The locations of all underground pipes and services should be established prior to digging. The general rule for any excavation greater than 1.25m (subject to actual ground conditions) is that it must be supported or have the sides of the trench sloped (“battered”) to a safe angle. In the case of deeper trenches the sides may also have to be “benched”. Care should also be taken to avoid injury to workers and other persons arising from:
Rock or other material falling into the trench.
People falling into trenches that do not have sufficient protection.
Accessing trench by any method other than a tied ladder.
Petrol or diesel fumes entering a trench.
Vehicles accidentally driving into unprotected excavations.
Diagram B5 - Trench support - Firm soil
Diagram B6 - Trench support - Soft soil
Diagram B7 - Trench support - Granular soil