Oil & Fuel Tank Demolition SWMS

Demolition of above-ground and below-ground oil and fuel storage tanks is one of the highest-consequence tasks in the Australian demolition sector, combining flammable vapour atmospheres, confined space entry, hot-cutting ignition sources and contaminated waste streams in a single work package. The task sequence typically runs from product draining, vapour purging and sludge removal through to atmospheric testing, controlled oxy or cold cutting, structural collapse management and lined transport of contaminated steel and residues to a licensed facility. Under WHS Regulation 2025, this work simultaneously triggers multiple Schedule 1 High Risk Construction Work categories, the confined spaces Part 4.3 duties and the hazardous chemicals Part 7.1 framework, making a documented Safe Work Method Statement mandatory before any worker steps onto the asset. The SWMS must be prepared in consultation with the workers performing the task, signed on by every person on the crew, kept available at the workplace for the duration of the works and retained for at least two years after any notifiable incident.

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 the tank intact by crane lift to a licensed offsite decommissioning yard rather than cutting on the live demolition site.
2. 2Elimination — Eliminate hot work entirely by specifying cold-cutting techniques such as hydraulic shears, diamond wire or abrasive water jet for primary shell separation.
3. 3Substitution — Substitute nitrogen inerting for steam purging where sludge heel cannot be fully removed, maintaining oxygen below 8% throughout cutting operations.
4. 4Substitution — Replace solvent-based residue cleaners with biodegradable bioremediation surfactants to reduce secondary flammable vapour generation during internal washdown.
5. 5Engineering — Install continuous multi-gas monitoring with LEL, O2, H2S and CO sensors at the cut line with audible alarms triggering automatic work cessation at 10% LEL.
6. 6Engineering — Provide mechanical ventilation delivering minimum 20 air changes per hour into the tank interior with intrinsically safe blowers and ducted exhaust away from ignition sources.
7. 7Administrative — Issue a Hot Work Permit signed by the PCBU representative after written gas-free certification by a competent person within 30 minutes of cutting commencement.
8. 8Administrative — Conduct daily pre-start SWMS sign-on, confined space entry permit review and dedicated fire watch posting for minimum 60 minutes post-cutting completion.
9. 9PPE — Provide FR coveralls to AS/NZS 4824, full-face supplied-air respirators to AS/NZS 1716 for internal entry, anti-static safety footwear and chemical-resistant nitrile gauntlets.
10. 10PPE — Equip fire watch with 9kg dry chemical and AFFF foam extinguishers, charged fire hose to AS 2419.1, and dedicated emergency retrieval tripod with mechanical winch.

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

On a regional bulk fuel depot decommissioning project, the site supervisor opens the pre-start brief at 6:30am with the four-person crew gathered at the 110kL diesel tank. The SWMS is laid out on the tailgate and each hazard line is read aloud — the supervisor pauses on the pyrophoric iron sulphide entry because the tank has been out of service for six months with a sludge heel still in place. The crew agrees to extend the nitrogen purge from the planned two hours to four hours and to wet the internal surfaces before any entry, both controls captured under the engineering and administrative rows of the SWMS. The gas tester demonstrates the four-gas monitor calibration and the fire watch confirms the AFFF extinguisher pressure and hose charge. Each worker signs the SWMS register, including a labour-hire rigger new to the crew, who initials the confined space entry permit separately. Mid-morning, the LEL meter spikes to 8% during initial shell cutting. Work stops immediately per the engineering control threshold written in the document, ventilation is increased and the cut is repositioned 400mm higher where vapour pooling is lower. The supervisor annotates the SWMS field copy with the deviation and the time, ensuring the live document reflects what actually happened on the asset for the regulator and the project safety file.

Related legislation

• WHS Act 2011 (model)
• WHS Regulation 2025
• AS 2865 — Confined spaces