60169 – National Certificate: Water and
Wastewater Reticulation Services
US ID 254059
Demonstrate Knowledge of Backfilling and
Compaction
Credits: 4
NQF Level 2
Demonstrate Knowledge of Backfilling and
Compaction
After this unit standard, you will be able to:
• Identify and describe backfill materials and compaction
equipment.
• Prepare for compacting operations.
• Accept and place materials.
• Assist with compaction of materials.
DEFINITION
BACKFILING:
the process of reusing or replacing the soil that is
removed during the excavation of foundations, ground
bearing slabs or other groundworks to support and
strengthen a structure.
COMPACTION:
is a process of increasing soil density and removing air,
usually by mechanical means.
Source: https://www.designingbuildings.co.uk/wiki/Backfilling#:~:text=Backfilling%20is%20the%20process%20of,walkways%20and%20other%20groundwork%20elements.
Source: https://environment.uwe.ac.uk/geocal/soilmech/compaction/compaction.htm
UNIT 1: Identify and describe backfill
materials and compaction equipment.
You will be able to:
• Demonstrate knowledge of backfilling materials.
• Compaction equipment are described in accordance with job requirements.
BACKFILLING
PURPOSE
Stability & structural Water flow
Environmental/Aesthetic
integrity management
VIDEO: https://www.youtube.com/watch?v=pfcBMx4x2wk
Source: https://trdsf.com/blogs/news/backfill-basics-materials-methods-expert-tips
BACKFILLING MATERIAL
TYPES OF MATERIAL
Natural Soil Gravel Sand Crushed Stone Concrete
• Most • Common – • Common – • Good • “Controlled
common improves improves material to density fill”-
material drainage compaction improve does not
• NOTE: Only if (provides stability & need
it meet stability) loadbearing mechanical
project capacity compaction
requirement • Improves • Useful in
drainage & narrow areas
compaction – machinery
cannot reach
Source: https://www.structuralguide.com/backfill-materials/
Source: https://www.bigrentz.com/blog/backfill-trench
BACKFILLING MATERIAL
PROPERTIES OF MATERIAL
COMPACTION
• Load distribution & stability
DRAINAGE
• Drainage of water to prevent the buildup of hydrostatic
pressure
STABILITY
• Maintain support & integrity of structure
BACKFILLING MATERIAL
BACKFILLING METHODS
COMPACTING
• Most costly method = Best results
• Testing per layer (regulated)
WATER JETTING
• Used on sand & soil (no clay)
FILLING
• Usually in concrete backfill
• Moisture & density needs to be monitored
DUMPING
• Not regulated
• Quickest
COMPACTION EQUIPMENT
Compacting is the most common type of backfilling
Rammer Plates Roller
• Uses physical impact • Uses vibrations • Uses weight of
• Trenches & ditches • Clay, sand & soil machine
• Covers large areas
Source: https://www.bigrentz.com/blog/backfill-trench
UNIT 2: Prepare for compacting operations.
You will be able to:
• Job instructions are confirmed with supervisor.
• Tools and equipment are selected in accordance with supervisor's instructions.
Job Instruction are confirmed with supervisor
• Location
• Extent of works
• material type
• depth of fill
• compaction requirements and requirements techniques.
DO NOT DO ANYTHING THAT IS NOT SET OUT ON THE JOB
INSTRUCTION
Tools and equipment are selected in accordance with
supervisor's instructions
The employer must ensure that each tool,
machine and piece of equipment in the
workplace is
• Capable of safely performing the functions for
which it is used,
• Selected, used and operated in accordance
with
• The manufacturer’s instructions, if available,
• Safe work practices and
• The requirements of this regulation
UNIT 3: Accept and place materials.
You will be able to:
• Delivered material is accepted in accordance with contract specifications for grade and
quality.
• Materials are placed in accordance with supervisor's instructions.
DELIVERED MATERIAL
Order Material Delivery Storage
• Prescribed SCM method • Verify Quantity & Quality • Maintain quality
• Clear specifications • Account Quantity
(Grade & Quality)
Delivered material is accepted in accordance with
contract specifications for grade and quality
material in accordance with contract specification for grade and quality
The backfill material in traffic areas shall comply with the following:
• For trenches less than 1.5 metres deep in traffic areas other than footpaths, the
backfill shall be 20 mm class 2 plant mixed wet mix crushed rock for the full
depth.
• For trenches 1.5 metres deep or greater in traffic areas other than footpaths, the
backfill shall be:
I. 20 mm class 2 plant mixed wet mix crushed rock for the top 600 mm.
II. 20 mm class 4 crushed rock for the remainder or other backfill material
specifically approved by road authority.
• All crushed backfill material shall comply with Vic roads standard specifications
Materials are placed in accordance with supervisor's
instructions.
Employers are responsible for the safe condition of tools and equipment used by
employees.
• Employees must notify supervisors and replace damaged tools.
• Employers shall not issue or permit the use of unsafe hand tools
UNIT 4: Assist with compaction of materials.
You will be able to:
• Material is placed in layers for compacting in accordance with specifications and job
requirements.
• Water is added to assist compaction in accordance with job requirements.
COMPACTION
• Where fill is placed around shafts or other structures, the fill shall be placed and
compacted evenly around the shaft or structure to prevent displacement.
• Care shall be taken to place and compact the fill evenly around the structure in
thin layers to prevent displacement.
• Care shall be taken to place and compact the fill evenly around the structure in
thin layers, to avoid unbalanced lateral loading.
• High compactive effort shall not be used against structures to ensure damage to
the structure is prevented.
• Particular care must be taken adjacent to the house sewer connection branches
and retaining walls.
COMPACTION
Water may be added during the compaction process to assist with compaction. The
following steps are recommended:
• Backfill in layers of 4- 6 (non-organic fill and clean of debris).
• Compact with a 454 kg compactor
• Water thoroughly
• Repeat first three steps
ACTIVITY 4
INDIVIDUAL (20 min)
Using your own experience in compaction – compile a process diagram
of the steps followed at your site.
NOTE: Demonstrate your understanding by including what you now
understand about the process.
