions (documentation of 3 previous similar and successful
installations), was directed to leave the job due to lack of performance. The project
special provisions also required the drilling to be done with minimal deleterious effects
(airborne drilling dust) to the sensitive "environmental area" and endangered species
(Arroyo Toad) in the creek 50 feet from the wall construction area. The constraints of the
work area, the requirement to maintain the road open to traffic, requiring the drilling
subcontractor to work at night, combined with the need to capture all dust, caused the
drilling subcontractor to throw in the towel and cease operations. The drilling
subcontractor had equipment that may or may not have been able to complete job.

The prime contractor is currently performing the drilling and had never done any drilling
prior to this project. The contractor purchased an Austrian made Triton drilling machine
that was designed to drill vertical blast holes for mining operations and redesigned and
modified it to drill horizontally. The machine creates a hole using a pneumatic hammer
and has the capability of capturing drill cuttings as well as using water to minimize dust.
The rig is used for installing both the 6-inch anchor holes 50 feet deep into hard and
fractured rock and the 12-inch micropile holes.

(Comments and project photos from Victor S. Francis, P.E.)

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 __________________ Appendix J – Micropile/Alternative Pile
November 2008

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 __________________ Appendix J – Micropile/Alternative Pile
November 2008

Micropile (NPS 8-XX Strong Steel Pipe) in a 300-mm dia drilled hole.
On the ground - Sections of Rock Anchors to be installed later. Date: 2007

Total wall length = 753 ft. The area is mostly comprised of very hard rock
croppings. The road, Rte 74, is open to traffic. Date: 2007

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November 2008

Case Study - Micropile

Seismic Retrofit
Contract No. 04-0438U4 04-CC,Mrn-580-6.1/7.8,0.0/2.6
Seismic Retrofit of the Richmond-San Rafael Bridge (Br. No. 28-0100)
Work started August 2001; work completed February 2004.

Description of Work:
The Richmond-San Rafael Bridge is one of the toll bridges in the San Francisco Bay
Area. The Richmond-San Rafael Bridge includes two single deck reinforced concrete
approach trestle, two steel plate girder approach structures which convert from single-
deck to double deck at each end of the bridge, two variable-depth, double-deck,
cantilever-truss-type structures and 38 constant-depth 289 foot span, double-deck trusses
which span between the two cantilever spans and between the cantilever spans and the
approach structures. The structure has a combined length of approximately 21,335 feet.

The bridge work on this project consisted of, in general, the replacement of the concrete
trestle portion and the seismic retrofit on the rest of the structure. The seismic retrofit
included constructing 481 micropiles in the substructure. The micropiles were driven
underwater.

Per the contract special provisions, micropiles (substructure) were specified to consist of
small diameter steel pipe reinforcement grouted in place and conforming to the design
requirements and layout shown on the plans and the special provisions.

(Photo from Caltrans Office of Geotechnical West Photo Gallery)

Caltrans ● Foundation Manual J - 17

APPENDIX J-18
 California Department of Transportation
Division of Maintenance

Structure Maintenance and Investigations

B RIDGE

I NSPECTION

R ECORDS

I NFORMATION

S YSTEM

The requested documents have been generated by BIRIS.

These documents are the property of the California Department of Transportation

and should be handled in accordance with Deputy Directive 55 and the State
Administrative Manual.

Records for “Confidential” bridges may only be released outside the Department of
Transportation upon execution of a confidentiality agreement.

APPENDIX J-19
 APPENDIX J-20
ClibPDF - www.fastio.com
 __________________ Appendix J – Micropile/Alternative Pile
November 2008

Case Study – Micropile Retaining

Wall Foundation (Devil’s Slide)
Contract No. 04-1123U4 04-SM-1 KP 61.2/64.9
South Portal Retaining Wall No.1 (retaining wall on micropiles) was completed in 2007.

Description of Work:
On Hwy 1, San Mateo County near the City of Pacifica in the San Francisco Bay Area,
construction was completed in 2007 on the South Portal Retaining Wall No. 1, a
retaining wall supported on micropiles. The retaining wall is on a steep cliff facing the
Pacific Ocean. On one portion of the wall, the micropiles are battered in opposite
directions providing lateral support. The retaining wall is also supported laterally with
tieback anchors and with anchor bars connected to an anchor beam. On top of the wall is
a concrete railing with chain link fence. A pedestrian sidewalk runs parallel to the
concrete railing.
The South Portal Retaining Wall No. 1 is part of the overall work to re-align Route 1 at
the south portal of the Devil’s Slide Tunnel. The micropile wall was placed to provide a
future parking lot and a turn-around when the tunnel is complete. In addition, the wall
provides valuable work space for construction (i.e., haul road and construction yard)
without closing Hwy 1 during the tunnel construction.
Total length of wall: 103-meters.
Total micropiles: 144 piles
Length of pile: 7.5m (piles 1 thru 36); 10.0m (piles 37 thru 144);
Construction Issues / Comments:
Comments from Peter Lam, P.E., Assistant Structure Representative:
- The micropiles were ConTech Titan System piles.
- The micropile contractor was Condon-Johnson & Associates.
- Specs required non-shrink grout, but normal grout was allowed.
- CT Foundation Testing Branch (FTB) specified pull tests into zones. Testing was by
FTB. The specs required non-shrink grout, which hydrates quicker and cost 2 to 3 times
more than regular grout. Regular grout is the industry standard for micropile installation.
Initially, the CT Geotechnical designer felt comfortable waving the load test requirement
if non-shrink grout was used. However since regular grout was used, load testing was
required. The test results came out great with little or no movement. The CT
Geotechnical designer speculated that a grout beam was created below grade due to the
piles being spaced so closely.
- In some areas, soft soil caused grout bubbling through adjacent piles; the excess grout
probably formed a grout curtain.

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 __________________ Appendix J – Micropile/Alternative Pile
November 2008

- Micropile operation is very messy operation; proper SWPPP measures are needed.
- Pile production/installation was approximately 1 pile per 30 to 40 minutes

Comments from Jeremy Light, Assistant Structure Representative:

- The original wall design did not provide enough embedment in the retaining wall for
wind load stability. The revised design specified a spread “L” footing that provided the
proper stability.
- The addition of the footing to the structure satisfied the wind load requirements and
enabled the Contractor to backfill the wall prior to anchor rod (Sta. 1+00 to 1+36) & tie-
back installation (Sta. 1+36 to 2+03). Tiebacks were installed from the outside of the wall
with a reach-over drill rig. The plans called for temporary supports (Sta 1+36 to 2+03) to
temporarily retain the wall during backfill operations and the footing satisfied this.
Installing the tiebacks from behind the wall and using them for temporary supports was
considered but tieback testing and working around the exposed tendons during the
backfill operation proved to be an inefficient method of construction. The designer
initially wanted tie-backs installed & tested behind the wall but it was brought up that the
tendons would be compromised by 'bite' marks from the wedges as well as the exposure
of the tendons during the construction operations (a temporary waler was called out in the
specs to achieve this; impractical with the geometry of the site). Following this, Design
proposed installing three sacrificial tendons for testing, but this proved to be a problem
with again, the issue of providing a temporary waler to support the tieback loads. This
was the main construction issue of this project…”How do we build it?”. The addition of
the footing, at a cost to the State in this case, proved to be a good solution.

Sketch -Revised Wall Design – “L” Footing.

Caltrans ● Foundation Manual J - 22

 Site photo, facing south. South Rock Cut Retaining Wall Foreground: battered micropiles, facing south.
(soil nail wall with sculptured face) on the upper left. Background: Pacific Ocean.

Drilling/installing micropiles. Pacific Ocean in the Battered micropiles. Facing north.

background.
PROJ/RTE/PM: 04-SM-1 KP 61.2/64.9 South Portal Retaining Wall No.1 Date: July 2007
PROJECT NO. 04-1123U4 (Micropiles) Photos by D.Dait, Sr Br Engr. Photo Page J-23
 Lifting micropile pipe into place. Drilling and flushing.

Adding another section of pipe (hollow treaded bar with Checking top of pile elevation with a laser level (grout
coupler). Grout hose is in front of the man on the left. hose is blocking view of the survey rod).
PROJ/RTE/PM: 04-SM-1 KP 61.2/64.9 South Portal Retaining Wall No.1 Date: July 2007
PROJECT NO. 04-1123U4 (Micropiles) Photo Page J-24
 Assembled micropile components (Con-Tech Titan Laborer assembling the micropile components (Con-Tech
System): drill head, pipe (TITAN bar), pipe coupler. Titan System): drill head, pipe (Titan bar), & pipe

Holes are used for grout flushing. When each micropile has been
drilled to depth, it is withdrawn back up then redrilled in a reaming
motion to flush out the drill cuttings and increase scouring of the grout
flush. Scouring creates a very rough, irregular shaped grout body
with a much greater mechanical connection to the soil, providing
greater pull-out resistance and lower settlement characteristics.
(Source: Ischebeck Titan brochure)
Drill bit / drill head with holes. Short section of pipe (Titan hollow threaded bar).
PROJ/RTE/PM: 04-SM-1 KP 61.2/64.9 South Portal Retaining Wall No.1 Date: July 2007
PROJECT NO. 04-1123U4 (Micropiles) Photo Page J-25
 Left: Crawler mounted drill rig w/hydraulic rotary percussive Grout mixer. Grout is pumped to the micropile drill rig.
head; hose grout hose on left. Right: excavator.

Forklift. Background: South Rock Cut Retaining Wall (soil Cement sacks covered with plastic.
nail wall with sculptured face)

PROJ/RTE/PM: 04-SM-1 KP 61.2/64.9 South Portal Retaining Wall No.1 Date: July 2007
PROJECT NO. 04-1123U4 (Micropiles) Photo Page J-26
 Micropile load test performed by Hydraulic jack and measuring device.
Foundation Testing Branch.

Hydraulic jack and caliper. (rotated view) Recording measurements using auto-level.
PROJ/RTE/PM: 04-SM-1 KP 61.2/64.9 South Portal Retaining Wall No.1 Date: July 2007
PROJECT NO. 04-1123U4 (Micropiles) Photo Page J-27
 Storm Water Pollution Prevention Plan (SWPPP). Right: SWPPP: grout settlement container / concrete washout
grout settlement container. Left: mobile tank and pump. container.

SWPPP: laborer is creating a check dam at each drill location Portable pump used to pump excess grout and drill cuttings
to prevent grout and drill cuttings from covering next pile into settlement containers. Behind pump is silt fence and
location. rolled straw.

PROJ/RTE/PM: 04-SM-1 KP 61.2/64.9 South Portal Retaining Wall No.1 Date: July 2007
PROJECT NO. 04-1123U4 (Micropiles) Photo Page J-28