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Introduction
The Need for Excavation Training
Controlling Excavation Risks
Overview of Excavation
Personal Protective Equipment and its’ Use
Considerations for choosing a Method of Excavation
Site Inspection
Work Plans
Backfilling
Summary
Headings:
 Welcome
 House Keeping
 Overview Course
To provide personnel with the knowledge and
skills to be regarded as the Competent
Person as described in the Bechtel SWPP
4MP-T81-03202
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Explain the need for excavation training
Identify the WH&S Act and Regulation
Describe the process for controlling excavation risks
Describe the purpose of a “Work Plan” IAW SWPP 4MP-T8103202
Identify the major steps of an excavation
Describe the process for dealing with staff who refuse to use
appropriate PPE
Describe the requirement for the conduct of site inspections
Identify factors that affect the stability of an excavation
Describe the backfilling process in accordance with SWPP 4MPT81-03202
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An Excavation is any man-made cut, cavity,
trench, or depression in the earth’s surface
formed by earth removal.
A trench is a narrow underground excavation
that is deeper than it is wide, and no wider
than 15 feet (4.5 meters)
A man has been rescued from a trench that collapsed in Melbourne's south-east
earlier this morning.
The 35-year-old construction worker spent almost two hours buried waist-deep
in soil on a new estate in Pakenham.
Fire crews were called to the scene just before 9am and used special equipment
to dig out the man and stabilise the surrounding soil. (The Age – August 11, 2012)
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When one looks at the cross section of a grave and an
unsafe trench of similar dimensions, it can be seen that
there is very little or no difference
Considering that a cubic metre of earth weighs
approximately one tonne, it would certainly make it
difficult for the work-person in the trench to breathe
with that load resting on him
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Soil type
Water content in soil
Weather conditions
Pressures – from near by loads
Vibration – from passing heavy vehicles
Time
Rock/clay seam
No shoring system used
Timber not strong enough
Timber badly placed
CP218
Excavation and Trenching
WH&S Act 2011
WH&S Regulation 2011
SWPP 4MP-T81-03202
Site Excavation and Backfill

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Act (2011)
o Imposes obligations on people at work places
to ensure freedom from disease and injury to
persons created by work places or activities.
Regulation (2011)
o You must do what it says
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CP218
States that it is a requirement at all projects to
implement a procedure that provides effective safety
measures and methods to protect personnel who are
required to work in and around excavations and
trenches
SWPP - 4MP-T81-03202
Site Excavation and Backfill
 Defines the standard work process for earthwork
related activities at the construction site. It also
defines a “Competent Person”
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The Queensland Workplace Health and Safety Regulation defines a confined
space confined space as an enclosed or partially enclosed space that:
(a) is not designed or intended primarily to be occupied by a
person; and
(b) is, or is designed or intended to be, at normal atmospheric
pressure while any person is in the space; and
(c) is or is likely to be a risk to health and safety from:
◦ (i)
an atmosphere that does not have a safe oxygen level; or
◦ (ii)
contaminants, including airborne gases, vapours and dusts, that may
injury from fire or explosion; or
◦ (iii) harmful concentrations of any airborne contaminants; or
◦ (iv) engulfment
cause
NB# - All of the above three (3) elements must be met to be considered a Confined Space
DOES NOT INCLUDE A MINE SHAFT OR THE WORKINGS OF A MINE.
A competent person is a person who has acquired through training,
qualification or experience the knowledge and skills to carry out the task.
This person should be knowledgeable on:
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the type of excavation being undertaken,
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appropriate control systems,
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and where possible should have experience relating to local
soil and rock conditions
The CP is the individual on the construction team who is capable of
identifying existing and predictable hazards in the surroundings, or
working conditions that are unsanitary, hazardous or dangerous to
employees and who has the authorisation to take prompt corrective
measure to eliminate them.
The Competent person is responsible for:
• Hazards in the surroundings, or working conditions that are
unsanitary, hazardous or dangerous to employees and who has
authorization to take prompt corrective measures to eliminate
them
• identifying hazards,
• conducting daily inspections,
• monitoring water removal operations and conducting inspections
during and/or following rainstorms.
• The CP is designated as being responsible for completing the Daily
Trench Report, as outlined in BESH Core Process CP-218, Excavation
and Trenching.
• daily trench safety report form.doc
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Systematic review
Communication tool
PFE determines criteria for work operations
requiring permit
Client Excavation Permit may also be required
(reviewed by all parties)
Approved prior to commencement of work
Permit Register
Sequential Permit Number
site excavation permit.doc
START
Site inspection
and preparation
Is the
excavation
1.2m or
greater?
Y
No person is
to enter
excavation
Responsible
Field Engineer
to organise
shoring,
battering or
benching
N
Is the
ground
unstable or
prone to
collapse?
Method of
stabilisation
complete
Y
N
Are there other
circumstances
posing threat of
collapse. E.g..,
structure,
vibration etc.
N
BECHTEL SWPP
4MP-T81-0302
to be followed
Competent person
to routinely inspect
excavated site
Y
Personnel can
enter
excavation
Complete work
in excavation
Backfill
END
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Minimise access of persons to an excavation
Inspections
Shore, batter or bench excavations where the
soil or rock is unstable or prone to collapse,
where these could cause injury to a person or
deeper than 1.2m
Access/Egress
Management Control of risk by supervision and
control of work
Barricades
The zone of influence:
The volume of soil around the excavation affected by any external load
(for example, vehicles, plant, excavated material). It is the zone in which
there may be an influence on the excavation, including possible ground
collapse – Site requirement for spoil material is 1m from edge of trench
Determined by the supplier of the shoring or a Geo Technical engineer
Depends on the ground conditions
The zone in which there may be an influence on excavation
Includes possible ground collapse
Considerations in Planning:
 The nature & type of Rock/ Soil
 Duration the Excavation will be open
 Proximity of Buildings
 Likely presence of Water-Seepage/ flooding
 Underground Water Table
 Size and profile of excavation
 Likely existence of filled land
 Method of excavation
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Proximity of underground services
Previously dug trenches
Surcharge on side of excavation (eg. plant )
Excavation across slopes
Potential site conditions (eg. bedding
planes, fissures)
Vibration from vehicles
Proximity of excavated material
Rain
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The Responsible Field Engineer will check this
prior to permit approval
Typically a drawing showing utilities near
excavations is provided
Additional controls as required to put in place
i.e., digging by hand
It is important that excavation methods include an initial examination of
the area to be excavated, for example sampling the area by exposing a
short section of underground services usually using water pressure and
a vacuum system to excavate or ‘pothole’ the area
Underground essential services exposed by ‘potholing’
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Complete as much work from outside the trench as possible
Minimise the time the trench is open
Barricade and sign - Especially unattended excavations
Material on high side could fall into trench
Dangerous Situation
Shear Plane Failure
Worker trapped and crushed
Worker smothered
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When the trench is greater than 1.2m in depth , shoring, battering or
benching is mandatory
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If less than1.2m, shoring, battering or benching required if the
trench walls unstable
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Person Conducting Business or Undertaking (PCBU) with
management or control of a workplace where excavation work is to
be carried out must:
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Obtain current underground essential services information (if applicable)
Have regard to the information
Provide the information to other duty holder involved in the work
Manage risks to health and safety associated with excavation work
Comply with specified controls for trenches at least 1.2 metres deep
Complete Excavation Permit
Conduct daily inspections
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Proprietary systems (IAW AS 4744.1 – 2000)
◦ Shorco boxes installed, used, maintained and
dismantled in accordance with manufacturer’s
specifications
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Non-Proprietary Systems
◦ designed by an engineer
◦ Meets all safety requirements
◦ installed by trained personnel
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No gaps between edge of trench & shoring
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Benching
◦ The creation of a series of steps in the vertical wall of an
excavation
◦ Steps no greater than 1.2m in Bechtel
◦ overall angle 45 degrees or less
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Batter
◦ The wall of an excavation is sloped back to a predetermined angle
◦ The wall beside the work area should not exceed 1.2m in Bechtel
◦ Overall angle 45 degrees or less
Batter
Combination of Bench and Batter
• The angle at which a sloping bank of soil or rock will stand
without lateral support
• The angle of repose should not exceed 45 degrees unless
certified by an engineer in writing
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Types of Soils
◦ Granular Soils
◦ Cohesive Soils
◦ Silts
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Soil faults
◦ Fissures
◦ Greasy Backs
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Decide which side of the excavation to place the excavated material if
ground is sloping
Things to consider:
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Access
Underground services
Earth moving machinery of vehicles
Service installation and backfilling
Manual work
Upper and lower side of excavation
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If soil is quite dense (hard to shovel) then type A
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If soil is loose (easy to shovel) then type B
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Wet / moist sand is considered type C
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Loose sand subject to any vibration is considered
type C
General Notes:
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If layered soils, then classify by weakest layer
If two or more layers of distinctly different soil or rock
types or clay seams in rock which dip towards the trench
with a slope of 4 Hor. To 1 vert. then consider type C
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Fractured rock is considered type B when dry or type C
when wet
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All rock is considered fractured unless tests and
inspections prove otherwise
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Gravel, sand, or silt, (coarse grained soil) with little or no
clay content. Granular soil has no cohesive strength.
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includes sands and gravels
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particles are visible
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feel gritty
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contains little or no fines
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Sticky soil such as clay or clayey silt whose
strength depends on the surface tension of
capillary water
If fissures are detected or suspected then a type A
soil becomes type B
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Contains clay either wholly or in part (70% clay
content)
Includes clay, silty clay, organic clay, gravelly clay,
sandy clay, clayey silt, etc.
Contains sufficient clay to mould a moist lump
without it disintegrating
Clays when moist to wet feel sticky and often greasy
If dry clay can be broken by hand but not powdered
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Contains clay either wholly or in part (70% clay
content)
Includes clay, silty clay, organic clay, gravelly clay,
sandy clay, clayey silt, etc.
Contains sufficient clay to mould a moist lump
without it disintegrating
Clays when moist to wet feel sticky and often
greasy
If dry clay can be broken by hand but not powdered
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Silt is created by a variety of physical processes capable
of splitting the generally sand-sized quartz crystals of
primary rocks by exploiting deficiencies in their lattice
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When in dry, powdered form- it feels fine and flour
like (possibly a bit gritty) and often stains the hand
When wet the soil does not feel sticky
Dry lumps can be easily powered between fingers
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Visual examination prior to excavation
Visual inspection when trench first dug and appearance after
excavation
observing chunks of soil spall
Visual observation for fissures parallel to the direction of the
trench
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Ladders or a means of egress shall be
provided every 7.6m (25 feet)
Stay within controlled area
Do not walk on shoring components
Wear PPE
Barricades and signs
Excavation depth greater than 6 meters
designed by a registered professional
engineer.
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Control of Access
◦ Control of people around excavation site
 Signage and barricading
 Unattended excavations
◦ Ensure staff within protected area
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Routine Inspections
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carried out by a competent person
for excavations deeper than 1.2 meters
before work in the excavation and during work in a trench
if deficiencies detected:
 cease work immediately & staff should not enter trench until
rectification has been carried out
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Shoring becoming unstable
Shoring components not secure
Premature removal of shoring
Cracks appearing near or parallel to the edge of an excavation
Excavated material being placed close to the edge of the trench
Machinery operating close to the edge of the excavation
Surface falling into the trench
Water seeping into excavation from side walls or base
Surface water entering the excavation or accumulating on the
surfaces near the excavation
Inclined bedding planes “dipping” into the excavation
Heaving or swelling of the ground at the bottom of the trench
Subsidence along side the excavations
After a rain event
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Hazard Identification
Risk Assessment
◦ Probability
◦ Severity
Risk Control
◦ Eliminate the Hazard
◦ Minimise the Risk
Provide “back-up” controls
◦ Administrative controls, safe work practices & PPE
Monitor & Review Control Measures
◦ Audits
◦ A written record should be kept (the work plan)
Employer
 Prevent the risk of injury to all personnel
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Monitoring of work activities
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Training as required
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Develop Work Procedures
Worker
 Prevent the risk of injury to yourself from collapsing excavations
 Comply with instruction given by your employer
 Ensure your activities do not place other persons at risk
Visitor
 A person not directly engaged in excavation work
 Must carry out a health or safety direction given by an employer or self
employed person
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The process of excavating
An overview of Site Excavation and
backfill SWPP 4MP-T81-03202
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Obtain a signed excavation permit
Personal Protective Equipment
Site Inspection and Preparation
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Site Inspection
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Locate services
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Barricade and sign the site
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Hand/ Machine
Shoring
Excavate
Bedding / Backfilling
Restoration
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SWPP 4MP-T81-03202 on Bechtel Website
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Workers' responsibility under the act.
PPE required for an excavation Safety
Absolute
◦ Hard Hat, Safety Boots, Safety Glasses and
Gloves
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Dealing with Workers who refuse to use
PPE
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Request compliance
Stop work
Request worker to leave work site
Log the event in diary
Report incident to ES&H Representative for
further action
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Hand Excavation
Machine Excavation
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Shallow trenches
Locations where a machine can not be
used
Pot holing
Cleaning of trenches
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Excavator:
Larger trenching systems; larger pipes; rock
breakers; Shorco Boxes; Greater Reach of Machine;
Largest Cost
Beware Blind Spots
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Backhoe:
Smaller trenches; Better Access; Variety of
Trenches; Multi-purpose
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Mini excavator:
Smaller/ shallow trenches; Good Access; Lowest
Cost; Less Restoration
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What is a Site Inspection?
How to Conduct a Site inspection for
an Excavation
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Provides on-going safety monitoring
Helps identify non-compliance and potential
safety risks
Assists in the implementation of hazard
control strategies
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Conduct Site Inspection
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Assess Site Conditions
Work and Storage Space
Locate Other Services
Night Work
First Aid and Emergency
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Why is a Work Plan Needed?
◦ To ensure that all labour, equipment, materials, and
methods are identified and coordinated to
maximum efficiency while meeting construction
schedule requirements
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The RFE shall inspect, test as required, and accepted
Upon acceptance, the RFE shall release the area for
backfill
The excavation shall be cleaned
The RFE shall inspect and accept the sub-grade for
backfill
The RS shall inspect stockpile areas
Restoration of site
Headings:
 What has been covered
◦ The Need for Excavation Training
◦
Controlling Excavation Risks
◦
Overview of Excavation
◦
Personal Protective Equipment and its’ Use
◦
Considerations for choosing a Method of
Excavation
◦
Site Inspection
◦
Work Plans
◦
Backfilling
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Using the learning's on site
Do you have any questions?