Gas Main Installation (PE / Steel) SWMS

Gas main installation covers the installation of gas mains — laying and connecting gas distribution mains and pipework in trenches, including the connection to the pressurised network. The defining hazards are the pressurised gas main and the flammable atmosphere with its explosion risk, the trench excavation and collapse, the underground services, and the powered mobile plant. This document is written on the basis that gas main installation is carried out with the gas, trench, services and plant controls in place, by competent gas workers, and a SWMS for the high risk construction work.

Gas main installation is carried out as construction work in connection with the excavation and gas requirements, with the pressurised gas and flammable atmosphere managed by isolation, purging, gas detection and no ignition, the trench collapse prevented, the underground services located and avoided, and the powered mobile plant operated safely. Because the work is on or near pressurised gas mains, may involve a flammable atmosphere, is in a trench deeper than 1.5 metres, and is in an area of powered mobile plant movement, it is high risk construction work. The gas and atmosphere, the trench, the services, and the plant are the considerations. This document coordinates the gas, trench, services and plant controls so the gas main installation is carried out safely.

Hazards identified

9 hazards covered, sorted by priority.

Control measures

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

1. 1Administrative: carry out the work on or near the pressurised gas main with the gas isolated, purged or controlled, gas detection and no ignition sources, by a competent gas worker, recognising the flammable atmosphere and explosion hazard.
2. 2Engineering: prevent trench and excavation collapse — the leading cause of fatality in excavation — by shoring, benching or battering the excavation, using trench boxes or shields, to a geotechnical assessment where required, because a collapse occurs quickly and can bury or crush a worker.
3. 3Administrative: obtain the essential services information before excavating — through Before You Dig Australia for underground assets and the Look Up and Live information for overhead assets — and locate, identify and avoid or isolate the services, because striking a gas, electrical or water service can cause explosion, electrocution or flooding.
4. 4Engineering: use the road and civil plant — pavers, rollers, profilers, graders, rigs and trucks — safely to the plant requirements and the manufacturer's instructions, with guarding, pre-operational checks, competent operators and the plant maintained.
5. 5Engineering: control ignition sources near the gas — no smoking, no naked flames, no spark-producing work — and use gas detection to manage a gas leak and the flammable atmosphere.
6. 6Engineering: where the work involves entry into a confined space such as a pit, drain, large pipe or chamber, apply the confined space controls — atmospheric testing, a confined space entry permit, ventilation, a standby person and rescue arrangements.
7. 7Engineering: use mechanical aids — excavators, cranes, pipe layers and lifting equipment — and team lifting for the heavy pipes, barriers, panels, rolls and materials, and manage the manual-handling and awkward-posture hazard with the hierarchy of controls for hazardous manual tasks.
8. 8Administrative: carry out the pressurised connection and purging by a competent gas worker to a procedure.
9. 9Administrative: because the work is on or near pressurised gas mains or piping and may involve a flammable atmosphere, prepare a SWMS for the high risk construction work before it commences, with the gas isolation and atmosphere controls implemented.
10. 10Administrative: because the work is in or near a shaft or trench with an excavated depth greater than 1.5 metres, prepare a SWMS for the high risk construction work before it commences, with the ground-support and access controls implemented.
11. 11Administrative: all workers must hold a valid White Card (General Construction Induction Training, CPCCWHS1001), with the plant tickets, traffic control accreditation, confined space, and other competencies required for the work.
12. 12Administrative: conduct a pre-start toolbox talk covering the day's work, identified hazards, the traffic and plant movements, required PPE and emergency procedures, and record attendance in the consultation section.
13. 13Administrative: consult workers and any health and safety representatives on the work and its risks, record the consultation, and keep this document available at the workplace.
14. 14PPE: high-visibility clothing to AS/NZS 4602.1, eye protection, hearing protection where required, gloves appropriate to the task, and Class I or Class II safety footwear with protective toecap to AS/NZS 2210.3.
15. 15Administrative: review and update this SWMS whenever the work scope changes, after any incident or near miss, when a worker or health and safety representative raises a concern, when new hazards are identified, or at minimum every 12 months.
16. 16Administrative: confirm the work is completed safely, the excavation, plant and area are left in a safe condition, and the site is secured.

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

A gas and civil crew is engaged to install a gas main. The pressurised gas and flammable atmosphere are managed by isolation, purging or control, gas detection and no ignition, by a competent gas worker. The trench collapse is prevented by shoring, benching or battering and trench boxes. The underground services are located through Before You Dig Australia, identified and avoided. The excavators and plant are operated safely. Ignition sources near the gas are controlled — no smoking, no naked flames, no spark-producing work — and gas detection used to manage a leak and the flammable atmosphere. Where entry into pits or confined connections occurs, the confined space controls are applied. The pipe and materials are handled with mechanical aids. The pressurised connection and purging are carried out by a competent gas worker to a procedure. Because the work is on a gas main, may involve a flammable atmosphere, and is in a trench over 1.5 metres, a SWMS is prepared for the high risk construction work. The gas main is installed, and the records retained.

Related legislation

• Model Work Health and Safety Act — primary duty of care; the duty to consult workers; the reckless-conduct offence; and notifiable-incident provisions, as enacted in each jurisdiction.
• Model Work Health and Safety Regulations — the construction work, excavation, plant, traffic, confined spaces and falls provisions, and the Section 291 high risk construction work and SWMS duties, as enacted in each jurisdiction.
• The construction work, excavation work, confined spaces and falls Codes of Practice, the traffic management guidance, and the relevant standards such as AS 5100 for bridges and AS 4678 for retaining structures, are called up by the relevant safety legislation for the civil road work.
• Essential services information is obtained through Before You Dig Australia for underground assets and the Look Up and Live information for overhead assets before excavating; plant operation, traffic control and confined space work require the relevant licences, accreditations and competencies.
• Victoria operates under the Occupational Health and Safety Act 2004 and the Occupational Health and Safety Regulations 2017, with the construction, excavation, plant and high risk construction work provisions applying in place of the model instruments.

Frequently asked questions