Gas-Water Leak Detection Safe Work Method Statement

Gas leak detection safety responses escalate based on combustible gas concentration measured as percentage of Lower Explosive Limit (LEL). At background levels (0-5% LEL), normal detection work can proceed with continuous monitoring and ignition source awareness. At 10% LEL, detector alarms activate requiring heightened awareness, work area restriction to essential personnel, and active ignition source elimination within minimum 10-metre radius. Between 20-40% LEL, enhanced controls apply including establishment of formal gas hazard zone with barrier perimeter, prohibition of all potential ignition sources within zone, use of intrinsically safe equipment only, notification of supervisor and gas supplier of significant leak, and consideration of building evacuation if gas detected in occupied structures. At 40-60% LEL, work must cease, immediate notification to gas supplier emergency line required, emergency services (fire brigade) should be notified, area evacuation implemented, and detection work transitions to emergency response mode with focus on public safety rather than leak investigation. Above 60% LEL or any gas accumulation in occupied buildings exceeding 20% LEL constitutes immediate danger requiring emergency evacuation (000), building occupant evacuation without introducing ignition sources, establishment of minimum 50-metre safety perimeter, and full emergency response procedures. These thresholds reflect increasing explosion risk as gas concentration approaches explosive range (5-15% methane in air constitutes explosive mixture). For oxygen deficiency, atmosphere below 19.5% oxygen requires immediate evacuation of confined spaces and prohibition of entry without supplied air respiratory protection. Workers must understand these action levels, have authority to cease work and implement emergency procedures without seeking approval, and prioritise safety over completing detection work or meeting customer expectations in dangerous situations.

Building gas leak investigations require systematic procedures protecting both detection workers and building occupants from explosion hazards. Before entering building, brief occupants to not operate electrical switches, appliances, phones, or other potential ignition sources during investigation. Request they evacuate to outdoor safe location if they prefer. Enter building with calibrated gas detector in hand, powered on, and in your breathing zone where you can observe display and hear alarms. Do not turn on lights or use electrical equipment - use torch (preferably intrinsically safe) for illumination if needed. Systematically test atmosphere starting near entry door then progressing to areas where gas odour reported or gas likely to accumulate. For natural gas (lighter than air), test ceiling areas, upper floors, roof spaces, and around ventilation systems. For LPG (heavier than air), test floor level, basements, sub-floors, low points, drains, and service ducts. Pay particular attention to meter locations, gas appliance connections, pipe routes, and areas where piping concealed in walls or floors. If gas detected above 20% LEL anywhere in building, immediately evacuate building occupants, establish exterior perimeter, prohibit re-entry, notify gas supplier emergency line, and call fire brigade if concentrations exceed 40% LEL. For lower concentrations, investigate further to locate source while maintaining continuous monitoring. Common sources include appliance connection leaks, meter installation defects, damaged internal pipes, or external gas migration through sub-floors from underground leaks. If leak source identified and can be isolated (shutting off meter or appliance valve), do so to stop gas flow. Ventilate building by opening windows and doors allowing gas to disperse, without introducing ignition sources during ventilation. Retest atmosphere after ventilation confirming gas concentrations fallen below detectable levels before permitting occupants to re-enter or conducting repairs. For gas accumulations exceeding safe levels where source cannot be immediately identified or isolated, building must remain evacuated until gas supplier or emergency services determine safe for re-entry. Document all findings including gas readings at various locations, suspected source, isolation actions taken, and occupant notifications provided. Building gas leak investigations require particular caution because occupants may be unaware of explosion hazards, may panic if asked to evacuate, or may resist leaving property - clearly explain hazards, provide reassurance, but insist on safety precautions even if occupants object. Never compromise safety to satisfy customer demands to 'just quickly check' or 'not make a fuss' - explosion risks are too severe to accept shortcuts in building gas investigations.

Leak detection method selection depends on pipe material, leak type, and accessibility. For metallic water pipes (copper, galvanised steel, ductile iron), acoustic leak detection is highly effective because metal transmits leak noise well. Use ground microphones along pipeline routes listening for characteristic hissing or rushing sounds from escaping water. Correlation equipment connected to two access points (meters, valves, hydrants) provides mathematical leak location by comparing leak sound arrival times at sensors - very accurate for metallic mains. For plastic water pipes (PVC, HDPE, PEX), acoustic transmission is poor requiring different approach. Tracer gas methods work well - isolate pipe section, introduce detectable tracer gas (hydrogen/nitrogen mixture), then scan ground surface with tracer gas detector locating where gas escapes at leak point. Alternatively, acoustic sensors applied directly to plastic pipes at access points detect leak noise in pipe wall before sound attenuates. For pressurised water services, observing meter for continuous movement with all fixtures closed indicates leak, then systematic isolation of circuit sections using valves narrows leak location before applying detailed detection. For drainage leaks, smoke testing effectively locates broken pipes - introduce non-toxic smoke into system and observe where smoke escapes indicating damaged sections. Dye testing using coloured tracers traces leak paths from drainage systems into structures or ground. CCTV drainage inspection provides visual confirmation of defects after preliminary location. For gas leaks, electronic combustible gas detectors excel at detecting natural gas or LPG in soil or air. Systematic surface probing along pipeline routes creates concentration map with peak above leak. Helium or tracer gas methods apply to gas pipes similar to water - introduce detectable gas into isolated section then scan with specialized detector. Infrared imaging can detect temperature variations from evaporating gas creating cold spots over leaks. Acoustic methods work for high-pressure gas leaks producing ultrasonic sound detectable with specialized equipment. For buried services in congested utility corridors, combining multiple methods provides best results - use electronic detection for preliminary location, refine with acoustic listening if metallic pipe, confirm with hand excavation or vacuum pothole before major excavation. Method selection must also consider safety - for gas leaks, electronic detection from surface avoids confined space entry risks; for water leaks, acoustic methods avoid need for service isolation during detection. Modern leak detection increasingly uses data logging pressure and flow monitoring to identify abnormal patterns indicating leaks, supplementing physical detection methods with analytical approaches for comprehensive leak management programs.

Gas leak detection workers require multiple qualifications addressing technical skills and safety competencies. Gas fitters conducting gas leak detection must hold current gas fitting licenses (Type A for natural gas work, Type B for LPG) issued by relevant state/territory licensing authorities, requiring technical training and examination in gas system installation, maintenance, and safety. While leak detection is sometimes performed by unlicensed technicians under gas fitter supervision, workers directly investigating gas leaks, isolating gas supplies, or working on gas systems require licensing. All leak detection workers need training in gas detection equipment operation covering calibration verification, bump testing, correct usage of combustible gas detectors, interpretation of readings, and response to alarm activation. Confined space entry training meeting AS 2865 requirements is essential for workers entering underground vaults, pits, or manholes during leak investigation, covering atmospheric testing, entry permits, emergency procedures, and rescue. Workers require training in emergency response procedures for gas leak situations including evacuation protocols, emergency service notification, perimeter establishment, and coordination with fire brigade - this training should be scenario-based with practice exercises. For water leak detection, while licensing not generally required, workers should have formal training in acoustic detection equipment operation, correlation system use, tracer gas detection methods, and interpretation of leak detection data. Understanding of water system hydraulics, pipe materials, and leak behaviour improves detection effectiveness. All leak detection workers require general construction induction (White Card) as baseline safety qualification. Traffic management training appropriate to work environment (ranging from awareness training for low-risk situations to traffic controller qualifications for roadway work) enables safe work in traffic environments common for leak detection. First aid training provides capability to respond to injuries during leak detection work. Some organisations provide formal leak detection technician training courses covering detection theory, equipment operation, leak location techniques, safety procedures, and practical exercises. Maintain training records documenting each worker's qualifications including gas fitting license numbers and expiry, confined space entry training dates, gas detector training completion, and any equipment-specific training for specialized detection systems. Implement supervised practice for newly trained detection workers - pair with experienced technicians for initial leak investigations, conduct increased verification of leak locations reported by new workers, and provide feedback and coaching. Regular competency review through observation of work practices, review of detection accuracy and time efficiency, and refresher training maintains detection quality and safety performance. For gas leak detection work, the combination of explosion hazards, confined space risks, and emergency response requirements makes comprehensive training and demonstrated competency essential for all personnel conducting this specialized and safety-critical work.