Trenches & Excavations — Case Study PDF Version

Versión en español

Robin Baker, Robert Downey, Mary Ruth Gross, Charles Reiter
Labor Occupational Health Program (LOHP) School of Public Health,
University of California, Berkeley Ca.

These case studies are part of tailgate/toolbox talks that were developed for use under California OSHA regulations. The American Conference of Government Industrial Hygienists (ACGIH) has adapted these talks to apply to federal OSHA regulations.) To contact ACGIH, visit its website (

Laborer Dies in Trench Cave-In

A 27-year-old laborer died after being trapped in soil over his head as a result of a trench cave-in.

The laborer was digging out the bottom of the trench to expose a drain pipe. On one side of the trench was a retaining wall. The other side was a dirt wall which was part of a hillside.

When the collapse occurred, another worker had been pulling up buckets filled with the spoil, placing it on the hillside above the trench wall as well as on the other side of the excavation. Eventually the hillside collapsed, burying the laborer.

The hillside that collapsed was not shored or otherwise protected from earth movement. The soil in the area had recently been disturbed by an earthquake.

There was no competent person on site to check the soil and excavation. No initial hazard assessment had been performed. The laborer had received no training from the company.

April 11, 1996

What should have been done to prevent this accident?

Preventive Measures

Cal/OSHA investigated this accident and made the following recommendations.

Employers should:

  • Assure that the sides of all excavations are shored, laid back to a stable slope, or provided with other equivalent protection where employees may be exposed to moving ground or cave-ins.
  • Have a competent person frequently inspect excavations in which the soil was previously disturbed, or where there is loading due to stored materials.
  • Train employees, including periodic refresher training, to be aware of and understand the hazards of the job.
  • Perform an initial hazard assessment of the job prior to beginning work and whenever there is a change (storm, earthquake, etc.) that may cause new hazards.

This Case Study is based on an actual California incident. For
details, refer to California Dept. of Health Services, Occupational
Health Branch, Fatality Assessment and Control Evaluation
(FACE) Report #96CA007.

Tailgate Meetings That Work : Collection

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