Radon Mitigation Installation SWMS

Radon mitigation installation involves designing and fitting active sub-slab depressurisation systems, sump pits, sealed membranes, in-line fans and discharge stacks to reduce indoor radon gas concentrations in existing dwellings, workplaces and below-ground structures. The work typically combines core drilling through slabs, excavation of sump pits below the floor, entry into subfloor voids and crawl spaces, penetrations through external walls and roofs, and electrical connection of extraction fans. Workers face confined space atmospheres, exposure to radon progeny and respirable crystalline silica from concrete cutting, trip and fall hazards in restricted access voids, and struck-by risks from mobile plant during external excavation for discharge routing.

Under the Work Health and Safety Regulation 2025 (NSW), this scope engages section 291 as high risk construction work — specifically work in or near a confined space, work in a trench deeper than 1.5 m, and work involving powered mobile plant. Section 299 requires a Safe Work Method Statement to be prepared before the work commences, identifying hazards, documenting controls applied through the hierarchy in section 36, and describing how controls will be monitored and reviewed.

Hazards identified

12 hazards covered, sorted by priority.

Control measures

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

1. 1Eliminate confined space entry where possible by installing external sump access points, remote-actuated fans and pre-fabricated discharge assemblies designed at the survey stage.
2. 2Substitute dry cutting with wet-cut core drilling equipment or tools fitted with on-tool H-class extraction (HEPA) to control respirable crystalline silica exposure below the workplace exposure standard of 0.05 mg/m³ (8-hour TWA).
3. 3Engineer confined space ventilation using powered forced-air ventilation and continuous atmospheric monitoring (O₂, CO, LEL) with radon screening measurements before and during entry, in accordance with AS 2865 Confined Spaces.
4. 4Shore, bench or batter all excavations deeper than 1.5 m in accordance with the SafeWork NSW Code of Practice: Excavation Work, with a competent person inspecting trenches daily and after weather events.
5. 5Establish exclusion zones and spotters around powered mobile plant, use plant fitted with reversing alarms and cameras, and separate pedestrian workers from plant travel paths per AS 2601 Demolition of structures principles and manufacturer traffic management guidance.
6. 6Complete a pre-work asbestos assessment for all pre-1990 structures; where ACM is confirmed or presumed, engage a Class A or B licensed asbestos removalist as required under section 458 of the WHS Regulation 2025 (NSW) before further work.
7. 7De-energise and lock out electrical circuits before penetration; verify with a licensed electrician and use non-conductive tools and RCD-protected temporary supplies in accordance with AS/NZS 3012 Electrical installations — Construction and demolition sites.
8. 8Provide edge protection, harness-based fall arrest anchored to certified points, or elevating work platforms for all roof and stack installation work above 2 m, in accordance with AS/NZS 1891.4 Industrial fall-arrest systems.
9. 9Issue P2/P3 respiratory protection selected and fit-tested in accordance with AS/NZS 1715 and AS/NZS 1716; supply Class 5 hearing protection to AS/NZS 1270, safety eyewear to AS/NZS 1337.1, cut-resistant gloves and safety footwear to AS/NZS 2210.3.
10. 10Implement a confined space entry permit system with standby person, retrieval harness and rescue plan; radon-specific dosimetry (integrating passive detectors or continuous radon monitors) where prior indoor readings exceed 200 Bq/m³.
11. 11Conduct daily pre-start toolbox talks covering the day's specific hazards, atmospheric test results and rescue arrangements; document sign-on to the SWMS.
12. 12All workers to hold CPCCWHS1001 General Construction Induction (White Card); consult workers under section 47 of the WHS Act 2011 (NSW) when developing and amending this SWMS, and review under section 302 of the WHS Regulation 2025 (NSW) when controls change, an incident occurs, or work methods are revised.

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

A specialist mitigation contractor is engaged to install an active sub-slab depressurisation system in a 1975-built two-storey office in Chatswood following indoor radon screening of 340 Bq/m³. The scope includes core drilling a 150 mm penetration through the ground-floor slab, excavating a 400 mm deep sump, entry into a 900 mm-high subfloor void to seal the membrane, and external trenching to 1.7 m depth along the eastern elevation to route the discharge stack behind the building. Before mobilisation, the PCBU consults the two-person crew and site supervisor under section 47 of the WHS Act, prepares this SWMS covering all three HRCW categories, and confirms a Class B asbestos clearance for the identified vinyl floor tiles. On day one, atmospheric testing of the subfloor void records 20.4% O₂ and 180 Bq/m³ radon; forced-air ventilation is deployed and continuous monitoring maintained. The 1.7 m trench is battered at 1:1 in the sandy fill and inspected by the supervisor. A spotter separates the mini-excavator from the pedestrian corridor. On day three, an unplanned second slab penetration is required; the SWMS is reviewed under section 302, the crew re-signed, and work resumes.

Related legislation

• Work Health and Safety Act 2011 (NSW) — sections 19, 31, 32, 47
• Work Health and Safety Regulation 2025 (NSW) — sections 36, 66-77 (confined spaces), 291, 299, 302
• Work Health and Safety Regulation 2025 (NSW) — Chapter 4 Part 4.1 (hazardous chemicals) and Part 4.4 (asbestos)
• Radiation Control Act 1990 (NSW) and Radiation Control Regulation 2013 (NSW)
• Protection of the Environment Operations Act 1997 (NSW) — discharge and spoil management
• Electricity (Consumer Safety) Act 2004 (NSW) — licensed electrical work

Frequently asked questions