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Health and Safety
Taking care with materials, equipment and work procedures and dealing with hazards.
Excavations and trenches
An excavation is any cut, cavity or trench formed by deliberate earth removal. All excavations must be made safe against collapse.
A trench is an excavation that is deeper than it is wide at the top. This presents a particular hazard if not shored up as there is nowhere that workers can be safe from collapse. Trenches that are to be entered by workers must have shoring or a trench shield to prevent the trench sides from collapsing onto them. Alternatively, workers may be protected from engulfment in a collapse by benching or battering the sides of the trench.
Trench safety practices:
- Support the trench sides with shoring or a trench shield.
- Bench or batter the trench sides.
- Keep the trench edges clear of spoil, materials or plant for a minimum of 600 mm.
- Provide barricades and warning signs around the trench.
- Ensure the trench remains safe from exhaust gases from nearby machinery.
- Ensure pumping is available where flooding could occur.
- Ensure that a safe access and egress are provided.
In July 2016, WorkSafe New Zealand issued Excavation safety – Good practice guidelines. This supercedes the old Approved Code of Practice for excavation and shafts for foundations.
Updated: 13 December 2017