Tradie Run Sheet Builder / Before you start / Trench 1.5 m or deeper
Trench 1.5 m or deeper
Printed on a job only when this tag is ticked or trench15 is in its tags column. Never read from the task text.
A sub-tick under digging; ticking it ticks that too.
What the sheet prints
- Secure the area; support all sides by shoring, shielding or comparable means, benching or battering WHS Regs r 306; Excavation Code of Practice 5.1, 6
The clauses behind it
Each clause below is our statement of it, cited to it, not the text verbatim.
the model WHS Regulations, r306
r 306 Trenches 1.5 metres or deeper: secure the area and support all sides. A PCBU proposing to excavate a trench at least 1.5 metres deep secures the work area from unauthorised or inadvertent entry so far as reasonably practicable, and minimises collapse risk by supporting all sides through shoring by shielding or comparable means, benching or battering, unless a geotechnical engineer advises in writing that all sides are safe from collapse (advice stating its period and any natural occurrences that could create a risk).
the model Code of Practice for excavation work, 5.1a
5.1 Secure trenches at least 1.5 metres deep from unauthorised entry (WHS Regulation 306). Under WHS Regulation 306, a PCBU that proposes digging a trench 1.5 metres or more deep has to ensure, as far as reasonably practicable, that nobody can get into the work area without authority, including by accident, by securing it.
the model Code of Practice for excavation work, 5.1b
5.1 Support all sides of trenches at least 1.5 metres deep by shoring, benching or battering (WHS Regulation 306). For a trench 1.5 metres or deeper, the PCBU must also minimise the risk of trench collapse to any person by making sure every side is adequately supported using one or more of: shoring by shielding or a comparable method; benching; or battering. A combination may work best depending on the environment and the material dug. In streets or built-up areas the excavation may need partial or full sheeting or support so local vehicle movement does not cause collapse. A competent person such as an engineer should be the one to design support systems or to help choose other collapse controls such as trench shields.
the model Code of Practice for excavation work, 5.1c
5.1 Support trenches of any depth where there is a risk of engulfment. Where a worker entering a trench could be engulfed, the Code recommends that shoring, benching or battering be used whatever the depth of the trench. The Code states this as a recommendation separate from the 1.5 metre trigger in WHS Regulation 306, so a shallow trench carrying an engulfment risk should still have its sides supported.
the model Code of Practice for excavation work, 6
6 Plan to prevent ground collapse and never enter an unsupported trench deeper than 1.5 m. Ground collapse is a primary excavation risk: it can happen fast and without warning, and a buried worker is likely to suffocate before help comes because soil covers the head or stops the chest expanding. The Code's Figure 8 states that nobody should be inside a trench deeper than 1.5 m until support is in place, lists water seeping into the excavation and tension cracks on the surface among the signs that collapse is near, and notes a wedge of sand over one metre of a two metre deep trench weighs about three tonnes. When selecting methods and controls, consider whether entry can be avoided, the type and strength of the ground (natural or backfilled), moisture, slope, groundwater, faults, nearby watercourses, drains or runoff, work area limits, planned face height, nearby traffic and plant, vibration from other work, adjacent loads such as buildings, tanks, retaining walls and trees, and underground services.
the model Code of Practice for 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.
the model Code of Practice for excavation work, 6.3a
6.3 Use shoring designed by a competent person where benching or battering will not work. Shoring is positive ground support for one or more excavated faces that stops soil moving and so prevents collapse. It is used where location or depth make benching and battering impracticable, and is common in trenches in unstable ground such as soft or wet ground, sand, silt or soft moist clay. Shoring should be used where the ground will not stand unsupported and benching or battering is not practical or effective, and where someone could be buried, struck or trapped by material forming or next to the excavation side. A competent person such as an engineer should always design it to suit the specific site conditions. Where the same risk applies to those installing the shoring, other controls must protect people entering the excavation.
the model Code of Practice for excavation work, 6.5a
6.5 Use trench shields and boxes designed for the depth and ground. A shield is usually a steel structure able to withstand a ground collapse and protect those inside; it may be fixed or portable and moved along as work proceeds. Trench shields and boxes are built for the earth pressures of particular depths and ground types and have designated lifting points. Unlike shoring, which prevents collapse, shields and boxes only protect workers if a collapse happens. They suit places where other support is not reasonably practicable and are mostly used in open areas where an excavator or backhoe can lift them in and out, but not where access or ground conditions rule out lifting equipment. Boxes may be light or heavy duty depending on depth and ground, and a competent person such as an engineer should design them, with manufacture to job-specific dimensions.
the model Code of Practice for excavation work, 6.7
6.7 Inspect excavations and ground support frequently. Soil around excavations can change quickly as it dries out, as the water table shifts or as it becomes saturated. A competent person should check the soil and the condition of shoring, batters and trench walls often for fretting, slipping, slumping or swelling. Where needed, the excavation should be repaired or the shoring strengthened from above before work below ground continues.
In Victoria
A Victorian sheet prints, in place of the lines above:
- A trench deeper than 1.5 m is high risk construction work, so a SWMS; engulfment rescue and first aid procedures set up before the work starts OHS Regs (Vic) r 322(g), r 331(2) and (3)
Victoria: the lines below cite the Victorian OHS Act and OHS Regulations; the Regulations are due to sunset, so check the version in force.
Each clause below is our statement of it, cited to it, not the text verbatim.
the Victorian OHS Regulations, P5.1-hrcw
rr 322 and 324 High risk construction work categories and SWMS content. High risk construction work (r 322) means construction work falling in any of these 19 categories: (a) a person risks a fall of over 2 metres; (b) the work is on a telecommunications tower; (c) demolition is involved; (d) asbestos is removed or is likely to be disturbed; (e) structural alterations need temporary support so the structure does not collapse; (f) a confined space is involved; (g) a trench or shaft is dug to a depth greater than 1.5 metres; (h) a tunnel is involved; (i) explosives are used; (j) the work is on or close to pressurised gas mains or gas distribution piping; (k) the work is on or close to lines carrying chemicals, fuel or refrigerant; (l) the work is on or close to live (energised) electrical installations or services; (m) the area may hold a flammable or contaminated atmosphere; (n) tilt-up or precast concrete is involved; (o) the work is on or beside a road or railway carrying traffic; (p) powered mobile plant moves about the workplace; (q) the area has artificially created temperature extremes; (r) the work is in, above or beside water or another liquid with a drowning risk; (s) diving is involved. Categories (j), (k) and (l) are how Part 5.1 treats work near gas, chemical, fuel, refrigerant and electrical services: they make the work high risk and so trigger a SWMS; Part 5.1 contains no separate services provision. A safe work method statement (SWMS, r 324) is a document that identifies the high risk construction work, states its hazards and risks, adequately describes the control measures and how they will be put in place, and is written so the people who use it can readily access and understand it.
the Victorian OHS Regulations, r331-2
r 331(2) and (3) Establish engulfment emergency procedures before work starts. Where construction work carries a risk of a person being engulfed by soil or other material, the employer, or the self-employed person, must set up emergency procedures before the work begins. The procedures must, as far as reasonably practicable, allow an engulfed person to be rescued and given first aid, and must be capable of being put into action immediately once a person is, or is likely to be, engulfed. The regulation does not apply to digging a mine, a Water Act 1989 bore, or a quarry as defined by the Victorian mineral resources Act of 1990, or to a shaft, trench or tunnel dug for emergency work, for an emergency service's rescue or emergency response work, or for burial or interment of the dead (r 331(6)). Act compliance is through ss 21, 23 and 24.
Trades that meet it most: plumbers, landscapers.