AS 3798—2007

(Incorporating Amendment No. 1)

AS 3798—2007

Australian Standard®

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 This Australian Standard® was prepared by Committee CE-027, Earthworks. It was approved
on behalf of the Council of Standards Australia on 11 December 2006.
This Standard was published on 12 March 2007.

The following are represented on Committee CE-027:

• AUSTROADS
• Association of Consulting Engineers Australia
• Association of Geotechnical Testing Authorities (Qld)
• Australian Building Codes Board
• Australian Geomechanics Society
• Institute of Public Works Engineering Australia
• National Association of Testing Authorities Australia
• University of New South Wales
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This Standard was issued in draft form for comment as DR 05390.

Standards Australia wishes to acknowledge the participation of the expert individuals that
contributed to the development of this Standard through their representation on the
Committee and through the public comment period.

Keeping Standards up-to-date

Australian Standards® are living documents that reflect progress in science, technology and
systems. To maintain their currency, all Standards are periodically reviewed, and new editions
are published. Between editions, amendments may be issued.
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Standards may also be withdrawn. It is important that readers assure themselves they are
using a current Standard, which should include any amendments that may have been
published since the Standard was published.

Detailed information about Australian Standards, drafts, amendments and new projects can
be found by visiting www.standards.org.au

Standards Australia welcomes suggestions for improvements, and encourages readers to

notify us immediately of any apparent inaccuracies or ambiguities. Contact us via email at
mail@standards.org.au, or write to Standards Australia, GPO Box 476, Sydney, NSW 2001.
 AS 3798—2007
(Incorporating Amendment No. 1)

Australian Standard®

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your on-line service. Guidelines on earthworks for commercial
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Originated as AS 3798—1990.
Third edition 2007.
Reissued incorporating Amendment No. 1 (August 2008).
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COPYRIGHT
© Standards Australia
All rights are reserved. No part of this work may be reproduced or copied in any form or by
any means, electronic or mechanical, including photocopying, without the written
permission of the publisher.
Published by Standards Australia GPO Box 476, Sydney, NSW 2001, Australia
ISBN 0 7337 8096 2
 AS 3798—2007 2

PREFACE
This Standard was prepared by the Standards Australia Committee CE-027, Earthworks, to
supersede AS 3798—1996.
This Standard incorporates Amendment No. 1 (August 2008). The changes required by the
Amendment are indicated in the text by a marginal bar and amendment number against the
clause, note, table, figure or part thereof affected.
The objective of this Standard is to provide guidance to those responsible for or involved in
the design, specification, supervision and control testing of earthworks for commercial and
residential developments.
This Standard is a guideline, which is an informative document only.
A1

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 3 AS 3798—2007

CONTENTS

Page

SECTION 1 SCOPE AND GENERAL

1.1 SCOPE ........................................................................................................................ 5
1.2 TERMS AND DEFINITIONS ..................................................................................... 5
1.3 DESIGNATION OF PERSONNEL ............................................................................. 7

SECTION 2 INVESTIGATION, PLANNING AND DESIGN ................................................ 8

SECTION 3 DOCUMENTATION
3.1 GENERAL ................................................................................................................ 12
3.2 INVESTIGATION AND PLANNING ...................................................................... 12
3.3 DESIGN AND SPECIFICATION ............................................................................. 12
3.4 CONSTRUCTION..................................................................................................... 13
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3.5 SITE RECORDS ....................................................................................................... 14

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SECTION 4 MATERIALS
4.1 GENERAL ................................................................................................................ 15
Please note4.2thatMATERIALS
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SOURCED ON SITEvia our on-line subscription 15services is
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not intended4.3forUNSUITABLE
off-line storage,
MATERIALSand such storage is contrary to15the
...................................................................................
4.4 SUITABLE MATERIALS......................................................................................... 16
licence under which the service is supplied.
SECTION 5 COMPACTION CRITERIA
5.1 GENERAL ................................................................................................................ 17
5.2 COMPACTION OF SOILS ....................................................................................... 17
5.3 PLACEMENT MOISTURE CONTENT ................................................................... 19
5.4 COARSE MATERIAL .............................................................................................. 19
5.5 TEST ROLLING ....................................................................................................... 20
5.6 OTHER MATERIALS .............................................................................................. 20
5.7 TRENCHES .............................................................................................................. 20

SECTION 6 CONSTRUCTION
6.1 SITE PREPARATION............................................................................................... 21
6.2 FILL CONSTRUCTION ........................................................................................... 23

SECTION 7 METHODS OF TESTING

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7.1 GENERAL ................................................................................................................ 26

7.2 FIELD DENSITY ...................................................................................................... 26
7.3 ESTABLISHMENT OF A REFERENCE DENSITY FOR CALCULATION OF
RELATIVE COMPACTION ..................................................................................... 26
7.4 SAMPLE SELECTION FOR REFERENCE DENSITY............................................ 27
7.5 USE OF DIFFERENT TEST PROCEDURE ............................................................. 27
7.6 PERMISSIBLE OVERSIZE ...................................................................................... 27
7.7 PREPARATION OF LABORATORY REFERENCE DENSITY SAMPLES ........... 27

SECTION 8 INSPECTION AND TESTING

8.1 GENERAL ................................................................................................................ 29
8.2 LEVEL 1 INSPECTION AND TESTING ................................................................. 29
8.3 LEVEL 2 SAMPLING AND TESTING .................................................................... 29
8.4 GEOTECHNICAL INSPECTION AND TESTING AUTHORITY (GITA) .............. 30
8.5 GEOTECHNICAL TESTING AUTHORITY (GTA) ................................................ 30
8.6 STATEMENTS OF COMPLIANCE ......................................................................... 30
8.7 FREQUENCY OF TESTING .................................................................................... 30
 AS 3798—2007 4

APPENDICES
A REFERENCED DOCUMENTS ................................................................................ 32
B TYPICAL SITE RECORD SHEETS ......................................................................... 34
C STATISTICAL METHODS IN EARTHWORKS ..................................................... 40
D SUITABILITY OF COMPACTION EQUIPMENT FOR VARIOUS TYPES OF
FILL MATERIALS ................................................................................................... 42

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 5 AS 3798—2007

STANDARDS AUSTRALIA

Australian Standard
Guidelines on earthworks for commercial and residential developments

SECT ION 1 SCOPE AND GENERA L

1.1 SCOPE
This Standard provides guidance on the specification, execution, and control testing of
earthworks and associated site preparation works for commercial and residential
developments. This Standard does not in itself constitute a specification for earthworks and
the specifier should consider the applicability of these guidelines to the project under
consideration.
This document hasis not
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intended toTo access
be used the major
for pavements, current document,
roadworks, please go to
or water-retaining
your on-line service.
structures. Such works require special consideration.

Please note that material

Residential developments accessed
in the context of via our on-line
this Standard subscription
are intended services is
to include single lot
development up to broad acre subdivisional development for detached or semi-detached
not intended for The
housing. off-line
Standardstorage, andto such
is not intended storage
be sufficient is contrary
for medium- to the
or high-density
residential development without due consideration by a suitably qualified professional.
licence under which the service is supplied.
Historically, previous editions of this Standard have been used to assist in the specification
and execution of earthworks beyond the intended scope of the document. Whilst with due
consideration some aspects of this Standard may be applicable to such works, designers and
specification writers should be aware the guidance given herein may not be applicable. In
such circumstances, appropriate advice should be sought from a suitably qualified
professional before adopting this Standard.
Where the depth of filling required for works to which this Standard would otherwise be
applicable exceeds 5 m, advice from a geotechnical professional should be sought.

1.2 TERMS AND DEFINITIONS

For the purpose of this Standard, the definitions below apply.
1.2.1 Cohesionless soil
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Poorly graded sand and gravel mixture, generally with less than 5% fines (i.e., particles
finer than 75 µm diameter), which is non-plastic and which does not exhibit a well-defined
moisture-density relationship when tested in accordance with AS 1289.5.1.1 or
AS 1289.5.2.1.
1.2.2 Cohesive soil
Material that has a well-defined moisture-density relationship when tested in accordance
with AS 1289.5.1.1 or AS 1289.5.2.1.
NOTE: This may include well-graded granular materials such as crushed rock.
1.2.3 Collapsing soil
Soil that may suffer a significant decrease in volume under load or when it becomes nearly
saturated, which may have existed in this metastable state for a long period.

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 AS 3798—2007 6

1.2.4 Compaction
The process whereby the density of a soil mass is increased by mechanical, usually
dynamic, means. This typically involves tamping, rolling, impact or vibration, or a
combination of these processes. This process results in a relocation of the soil particles and
in the expulsion of air from the soil mass, usually without significantly altering the amount
of water in the soil.
1.2.5 Consolidation
The process by which water, and sometimes air, is expelled from a soil mass over time due
to the action of an imposed static stress and causes settlement.
NOTE: The terms compaction and consolidation are not interchangeable and consolidation should
not be referred to in earthworks specifications.
1.2.6 Dispersive soil
Soil that has the ability to pass rapidly into suspension in the presence of water.
1.2.7 Foundation
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structure; thus,
the foundation for a fill is the stripped surface and a fill itself can be a foundation for a
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building.
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compaction technique, and which has been used
for the assessment of the relative compaction of an area of work.
1.2.9 Pavement material
Material that is used in the construction of pavements.
NOTE: Pavement material is generally granular and often manufactured from hard rock sources
(e.g., crushed rock).
1.2.10 Reactive soil
Clay soil, for which a change in moisture content results in a sufficient change in volume to
affect the engineering performance of any structure in contact with it.
1.2.11 Relative compaction
1 For cohesive soils, the dry density ratio determined in accordance with
AS 1289.5.4.1, or the Hilf density ratio determined in accordance with AS 1289.5.7.1.
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2 For cohesionless soils, the density index determined in accordance with

AS 1289.5.6.1.
1.2.12 Rockfill
Fill composed almost exclusively of fragments of broken rock. It generally consists of a
large portion of gravel and larger sized fragments, and may contain large open voids.
1.2.13 Structural fill
Any fill that will be (or may be), required to support structures or associated pavements, or
for which engineering properties are to be controlled. Sometimes referred to as controlled
or engineered fill.
1.2.14 Subgrade
The earth material on which it is proposed to construct a pavement. This is often taken as
being to a depth of 300 mm below the level from which the formal pavement is constructed.

© Standards Australia www.standards.org.au

 7 AS 3798—2007

1.2.15 Topsoil
A surficial soil containing some organic matter, usually darker than the underlying soils.

1.3 DESIGNATION OF PERSONNEL

For the purpose of this Standard, the following terms are relevant:
(a) The owner—sometimes referred to as the proprietor or the principal.
(b) The designer.
(c) The geotechnical professional—a person suitably qualified and experienced in
geotechnical principles as applied to earthworks.
(d) The superintendent—the principal’s authorized person, sometimes referred to as the
engineer or the architect.
(e) The constructor—sometimes referred to as the contractor or the builder.
(f) The geotechnical inspection and testing authority (GITA)—an organization that
should be used for the inspection and testing as detailed in Section 7 and Section 8.
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(g) The geotechnical testing authority (GTA)—an organization that should be used for the
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testing as detailed in Section 7 and Section 8.
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 AS 3798—2007 8

SECT ION 2 I NVEST I G AT I ON, P L A NN I NG

AND DES I GN
The investigation, planning and design for projects involving earthworks require the
designer give consideration to those factors that may affect the works. Before site works are
commenced, some or all of the following details may need to be taken into account:
(a) Approvals The precise terms of approval of the project by relevant authorities,
including local government and heritage, planning and environmental protection
agencies, can influence the execution of the works.
The necessity to obtain approvals will extend to off-site locations, such as borrow
areas and haul routes.
(b) Services Inspections, in conjunction with the relevant authority where necessary, to
locate existing and proposed public utility services, which may be affected by or
A1 affect the works. Written requirements, in respect of such services, should be
obtained from each relevant authority.
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(c) Adjoining property Examination to assess whether there is a potential for damage
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due to vibration, excavation, filling, noise, run-off, dust or other effects of the
earthworks, and liaison with the adjoining owners.
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(d) Regulations Working hours on site, warning signs, fencing or security requirements
not intended for
and off-line
emanations storage,
from the siteand such
including dust,storage
water, silt,isnoise
contrary
or smoke,to
arethe
licence under controlled
which by the service
regulations. is regulations
These supplied. are in addition to the civil rights of
adjoining owners and the public.
(e) Preservation items Surveys necessary to identify and locate aboriginal or historic
relics, heritage items or rare flora or fauna, which may require preservation or
relocation.
(f) Rehabilitation Rehabilitation of areas affected by construction activities such as
borrow pits, stockpiles, excavated or fill batters, spoil disposal areas, haul routes,
stormwater control, camp, office and workshop sites, should be included in the
drawings and specifications so that materials such as topsoil, mulched native
vegetation (which can contain useful seedstock and nutrients) and bulk fill materials
used for rehabilitation are identified and preserved for re-use. Rehabilitation works
should be completed before the constructor vacates the site.
(g) Drainage Temporary or permanent diversion of permanent or ephemeral
watercourses prior to or during construction of the earthworks and associated works
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may affect the quantity or quality, or both, of the stormwater run-off. Therefore,
special provisions may be necessary to minimize the effects and to protect the legal
rights of adjacent and downstream landowners. Failure in providing for such
provisions could lead to litigation and delay in completion of the earthworks project.
Approval from the relevant authorities should be obtained prior to either the
placement of fill on flood-prone lands or construction of drainage structures, i.e.,
culverts in natural watercourses.
The placement of fill or construction of cuts may impact the flow of subsurface water
and may lead to localized instability. Special provisions may be necessary to account
for the potential effect of the works in this situation.
(h) Erosion and siltation Protection of the earthworks from erosion, both during
construction and after construction, needs to be taken into account. Run-off from the
works, and areas affected by the works, may be subject to special provisions (see
Item (g) above).

© Standards Australia www.standards.org.au

 9 AS 3798—2007

(i) Sloping ground Special precautions where the earthworks are constructed on sloping
ground include—
(i) benching of the surface of the natural ground to assist in the placing of the fill
and to key the fill to the foundation soil;
(ii) berms or benches above, within, or at the foot of cuts to intercept stormwater
run-off or detritus; and
(iii) special works.
(j) Slope stability The basis for the assessment of the short- and long-term stabilities of
natural slopes, cut-face slopes and fill slopes is—
(i) local experience with similar materials under similar conditions; or
(ii) geotechnical investigation and analysis.
Each stability assessment needs to take into account any existing slopes, proposed
undercut and surcharge of the slopes and the effect of water seepage on the slopes.
Each slope should be selected with regard to the required access, including
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maintenance, e.g., mowing.
(k) Zoning Zones for fill may be designated by specific locations and levels within the
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earthworks. The bases for the selection of fill within zones are—
Please note that
(i) material
easily compactedaccessed viastructures,
fill near existing our on-line subscription
to minimize services is
the compactive effort
not intended for off-line storage,
and consequent and such storage is contrary to the
risk of damage;

licence under (ii)

which the
granular fill service
in areas that is
maysupplied.
become wet during compaction;
(iii) fill containing large fragments, i.e., rock or building rubble, not within the top
600 mm or at greater depth if trenches are to be constructed for footings or
services, or piers or piles have to penetrate the fill; and
(iv) saline fill not within the top 600 mm where vegetation may be established.
(l) Soft or compressible foundation soils Soft or compressible soils do not form a good
foundation on which to place and compact fills, and may need to be excavated.
Alternatively, fill (which is readily compactable) may be placed in the lower levels of
the earthworks immediately above such soils. Geosynthetics or some other ground
improvement techniques may also be considered (see Item (v)).
To minimize displacement of such soils during construction, the earthworks should be
programmed to avoid unnecessary loading of the foundation, e.g., appropriate routing
of fill haulage equipment or stage construction.
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The calculation of quantities needs to take into account the effect of compression of
the foundation soils.
(m) Reactive soils The moisture content of reactive soils after compaction of fills should
approximate the estimated long-term moisture content, which may be about the same
as the moisture content for the undisturbed reactive soils at or about the depth of
seasonal influence.
(n) Low density or potentially collapsing soils Low density or potentially collapsing
soils lose volume when compacted in or beneath the earthworks. Calculation of
quantities needs to take into account the effect of compression of the fill or
foundation, or both.
(o) Existing filled ground Existing filled ground, for which the conditions of the
placement are not adequately documented as described in Clause 3.4, should not be
assumed to be either of the standard of compaction or of the composition adequate to
support fill or any other loads.

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 AS 3798—2007 10

Site investigations, which may include test pits, test bores, test rolling (see
Clause 5.5), or other methods, are necessary to assess the degree of compaction and
composition of the existing filled ground. Analysis of the results obtained from these
investigations will allow an assessment of the adequacy of the existing filled ground
or the extent of remedial works that may be required. Such remedial works could
include complete removal.
(p) Non-potable water The suitability of non-potable water for increasing the moisture
content of fill should be evaluated by field and laboratory trials. Saline waters should
not be used—
(i) in the upper layers of fill, beneath either bituminous sealed pavements or areas
where vegetation may be established; and
(ii) in fill where steel is buried.
(q) Trenches Excavations for trenches require special consideration for support.
Relevant authorities place limitations on the maximum depth to which trenches may
be excavated without shoring.

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moisture content the current
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laboratory methods is only a guide for field construction, as the optimum moisture
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content for compaction under field conditions will depend on the material type,
equipment used, the layer thickness and the nature of the foundation. In general, the
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heavier the compaction effort or the thinner the layer, the lower the optimum moisture
not intended for off-line
content. storage,
Increased andmay
compaction effort suchcausestorage is contrary
the soil to approach saturationto
andthe
higher densities may not result.
licence under which the service is supplied.
(s) Surcharging of slopes Cut face and fill slopes, sides of trenches and slopes
supported by retaining walls should not be loaded, e.g., by construction equipment,
materials, soil and the like, unless the assessment of the slope stability (see Item (j))
included an allowance for particular load(s).
(t) Calculation of quantities In calculating quantities of fill, the following should be
taken into account:
(i) Volume changes due to excavation, spreading and compaction.
A1 NOTE: The degree of volume change is dependent on the type and geological origin of
the material and required relative compaction. It can be assessed as part of the site
investigation, using field density tests and laboratory compaction tests.
(ii) Compression of the foundation (see Items (l) and (n)).
(u) Physical separation of dissimilar materials Filters, comprising material of selected
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particle size distribution and geosynthetics (see Item (v)), may be used to avoid the
mixing of materials after placement. Filters and geosynthetics are used to avoid—
(i) soft materials being forced into voids of granular material; or
(ii) erosion of fine material into adjacent granular material.
(v) Geosynthetics Proprietary products are available with particular properties suitable
to act as a filter, drainage layer and/or physical separator to allow water flow whilst
avoiding migration of soil particles or as a tensile reinforcement layer. Such materials
may be construction expedients, or may form part of the permanent earthworks.
Geosynthetics should be carefully chosen for the intended purpose and have an
adequate service life under the intended conditions.
(w) Vibration Construction activities, particularly those using equipment such as
compactors or blasting, may cause vibrations that could damage nearby structures,
either directly (due to the vibration transmitted to the structure) or indirectly (for
example, by causing settlement of the foundations).

© Standards Australia www.standards.org.au

 11 AS 3798—2007

(x) Contamination Any known or suspected ground or groundwater contamination

should be investigated. Relevant authorities have set limits on the quantity of
contaminants permitted in ground, in various applications. Removal of contaminated
soil from the site is likely to require special consideration, such as classification.
Similarly, allowing contaminated soil to be imported or to remain on site may require
approval from the relevant authority. The impact of any investigation on planned
earthworks, including safety and environmental aspects, should be considered.
(y) Retaining walls The compaction of fill against retaining walls may induce higher
pressures than adopted in the design. The nature of the fill to be used, the specified
level of compaction, and the type of compaction equipment to be used, should be
assessed in selecting design fill loads on retaining walls.
(z) Potential acid sulfate soils In certain areas, particularly in coastal marine deposit
areas, the presence of considerable amounts of iron sulfates is possible. Disturbing or
exposing these soils to air may cause the formation of sulfuric acid. Excavation and
movement of such soils are subject to strict environmental controls that normally
expect chemical treatment to avoid contamination of streams and drains. Consultation
with the relevant environmental authority is required prior to the excavation or use of
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such soils.
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A1 service.
NOTE: For sampling and investigation of soil for iron sulfate content, see AS 4482.1.

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 AS 3798—2007 12

SECT ION 3 DOCUMEN TAT I ON

3.1 GENERAL
This Section includes details of the documentation for the design and construction of an
earthworks project.

3.2 INVESTIGATION AND PLANNING

Investigations for the planning of earthworks for use by the designer, the constructor and
other interested parties should include the following:
(a) Outline of the need for, and objectives of, the project.
(b) Site investigation of the project and any associated sites, covering, where applicable,
the—
(i) condition of the site(s) including—
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present uses, To access
i.e., buildings and the current
vegetation; and document, please go to
your on-line service.(B) evidence of past uses, i.e., demolition, filling and vegetation;
Please note that
(ii) material
foundation andaccessed via our on-line subscription services is
subgrade materials;
not intended for
(iii) off-line storage,
special areas and such
due to groundwater, seepage, storage
rock, reactiveisandcontrary to the
collapsing soils;

licence under (iv)

which thefillservice
available iswhere
materials and, supplied.
applicable, details of the overburden;
(v) suitability of the fill materials for the intended purposes;
(vi) classification of materials to be removed off site;
(vii) availability of suitable pavement materials;
(viii) quantity and quality of the available water; and
(ix) suitability of water for the placement of the fill.
(c) Where applicable, an outline of other plans that have been considered in the
investigation. This should include the points discussed in Section 2.
(d) The quality assurance requirements for the project.

3.3 DESIGN AND SPECIFICATION

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The functional requirements of the design should be documented in the specification and
drawings for the earthworks project. This documentation should be sufficiently complete to
allow the constructor to unambiguously carry out the works, and for the superintendent (and
the geotechnical inspection and testing authority, as necessary) to be able to interpret the
design and administer the contract.
Such documentation will typically include (or have consciously excluded), the following, as
well as any other matters that may be of particular importance to the particular project:
(a) Adequate specification and drawings to allow the proper pricing, planning, execution
and supervision of the works. Plans, sections and elevations should clearly show areas
of earthworks, identifying areas requiring specific treatments. Particularly on larger
projects, the specification and drawings should adequately define the following:
(i) The areas in which spoil may be dumped or stockpiled.
(ii) Restrictions on clearing and stripping.
(iii) Drainage requirements during and after construction.

© Standards Australia www.standards.org.au

 13 AS 3798—2007

(iv) Criteria for selection of materials for placement in various parts of the fill and
for material to be excluded from fill. Material descriptions should be clear,
unambiguous and in accordance with AS 1726.
(v) Criteria for standard of surface trim of completed earthworks.
(vi) Details of tests, including minimum frequency, to be carried out for testing to
ensure the fill complies with the specified criteria.
(vii) The scope of the commission to be given to the geotechnical inspection and
testing authority (see Clause 1.3).
(viii) Either the methods to be used for construction or the requirements to be met by
test in the finished project. It is generally unwise to mix performance and
method specifications. Where a performance specification is adopted,
restrictions on methods should be limited to those absolutely necessary (for
example, to limit the risk of damage to nearby structures).
(b) Site investigation information, including that given in Clause 3.2(b), together with
details of, and provision for, access to any further relevant information for the
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purpose of design or construction planning. Selective provision of available site
investigation data can give rise to serious problems, either engineering or legal, or
your on-line service. both, and should not be done without due consideration of the issues involved. An
overview of the issues is given in a monograph on this subject.*
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(c) Any other relevant information in the possession of the designer.
not intended for off-line storage, and such storage is contrary to the
licence under which the service is supplied.
3.4 CONSTRUCTION
Adequate records need to be kept during construction, including conditions encountered,
works as executed, testing and any alterations to the specification and drawings. As a
minimum, these records should show the following:
(a) The areas in which fill is placed.
(b) Levels after stripping.
(c) Location of any trees or large shrubs that may have been removed.
(d) Materials exposed after stripping and the criteria upon which the decision to cease
stripping was made.
(e) Levels after completion of the filling.
(f) Details of test rolling, if undertaken.
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(g) Types of fill material in various zones.

(h) Sources of fill material in various zones, where applicable.
(i) Location and level of each compliance test, together with test results. Where a test is
a retest of a lot that was previously rejected, this should be stated.
(j) Action taken where testing indicated that the specified criteria had not been met.
Any areas in which the fill material or compaction is to be of a lesser standard or a greater
standard than elsewhere on the site should be clearly identified.

*Guidelines for the provision of geotechnical information in construction contracts, Canberra, The Institution
of Engineers, Australia, 1987

www.standards.org.au © Standards Australia

 AS 3798—2007 14

3.5 SITE RECORDS

Daily diaries and detailed drawings of works, as executed, should be maintained by site
staff. Typical site records are—
(a) a daily geotechnical report, generally appropriate for larger projects;
(b) a geotechnical site visit record; and
(c) an earthworks summary report, generally appropriate for small projects.
NOTE: Typical examples are given in Appendix B and contain only relevant technical
information relating to the work as executed. It is likely that records of other aspects of the
works, such as weather conditions, work hours, breakdown and standby times, instructions issued,
conversations between parties, visitors to the site and the like may need to be kept by the
superintendent, the constructor or other parties, for the purpose of contract administration.

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your on-line service.
Please note that material accessed via our on-line subscription services is
not intended for off-line storage, and such storage is contrary to the
licence under which the service is supplied.
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© Standards Australia www.standards.org.au

 15 AS 3798—2007

S E C T I ON 4 M A T E R I A L S

4.1 GENERAL
The earthworks for most projects for which this Standard is intended will involve cut-to-fill
operations using on-site materials. Importation of suitable material on to the site may also
be required.
In some instances, materials may be encountered which are unsuitable for use as fill, or
which may require particular attention in their placement and control, if they are to be used.
This Section provides guidelines regarding material acceptance and control. It is important
to note that the primary requirement of a fill is dimensional stability, that is, a fill should
not settle nor heave excessively in service. This relies upon control of (among other things)
the shrink-swell properties of the near surface materials and the modulus or stiffness of the
material. It is neither usual nor convenient for these properties to be directly controlled in
works and as such the usual forms of specification only indirectly consider these properties.
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4.2 MATERIALS SOURCED ON SITE
your on-line service.
On many projects it may be assessed that material, or portion of the material, to be won
Please notefromthat
cuts ormaterial accessed
borrow pits on via our
site will be suitable for theon-line subscription
works. In such services is
cases, the specifier
may have an adequate understanding of this material to be able to relax the requirements
not intended for off-line storage, and such storage is contrary to the
that might apply to imported or other material.
licence under which the service is supplied.
4.3 UNSUITABLE MATERIALS
Some materials are unsuitable for forming structural fill and should be either removed to
spoil or used in non-critical areas. Unsuitable materials may include—
(a) organic soils, such as many topsoils, severely root-affected subsoils and peat;
(b) materials contaminated through past site usage which may contain toxic substances or
soluble compounds harmful to water supply or agriculture;
NOTE: Disposal of such materials will generally require special consideration, and often will
be subject to control by regulatory authorities.
(c) materials containing substances that can be dissolved or leached out in the presence
of moisture (e.g., gypsum), or which undergo volume change or loss of strength when
disturbed and exposed to moisture (e.g., some shales and sandstones), unless these
matters are specifically addressed in the design;
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(d) silts, or materials that have the deleterious engineering properties of silt;
(e) other materials with properties that are unsuitable for the forming of structural fill;
and
(f) fill that contains wood, metal, plastic, boulders or other deleterious material, in
sufficient proportions to affect the required performance of the fill.
A1
In some circumstances a design may allow for the use of some of these materials in
structural fill. Before allowing for such use, advice from a geotechnical professional should
be sought.

www.standards.org.au © Standards Australia

 AS 3798—2007 16

A1 4.4 SUITABLE MATERIALS

Most naturally occurring soils, with the exceptions specified in Clause 4.3, are capable of
being compacted to form a structural fill. Similarly, weathered rock that can be ripped and
broken down by compaction will be generally suitable for use as structural fill.
The applicability of some materials will depend, among other things, on their in situ
condition at the time of the work, the intended end use of the fill, and on the economics of
winning, and placement to, the specification requirements.
Special consideration may be required for the following:
(a) Clays of high plasticity, which may be reactive and need to be selectively placed
within the fill and under strict moisture and density control.
(b) Material, which, after compaction, contains large particles, which may lead to
difficulties in the excavation of trenches for footings or services, driving of piles or
drilling of piers (if this is necessary).
(c) Overwet materials (as may be encountered in low-lying areas), which may be difficult
to satisfactorily dry out within an economical time for use in the project.
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(d) Single-sized or gap-graded gravels or rock fill that will not break down on
your on-line service.
compaction, leaving voids into which finer material may subsequently migrate.
Please note(e) that
Saline,material
chemically accessed via our
aggressive or polluted soils,on-line subscription
and carbonate services is
soils where acid
disposal may occur.
not intended for off-line storage, and such storage is contrary to the
(f) Potential acid sulfate soils.
licence under which the service is supplied.
(g) Materials that cannot be tested to demonstrate compliance with the specification.
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© Standards Australia www.standards.org.au

 17 AS 3798—2007

SE C T I O N 5 CO M PA CT I O N CR I T E RI A

5.1 GENERAL
In most situations, the required compaction should be specified as a minimum relative
compaction and not as an absolute dry density. The means by which such minimum relative
compaction will be specified will vary for each earthworks project. Projects involving large
areas of fill may use ‘statistical’ acceptance criteria (see Note), but otherwise it will be
common to adopt a ‘no value to be less than’ acceptance criterion. It should be appreciated
that the minimum value of relative compaction specified may be different for each type of
acceptance criterion for the same expected overall level of compaction.
NOTE: The use of averaging or so-called ‘statistical’ acceptance criteria for earthworks is
common practice for large projects and is likely to further increase as this method of quality
acceptance testing becomes familiar; however, control-testing schemes involving statistical
acceptance criteria will be generally outside the scope of the projects to which this Standard
applies. Some notes on the basis of such schemes are given in Appendix C. If, in the view of the
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project personnel, statistical criteria should be applied, specific advice should be obtained from a
geotechnical professional.
your on-line service.
5.2 COMPACTION OF SOILS
Please note that material accessed via our on-line subscription services is
This Section is applicable to soils that contain less than 20% by mass of particles coarser
not intended
than for off-line
37.5 mm storage,
after field compaction.andThis such storage
will include many ofis thecontrary tointhe
materials used
licence under which
earthworks the
projects service
to which is supplied.
this Standard is applicable. Soils containing more than 20% of
particles coarser than 37.5 mm cannot be tested for relative compaction using the
procedures of AS 1289. Clause 5.4 discusses this situation.
Minimum relative compaction values for different applications of various projects are given
in Table 5.1. The values are based on historical data, which have taken into account the
uncertainty of measurement for each of the tests involved. They have been found to deliver
acceptable performance, and are for a specification of the ‘no value to be less than’ type.
They are not applicable where statistical control criteria (see Note to Clause 5.1) are
applied. In the latter circumstances, the minimum acceptance criteria will be different, and
dependent upon the scheme adopted. This Standard does not give guidance on such values.
Guidelines for minimum relative compaction values are given below. These should be taken
as minimum values in areas of structural fill. It is possible that more stringent criteria may
be applicable in some circumstances, e.g., to assist in settlement control, shrink-swell
behaviour or to provide increased strength. Similarly, in non-structural fill areas, the
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designer may wish to provide for less stringent requirements.

www.standards.org.au © Standards Australia

 AS 3798—2007 18

TABLE 5.1
MINIMUM RELATIVE COMPACTION
Minimum relative compaction, %
Minimum density ratio Minimum density
Item Application (at standard compactive effort) index
(Cohesive soils) (Cohesionless soils)
(see Note 1) (see Note 2)
1 Residential—lot, fill, house, sites 95
70
(see Note 3)
2 Commercial—fills to support minor loadings,
98
including floor loadings of up to 20 kPa and 75
(see Note 4)
isolated pad or strip footings to 100 kPa
3 Fill to support pavements (see Note 5)
(a) General fill 95 70
(b) Subgrade (to a depth of 0.3 m) 98 75
NOTES:
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1 Density ratio may be either dry density ratio (see AS 1289.5.4.1) or Hilf density ratio (see AS 1289.5.7.1) as
your on-lineapplicable.
service. These test methods require reporting to the nearest 0.5% and this is assumed in these values.
2 Density index as a means for control of achieved relative compaction may be difficult to use and interpret.
Please note that material accessed via our on-line subscription services is
Local correlations with other methods may exist and can be used where these are well established.
not intended for off-line
3 Development on this fill storage,
will be restricted and
to single-such
and some storage is contrary
double-storey houses, to the
with floor slab average
imposed bearing pressure not exceeding 20 kPa, and strip or pad footings not exceeding imposed bearing
licence under which
pressures the
of 100 kPa. service
Residential is supplied.
developments imposing higher pressures other than these are considered as
commercial. A minimum dry density ratio of 98% or higher may need to be considered if collapse on
saturation or excessive settlement is likely to occur.
4 Commercial developments are likely to impose loads on fills that will have a more severe effect than those of
houses, even where contact pressures are limited to those stated. The designer, in association with a
geotechnical professional, should assess the load-carrying capacity and expected deformations associated
with proposed filling and be satisfied the fill can perform its required function. Where highly loaded fills are
proposed, the minimum relative compaction may need to be increased.
5 Where pavements will be required to carry a significant volume of heavy vehicles, the minimum compaction
criteria for the upper levels of the fill may need to be reviewed. For all pavements, it is essential that the
specification for compaction of subgrade materials reflects the condition under which tests carried out for
pavement thickness design are conducted.
6 Local practice in some areas for well-known materials may rely on acceptance criteria based on other
parameters, e.g., penetrometers as described in AS 1289.6.3.2 and AS 1289.6.3.3.
7 The ground surface exposed after stripping should also be compacted in accordance with Table 5.1, to a depth
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of not less than 150 mm. If this is not carried out or not possible (for example, due to presence of soft
ground), the consequences should be taken into account by the designer.
8 The above criteria should be applied in conjunction with visual appraisal of the standard of compaction by
the superintendent or as otherwise provided in the contract. The specification should define the circumstances
where visual appraisal (including test rolling, if appropriate) may override test results for relative
compaction, as per Section 7.1.
9 It is recognized that in some parts of Australia, such as Central Australia and much of Western Australia, the
use of modified compactive effort is preferred, because the natural moisture content more closely
approximates the modified optimum rather than the standard optimum. This Standard does not give guidance
on minimum relative compaction requirements in these areas.

Advice from a geotechnical professional should be taken in relation to relative compaction

and placement moisture contents. The designer should be conscious of not over-specifying
the level of compaction required, simply for the sake of expediency. In some soils, e.g.,
reactive clay soils, over-compaction may actually impair subsequent performance.
Furthermore, increasing the required relative compaction may result in substantial cost
increases and possible delays in completion.

© Standards Australia www.standards.org.au

 19 AS 3798—2007

In clay soils, large modern compaction equipment will often operate more effectively at
moisture contents that are substantially lower than the optimum moisture content
determined in the standard compaction test (see AS 1289.5.1.1); however, many types of
clays placed in this manner may swell significantly and lose strength if they are wetted up
after compaction. Such compaction of fill may affect the site classification determined in
accordance with AS 2870, or result in subgrade strengths less than assumed in design.
Some materials degrade rapidly during compaction (e.g., some weak or weathered rocks);
therefore, care is required to avoid over-compaction of such materials. In such a situation,
the designer may need to consider revision of the relative compaction guidelines of
Table 5.1 to take account of the associated changing compaction characteristics. This will
be particularly important where further breakdown occurs during laboratory compaction.
NOTE: If further breakdown occurs during laboratory compaction, the resulting moisture density
relationship may not satisfactorily relate to that which existed at the time of field compaction. As
a consequence, comparison of the field dry density to the laboratory maximum dry density
(MDD) may not adequately reflect the design intent (if MDD reduces with breakdown), or may
unfairly penalize the constructor (if MDD increases with breakdown). Where such variations are
likely, testing should be carried out at the time of design and realistic requirements, which reflect
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the design intentions, should then be specified. It is not appropriate in these circumstances to
sample material for laboratory testing before field compaction (see Clause 7.4).
your on-line service.
5.3 PLACEMENT MOISTURE CONTENT
Please note that material accessed via our on-line subscription services is
For potentially reactive or moisture-sensitive soils it will be necessary to specify a range of
not intended forcontent
moisture off-linewithinstorage,
which the filland such
is to be placedstorage is contrary
and compacted, to the
as their subsequent
licence under which
engineering the service
performance is supplied.
may be dependent upon their placement moisture.
It is not necessary to routinely specify and enforce moisture control in other non-critical
areas, or in materials where subsequent engineering performance is unlikely to be adversely
affected by placement moisture. Inclusion of such a requirement is likely to increase the
cost of placement.
Where it is required to reduce the potential for swelling of reactive clays when placed as
compacted fill, it may be desirable to specify a maximum as well as a minimum level of
relative compaction, and to be quite specific about the moisture content at which the
compacted fill is to be placed and maintained, until topsoiling or similar takes place. It is
desirable for reactive clays to be placed close to their equilibrium moisture content (not a
soil property, but dependent on the soil and environment). In temperate climates, the
equilibrium moisture content is often close to the optimum moisture content (standard
compaction). In arid and semi-arid environments, the equilibrium moisture content may be
considerably drier than in temperate climates. Material in borrow areas at or about the depth
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of seasonal influence is often close to the equilibrium moisture content and, therefore, the
potential for problems may be minimized by placing material directly from cut to fill.
Where reactive soils are to be used as fill, it will normally be necessary to specify the
placement moisture content to be within a specified range, e.g., ‘90% to 110% of the
standard optimum moisture content (see AS 1289.5.1.1), or ‘moisture variation to not
exceed ± 2%’.

5.4 COARSE MATERIAL

Where ripped rock or coarse material is used for filling, the after-compaction quantity of
material coarser than 37.5 mm may exceed 20%. With such material, the test procedures for
in situ determination of dry density ratio specified in the relevant parts of AS 1289 are not
applicable and special consideration should be given to alternative methods of testing for
compaction. In such circumstances, it is common to adopt a method specification.

www.standards.org.au © Standards Australia

 AS 3798—2007 20

A method specification will usually include required moisture conditioning, a minimum

number of passes of a given roller and a maximum layer thickness. Such method
specification should be decided upon once the nature of the material to be placed is known
and after consideration of the proposed use of the fill. The method specification should be
part of the documentation (see Clause 3.3), although it may need to be developed in
conjunction with a geotechnical professional.
The method specification for placement of coarse granular material may include test rolling,
to assist in evaluating the stability of fill materials being placed (see Clause 5.5).

5.5 TEST ROLLING

Areas upon which structural fills are to be constructed, all layers of structural fill, and
materials within 150 mm of permanent subgrade level in cuttings should be compacted so as
to be capable of withstanding test rolling without visible deformation or springing.
Suitable plant for test rolling procedures may consist of the following:
(a) Static smooth steel wheeled rollers with a mass of not less than 12 t and a load
intensity under either the front or rear wheels of not less than 6 t/m width of wheel.
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(b) Pneumatic Toa mass
tyred plant with access the
of not less thancurrent document,
20 t and a ground please go to
contact pressure
your on-line service.
under either the front or rear wheels of not less than 450 kPa per tyre. The area over
2
which this ground contact pressure is applied should be not less than 0.035 m per
Please note thattyre. material accessed via our on-line subscription services is
not intended
(c) for off-line
Highway storage,
truck with and
rear axle or axlessuch
loaded storage is contrary
to not less than 8 t each with to
tyresthe
licence under inflated
which to 550 kPa.
the service is supplied.
Fill layers should be test-rolled immediately following completion of compaction. If further
test-rolling is required at some later date, the surface should be moisture-conditioned, as
required, and given not less than four coverages of the testing roller before test rolling
resumes.
Any areas where visible deformation or springing is detected by test-rolling should be
rectified and represented for test-rolling, or the opinion of the designer should be sought.
Where unstable areas exceed 20% of the area being considered by test-rolling, the whole of
the area should be ripped, recompacted and re-presented for test rolling.
An alternative method for test-rolling is to use an impact roller or impact compaction, a
non-circular towed or self-propelled module that imparts a high energy dynamic force.
Impact rollers can be utilized to identify weak zones or soft spots, but will tend to loosen
the surface layer.
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5.6 OTHER MATERIALS

Unprocessed waste materials such as demolition rubble are extremely variable and should
only be accepted as structural fill after due consideration by the designer, preferably in
conjunction with field trials. The specification for the supply, placement and compaction of
such fill should then be clearly stated. Impact rollers are often suited to test rolling such
fills, although the testing regime requires site-specific attention.

5.7 TRENCHES
Trenching infill for service installation, or like works, is common in commercial and
residential developments. It is important that, in such areas, rapid lateral changes in the
engineering properties of the ground do not occur. Compaction of backfill is important and
should be clearly specified, in terms of relative compaction, and controlled. The compaction
of the backfill should be compatible with that specified by the designer and the minimum
requirements of the relevant statutory authority. The practice of flooding sands may be
insufficient to achieve compaction of backfill and additional compaction methods may be
required.

© Standards Australia www.standards.org.au

 21 AS 3798—2007

SECT ION 6 CONSTRUCT IO N

6.1 SITE PREPARATION

6.1.1 General
This Section covers specific activities that are likely to form part of any earthworks project
and are presented in the approximate order of works. Government environmental
regulations may apply to some aspects covered herein and, where conflict between these
exists, such regulations will take precedence over these guidelines.
6.1.2 Fencing
Fencing should be installed as required, before earthworks commence, to define the limits
of the work, to restrict construction plant to the site or for public protection.
6.1.3 Drainage, erosion and sedimentation control
Earthworks should avoid the siltation or erosion of adjoining lands, streams or
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watercourses.
your on-line service.
Drainage, erosion and sedimentation control should be installed before the natural surface is
disturbed. Sedimentation basins, stream diversion or other works may be appropriate in
Please note that material accessed via our on-line subscription services is
some environments or topography. Careful planning is required for these works.
not intended forandoff-line
Erosion storage,
sedimentation control mayand such
be aided storage
by minimizing the is
areacontrary
of disturbancetoandthe
licence under which the
by the progressive service
re-vegetation is supplied.
or development of the site.
6.1.4 Site clearing
The site should be cleared (to the minimum extent required for the work) of all trees,
stumps and other materials unsuitable for incorporation in the works.
The roots of all trees and debris, such as old foundations, buried pipelines (and the like)
should be removed to sufficient depth to prevent inconveniences during subsequent
excavation or foundation works. Resulting excavations should be backfilled and compacted
to the same standard as that required for subsequent filling operations.
Disposal of cleared combustible material may have to be off-site if clean air or bushfire
regulations prevent on-site burning (see Clause 6.1.8).
6.1.5 Stripping
The area on which the fill is to be placed and the area from which the cut is to be removed
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should be stripped of all vegetation and of such soils as may be unsuitable to support the
proposed loadings or for incorporation in fills subject to density, moisture or other specified
controls. Topsoil and severely root-affected soils may need to be stripped as unsuitable
A1 material or as required for subsequent revegetation.
Geotechnical assessment of the depth and quality of topsoil or vegetal cover of the
underlying soils and of the quality and depth of the proposed fill may obviate the need for
such stripping in some circumstances.
All stripped materials should be deposited in temporary stockpiles or permanent dumps in
locations available for subsequent re-use if required, and where there is no possibility of the
material being unintentionally covered by, or incorporated in, the earthworks.
A1
Special care is needed to ensure that materials that will inhibit or prevent the satisfactory
placement of subsequent fill layers are not allowed to remain in the foundations of fills.

www.standards.org.au © Standards Australia

 AS 3798—2007 22

Consideration should be given to the in-service drainage characteristic of the fill to be

placed, particularly to the likelihood of instability caused by moisture build-up over
impervious foundation layers or their inability to form a continuous or homogeneous mass.
6.1.6 Slope preparation
Where a fill abuts sloping ground, benches should be cut in the ground. It is unlikely that
slopes flatter than an 8:1 (horizontal to vertical) gradient will require benching. The
benches should be shaped to provide free drainage. The depth of bench should be not less
than 100 mm, but generally be of the order of 300 mm; however, it may vary depending on
the natural slope of the ground, the nature and proposed end-use of the fill and the
equipment being used.
The boundary of cut-and-fill areas requires special consideration. All topsoil and other
compressible materials should be stripped prior to benching into the natural material of the
cut zone.
6.1.7 Foundation preparation
Wherever practicable, the ground surface exposed after stripping should be shaped to assist
This document
drainage has
and beexpired.
compacted toTo access
the same the current
requirements document,
as for the overlying layers of please
fill, go to
utilizing suitable equipment, in accordance with Note 7 to Table 5.1.
your on-line service.
Subject to the required end-use of a site, the surface exposed upon completion of excavation
Please noteworksthat material
may also accessed
require preparation prior to via our on-line
fill placement subscription
proceeding. services is
This will typically be
not intended for whenever
the case off-linesubsequent
storage, fill isand
to be such
placed, storage
as might be isthe contrary to the
case for pavement
construction or base material beneath a floor slab, or in the case of existing fill that is to be
licence under
retainedwhich
in situ orthe service
for the is supplied.
identification of potential weakness in the subgrade. In such
circumstances, it will be necessary to treat the area in an appropriate manner.
Such treatment may include loosening the exposed excavation surface by scarifying to a
depth of at least 150 mm, and to then moisture-condition and compact this loosened
material. The depth to which scarifying carried out should not exceed that which can be
compacted.
Alternatively, existing fill or weak or variable subgrade materials may respond to ground
improvement using an impact roller or impact compaction and, if considered appropriate, a
trial or specification should be applied.
In ground where it is impracticable to achieve compaction of the existing or stripped
surface, design advice should be sought from a geotechnical professional. In such cases, a
working platform generally of granular material, end-dumped and spread in sufficient depth
to allow the passage of earthmoving equipment with minimal surface deflection, may
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provide a suitable foundation for subsequent filling. In some cases, it may be appropriate to
place geosynthetics across the natural or stripped surface before such fill placement is
carried out.
Localized springs or seepages in the foundation area, detected during site investigation for
the work, should be noted and allowed for in the design. If such problems are not detected
until the works are in progress, they should be investigated so that measures such as subsoil
or rock rubble drains may be designed for incorporation in the works.
6.1.8 Off-site disposal
All materials arising from site preparation works should be managed in accordance with the
requirements of the relevant regulatory authorities. This may require segregation by
material type, classification and, where required, disposal at facilities appropriately licensed
to receive the particular materials.

© Standards Australia www.standards.org.au

 23 AS 3798—2007

6.2 FILL CONSTRUCTION

6.2.1 General
Planning for fill construction should include, but not be limited to—
(a) the quantity and quality of the fill material;
(b) the expected rate of output of the earthmoving, delivery and spreading equipment;
(c) the compaction specification to be met; and
(d) the availability and effectiveness of particular items or types of compaction
equipment.
The number of passes of a particular roller required to compact a layer of specified
thickness at a given moisture content (or within a specified moisture range) can only be
established in the field.
NOTE: Guidance on the suitability of compaction equipment for various types of fill material is
given in Appendix D.
6.2.2 Placing fill
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The quality of fill material and the control tests to be used as the acceptance criteria should
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be specified in the documentation (see Clause 3.3).
Please noteFill that
materialmaterial accessed
should be placed via our
in near-horizontal on-line
layers subscription
of uniform services is
thickness, deposited
systematically across the fill area. The thickness of each layer should be appropriate to the
not intended for off-line
equipment storage,
to be used and andtosuch
test procedures storage
be adopted. This willis contrary
vary according totothethe
licence under which
material theand
being placed service is supplied.
the equipment being used. For example, in open areas and with
large rollers it may be possible to satisfactorily compact fill in layers of up to 400 mm loose
thickness. In confined areas layers as thin as 100 mm may be required. With careful
consideration, adequate compaction may be achieved on thicker layers with some
equipment.
It may be necessary to excavate or ‘box’ into the existing surface at the edge of fills to
provide a suitable junction with the existing surface to avoid feathered edges.
The method of excavation, transport and depositing of fill material should ensure that the
fill is placed in a mixture as uniform as practicable. Such uniformity will assist in providing
consistent relative compaction from the chosen plant and work practices, and in avoiding
material variations, which may affect the long-term performance of the fill.
Each fill layer thickness should be such that the bottom of each layer is compacted to the
specified relative compaction and can be tested by the specified test methods. Whilst
compaction may be achieved in deeper layers by using heavier equipment or increasing the
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number of passes, the relative economy of various options may need to be examined, if a
particular layer thickness is not specified.
Before any loose layer of fill is compacted, the material and its moisture condition should
be as uniform as practicable throughout its depth.
The maximum particle size of any rocks or other lumps within the layer, after compaction,
generally should not exceed two-thirds of the compacted layer thickness.
If there is a delay in the placement of subsequent fill layers, previously accepted layers
should conform with the specification before further fill is placed. If these layers have
wetted up or dried out, they may inhibit compaction or cause heaving of subsequent layers.
In some instances, drying of the fill may be deleterious, especially with reactive soils.
The standard of surface trim of the completed earthworks should be specified in the
documentation (see Clause 3.3).

www.standards.org.au © Standards Australia

 AS 3798—2007 24

6.2.3 Fill moisture control

If limits on the moisture condition of fill material during compaction are specified, they
should be such that they still allow the required degree of compaction to be achieved with
reasonable effort.
If the moisture content of the fill falls below the specified minimum, water should be added
either on the fill or in the cut/borrow area before it is transported to the fill area. Water
applied on the fill should be finely sprayed and uniformly blended throughout the full depth
of uncompacted material. If the moisture content of the uncompacted fill is non-uniform,
the material should be mixed to provide a consistent moisture distribution. Care is needed
to ensure that mixing or blending does not produce segregation of the fill material.
If the moisture content of material is above the specified maximum, drying of the material
may be accelerated by aeration or by blending with drier materials. If the moisture content
is such that it approaches saturation at the specified density, it may be difficult, if not
impossible, to achieve the specified compaction.
Control of moisture content should be applied not only to the upper layer of uncompacted
material, but also to the material of the previously compacted layer. This surface material
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should be brought to within the specified moisture range before it is covered by a new
your on-line service. layer.
If rain is threatening or the site is to be left unattended, the upper surfaces of fills should be
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crowned and, if possible, sealed with rubber-tyred or smooth-wheeled plant and graded to
not intended forponding.
prevent off-line storage, and such storage is contrary to the
licence under
6.2.4 which the service is supplied.
Fill compaction
Each layer of fill should be compacted as a systematic construction operation, using plant
that is specifically assigned to the compaction task and which tracks progressively across
the surface of the fill. Construction and earthmoving plant may be routed to assist in this
regard.
Selection of the compaction equipment requires careful consideration of the job
specification requirements. The plant should be capable of compacting all of the fill area,
including its edges and junctions with the natural ground.
Fill batter faces should be compacted as a separate operation or, alternatively, overfilled
and cut back. The trimmed and compacted batter face should have a roughened surface to
reduce run-off velocities and aid revegetation, if required.
Where testing of a lot shows that it does not comply with the specification it should be
reworked and retested, as necessary, to confirm compliance.
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Additional moisture blending or drying out may be required to facilitate recompaction. The
surfaces of all fill layers should be shaped to provide drainage and to prevent ponding,
which will cause deterioration of previously compacted fill layers.
6.2.5 Surface heaving
Surface heaving results from the compaction of materials approaching saturation and
inhibits further compaction. The development of surface heaving on fills may be avoided by
the following:
(a) Ensuring that the moisture content of materials during placement avoids near
saturation at the specified density.
(b) Providing drainage on the surface of fills and preventing the ponding of water on fill
layers.
(c) Selecting appropriate earthmoving and compaction equipment.

© Standards Australia www.standards.org.au

 25 AS 3798—2007

6.2.6 Fill adjacent to structures and in trenches

Fill adjacent to structures such as pipes, culverts, abutments, retaining walls or other
A1
structural components, or the backfill of trenches, may need to take into account of some or
all of the following:
(a) The strength or age of the structure(s), e.g., the quality of cast in situ concrete, before
filling can commence.
(b) The filter zone to be provided adjacent to weep holes or other subsoil drainage
systems.
(c) The quality of fill. Sand, natural gravel or quarry products may be specified to
facilitate compaction in confined areas to minimize differential settlement, which
might otherwise overload the structure or to divert seepage to subsoil or other
foundation drainage systems.
(d) The type and method of compaction compared with normal fill construction. Fill
should be brought up equally on each side of pipes and culverts, to avoid unbalanced
loading. The first layers of fill over the top of structures will require careful
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placement. The design should specify the depth of fill to be placed over pipes or
culverts, or special conditions that might apply to other structures. In some cases,
your on-line service. internal propping may be required if normal compaction is to be used immediately
above or adjacent to structures.
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(e) The excavation and filling of trenches, or testing of trench backfill, may require
not intended for off-line
special storage,
precautions and
to protect the such
safety storage
of personnel is contrary
or equipment involved into
thethe
licence under work,
whichbasedthe service
on relevant is supplied.
regulations and site-specific risk assessments.
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www.standards.org.au © Standards Australia

 AS 3798—2007 26

SE C T I ON 7 M E T H O D S O F T E ST I N G

7.1 GENERAL
This Section describes the procedures to be followed when carrying out acceptance testing
of field compaction. In considering this Section, it will be necessary to have established the
requirements of the specification for the work to be tested and of the relevant test
procedures.
Acceptance testing, based on a comparison of the density achieved in the field with that of
some reference density established in a laboratory, provides an indirect measurement of the
performance of the compacted fill material. Consequently, it is essential that the
documentation (see Clause 3.3) include a satisfactory basis for achieving the required
performance. Measurement of relative compaction in general is not sufficient to assess
compliance and should be used in conjunction with visual inspection of the compaction
process and, where applicable, test rolling.

This document has

Strength or otherexpired. To aaccess
tests may provide measurement the current
of the performancedocument,
of the compactedplease
fill go to
material.
your on-lineNOTE:
service.
Comment on the application of statistical methods in earthworks is given in Appendix C.
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7.2 FIELD DENSITY
not intended for off-line storage, and such storage is contrary to the
Methods for the determination of field dry density are as follows:
licence under which the service is supplied.
(a) Direct The methods are as specified in AS 1289.5.3.1, AS 1289.5.3.2, AS 1289.5.8.1
and AS 1289.5.5.
NOTE:Although the method specified in AS 1289.5.8.1 relies upon correlation of recorded
density count against standard blocks (see AS 1289.5.8.4), provided calibration has been
carried out as specified, it is for the purpose of this Standard, a direct method.
(b) Indirect These methods provide an empirical measure of achieved density by
measurement of another engineering property, principally shear strength. Correlation
with local materials and conditions is required. The methods include those specified
in AS 1289.6.3.2, AS 1289.6.3.3 and AS 1289.6.5.1. Correlation with local materials
and conditions is required. Such correlation should include the effects of
depth/confining pressure, moisture content, material type and local conditions when
comparisons with the methods specified in Item (a) (this Clause) are proposed.
The specification should designate which test procedure governs acceptance.
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7.3 ESTABLISHMENT OF A REFERENCE DENSITY FOR CALCULATION OF

RELATIVE COMPACTION
To permit relative compaction to be calculated, it is necessary to establish a laboratory
reference density. Procedures for establishing such reference densities have been developed
empirically over many years and standardized with the test procedures of AS 1289.5.1.1,
AS 1289.5.2.1, AS 1289.5.5.1 and AS 1289.5.7.1.
In each of the above procedures, a ‘maximum’ density is obtained (in AS 1289.5.5.1, a
‘minimum’ dry density is also obtained). It must be appreciated that these do not represent
the maximum (or minimum) achievable, but that which can be achieved using the test
procedures specified.

© Standards Australia www.standards.org.au

 27 AS 3798—2007

7.4 SAMPLE SELECTION FOR REFERENCE DENSITY

For routine compaction testing, the sample for determination of the laboratory reference
density (see Clause 7.3) should be obtained in accordance with AS 1289.5.4.1 or
AS 1289.5.7.1.
NOTE: The sample will comprise either the material recovered from the field density
determinations or from that volume of material considered in the field density determination as in
the case of testing using nuclear gauges. In most instances, the amount of soil will be insufficient
to allow satisfactory completion of the laboratory reference density test. In such circumstances,
additional material should be recovered immediately from around the zone in which the field
density determination was made and over the full depth considered in that determination, but no
deeper. The sides of any excavation made to recover such material should be approximately
vertical.
The sample for the laboratory reference density test should be taken from the compacted
material immediately after (or during) the field density determination. Only when it has
been established that the influences of field compaction do not affect the value of the
laboratory reference density, is it appropriate to sample from the stockpile or the test area
prior to compaction.
This document has and
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AS 1289.5.7.1 access that the current
a laboratory document,
reference density valueplease
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determined for each field density determination.

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requirement accessed
for a laboratory reference via our
density test on-line subscription
for each field services is
density should apply
equally to any retest of an area, whether such retesting be required after previous testing has
not intended for inadequate
indicated off-linecompaction
storage, and and
further such storage
compaction has been is contrary
carried to the
out, or whether
merely checking compaction after some period of time but without further work having
licence under which the service is supplied.
been carried out on the area.

7.5 USE OF DIFFERENT TEST PROCEDURE

In general, the test procedure for determination of relative compaction should not be varied
for a given soil type by using more than one test procedure for either field density or
reference density. In particular, control of moisture content, relative to optimum moisture
content determined in accordance with AS 1289.5.7.1, should not be included with or
compared to those determined in accordance with AS 1289.5.1.1 and AS 1289.5.2.1,
as different results may be obtained. The use of different test procedures may be misleading
for some clays of high plasticity.
In certain circumstances, alternative testing strategies may be appropriate, e.g., in the case
of verifying deep compaction achieved by impact rollers or impact compaction. Trial
programs may be required to develop the most appropriate testing regime for any particular
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project or site.

7.6 PERMISSIBLE OVERSIZE

AS 1289.5.1.1 and AS 1289.5.2.1 restrict the maximum particle size in the test specimen to
37.5 mm. Many engineering materials contain a proportion of larger material, which can be
accommodated in the field density determination, provided appropriate test procedures are
followed. AS 1289.5.4.1 and AS 1289.5.7.1 provide a basis for adjusting the reference
density to make allowance for the presence of this oversize material in the field and its
exclusion from the laboratory reference density test.

7.7 PREPARATION OF LABORATORY REFERENCE DENSITY SAMPLES

All samples for laboratory reference density testing should be prepared in accordance with
AS 1289.1.1. This requires the soil to be prepared over a 10 mm screen.

www.standards.org.au © Standards Australia

 AS 3798—2007 28

It is generally accepted that to establish repeatable well-conditioned laboratory compaction

curves in heavy clay soils (see AS 1289.5.1.1 and AS 1289.5.2.1) up to one week of
moisture curing of each subsample for the compaction test may be required. Lesser curing
times are required for lower plasticity clays, sandy clays and the like; however, for routine
compaction control testing, rarely is it practical to permit such curing time. Where such
curing is not undertaken, the implications of poorly conditioned curves should be taken into
account. In particular, the influence of differential moisture within the test samples and the
potential for shifts in the apparent compaction characteristics of the material should be
recognized (see AS 1289).
The time allowed for moisture conditioning relies upon experience and judgement.
Consequently, it can be expected that variability in test results will occur and should be
allowed for in the specification if deviation from the requirements of AS 1289 is to be
tolerated. Test reports should include the curing procedures and sample preparation
procedures adopted.
The Hilf rapid compaction method (see AS 1289.5.7.1), allows the test to be performed
provided the added moisture value is between −4% and +6%. For materials with moisture
contents outside these limits, curing for a prolonged time will generally be necessary and
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the maximum dry density and optimum moisture content need to be determined in
your on-line service. accordance with AS 1289.5.1.1 or AS 1289.5.2.1, as appropriate.

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not intended for off-line storage, and such storage is contrary to the
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© Standards Australia www.standards.org.au

 29 AS 3798—2007

SECT ION 8 I NSPECT I ON AND TES T I NG

8.1 GENERAL
To assess whether the quality of materials and workmanship provided on a project are
consistent with the design requirements, the earthworks for a project should be inspected
and tested at regular and appropriate intervals, having regard to the nature of the work, its
required function and the specification. The specification should detail the level of
inspection and testing required as detailed in Clauses 8.2 and 8.3.
Adequate control of earthworks will require appropriate inspection and should not rely on
test results alone. These inspection measures may include visual assessment of fill or
foundation materials, test rolling, surveillance of compaction procedures and compaction
trials. Relative compaction testing may be supplemented by other testing.

8.2 LEVEL 1 INSPECTION AND TESTING

This document has
The primary expired.
objective of LevelTo access
1 Inspection and the current
Testing document,
is for the geotechnical please go to
inspection
and testing authority (GITA) to be able to express an opinion on the compliance of the
your on-line
work.service.
The GITA is responsible for ensuring that the inspection and testing is sufficient for
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this purpose.
The GITA needs to have competent personnel on site at all times while earthwork
not intended for off-line storage, and such storage is contrary to the
operations are undertaken. Such operations include the following:
licence under which the
(a) Completion service
of removal is supplied.
of topsoil.
(b) Placing of imported or cut material.
(c) Compaction and adding/removal of moisture.
(d) Trenching and backfilling, where applicable.
(e) Test rolling.
(f) Testing.
The superintendent should agree on a suitable inspection and testing plan prior to the
commencement of the works.
On completion of the earthworks, the GITA will usually be required to provide a report
setting out the inspections, sampling and testing it has carried out, and the locations and
results thereof. Unless very unusual conditions apply, the GITA should also be able to
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express an opinion that the works (as far as it has been able to determine) comply with the
specification and drawings.
A1
8.3 LEVEL 2 SAMPLING AND TESTING
A geotechnical testing authority (GTA) will be appointed to carry out sampling and testing
as required or specified. The GTA is responsible for selecting the location of sampling and
testing operations within each visit made to the site. The superintendent is responsible for
advice as to when such visits are required and is responsible for ensuring that sufficient
samples and tests are taken over the project.
On completion of the earthworks, the GTA may be required to provide a report, setting out
the sampling and testing it has carried out, and the locations and results thereof. The GTA
will not be in a position to express any opinion beyond this as to the compliance of the
works with the specification or their suitability for any particular purpose.

www.standards.org.au © Standards Australia

 AS 3798—2007 30

8.4 GEOTECHNICAL INSPECTION AND TESTING AUTHORITY (GITA)

The GITA should have the necessary independence, equipment and competence to be able
to undertake all inspections and testing called for. Inspections and testing should be carried
out by competent personnel experienced and knowledgeable in earthworks, materials and
have a sound understanding of the implication of the specification requirements, e.g.,
geotechnical professional, geotechnician experienced in earthworks or an inspection
authority accredited in accordance with ISO/IEC 17020 to perform such earthworks
inspections.
The GITA may provide on-site field density and moisture content testing and sampling of
earthwork materials. It is unlikely (except for very small projects) that the inspector of the
works will be able to adequately fulfil this function and undertake the necessary laboratory
reference density testing. Such reference density testing may be undertaken offsite or
separately by a dedicated site laboratory.
A1
A GITA may also operate as a GTA where only Level 2 sampling and testing is specified.

8.5 GEOTECHNICAL TESTING AUTHORITY (GTA)

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have the necessary independence,the current
equipment document,
and competence please
to be able to go to
undertake all testing called for.
your on-line service.
The GTA should perform all sampling and testing both on site and at the laboratory. When
Please note that material
the earthworks accessed
site is remote viatesting
from a central our laboratory,
on-lineinsubscription services is
order to assist in the
not intended
timelyfor off-line
production of thestorage,
test results, a and such
laboratory storage
may be established is contrary to the
on site.
On very large projects, the amount of laboratory testing required may require separate staff
licence under which
to perform the and
field testing service
laboratoryistesting.
supplied.
8.6 STATEMENTS OF COMPLIANCE
Having regard to relevant State regulations, the superintendent may request suitable
statements of compliance to specifications and codes at the time of employing a GITA. In
cases where a GTA is employed for Level 2 supervision only, the statement of compliance
is the responsibility of the superintendent.

8.7 FREQUENCY OF TESTING

Testing is expensive and time-consuming; therefore, the frequency and extent of testing
should be carefully chosen, in conjunction with test rolling, to assess the compliance of
completed work without adding unnecessary costs or delays. Such testing should be carried
out by competent personnel experienced in earthworks testing. The project may require that
the testing authority be accredited in accordance with ISO/IEC 17025 to perform the
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testing.
The precise scope of services to be provided by the GITA or the GTA may differ from one
contract to another and, therefore, should be ascertained before work begins. A testing
strategy established at the commencement of work may be reassessed if a high degree of
uniformity becomes evident during construction.
A guide to the required frequency of testing for earthworks projects, to which this Standard
is applicable, is given in Table 8.1. In variable or difficult conditions, more frequent testing
may be required. These testing frequencies relate to acceptance on a ‘not one to fail’ basis,
and may need to be varied if statistical control techniques are employed (see Appendix C).
For projects requiring more than just a few tests to check compliance, the testing should
essentially be carried out in a number of randomly chosen locations and at the frequencies
given in Table 8.1. However, for small projects, it may be appropriate to undertake testing
in specific locations, based on visual appearance or past experience (e.g., compaction may
be more difficult to achieve adjacent to access holes, kerbs or over backfilled service
trenches).

© Standards Australia www.standards.org.au

 31 AS 3798—2007

It should not be assumed that a test result applies only to the area immediately surrounding
it. Where any test in a lot (see Clause 1.2.8) indicates that compliance with the specification
has not been achieved, the lot is considered to have failed. On this basis, the entire lot needs
to be reworked and retested. Selection of a lot for testing requires careful consideration.

TABLE 8.1
FREQUENCY OF FIELD DENSITY TESTS
Type of earthworks Frequency of tests (see Note 2)
Type 1 Large scale operations 1 test per layer per material type per 2500m 2;
(greater than 1500m 2 e.g., or
subdivisions, large industrial lots,
1 test per 500m 3 distributed reasonably evenly throughout full depth and
road embankments)
area;
or
3 tests per lot (Clause 1.2.8)
Whichever requires the most tests
2
Type 2 Small scale operations 1 test per layer (see Note 3) per 1000m ;
This document hasresidential
(e.g., individual expired.lots) To
or access the current document, please go to
your on-line service. 1 test per 200m distributed reasonably evenly throughout full depth and 3

area;
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not intended for off-line storage, and
1 test per such
residential lot perstorage
layer is contrary to the
Whichever requires the most tests
licence under which the service
Type 3 Concentrated operations
is supplied.
1 test per layer (see Note 3) per 500m ; 2
2
less than 500m (e.g., back filling of or
small farm dams, gullies and similar)
1 test per 100m 3 distributed reasonably evenly throughout full depth and
area;
or
3 tests per visit
Whichever requires the most tests
Type 4 Confined operations 1 test per 2 layers per 50m 2
(e.g., filling behind structures)
(see Note 4)
A1 Trenches 1 test per 2 layers per 40 linear metres
NOTES:
1 The above guidelines refer to the determination of relative compaction using a direct method; however,
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where an indirect method is used, e.g., Perth sand penetrometer (AS 1289.6.3.3), some interpretation of
the guidelines may be required.
2 Tests in areas of uncertain compaction and retests of failed areas should be carried out. These are
additional to the testing recommended in this Table.
A1
3 Where Level 2 sampling and testing has been specified it may be acceptable to test more than one layer
per site visit, by excavating to the test level. When testing a layer that has already been overlain by
additional earthworks, the test site should be prepared by scraping off the overlying layer(s) and preparing
a suitable pad for testing as required by AS 1289.5.3.1, AS 1289.5.3.2 or AS 1289.5.8.1.
4 Implies hand-operated or small equipment.

www.standards.org.au © Standards Australia

 AS 3798—2007 32

APPENDIX A
REFERENCED DOCUMENTS
AS
1289 Methods of testing soils for engineering purposes
1289.1.1 Method 1.1: Sampling and preparation of soils—Preparation of disturbed
soil samples for testing
1289.1.4.2 Method 1.4.2: Sampling and preparation of soils—Selection of sampling or
test sites—Stratified random number method
1289.5.1.1 Method 5.1.1: Soil compaction and density tests—Determination of the dry
density/moisture content relation of a soil using standard
compactive effort
1289.5.2.1 Method 5.2.1: Soil compaction and density tests—Determination of the dry
density or moisture content relation of a soil using modified
compactive effort
1289.5.3.1 Method 5.3.1: Determination of the field density of a soil—Sand
This document has expired. To access the current document, please go to replacement method using a sand-cone pouring apparatus
your on-line service.
1289.5.3.2 Method 5.3.2: Soil compaction and density tests—Determination of the
field dry density of a soil—Sand replacement method using a
Please note that material accessed via our on-line subscription services is sand pouring can, with or without a volume displacer
1289.5.3.5 Method 5.3.5: Soil compaction and density tests—Determination of the
not intended for off-line storage, and such storage is contrary to the field dry density of a soil—Water replacement method
licence under which the service is supplied.
1289.5.4.1 Method 5.4.1: Soil compaction and density tests—Compaction control
test— Dry density ratio, moisture variation and moisture
ratio
1289.5.5.1 Method 5.5.1: Soil compaction and density tests—Determination of the
minimum and maximum dry density of a cohesionless
material— Standard method
1289.5.6.1 Method 5.6.1: Soil compaction and density tests—Compaction control
test— Density index method for a cohesionless material
1289.5.7.1 Method 5.7.1: Soil compaction and density tests—Compaction control
test— Hilf density ratio and Hilf moisture variation (rapid
method)
1289.5.8.1 Method 5.8.1: Soil compaction and density tests—Determination of field
density and field moisture content of a soil using a nuclear
surface moisture-density gauge—Direct transmission mode
1289.6.3.2 Method 6.3.2: Soil strength and consolidation tests—Determination of the
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penetration resistance of a soil—9 kg dynamic cone

penetrometer test
1289.6.3.3 Method 6.3.3: Soil strength and consolidation tests—Determination of the
penetration resistance of a soil—Perth sand penetrometer test
1289.6.5.1 Method 6.5.1: Soil strength and consolidation tests—Determination of the
static cone penetration resistance of a soil—Field test using a
mechanical and electrical cone or friction-cone penetrometer
1726 Geotechnical site investigations
2870 Residential slabs and footings—Construction
4482 Guide to the investigation and sampling of sites with potentially
contaminated soil
4482.1 Part 1: Non-volatile and semi-volatile compounds

© Standards Australia www.standards.org.au

 33 AS 3798—2007

ISO
ISO/IEC General criteria for the operation of various types of bodies performing
17020 inspection
17025 General requirements for the competence of testing and calibration
laboratories
AUSTROADS
NTR-09 Pavement materials: statistical assessment of quality

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 AS 3798—2007 34

APPENDIX B
TYPICAL SITE RECORD SHEETS
This Appendix sets out typical site records, which may be appropriate to keep in respect of
the earthworks undertaken for projects to which this Standard applies; however, each
project will have its own specific needs, which should also be addressed. Modifications to
the given examples may be necessary to suit individual requirements.

DAILY GEOTECHNICAL REPORT

NAME OF ORGANIZATION PREPARING SHEET: Sheet No.:
Date:
Job No.:
Project:
Owner:
This document has expired. To access the current document, please go to
Constructor:

your on-lineSuperintendent:
service.
Inspection and testing by (GITA/GTA):
Please note that material accessed via our on-line subscription services is
Level 1 or 2:
not intended for off-line
GITA/GTA retained by:storage, and such storage is contrary to the

licence under which

Earthworks the progress:
in current service is supplied.

Materials testing: Refer to material, type, source, purpose of testing, sampling methods
and locations, test types, sample reference numbers, results obtained, and to whom
distributed.

Field density testing: Refer to types of test, section of work to which tests apply, test
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locations and levels, test reference numbers, results obtained, and to whom distributed.

© Standards Australia www.standards.org.au

 35 AS 3798—2007

DAILY GEOTECHNICAL REPORT (continued)

Laboratory compaction testing: Refer to test methods, location of sampling, sample
reference numbers, results obtained, and to whom distributed.

Works meeting geotechnical requirements: Refer to work type (e.g. stripping, subgrade
compaction), basis of assessment (e.g. inspection, test reference numbers, and the like),
extent of works apparently complying and requirements met.†

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your on-line service.
Works failing to meet geotechnical requirements: Refer to work type (e.g., stripping,
Please note that compaction),
subgrade materialbasis accessed
of assessment via our
(e.g., on-line
inspection, subscription
test reference numbers, services is
and the like), extent of work apparently failing to comply, requirements not met, action
not intended for
taken off-line
(instructions storage,
issued, and and
retests ordered, such storage is contrary to the
the like)†.
licence under which the service is supplied.

Remarks: Include observations on works, site conditions, meetings or conversations on

site, and the like.
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SIGNED: POSITION: DATE:

† As appropriate

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 AS 3798—2007 36

SITE TESTING RECORD

NAME OF GEOTECHNICAL TESTING AUTHORITY: Sheet No.:
Date:
Job No.:
Project:
Owner:
Constructor:
Superintendent:
Level 1 or 2:
GTA retained by:
Testing requested by:

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your on-line service.
Weather:
Please note that material accessed via our on-line subscription services is
not intended for off-line storage, and such storage is contrary to the
licence under which the service is supplied.
Earthworks in current progress:

Sections of work presented for testing:

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© Standards Australia www.standards.org.au

 37 AS 3798—2007

SITE TESTING RECORD (continued)

Sampling/Testing carried out: Refer to material types, sources, methods of sampling and
field testing, locations and levels of sampling and field testing; test and sample reference
numbers.

Instructions received on site: Nature of instructions, from whom, action taken.

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Method of recording locations and/or levels: By whom, reference marks, bench marks,
where recorded.

Remarks: Include observations on works, site conditions, meetings or conversations on

site, etc.
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SIGNED: POSITION: DATE:

www.standards.org.au © Standards Australia

 AS 3798—2007 38

EARTHWORKS SUMMARY REPORT

NAME OF ORGANIZATION PREPARING SHEET: Sheet No.:
Job No.:

Project:
Owner:
Constructor:
Superintendent:
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Broad description of earthworks undertaken, extent of fill, etc.:

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Observations on stripping and site preparation:

© Standards Australia www.standards.org.au

 39 AS 3798—2007

EARTHWORKS SUMMARY REPORT (continued)

Observations of fill materials.

Summary of testing: Refer to attached result certificates, location plans, etc.

Estimated Number of tests

Location on site and type volume Material quality Field density
of earthworks
Compaction
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Note—Unless engaged at Level 1 (see AS 3798 Clause 8.2) a testing authority is not in a
position to express an opinion as to whether the works comply with the drawings or
specification or are suitable for a particular purpose.
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Signed: _______________________________________

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 AS 3798—2007 40

APPENDIX C
STATISTICAL METHODS IN EARTHWORKS

C1 GENERAL
Earth materials are inherently variable and, whilst working from borrow to fill often acts to
reduce the variability, compacted fill is also variable. Thus the density and moisture content
of a fill will vary from any one location to other locations, even if considerable care is
taken to attempt to achieve a uniform result.
The ‘not any to fail’ specification commonly applied to small earthwork projects is based
on a successful history of producing suitable fills and only indirectly accounts for the
inherent variability. So-called ‘statistical’ methods have been applied to earthworks, in an
attempt to quantify the variability. These methods are used for two general purposes as
follows:
(a) Quality control (QC)—to control the process, the contractor uses quality control to
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can be changed to ensure continuing satisfactory placement. It can also be used to
estimate the in situ properties of the fill.
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(b) Quality assurance (QA)—to ensure that the product (fill) quality is within
not intended for off-line
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that is being
considered and two terms require definition as follows:
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(i) Owner’s risk (often B)—the risk of accepting fill as having a certain quality
when, in fact, it does not.
(ii) Contractor’s risk (often α)—the risk of fill being rejected as not having a
certain quality when, in fact, it does.
The owner’s risk can always be reduced to zero simply by always rejecting the product.
There is then no chance of accepting poor quality material. The obvious problem with this
is that the contractor’s risk is 100% and good quality material is always rejected. Statistical
methods should aim to balance these risks. To reduce both risks simultaneously requires a
reduction in the uncertainty regarding the actual quality of the product, which is generally
achieved by increasing the number of samples used in decision-making.
At present, statistical QA schemes find little application in works within the scope of this
Standard. In Australia, such schemes find their main use in larger road construction
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projects, under the control of state road authorities.

In large areas or for large volumes of earthworks, the amount of testing for field moisture
content and density may be considerable. More efficient use of testing may be made by
applying statistical methods to selection of test sites and to the test results based on lots of
work.
The publication AUSTROADS NTR-09 provides a working basis for the development of
suitable statistical specifications for earthworks covered by this Standard, by the suitable
selection of proportion defective, acceptable quality levels and operating characteristic
curves.

© Standards Australia www.standards.org.au

 41 AS 3798—2007

C2 SELECTION OF TEST SITES IN A TEST LOT SAMPLING

The selection of test sites in a test lot should be as follows:
(a) Stratified random sampling To ensure independence, lots are frequently divided into
equal areas or portions called strata. Where the number of sample tests required is
known, the lot is subdivided so that one test is selected from each stratum. Random
numbers are used sequentially to define the longitudinal and lateral position for each
site within each stratum in turn. This process is termed random stratified sampling.
(b) Systematic sampling Systematic sampling occurs when the longitudinal and the
lateral locations of test sites are selected at fixed intervals.

C3 ACCEPTANCE
When using statistical acceptance schemes, the acceptance values are based on
characteristic values of the properties, e.g., density ratio.
The characteristic values are calculated using the following equation:

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s = standard deviation of the values in the lot for the number of tests performed
Acceptance may be unconditional or conditional as follows:
(a) Unconditional quality acceptance In an unconditional quality assessment system,
the choice lies between acceptance or rejection of the product without application of
conditions or demand for further treatment.
(b) Conditional quality acceptance In a conditional acceptance system, work that meets
a specification limit is accepted without condition but work just outside the
specification limits may be accepted subject to either—
(i) further treatment, and possibly further testing; or
(ii) adjusted payment.
Suitable k values for different number of tests and different levels of risk are shown in
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AUSTROADS NTR-09.

C4 OUTLIER RESULTS
AUSTROADS NTR-09 provides information on the treatment of outlier results. In cases
where a result or results are outliers, it is preferable to retest the lot rather than to adjust the
acceptance criteria based on a reduced number of samples in order to reduce bias.

www.standards.org.au © Standards Australia

 AS 3798—2007 42

APPENDIX D
SUITABILITY OF COMPACTION EQUIPMENT FOR VARIOUS TYPES OF
FILL MATERIALS

Equipment Most suitable soils

Smooth wheel rollers, static or Well-graded sand-gravel mixtures, crushed
vibrating rock
Rubber-tyred rollers Coarse-grained soils with some fines
Grid rollers Weathered rock, well-graded coarse soils
Sheepsfoot rollers:
Static Fine-grained soils with more than 20% fines
Vibrating As for static, sand-gravel mixtures
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Coarse-grained soils with 4–8% fines
your on-line Tampers,
service. rollers All types
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impact compaction via range
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soil types and moisture services is
not intended for off-line storage, andregimes such storage is contrary to the
licence underNOTE:
whichThis Appendix
the is based is
service on supplied.
Table 2.3 in Hausmann, Manfred R. (1990),
Engineering Principles of Ground Modification. McGraw-Hill.
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© Standards Australia www.standards.org.au

 43 AS 3798—2007

AMENDMENT CONTROL SHEET

AS 3798—2007

Amendment No. 1 (2008)

CORRECTION
SUMMARY: This Amendment applies to the Preface, Section 2, Clauses 4.3, 4.4, 6.1.5, 6.2.6, 8.3 and 8.4, and
Table 8.1.
Published on 5 August 2008.

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 AS 3798—2007 44

NOTES

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