Aerated treatment safety, where the hazard is machinery and water.
Aeration basins, oxidation ditches, SBR reactors, clarifiers and aerobic digesters — the hazard shifts to drowning, machine contact and electricity. Six NSW documents built for aerated assets, with the two conditions that bring the gas back.
The documented system, not just the method
Aerobic treatment inverts the hazard profile, and crews trained on sewers get it wrong in both directions. Aeration strips dissolved gases and oxygen suppresses the sulfate reduction and methanogenesis that generate hydrogen sulphide and methane, so an aeration basin is not gas-dominant the way a wet well is. What replaces the gas hazard is machinery and electricity: aerators, mixers and impellers, rotating bridges and scrapers, blowers and diffusers, all electrically driven in a permanently wet environment over deep liquid. And aerated water is a worse drowning medium than still water — entrained air lowers the liquid density, so buoyancy drops and a person sinks faster.
This pack covers aerated assets: aeration basins, oxidation ditches, IDEA and SBR reactors, aerobic digesters, clarifiers and aerated lagoons. Six documents: two Safe Work Method Statements — Wastewater Confined Space Entry and Aerobic Systems General Management — plus a confined space entry permit, a non-entry rescue plan, a gas detector calibration and bump test procedure, and an H2S exposure and Workplace Exposure Limit readiness summary. The gas documents are here for two specific reasons: stop the aeration and the tank turns anaerobic within hours, and the settled sludge blanket at the base is anaerobic even under fully aerated water. Note this pack does not cover your collection network, which is anaerobic regardless of how your plant treats. Authored for New South Wales. Regulator: SafeWork NSW.
- ✗The confined space entry permit
- ✗The non-entry rescue plan
- ✗The gas detector calibration & bump-test regime
- ✗The exposure-monitoring position for H₂S
Part 4.3 of the WHS Regulation 2025 (NSW) requires all four for every tank, reactor or digester entry — whether or not it is construction work. This pack is what documents them.
The 6 documents, in detail
Every document is authored for NSW, supplied as an editable, unbranded Microsoft Word file, and ready to complete for your specific assets. No blind purchase — here is exactly what you receive.
Wastewater Confined Space Entry SWMS
the entry task for any wastewater space including aerated tanks, reactors and aerobic digesters, with 20 hazards and full in-tank plant isolation.
Aerobic Systems General Management SWMS (Non-Entry)
the daily work — walkway and bridge inspection, aerator, mixer and scraper servicing, blower and diffuser operation, weir cleaning, sampling and process monitoring.
Confined Space Entry Permit
a working permit covering hazard identification, isolation verification, pre-entry testing, ventilation, personnel, rescue verification, entry log, periodic re-test log and close-out.
Non-Entry Rescue Plan
space-specific arrangements built on retrieval from outside, with roles, equipment verification, retrieval-failure escalation and a rescue drill record.
Gas Detector Calibration & Bump Test Procedure
needed here too, because an aerated tank is only conditionally gas-free — with procedures, frequencies, sensor cautions and logs.
H2S Exposure & WEL Readiness Summary
health effects by concentration, the current standard, the monitoring obligation, and a pre-1 December 2026 action checklist.
Pack Index
contents, why an aerated plant still needs gas documents, an implementation sequence, the three facts to brief every worker on, and an explicit statement of what the pack does not cover.
✓The aeration-outage rule and the anaerobic sludge blanket hazard built into the documents — the two conditions that bring the gas back to an aerated tank.
✓All seven documents as editable Microsoft Word (.docx) files, unbranded, compatible with Word 2016 and newer, Google Docs and LibreOffice Writer, with editable fields for PCBU, ABN, site, prepared by, reviewed by, approved by and review date.
Aerobic Wastewater Treatment Compliance Pack, ready to use
Six-document compliance set for aerobic wastewater treatment operations — aeration tanks, clarifiers, blowers and biosolids: two SWMS (wastewater confined space entry, aerobic systems general management) plus a working confined space entry permit, a non-entry rescue plan, a gas detector calibration and bump test procedure, and an H2S exposure and WEL readiness summary. Authored for NSW against the WHS Act 2011 (NSW) and WHS Regulation 2025 (NSW).
- ✓All 6 documents, authored to NSW law
- ✓Editable, unbranded Microsoft Word (.docx)
- ✓Single-site licence · use across your ABN
- ✓Instant download after payment
- ✓12 months of regulatory updates included
6 documents — about $216 each.
Secure checkout via Stripe. Instant download of all 6 documents after payment.
14 hazards, identified and controlled
These are the hazards the documents are built around — each with the consequence that makes it matter, rated by priority. This is the depth a regulator expects and a generic template does not carry.
Rapid drowning; a lifebuoy thrown into an aerated zone is far less effective than it looks
Amputation or fatal entanglement; a clarifier bridge travels slowly, silently, and will not stop
Electrocution or arc flash from equipment living permanently in water
Plant starts on a timer, a level signal or remotely from SCADA with a worker in contact with it
An asset believed gas-free begins generating toxic and flammable gas after a blower trip, power failure or planned outage
H2S released from the bottom of a tank that reads perfectly clean at the surface during desludging or a scraper pass
Respiratory infection or illness for anyone standing downwind on a walkway over an aerated zone
Fall injury and drowning, frequently from a corroded walkway on an older plant
An unmonitored entry into a space with un-isolated plant and an anaerobic base
Multiple fatalities; the rescue instinct kills in aerated tanks as surely as in sewers
Chemical burns, eye damage or respiratory injury at dosing points
The instrument that would tell you the aeration has been off, or the blanket is releasing, reads low
Crush injury from a dropped assembly, and loss of the load into the tank
Noise-induced hearing loss in blower rooms and near aerators
Where holding only a SWMS goes wrong
A fitter is sent to a clarifier to free a jammed scraper. The plant is aerated, the water looks clean, and there is no gas smell — so he treats it as a mechanical job, which it mostly is. He walks the bridge, leans over the rail, and works the rake with a bar. Three things are wrong. The bridge drive is stopped at the panel but not locked out, and a clarifier bridge starts on a timer, travels slowly and makes almost no noise — it will simply keep going with him on it. He is leaning over deep aerated liquid with no edge protection, and if he goes in, the entrained air means he sinks rather than floats and the lifebuoy on the rail is close to decorative unless someone kills the aeration first. And the thing he is levering at is the sludge blanket, which is anaerobic no matter how clean the water above it looks, so he is about to release H2S from the base of a tank nobody is monitoring. Not one of those is the hazard a sewer-trained crew would have been watching for. This pack controls all three.
High risk construction work under s291
Why this work is high risk construction work, category by category — and what the law requires once it is.
Construction work carried out in or near water or other liquid that involves a risk of drowning
Aeration basins, ditches, reactors and clarifiers hold deep liquid, and aerated water gives markedly reduced buoyancy — a person who falls in sinks faster than in still water.
Construction work carried out on or near energised electrical installations or services
Aerator and blower motors, variable speed drives and control circuits are worked on in a permanently wet environment.
Construction work carried out in or near a confined space
Aeration basins, reactors, aerobic digesters and clarifiers are enclosed structures not intended for human occupancy, entered for maintenance with restricted entry and egress.
Construction work involving a risk of a person falling more than 2 metres
Walkways, bridges, platforms and tank edges sit well above the liquid surface, and corroded walkways are common on older plants.
Construction work carried out in or near a contaminated or flammable atmosphere
If aeration stops the tank turns anaerobic within hours and generates H2S and methane, and the settled sludge blanket at the base is anaerobic even under fully aerated water.
Construction work carried out in an area at a workplace in which there is any movement of powered mobile plant
Aerator, mixer and diffuser assemblies are lifted over open liquid by crane or hoist.
The work covered by this pack is high risk construction work under Section 291 of the WHS Regulation 2025 (NSW), so a SWMS must be prepared before work commences (Section 299), kept readily accessible, reviewed as necessary (Section 302), and given to the principal contractor if one is appointed. Energised electrical work is separately prohibited under Part 4.7 Division 4, sections 154 and 157 unless de-energisation is not reasonably practicable — convenience is never a valid reason. Plant must be guarded and isolated under Chapter 5, and walkways, bridges and tank edges require edge protection under Part 4.4. An aeration basin, reactor, aerobic digester or clarifier is a confined space, so any entry engages the Part 4.3 duties in full — permit, atmospheric monitoring, standby person and rescue arrangements established before entry — whether or not the entry is construction work. A drowning, an electric shock, an entanglement, an amputation, a fall or an H2S exposure causing death or serious injury is prosecuted as a Category 1 or Category 2 offence under the WHS Act 2011 (NSW), with the most serious breaches carrying imprisonment for individuals.
The plant, electrical and confined spaces Codes of Practice are the benchmark a regulator will measure this work against, with AS/NZS 4836 for any unavoidable live work, AS 2865 governing entry and AS 4775 for eyewash and shower provision at dosing points.
The control measures in every document
Not generic advice — the specific, hierarchy-of-controls measures written into the pack, matched to how these assets actually fail.
Built for the people who do this work
If you operate, maintain or contract to these assets in NSW, this pack is written for your duties.
- ✓Local councils and water utilities operating aerated treatment plants — aeration basins, oxidation ditches, IDEA and SBR reactors, aerobic digesters, clarifiers and aerated lagoons.
- ✓Treatment plant operators and process controllers monitoring, sampling and operating aerators, blowers and scrapers.
- ✓Mechanical fitters servicing aerators, mixers, scrapers, rotating bridges and drives.
- ✓Licensed electrical workers maintaining aerator and blower motors, VSDs and control circuits in wet environments.
- ✓WHS managers and HSE advisors responsible for machine safety, drowning risk and bioaerosol exposure across an aerated treatment plant.
Authored to the codes and the law
The Codes of Practice and Australian Standards these documents are measured against, and the legislation behind them.
Managing risks of plant in the workplace
Binding 1 Jul 2026The benchmark for guarding, isolation and lock-out of aerators, mixers, scrapers, rotating bridges and drives.
Managing electrical risks in the workplace
Binding 1 Jul 2026The benchmark for de-energisation, isolation and proving dead on motors and VSDs in a permanently wet environment.
Confined spaces
Binding 1 Jul 2026The benchmark for the entry permit, atmospheric testing, standby person and rescue arrangements for tank, reactor and digester entry.
AS 2865 — Confined spaces
The technical standard underpinning the entry permit, atmospheric limits, standby and rescue arrangements.
AS/NZS 4836 — Safe working on or near low-voltage electrical installations
The technical standard for any electrical work that cannot be carried out de-energised.
Workplace exposure standards for airborne contaminants (transitioning to Workplace Exposure Limits from 1 December 2026)
The H2S values applying whenever aeration stops or the anaerobic sludge blanket is disturbed.
- §Work Health and Safety Act 2011 (NSW) — Section 19 primary duty of care; Section 47 consultation; Sections 35-38 notifiable incidents.
- §Work Health and Safety Regulation 2025 (NSW) — Section 291 (high risk construction work) and Section 299 (preparation and content of a SWMS), with review under Section 302.
- §Work Health and Safety Regulation 2025 (NSW) — Part 4.7 (electrical) including the prohibition on energised electrical work at Division 4, sections 154 and 157; Chapter 5 (plant) for guarding and isolation; Part 4.4 (falls).
- §Work Health and Safety Regulation 2025 (NSW) — Part 4.3 (confined spaces) governing any entry into a tank, reactor or aerobic digester, and Part 7.1 (hazardous chemicals) with the H2S workplace exposure standard transitioning to Workplace Exposure Limits from 1 December 2026.
- §AS 2865 (Confined spaces), AS/NZS 4836 and AS/NZS 3000 (electrical), AS/NZS 1891.1 (fall arrest), AS/NZS 1715 and 1716 (respiratory protective equipment), AS 4991 (lifting gear) and AS 4775 (eyewash and shower).
Frequently asked questions
The documented system, ready to complete.
6 NSW documents, instant download, editable and unbranded, yours to own — authored to the WHS Act 2011 (NSW) and WHS Regulation 2025 (NSW).
All prices AUD, GST exclusive · Instant download · Single-site licence · 12 months of updates
This pack is a documentation set to support due diligence — it is not compliance in itself. You must complete the documents for your specific assets, have trained and competent workers, hold calibrated equipment, drill any rescue plan on your actual assets, and — where exposure is uncertain — obtain personal exposure monitoring data from a competent person. See the full Disclaimer & Terms of Use within each downloaded document.