Trenching and Excavation

Why it matters

A cubic metre of soil weighs more than a tonne. A trench collapse gives no warning and buries a worker faster than anyone can pull them out. Work in a trench deeper than 1.5 metres is high risk construction work, but shallow trenches have killed people too. The ground is heavier and less stable than it looks.

Hazards

• ⚠ Trench collapse from unsupported walls
• ⚠ Spoil and plant loaded too close to the edge
• ⚠ Underground services: power, gas, water, comms
• ⚠ Water ingress undermining the walls
• ⚠ No safe way in and out
• ⚠ People working under a suspended load or swinging bucket

Controls and safe practices

• ✓ For trenches 1.5 metres or deeper, support the walls under reg 306: shoring, benching, or battering, with a geotechnical assessment where needed.
• ✓ Manage the excavation risks under reg 304 and reg 305 regardless of depth.
• ✓ Keep spoil, plant, and materials back from the edge by at least the trench depth.
• ✓ Locate services with Dial Before You Dig and pothole by hand before machine digging.
• ✓ Provide safe access and egress within 25 metres of any worker in the trench.
• ✓ Keep workers clear of the excavator's slew zone and never under a suspended bucket.

Crew discussion questions

1. How deep are we going, and what support are we using?
2. Where are the underground services, and have we potholed?
3. How does someone get out fast if the wall moves?
4. Where is the spoil going, and is it back far enough?

Applicable WHS citations

reg 304, reg 305, reg 306

More toolbox talks

• Confined Spaces
• Working Around Mobile Plant
• Manual Handling and Your Back
• Hazardous Chemicals on Site
• White Cards and Site Induction
• The SWMS You Just Signed

Talks by trade

PlumberExcavation / EarthmovingAll toolbox talks

SWMS by trade

PlumberExcavation / Earthmoving