Industrial Vacuum / Sludge Removal SWMS

Industrial vacuum and sludge removal work involves the extraction of liquid, semi-solid and solid waste from pits, sumps, tanks, interceptors and process vessels using high-flow vacuum trucks or skid-mounted units. The task is classified as High Risk Construction Work under WHS Regulation 2011 r291 because it almost invariably involves entry to or work adjacent to a confined space, and routinely exposes workers to hazardous chemicals, biological sludges, hydrogen sulphide and oxygen-deficient atmospheres. A documented Safe Work Method Statement is mandatory before work commences, must be developed in consultation with workers under WHS Act s47-49, and must be available at the workplace under r299. This SWMS template addresses atmospheric testing, vacuum hose management, decontamination and emergency retrieval — controls that a generic cleaning SWMS will not cover. Failure to prepare, comply with or retain this SWMS exposes the PCBU to enforcement action and invalidates the principal contractor's WHS Management Plan.

Hazards identified

7 hazards covered, sorted by priority.

Control measures

Hierarchy-of-controls order: elimination → substitution → isolation → engineering → administrative → PPE.

1. 1Elimination — Where feasible, remove sludge by gravity drain, in-situ dewatering or chemical solidification so no human entry to the confined space is required at any phase.
2. 2Elimination — Decommission and isolate upstream feeds, blanking off all lines with locked tags before any vacuum coupling, eliminating the risk of live product re-entering the vessel.
3. 3Substitution — Replace solvent-based degreasers used during pre-cleaning with water-based or biodegradable alternatives to reduce flammable vapour load and dermal toxicity.
4. 4Engineering — Conduct continuous four-gas atmospheric monitoring (O2, LEL, H2S, CO) with calibrated detectors before entry and throughout work, with audible alarms set per AS/NZS 2865.
5. 5Engineering — Use mechanical forced-air ventilation delivering minimum 20 air changes per hour, with ducting positioned to sweep the breathing zone, not recirculate contaminants.
6. 6Engineering — Bond and earth the vacuum truck to the vessel and ground per AS/NZS 1020 to dissipate static during hydrocarbon transfer operations.
7. 7Administrative — Issue a confined space entry permit under AS 2865:2009 listing standby person, communications method, rescue plan and atmospheric test results before each shift.
8. 8Administrative — Conduct documented pre-start briefing referencing this SWMS, with all workers signing on and confirming understanding of emergency retrieval signals and exclusion zones.
9. 9PPE — Supply Type 5/6 chemical splash coveralls, nitrile gauntlets, P3 cartridge respirators or supplied-air BA per AS/NZS 1715 where atmospheric tests indicate IDLH potential.
10. 10PPE — Full-body harness with retrieval winch line per AS/NZS 1891 anchored to a tripod at the access point, attended by trained standby person with charged comms throughout entry.

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

On a mid-sized water treatment plant upgrade, a vacuum crew is tasked with desludging a 6-metre-deep balance tank before structural lining works. The site supervisor opens this SWMS at the 6:30am pre-start in the site office, projecting it on screen alongside the confined space entry permit. The crew walks through each hazard row — the standby operator flags that yesterday's gas test recorded elevated H2S near the inlet pipe, so the control for continuous four-gas monitoring with lowered alarm thresholds is reinforced, and the team agrees to extend forced-air ventilation runtime to 30 minutes pre-entry rather than the SWMS minimum. Each worker signs the SWMS sign-on register, confirming they hold current confined space tickets and have been fitted for supplied-air BA. Two hours into the task, the vacuum hose blocks on a compacted clay band. Rather than improvise, the lead operator stops work, retrieves the SWMS from the truck cab, and applies the documented blockage-clearance control: depressurise, isolate, and clear from outside the vessel using the extension lance. The standby person logs the deviation and resumption time on the permit. At handover, the completed SWMS, permit and gas logs are filed with the principal contractor's WHS records.

Related legislation

• WHS Act 2011 (model)
• WHS Regulation 2025
• Managing Risks of Hazardous Chemicals CoP; Construction Work CoP

Frequently asked questions