Sewer Maintenance Hole Entry (Traffic Corridor) SWMS
SWMS variants reference your state’s WHS legislation. Instant download after payment.
Entry into a sewer maintenance hole (access chamber, manhole) located in a road reserve brings together two life-threatening hazard sets at the same moment: a toxic, potentially oxygen-deficient atmosphere below ground, and live traffic at the point of entry and rescue. The chamber is dominated by hydrogen sulphide (H2S), which forms naturally in wastewater under anaerobic (septic) conditions. It is acutely toxic, heavier than air so it pools in the chamber, and treacherous because its rotten-egg odour cannot be relied on as a warning — at higher concentrations it rapidly deadens the sense of smell, so a worker can lose the ability to smell it just as it reaches a dangerous level. The current Australian workplace exposure standard for H2S is an 8-hour time-weighted average of 10 ppm and a 15-minute short-term exposure limit of 15 ppm, transitioning to Workplace Exposure Limits from 1 December 2026.
Above ground, the open access point sits in or beside a carriageway in use by traffic, which is what makes this work distinct from a wet-well or plant entry. Opening a chamber in a live road is high risk construction work in its own right under Section 291 of the WHS Regulation 2025 (NSW), so a traffic guidance scheme to AS 1742.3 must be designed and set up before the lid is lifted — the entrant, the standby person and the non-entry rescue system all have to operate safely in that corridor. This SWMS sets out the combined method: traffic control first, then a confined space entry permit under AS 2865 with continuous atmospheric monitoring, forced ventilation, a standby person and non-entry rescue rigged before entry, with upstream flow and pump starts isolated or controlled throughout. Regulator: SafeWork NSW.
Hazards identified
14 hazards covered, sorted by priority.
Rapid collapse and death from H2S, with the sense of smell deadened just as the gas reaches a lethal level
Asphyxiation in an oxygen-depleted chamber, often without warning to the entrant
Fatal or serious injury to an entrant, standby person or rescuer struck by a vehicle
Fire or explosion in the chamber from an ignition source in a flammable atmosphere
Drowning or entrapment when the chamber fills without warning during entry
Multiple fatalities, the signature outcome of wastewater confined space incidents
Infection or illness from contact with sewage or inhalation of aerosols
A slow or failed retrieval through a narrow opening during an emergency
Fall injury into an unguarded open chamber, including by a member of the public
Unexpected exposure to a contaminant the crew was not testing for
A collapsed entrant not identified in time, in an environment with high traffic noise
Slips, falls and missed hazards in a poorly lit chamber
Musculoskeletal injury handling heavy covers and equipment
Slip or trip injury on wet, cluttered surfaces beside a live carriageway
Control measures
Hierarchy-of-controls order: elimination → substitution → isolation → engineering → administrative → PPE.
- 1Design and set up a traffic guidance scheme to AS 1742.3 before the cover is lifted — work area, buffer and taper, signage and devices in place, a traffic controller where required, and a full or partial road closure where practicable.
- 2Treat the maintenance hole as a confined space under AS 2865 and enter only under a confined space entry permit issued by a competent person after isolation, testing and ventilation are verified.
- 3Test the atmosphere before entry and monitor continuously throughout with calibrated, bump-tested instruments: oxygen 19.5-23.5%, H2S against the workplace exposure standard, and flammable gas below 5% LEL.
- 4Apply forced ventilation to the chamber before and during entry, and never rely on natural ventilation or on odour as an indicator of H2S.
- 5Withdraw the entrant immediately on any monitor alarm and do not re-enter until the atmosphere is re-tested and made safe.
- 6Provide supplied-air respiratory protection where the atmosphere cannot be made and kept safe, and do not substitute a filtering respirator for supplied air in an oxygen-deficient or H2S atmosphere.
- 7Isolate or divert upstream flow and lock out pump starts with the network controller for the duration of the entry, and withdraw immediately on any rising level.
- 8Rig a non-entry rescue system — tripod or davit, winch and retrieval line — before entry, and base the rescue plan on non-entry retrieval; never permit an unprotected rescuer to enter after a casualty.
- 9Station a trained standby person outside the chamber in constant communication with the entrant for the whole entry; the standby person does not enter and does not take on other duties.
- 10Guard the open chamber against falls by workers and the public, and use a harness and retrieval line for every entry.
- 11Control biological exposure with waterproof gloves, coveralls, eye protection and respiratory protection against aerosols, plus hygiene, covering cuts, no eating or drinking, and vaccination where recommended.
- 12Wear high-visibility clothing to AS/NZS 4602.1 for all surface work in the corridor, and use intrinsically safe task lighting in the chamber.
- 13Ensure all workers hold a valid White Card (CPCCWHS1001) where the work is on a construction site, together with confined space entry and, where required, traffic control competencies, and conduct a pre-start briefing on this SWMS, the atmospheric limits and the non-entry rescue plan.
- 14Consult workers on WHS matters affecting them per Section 47 of the WHS Act 2011 (NSW), record the consultation, and review this SWMS and the rescue plan whenever the site, network, method or exposure standard changes, after any incident or near miss, or at minimum every 12 months.
Applicable Codes of Practice
The entry permit system, atmospheric testing and monitoring, ventilation, standby person and rescue arrangements for entry into a sewer maintenance hole.
Guarding the open chamber and controlling the fall risk into the maintenance hole from the surface.
The technical standard for confined space entry: hazard identification, atmospheric limits, entry procedures, standby and rescue.
The traffic guidance scheme, work area, buffer and taper, signage and devices protecting the entry and rescue set-up from live traffic.
Selection, use and maintenance of supplied-air respiratory protection where the chamber atmosphere cannot be made safe.
The H2S exposure standard of 10 ppm TWA and 15 ppm STEL against which chamber atmospheres are assessed, and the basis for reviewing controls before the WEL transition.
High-Risk Construction Work triggered
A sewer maintenance hole is an enclosed structure not intended for human occupancy, entered for maintenance, with restricted entry and egress and a hazardous atmosphere — so the work is carried out in a confined space.
The chamber atmosphere routinely contains hydrogen sulphide, may be oxygen-deficient, and can contain flammable methane from decomposition, so the work is carried out in a contaminated or flammable atmosphere.
Maintenance holes in a road reserve are opened and entered from within or beside a live carriageway, so the work is carried out on or adjacent to a traffic corridor in use by vehicles — this is what distinguishes it from a wet-well or treatment plant entry.
A maintenance hole carries live sewage flow and can surge or fill from an upstream discharge or pump start while a worker is inside, creating a risk of drowning.
Sewer maintenance hole entry in a road reserve is high risk construction work under Section 291 of the WHS Regulation 2025 (NSW) — work in a confined space, work in or near a contaminated or flammable atmosphere, work on or adjacent to a traffic corridor in use by traffic, and a risk of drowning — so a SWMS must be prepared before the work commences (Section 299), kept readily accessible, reviewed as necessary (Section 302), and given to the principal contractor if one is appointed. The confined space provisions in Part 4.3 apply in full and independently of construction status: an entry permit, atmospheric monitoring, a standby person and rescue arrangements are required for any confined space entry. Hydrogen sulphide is a hazardous chemical and a PCBU must ensure no person is exposed above the workplace exposure standard, which in a sewer chamber generally requires monitoring data rather than assumption. An H2S exposure, an asphyxiation, a confined space incident or a traffic strike 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, and the duty of care extends to members of the public near the open chamber.
Who this is for
- →Local councils and water utilities maintaining a reticulated sewer network in township streets and road reserves.
- →Sewer maintenance, cleaning and condition-assessment crews entering maintenance holes and access chambers.
- →Civil, drainage and pipeline contractors carrying out wastewater confined space work in trafficked areas.
- →Confined space entrants, standby persons, traffic controllers and atmospheric monitoring operators.
- →Network controllers, supervisors and HSE advisors managing confined space entry and rescue in a road corridor.
What you receive
- ✓Editable Microsoft Word document (.docx) fully compatible with Microsoft Word 2016 and newer, Google Docs, and LibreOffice Writer.
- ✓Title page with editable fields for PCBU name, ABN, site address, project name, prepared by, reviewed by, approved by and document revision date.
- ✓Hazard register with the 14 maintenance hole entry hazards — each with a documented consequence, inherent risk rating on a 5x5 likelihood-consequence matrix, hierarchy-of-control measures, and residual risk rating.
- ✓Colour-banded 5x5 risk matrix legend so likelihood and consequence scoring is transparent to a reviewer or auditor.
- ✓Confined space entry control set — permit, atmospheric limits (O2 19.5-23.5%, H2S against the exposure standard, below 5% LEL), forced ventilation, standby person and continuous monitoring.
- ✓Traffic guidance scheme prompts to AS 1742.3 — set up before the lid is lifted, with work area, buffer, taper, devices and traffic controller.
- ✓Non-entry rescue plan prompts (tripod or davit, winch, retrieval line) and flow and pump-start isolation prompts for the network controller.
- ✓Worker consultation record per WHS Act s.47 and a worker sign-on register (blank, expandable).
- ✓Applicable legislation and Codes of Practice schedule pre-populated for NSW with a state-variance reference table covering VIC (OHS Act 2004), QLD, SA, WA, TAS, NT, and ACT.
Worked example
A NSW council maintenance crew is scheduled to inspect and clean a sewer maintenance hole in a township main street, so the work is carried out under this SWMS. The traffic guidance scheme goes in first: the crew closes the kerbside lane to AS 1742.3 with advance warning signs, a taper and a buffer, and a traffic controller manages the remaining lane, so that the chamber, the standby person and the rescue tripod all sit inside a protected work area before the cover is touched. The network controller confirms the upstream pump station is locked out and the flow diverted for the duration of the entry. The permit issuer tests the chamber from the surface with a calibrated multi-gas monitor: H2S reads above the exposure standard on the first test, so forced ventilation runs until oxygen is 19.5-23.5%, H2S is below the standard and flammable gas is below 5% LEL, and the entry permit is only then issued. The entrant descends on a harness and retrieval line rigged to a tripod, with continuous monitoring on their person and a trained standby person in constant communication above. Mid-task the H2S alarm sounds; the entrant withdraws immediately and is retrieved, ventilation is extended, and re-entry occurs only after re-testing confirms the atmosphere is safe. The crew signed on to the SWMS at the pre-start, and the SWMS is reviewed before the next chamber downstream of a rising main discharge, where H2S is expected to be markedly higher.
Related legislation
- Work Health and Safety Act 2011 (NSW) — Section 19 primary duty of care, owed to workers and the public; Section 47 consultation; Sections 35-38 notifiable incidents (an H2S exposure, asphyxiation, confined space incident or traffic strike is notifiable).
- Work Health and Safety Regulation 2025 (NSW) — Section 291 (high risk construction work: confined space, contaminated or flammable atmosphere, traffic corridor, risk of drowning) and Section 299 (preparation and content of a SWMS), with review under Section 302.
- Work Health and Safety Regulation 2025 (NSW) — confined spaces (Part 4.3): entry permits, atmospheric monitoring, standby person and emergency procedures, applying independently of construction status.
- Work Health and Safety Regulation 2025 (NSW) — hazardous chemicals (Part 7.1) and the workplace exposure standard for hydrogen sulphide (10 ppm TWA / 15 ppm STEL), transitioning to Workplace Exposure Limits from 1 December 2026.
- AS 2865 (Confined spaces), AS 1742.3 (Traffic control for works on roads), AS/NZS 1891.1 (fall arrest) and AS/NZS 1715 and 1716 (respiratory protective equipment), with the road authority traffic control requirements.
Frequently asked questions
Why is a maintenance hole SWMS different from a wet-well or pump station SWMS?
Because of where the opening is. The confined space and hydrogen sulphide hazards are much the same, but a maintenance hole in a road reserve is opened and entered from within or beside a live carriageway. That makes the work high risk construction work on a traffic corridor in its own right, and it means the entrant, the standby person and the whole non-entry rescue set-up have to operate safely among vehicles. A traffic guidance scheme to AS 1742.3 must be designed and installed before the lid is lifted — a wet-well procedure does not cover that.
Can workers rely on smell to detect hydrogen sulphide?
No, and this is what makes H2S so dangerous. It has a distinctive rotten-egg odour at low concentrations, but at higher concentrations it rapidly deadens the sense of smell, so a worker loses the ability to detect it at exactly the point it becomes life-threatening. The smell disappearing is the worst possible sign, not a good one. The only reliable control is calibrated, continuous atmospheric monitoring, with forced ventilation and immediate withdrawal on alarm.
Why is rescue a non-entry system?
Because most multiple-fatality incidents in wastewater confined spaces are rescuers. A worker collapses in the chamber, a colleague goes in to help without protection, and both are overcome by the same atmosphere. The rescue plan is therefore built on retrieval from outside — a tripod or davit, winch and retrieval line rigged before entry — with a trained standby person who never enters. Any planned entry rescue requires supplied-air respiratory protection and its own procedure.
Does the hydrogen sulphide exposure standard change in 2026?
The national workplace exposure standards transition to Workplace Exposure Limits from 1 December 2026, with the transition period ending 30 November 2026. The current H2S values are an 8-hour time-weighted average of 10 ppm and a 15-minute short-term exposure limit of 15 ppm. The H2S value has been under review and a lower limit was considered, with the final position pending an impact assessment, so water utilities in particular should review their controls and exposure data ahead of the transition. This SWMS is written so the method carries across the change.