Non-Destructive Vacuum Excavation (NDD) — Safe Work Method Statement
Safe Work Method Statement for non-destructive digging using hydro (water) or air vacuum excavation trucks to expose underground services, dig potholes and excavate around assets.
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Non-destructive digging (NDD) with a vacuum excavation truck is the accepted way to expose underground services before mechanical excavation or boring. It removes much of the strike risk, but it does not remove it: a high-pressure water lance can still cut through cable sheathing or PE gas pipe if it is held still on an asset, and the work happens next to services that are live. NDD is usually High Risk Construction Work because it involves powered mobile plant, is often done on or beside a road in use, and is carried out on or adjacent to energised electrical services and pressurised gas mains. Holes deeper than 1.5 metres also trigger the trench HRCW category.
The hazards specific to this task are the high-pressure water lance (injection injuries, flying debris and service damage), the vacuum hose (suction can grab hands, clothing and loose objects), reversing a heavy truck in a tight road corridor, noise from the vacuum blower, and the open hole left behind. Air vacuum excavation adds dust from the air lance, which can include respirable crystalline silica in some soils. Decanting the spoil tank creates its own hazards and must happen only at an authorised disposal site.
Every job starts with a Before You Dig Australia (BYDA) enquiry and the asset owners' plans, and the operator must follow each asset owner's conditions for pressure, nozzle type and clearances. Operators must be trained and competent on the specific truck and lance, and the truck driver must hold the licence class for the vehicle. Traffic controllers need the accreditation required by your state or territory.
The SWMS should set the maximum lance pressure and nozzle type for working near services, the exclusion zone around the lance, how the operator and vacuum hose handler communicate, and how holes are made safe when left open.
Customise this template with the BYDA reference and asset owner conditions, the truck model and type (hydro or air), the lance pressure limits used near services, the traffic guidance scheme reference, the number and depth of holes, and the spoil disposal facility.
Personal Protective Equipment
High Risk Construction Work Types
- •Work in or near a shaft or trench deeper than 1.5 metres, or a tunnel
- •Work on or near pressurised gas distribution mains or piping
- •Work on or near energised electrical installations or services
- •Work on, in or adjacent to a road, railway or other traffic corridor in use by traffic
- •Work in an area with movement of powered mobile plant
Risk Assessment
1.Pre-start planning and service plans
| Hazard / Risk | Initial Risk | Control Measures | Residual Risk | Responsibility |
|---|---|---|---|---|
| Excavating without knowing what services are present | High | Obtain BYDA plans and asset owner conditions before mobilising. Locator marks services on the ground. Operator reads all asset owner conditions, including pressure limits and whether a standby officer is required. | Low | Supervisor / Operator |
| Truck or equipment defects | Moderate | Daily pre-start on truck, boom, hoses, lance, dead-man trigger, tank door seals and emergency stops. Defective items tagged out until repaired. | Low | Operator |
2.Truck positioning and traffic control
| Hazard / Risk | Initial Risk | Control Measures | Residual Risk | Responsibility |
|---|---|---|---|---|
| Workers or public struck by reversing truck | High | Spotter guides all reversing. Reversing camera and alarm working. Truck positioned so the crew works away from live traffic. | Low | Driver / Spotter |
| Workers struck by road traffic | Catastrophic | Traffic control set up to approved traffic guidance scheme before work. Work zone delineated and kept clear of pedestrians. Accredited traffic controllers where required. | Moderate | Supervisor / Traffic Controller |
| Boom contacts overhead power lines | Catastrophic | Check for overhead lines before raising the boom. Keep the boom outside the approach distance set by the network operator or your state regulator. Use a spotter when working near lines. | Low | Operator / Spotter |
3.Hydro or air excavation around services
| Hazard / Risk | Initial Risk | Control Measures | Residual Risk | Responsibility |
|---|---|---|---|---|
| Water jet injection injury to hands, feet or legs | High | Lance fitted with a working dead-man trigger. Operator never points the lance at a person or their own feet. Nobody else within 2 m of the lance tip while it is pressurised. Any water injection injury treated as a medical emergency even if the wound looks small. | Low | Lance Operator |
| Lance damages cable sheathing, PE gas pipe or fibre | High | Use the pressure and nozzle type allowed by the asset owner near their services; use a rotating or fan nozzle, not a zero-degree tip. Keep the lance moving and work in from the side, never directly at the asset. Stop and notify the asset owner immediately if any damage occurs, even a scratch. | Moderate | Lance Operator |
| Gas leak after a strike on a gas service | Catastrophic | If gas is smelt or heard: stop, shut down the truck engine, move everyone upwind, eliminate ignition sources and call the gas distributor's emergency number and emergency services. Do not attempt to repair. | Moderate | Operator / Supervisor |
| Flying debris and dust (air excavation) | Moderate | Face shield and safety glasses for lance operator. Keep vacuum tube close to the air lance to capture debris. P2 respirator where soils are dry or likely to contain silica. | Low | Lance Operator |
4.Vacuum hose handling
| Hazard / Risk | Initial Risk | Control Measures | Residual Risk | Responsibility |
|---|---|---|---|---|
| Hand, limb or clothing sucked into the vacuum tube | High | Never put hands near the open end of the vacuum tube. Keep loose clothing, rags and gloves away from the inlet. Use the boom or a tube handle rather than holding the end. Operator and hose handler agree a stop signal before starting. | Low | Hose Handler / Operator |
| Blockage cleared under vacuum | Moderate | Shut off vacuum before clearing any blockage. Clear with tools, not hands. | Low | Hose Handler |
5.Noise exposure
| Hazard / Risk | Initial Risk | Control Measures | Residual Risk | Responsibility |
|---|---|---|---|---|
| Hearing loss from vacuum blower and lance | High | Hearing protection worn by all crew within the work zone while the vacuum runs. Use the truck's lowest blower setting that does the job. Rotate tasks on long shifts. | Low | All Crew |
6.Leaving holes open and backfilling
| Hazard / Risk | Initial Risk | Control Measures | Residual Risk | Responsibility |
|---|---|---|---|---|
| Falls into open holes | Moderate | Holes left open are covered with plates rated for the expected traffic or barricaded with mesh barriers and lit at night. Exposed services protected from damage. | Low | Supervisor |
| Damage to exposed services during backfill | Moderate | Backfill around services with sand or approved material by hand or hydro; do not compact directly on the asset. Reinstate marker tape where removed. | Low | Crew |
7.Decanting the spoil tank
| Hazard / Risk | Initial Risk | Control Measures | Residual Risk | Responsibility |
|---|---|---|---|---|
| Struck by tank door or slurry surge during tipping | High | Decant only at an authorised facility. Nobody behind the tank or under the door when tipping. Raise tank on level ground; follow manufacturer's tipping sequence. | Low | Driver |
Relevant Codes of Practice
Worker Acknowledgement
By signing below, I confirm that I have read, understood and agree to comply with this Safe Work Method Statement.