Comcare - Australian Goverment
Comcare - Australian Goverment
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Excavation

Excavation in construction is any operation in which earth, rock, or other material in or on the ground is moved or otherwise displaced by means of tools, equipment, or explosives, and includes earthwork, trenching, wall shafts, tunnelling and underground work. High-risk obligations apply to excavations with a depth greater than 1.5 metres.

The regulations covering construction work are contained in Part 12 of the Occupational Health and Safety (Safety Standards) Regulations 1994.

Hazards associated with excavation work

Without careful planing and management, an excavation site can be hazardous to all persons in the vicinity of the construction work. Particular hazards identified in relation to excavation work include:

  • the depth of the excavation
  • nature of the strata (soil variations creating the potential for the sides to collapse)
  • fractures or faults
  • the presence of water (from other sources)
  • exposure to wet weather
  • any load close to the edge of the zoned of influence
  • the exposure time
  • any previous disturbance
  • adjoining buildings
  • adjacent excavations
  • vibration which may increase the potential to collapse
  • the presence of existing underground services
  • chemical gases

Risks associated with excavation work

Excavation work is inherently dangerous and regarded as the most dangerous construction work. Excavation failures occur quickly and this limits the ability of the worker to escape especially if the collapse is extensive or is a trench.

The speed of an excavation collapse increases the risk associated with this type of work and the consequences are significant as the falling earth can bury or crush any person in its path. This can result in death by suffocation or internal crush injuries.

The magnitude of the consequences particularly in relation to trench collapse highlights the need to protect the employees and other person working at or near excavation sites.

Employer’ duties

Under the Occupational Health and Safety Act 1991 (the Act) employers are required to provide and maintain, as far as is practicable, a working environment that is safe and without risks to health.

To ensure that the risks are managed in accordance with the duties outlined under the Act employers should systematically manage the risks to health and safety which arise from excavation work

Employers can systematically manage the risks by undertaking the following four-step risk management process:

1. identify the hazards
2. assess the risk associated with the hazards
3. control the risk
4. review the process

When undertaking risk management, employers must give consideration to relevant Commonwealth regulation and codes of practice. If no regulation or code exists in relation to a specific identified hazard or risk, employers must choose a reliable source of guidance to follow.

Relevant Commonwealth Regulations

Part 12 of the Occupational Health and Safety (Safety Standards) Regulations 1994 specifies mandatory requirements for all employers and other duty holders in control of a construction project. Excavation to a depth of 1.5 metres and the construction of tunnels is regarded as high-risk construction work and as such further obligations apply to employers in control of a construction project.

Other parts of the regulations may also apply to excavation work:

  • Part 2 Competency Requirements
  • Part 3 Occupational Noise
  • Part 4 Plant
  • Part 5 Manual Handling
  • Part 6 Hazardous Substances
  • Part 8 Storage and Handling of Dangerous Goods
  • Part 10 Electricity
  • Part 13 Falls from 2 metres

Relevant Commonwealth Codes of Practice

In particular, the Occupational Health and Safety Code of Practice 2008:

  • Part 1 - Risk Management
  • Part 2 - First Aid
  • Part 3 - Noise
  • Part 5 - Vibration
  • Part 7 - Confined Spaces
  • Part 10 - Asbestos in Situ (under development)
  • Part 12 - Hazardous Substances 
  • Part 13 - Synthetic Mineral Fibres (SMF)
  • Part 15 - Carcinogenic Substances
  • Part 19 - Ultraviolet Radiation in Sunlight

Relevant Guidance Material

More information

Additional fact sheets in this series on construction work:
  • Construction work - An overview
  • Demolition
  • Induction training in construction
  • Tilt up wall panels and precast concrete

Government authorities

Safe Work Australia:

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