Safety in Excavations

Construction By Matthew Coombes

One of the most important things to consider for any excavation activity is how that excavation is being prevented from collapsing, and importantly, how the structures and areas around the excavation will be affected by the removal of the ground.

Excavating land changes the way that pressure is able to be exerted around nearby structures, so any excavation needs to be made in consideration for neighbouring structures, to prevent them from subsiding or collapsing. The same applies for trees, which when damaged by an excavation could become unstable or damaged, resulting in the potential for the tree or parts of the tree to collapse.

It’s important that those involved in planning and digging an excavation are competent and capable to do so, and that they are able to fulfil their duties under the various legislation relating to excavations, such as: the Health and Safety at Work Act 1974; Construction (Design and Management) Regulations 2015; Working at Height Regulations 2005; and the Confined Spaces Regulations 1997. Each of these pieces of legislation will have requirements which must be met by those planning or carrying out excavations, without necessarily directly mentioning excavations.

Prevent collapse

One piece of legislation that directly talks about excavations is The Construction (Design and Management) Regulations 2015, Section 22.

This section highlights that ‘All practicable steps must be taken to prevent danger to any person’, and that you must ensure that no excavation or part of an excavation collapses.

Before any worker puts so much as a toe into the excavation, it is essential that it has been appropriately supported to prevent the excavation from collapsing. This also goes for further extending the excavation – if you’re excavating deeper or further in any direction, it will need to be supported as you go along.

Guard the pit

Section 22, part 2 also states “Suitable and sufficient steps must be taken to prevent any person, work equipment, or any accumulation of material from falling into any excavation”.

Prior to entering an excavation, ensure that there are sufficient barriers to prevent materials or even people from falling into the excavation on top of those working within the excavation. Falling into an excavation is likely to result in serious injuries or death, and a consideration must be made for any members of the public, visitors, or other workers who may be unaware of the excavation or it’s dangers.

Plan the work area

Plant and materials, especially heavy or loose materials should be kept well away from the edge of the excavation. This is both to prevent the excavation from collapsing due to increased weight/pressure and to ensure that they don’t fall into the excavation.

Information is key

Working in an excavation is high risk work if effective controls are not in place, so any expectations to work in an excavation should include information on the risks, controls that are in place to prevent injury or death, and a procedure to follow when entering an excavation, including what Personal Protective Equipment is expected.

These should be clear to understand and include relevant signage and other communication where required, such as signage saying “Hard hats must be worn in excavations” right next to the ladder.

Underground services

Additionally, it’s important that no underground services are struck during the work, both by any plant present or workers using hand tools. The way in which services will be identified and avoided will depend on the excavation, its purpose, and the services present. You can read more about this in our article Avoiding Danger When Digging Near Underground Services.

Inspect the excavation

The excavation should be checked each day before work starts, and if anything happens that may affect stability, such as plant driving nearby, rainfall, or high sun (which may change the composition of the excavated area).

Entering and exiting the excavation

The Work at Height Regulations 2005 specifically highlight that “work at height” means work in any place at or below ground level.

There must be a safe means of getting in and out of the excavation appropriate to the type of excavation, the work being carried out, and the risks present. For example, if you have 10 persons working in an excavation around a watermain, and that water main bursts, the excavation may quickly fill with water, and it may not be possible for all 10 workers to quickly and effectively evacuate up one ladder.

Working below the ground – Asphyxiation / Explosion

Heavier than air gasses such as propane, hydrogen sulphide, butane, and sulphur dioxide are heavier than the atmosphere, meaning that they will pool in any space below ground level. Heavier than air gasses need to be kept well away from excavation pits, as a build-up of them will remove the breathable air from the excavation pit.

Additionally, a build-up of propane or another flammable gas in an excavation could result in an explosive atmosphere.

Personal Protective Equipment

The type of equipment required will depend greatly on the hazards present in the environment. Working at height may mean that you’re required to wear a hardhat while inside the excavation pit, to prevent injuries from things falling on your head. Other equipment required may be due to specific hazards present, these should have been identified by the risk assessment.

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