Do I Need a SWMS for Excavation and Trenching?
Excavating a shaft or trench deeper than 1.5 metres, or any tunnel, is high risk construction work under the model WHS Regulations — and several other s.291 categories catch shallower digs. Here is when the law requires a SWMS for excavation, and what it must contain.
Last updated 2026-08-27
The short answer: at 1.5 metres, always — and often before that
Under the model WHS Regulations, s.291 lists the excavation of a shaft or trench with an excavated depth greater than 1.5 metres, or the construction of a tunnel, as high risk construction work (HRCW) — that is paragraph s.291(g). Once work is HRCW, s.299 requires a safe work method statement to be prepared before the work starts.
The 1.5 metre figure is not the whole story. Shallower excavations are still high risk construction work whenever another s.291 category applies to the same job — digging near live services is the common one — so the honest question is never just how deep the trench is.
Trenches, shafts and tunnels — s.291(g)
The trigger is the excavated depth of a shaft or trench passing 1.5 metres, measured from the natural surface level. Tunnelling is HRCW at any depth. This is the same category and numbering across NSW, Queensland, the ACT, the Northern Territory, South Australia and Tasmania, which all run the model WHS Regulations.
Excavation contractors should also expect principal contractors to ask for a SWMS on trenches shallower than 1.5 metres as a site rule. That is not a legislative requirement, but refusing the paperwork rarely wins the argument — and if any other HRCW category applies, it stops being optional.
Shallow digs that are still high risk construction work
The s.291 categories that most often catch shallow excavation work:
- Work on or near energised electrical installations or services — s.291(k). Striking a live underground cable is the classic excavation incident, which is why a Before You Dig Australia (BYDA) search belongs in the planning step of any dig.
- Work on or near pressurised gas mains or piping, and near chemical or fuel lines — separate s.291 categories that apply wherever services run through the dig area.
- Work in an area with movement of powered mobile plant — excavators, bobcats, trucks and compactors moving around the excavation make the surrounding work HRCW under s.291.
- Work near a road, railway or other traffic corridor that is in use — a further s.291 category that catches service trenching along roads and footpaths.
What your excavation SWMS must cover
s.299(2) sets the required content: the SWMS must identify the high risk construction work being carried out, specify the hazards and risks arising from it, describe the control measures to be implemented, and describe how those measures are implemented, monitored and reviewed. Controls must be selected using the hierarchy of controls in Reg 36.
The SWMS has to be prepared before the HRCW starts, be available to workers, and be given to the principal contractor before work begins (s.301). It must be reviewed when the work or the controls change (s.302) and kept until the work is complete, or for at least 2 years after a notifiable incident (s.303).
Which GSR documents cover excavation work
GSR carries seven excavation-related SWMS documents across five trade packs, each delivered as an editable Word file with your business details pre-filled: Bulk Earthmoving and Site Cut plus Trench Excavation for Services in the Civil Works pack, Excavation and Trenching for Plumbing in the Plumbing pack, Excavation and Earthworks in the Demolition pack, Site Earthworks, Grading and Levelling plus Bobcat and Mini Excavator Operations in the Landscaping pack, and Swimming Pool Excavation and Benching in the Swimming Pool pack.
Pick the pack that matches your trade rather than a generic excavation template — the surrounding documents (plant operations, services location, traffic management) are trade-specific, and principal contractors read them as a set.
Victoria and Western Australia use different numbering
Victoria is not part of the national WHS scheme. Excavation-related high risk construction work is regulated under the Occupational Health and Safety Regulations 2017 (Vic), and the SWMS-equivalent duty sits at Reg 327 — the content requirements are substantively the same, but a Victorian document must cite Victorian law.
Western Australia adopted the model laws in 2022, so the duty exists under the Work Health and Safety (General) Regulations 2022 (WA) at Reg 299. The Act name and year differ from the eastern states; the requirements are the same.
Frequently asked questions
How deep can I dig before I need a SWMS?
A shaft or trench becomes high risk construction work when its excavated depth passes 1.5 metres (model WHS Regulations s.291(g)), and a tunnel is HRCW at any depth. A SWMS is then required before work starts under s.299. Shallower digs still need a SWMS whenever another s.291 category applies — most commonly work near energised electrical services.
Does trenching for plumbing or drainage need a SWMS?
Yes when the trench is deeper than 1.5 metres, and often before that — service trenches routinely run near live electrical, gas or fuel lines, which are their own high risk construction work categories under s.291. GSR's Plumbing pack includes a dedicated Excavation and Trenching for Plumbing SWMS in editable Word format.
Do I need a SWMS to operate an excavator or bobcat?
Operating the machine is not automatically high risk construction work by itself, but work in an area with movement of powered mobile plant is an HRCW category under the model WHS Regulations s.291 — which catches most real excavation sites — and many principal contractors require a SWMS for plant operations regardless. GSR's Landscaping pack includes a Bobcat and Mini Excavator Operations SWMS.
Is a SWMS required for excavation in Victoria?
Victoria runs its own scheme: the Occupational Health and Safety Regulations 2017 (Vic) require a SWMS-equivalent for high risk construction work under Reg 327, and trenches deeper than 1.5 metres are within scope. The content requirements match the national model, but the document must cite Victorian legislation rather than the WHS Regulations.
What must an excavation SWMS include?
The structure set by WHS Regulations s.299(2): the high risk construction work being carried out, the hazards and risks arising from it, the control measures applied using the hierarchy of controls in Reg 36, and how those measures are implemented, monitored and reviewed. It must be prepared before work starts and given to the principal contractor under s.301.
Get the documents
WHS-audited, editable Word documents that cite the exact provisions covered in this guide — pre-filled with your business details.
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Related guides
This guide is general information about work health and safety legislation, not legal advice. Requirements vary by state and by the specifics of your work — check with your regulator or a qualified professional before relying on it. Documents are templates and must be reviewed and adapted to your specific site conditions.