Real-Life Scenario
Trench Collapse
Two employees were installing storm drain pipes in a trench, approximately 20-30 feet long, 12-13 feet deep and 5-6 feet wide. The side walls consisted of unstable soil undermined by sand and water. There was 3-5 feet of water in the north end of the trench and 5-6 inches of water in the south end.
At the time of the accident, a backhoe was being used to clear the trench. The west wall of the trench collapsed, and one employee was crushed and killed.
Inspection Results
As result of the investigation, OSHA issued citations for one willful, one serious, and one-other-than-serious violation of its construction standards.
OSHA's construction safety standards include several requirements which, if they had been followed here, might have prevented this fatality.
Accident Prevention Recommendations
- Employers must shore, slope sheet or brace sides of trenches in unstable material (29 CFR 1926.652(b) or 1926.651(c)).
- There must be a means of escape from a trench such as ladder (29 CFR 1926.652(h)).
- Trench work is to be inspected daily by a "competent person". When there's evidence of cave-ins or slides, all work must stop (29 CFR 1926.650(i)).
- Water must not be allowed to accumulate in a trench (29 CFR 1926.651(p)).
- Excavation material must be moved at least two feet from the edge of the trench (29 CFR 1926.651(i)).
- Where heavy equipment is operating near a trench, extra precautions must be taken due to the extra load imposed on the ground (29 CFR 1926.651(q)).
Knowledge Check Choose the best answer for the question.
6-8. A trench is 12 feet deep and 5 feet wide. The unprotected walls consist of unstable soil and are beginning to seep into the trench. You are the competent person. What are your actions?
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