Excavation (1) Excavation Excavation Excavation .ppt

Excavation Excavation Excavation Excavation Excavation Excavation Excavation Excavation Excavation Excavation Excavation Excavation

1. Excavation
Hazards & Controls

2. Hazards

3. Collapse of sides
Type of soil
structure is an
important factor
What might appear
to be a safe soil
structure can
change dramatically
with changes in the
weather

4. Hazards - Physical
Materials falling onto people working in
the excavation
People & vehicles falling into excavation
People being struck by plant
Undermining nearby structures
Contact with underground services
Access to excavation

5. Hazards - Chemical
Fumes from vehicles/plant (C02)
Methane/other gases
Contaminated land/previous use?

6. Hazards - Biological
Leptospirosis
Previous use e.g. hospitals
Drains/sewers
Rubbish and waste

7. Control Measures
Supported by
timbering and props
Poling boards extend
above edge to act as
toeboards
Guard rails to prevent
falls
Tied ladder provides
safe access and egress
Exposed services are
supported

8. Collapse of Sides
Batter sides and ends
Support with timber, sheeting or
proprietary support systems
Use 1.2m as a guide for support, but
assess conditions at all times
Even work in shallow trenches can be
dangerous, especially if bending or
kneeling

9. Materials Falling into
Excavations
Do not store spoil or other materials
close to excavation – they could fall in
or cause sides to collapse
Provide guard rails and toe boards
where necessary
Wear hard hat in excavations

10. People & Vehicles Falling
into Excavations
Provide guard rails &
toe boards (2m)
Use stop blocks to
prevent vehicles over-
running
Keep vehicles away
from excavations
wherever necessary

11. People Being Struck by
Plant
Keep workers separate from moving
plant where possible
Plant operators should be trained and
competent
High visibility PPE

12. Undermining Nearby
Structures
Make sure excavations do not affect
footings of scaffolds or foundations of
nearby structures
Provide temporary support for
structure if necessary
Surveys of foundations and advice of a
structural engineer may be necessary

13. Avoiding Underground
Services
Look around for obvious signs of underground
services e.g. drains, patching of surface etc.
Use cable locators to trace any services. Mark
the ground accordingly
Use service plan
Dig trial holes by hand
Hand dig if in doubt (particularly for plastic
cables which cannot be detected)
Have emergency procedures/contact in place

14. Safe Access & Egress
Create steps in excavation
Provide good ladder access or other
safe ways of getting in and out of the
excavation

15. Fumes
Do not site petrol or diesel engined
equipment such as generators or
compressors in, or near the edge of, an
excavation unless fumes can be ducted
away or area can be ventilated

16. Protecting the Public
Barrier off all excavations in public
places to prevent falls
NRSWA
Where people may get onto the site out
of hours, backfill or cover excavations
to reduce risks

17. Supervision
A competent person must supervise the
installation, alteration or removal of
excavation support
People working in excavations should
be given clear instructions on how to
work safely

18. Inspections
Competent person must inspect:
At start of shift;
After any event likely to have affected
strength or stability of excavation; and
After any accidental fall of rock, earth and
other material.
A written report should be made after
most inspections
Stop work if inspection shows excavation
to be unsafe