Australia Model Code of Practice: Excavation Work 6.2c: 6.2 Design benches and batters by a competent person and limit slopes to 45 degrees unless certified

Benching and battering lower the chance that material from the walls slides into the hole, and a competent person such as a geotechnical engineer should design them, taking account of the soil type and moisture, planned face height and surcharge loads. They are not needed where a competent person determines stable rock is present, or has assessed the collapse risk as nil. When benching or battering, slopes should be no steeper than 45 degrees unless a competent person designs it and certifies it in writing. Each bench should have enough width to stabilise the slope and catch material from above, and sloped to limit water scouring, and the size of machinery and haul routes should be allowed for when setting slopes and bench widths.