Excavation injures and kills builders in two ways: the ground falls in, or the bucket finds a service nobody located. Both are almost always preventable with planning done before the machine arrives. An excavation permit forces that planning: it cannot be signed until the services are located and the ground support is in place.
Services first: plans, then the ground
Lodge a Before You Dig Australia enquiry well ahead of the work. Asset owners respond with plans of their gas, electricity, water, sewer and telecommunications assets near the site. Read them, check they cover the dates of your work, and note any conditions the owners set for working near their assets.
Then treat the plans as a starting point, not an answer. Service plans are indicative: depths change, services are moved, and private services on the property are usually not shown at all. Locate services on the ground with a locator, and expose them by hand or with vacuum excavation before machine digging near them. Mark them, and show the operator.
Keeping the sides up
Soil that looks solid can collapse without warning, especially after rain, near vibration or where spoil has been heaped on the edge. There are three main ways to protect an excavation:
| Method | What it is | Suits |
|---|---|---|
| Battering | Sloping the sides back to a stable angle | Open sites with room to slope, stable soils |
| Benching | Cutting the sides into steps | Cohesive soils where steps stay stable |
| Shoring | Supporting vertical sides with shields, props or sheeting | Tight sites, deeper trenches, poor or wet soils |
The choice depends on the soil, depth, water, space and nearby loads, and should be made by a competent person, with shoring designed or certified where required. Deeper than 1.5 metres, the work is on the high-risk construction work list and needs a SWMS.
Spoil, plant and edges
Spoil heaped on the edge adds load to the side and can fall back onto anyone below. Plant and trucks near the edge do the same. Set the distances in the plan. Put barriers or covers around the excavation, especially where the public or other trades pass, and never have anyone in the excavation while the machine is still digging.
Getting in and out
People in a trench need a way out that is quick in an emergency: ladders or ramps close to where they are working. Plan rescue before anyone goes in. If the excavation could collect gas or lack oxygen, such as near sewer lines or in low-lying ground, check the atmosphere.
Inspections
Excavations change. Inspect before each shift, after rain, and after anything that could affect stability: heavy plant nearby, vibration, a burst pipe. The inspection table on the permit records who looked and whether it was safe to enter. If in doubt, no one goes in until a competent person has checked it.
When things go wrong
If a service is struck, stop, keep people away, and follow the emergency procedure for that service: evacuate upwind for gas, stay clear of damaged cables, call the asset owner and emergency services. A collapse or a strike may be a notifiable incident, so record it on an incident report and check whether the regulator must be told.
Renovation and small-site excavation
Many excavation incidents on residential work happen on small jobs: a trench for a stormwater line beside the house, underpinning, a footing for a deck, a sewer connection. These jobs often feel too small for a permit, but they concentrate the hazards. Trenches beside existing footings can undermine them. Private services on the property, such as the sewer line, a garden lighting cable or a gas line to a barbecue, are rarely on Before You Dig plans. Access is tight, so spoil ends up on the edge. A short permit still asks the right questions: where are the services, how will the sides be kept up, where does the spoil go, and is anyone going in?
Pool excavations
Swimming pool excavations combine depth, often well beyond 1.5 metres, tight rear-yard access, spoil that has nowhere to go, and neighbours’ structures close to the boundary. They also often happen after the house is occupied, with children and pets nearby. Treat them as high-risk construction work with a SWMS, plan the spoil removal before digging, protect adjoining structures with engineering advice where the excavation is near them, fence the excavation securely at the end of each day, and check it after rain before anyone enters. Coordinate with the dilapidation report for neighbouring properties, which is often a consent condition for pool work near boundaries.
