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CROSS Safety Report

Worker trapped in excavation

Report ID: 576 Published: 1 July 2016 Region: CROSS-UK

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Overview

An operative received serious injuries when the excavation they were working in collapsed.

Key Learning Outcomes

For construction professionals:

  • It is good practice to carry out a risk assessment and method statement (RAMS) for all construction activities. This can ensure the sequencing of work activities such as trench excavation are considered and planned.
  • Consider appointing a competent temporary works coordinator (TWC) on site who should be able to identify and address the risk of a potential trench collapse
  • Regular toolbox talks are a good way of engaging with work crews and highlighting any risks associated with work activities

For all built environment professionals:

  • It is desirable to create a safety aware culture whereby everyone on construction sites or other hazardous environments is looking out for risks and looking out for each other

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A report says than an operative received serious injuries when the excavation they were in collapsed. The works consisted of the construction of a manhole chamber, the excavation of a 1.8m deep trench, and the installation of ducting. Ground water was found in the excavation but not noted as a hazard.

The trench was not supported, and the risk of an unsupported trench collapsing was not well enough recognised either before work was undertaken, or whilst it was in progress. Collapse was due to the instability of the trench sides.

The trench was not supported, and the risk of an unsupported trench collapsing was not well enough recognised either before work was undertaken, or whilst it was in progress

There were extensive management procedures in place from design through to construction to identify and manage risk, but it was found that some of them were not completed. Because of the position and nature of the works, there could have been other serious consequences had the collapse been of greater magnitude.

The reporter's organisation subsequently instituted measures to stress the importance of communication and control. Also, the need to recognise the importance of appropriate temporary works when necessary was emphasised.

Expert Panel Comments

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There can be few hazards more well-known than the dangers consequent on deep trench collapse. All excavations are inherently dangerous and something as deep as 1.8m requires proper engineering consideration for assuring wall stability. The dangers are heightened by the presence of percolating water.

Recent fatalities due to trench collapse

The responsibility to avoid danger to those in excavations is absolute, qualified only by what is practicable (not what is ‘reasonably practicable’). Should a fatality have occurred in this instance corporate and/or gross-negligence manslaughter charges might have followed (see R v Cotswold Geotechnics).

A construction company has recently been fined over £2m after an employee died when the 2.4m deep trench he was working in collapsed. The penalty was imposed under new sentencing guidelines for health and safety offences which came into operation for cases sentenced after February 2016.

It appears that there was a lack of corporate capability on the part of the organisations onsite, and individually, for the safety of those present. The circumstances might suggest that BS5975:2011 was not being applied. General guidance is given in the Health and Safety Executive (HSE) document Managing for health and safety (HSG 65) (Figure 1) and reference should be made to the role of the temporary works coordinator, (TWC) named in BS 5975:2011.

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Figure 1: The Plan, Do, Check, Act flowchart (Source: the HSE)

Creating a safety aware culture

Whilst management procedures, method statements and risk registers are all important tools for mitigating safety related risks, it is also desirable to create a safety aware culture whereby everyone on construction sites or other hazardous environments is looking out for risks and looking out for each other. Many experienced people probably passed the unsupported trench. If just one of them had spoken up, the incident would have been avoided.

Documented procedures are necessary, but not sufficient, for safety aware behaviour. They are of no value if not enforced on site by experienced supervisors who understand the inherent risks and have the authority to take responsive action. The supervisor should have not just the right experience, but also the relevant authority.

Furthermore, it is essential that those in a supervisory role are not put under undue pressure to deliver to programme come what may, but they have the authority to deliver safely, and stop proceedings when there is undue risk. This demands a culture shift within parts of the industry to prevent such wholly avoidable circumstances from occurring. The case demonstrates yet again that unless people are prepared to actually observe all the relevant safe working procedures, serious incidents will keep on happening.

Furthermore, it is essential that those in a supervisory role are not put under undue pressure to deliver to programme come what may, but they have the authority to deliver safely, and stop proceedings when there is undue risk

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