Date of incident: February 2016
Notice of incident number: 2016166920005
Employer: Excavation company

Incident summary
At a residential construction site, a worker was in a recently excavated trench more than 1.2 m (4 ft.) deep. While the worker was shovelling around a pipe, the east wall of the trench suddenly collapsed and buried him. The workplace supervisor and another worker attempted to dig the worker out, initially with an excavator and then by hand and using shovels. Local fire rescue attended the location and extricated the worker from the collapsed trench. The worker sustained fatal injuries.

Investigation conclusions

Cause

• Unsafe work process caused excavation collapse. The worker was completely buried in an excavated trench deeper than 1.2 m (4 ft.) after one of its vertical walls collapsed. The trench had not been sloped, benched, or shored (critical to ensuring excavation stability). The worker should not have been in the excavation without someone ensuring that the excavation was adequately sloped, benched, or shored.

Contributing factors

• No written instructions by a qualified professional. The nature of this excavation project required a qualified registered professional to have provided written instructions to safely undertake the excavation work. The excavation work was within 6 feet of an existing structure and beneath pavement. The absence of an assessment and lack of written instructions led to a failure to understand the hazardous nature of the excavation. Written instructions from a qualified professional would have helped provide direction on how to support the excavation walls prior to any worker entering the trench, ensuring that workers could safely perform the work.
• Employer failed to ensure workers’ safety and directed unsafe work. The excavation that collapsed had not been sloped, benched, or shored as required. The worker who was directed to enter the excavated trench was exposed to a high risk of serious injury or death from a collapse of the excavation. The employer did not have any safe work procedures for conducting excavation work.
• Lack of excavation-related knowledge. Safe work requirements associated with the excavation process were not understood, and a worker was directed to conduct work inside a recently excavated trench that was deeper than 1.2 m (4 ft.) and that lacked sloping, benching, and shoring, all requirements of section 20.81 of the Occupational Health and Safety Regulation for excavations of this depth.
• Lack of adequate training and supervision. The employer did not provide its workers with an orientation or training in excavation work, nor with adquate supervision. The employer failed to adequately ensure the safety of its workers.

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