Accident Report No. 31 - Fatal Facts

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OSHA Office of Construction & Engineering

Summary Statement

OSHA handout showing how a pipelayer working in an unshored trench was killed when a cave-in buried him up to the waist.

Accident Summary

Accident Type Cave-in
Weather Cloudy and Dry
Type of Operation Trenching and excavation
Crew Size 4
Collective Bargaining No
Competent Safety Monitor on Site? Yes
Safety and Health Program in Effect? Yes
Was the Worksite Inspected Regularly? Yes
Training and Education Provided? No
Employee Job Title Pipe Layer
Age/Sex 32/M
Experience at this Type of Work 9 months
Time on Project 2 weeks


Employees were laying sewer pipe in a trench 15 feet deep. The sides of the trench, 4 feet wide at the bottom and 15 feet wide at the top, were not shored or protected to prevent a cave-in. Soil in the lower portion of the trench was mostly sand and gravel and the upper portion was clay and loam. The trench was not protected from vibration caused by heavy vehicle traffic on the road nearby. To leave the trench, employees had to exit by climbing over the backfill. As they attempted to leave the trench, there was a small cave-in covering one employee to his ankles. When the other employee went to his co-worker's aid another cave-in occurred covering him to his waist. The first employee died of a rupture of the right ventricle of his heart at the scene of the cave-in. The other employee suffered a hip injury.


Following investigation, citations were is sued alleging three willful, four serious and two non-serious violations of construction standards. Had the trench been shored to prevent slides or cave-ins and had employees been trained to recognize and avoid unsafe conditions, the accident could have been prevented.

  1. Employers must instruct employees on how to recognize and avoid hazardous conditions and on regulations applicable to the work environment (29 CFR 1926.21(b)(2)).
  2. Excavated and other materials must be effectively stored and retained at least two feet from the edge of the excavation (29 CFR 1926.651(i)(1)).
  3. The employer must ensure that the walls or side of trenches in unstable or soft material 5 feet or more in depth, be shored, sheeted, braced, sloped, or protected in some manner to prevent cave-ins and to protect employees required to work within them (29 CFR 1926.652(b)).
  4. When excavations are subjected to vibrations from highway traffic, additional precautions must be taken to prevent cave-ins (29 CFR 1926.652 (e)).
  5. Ladders must be provided as a means of exit when employees are required to be in trenches 4 or more feet deep (29 CFR 1926.652(h)).
  • Construction Safety and Health Standards (OSHA 2207) which contains all OSHA job safety and health rules and regulations covering construction.
  • OSHA-funded free consultation services. Consult your telephone directory for the number of your local OSHA area or regional office for further assistance and advice (listed under US Labor Department or under the state government section where states administer their own OSHA programs).
  • OSHA Safety and Health Training Guidelines for Construction (available from the National Technical Information Service - Order No. PB-239-312/AS) comprised of a set of 15 guidelines to help construction employees establish a training program in the safe use of equipment, tools, and machinery on the job.
  • Excavation and Trenching Operations (OSHA 2226), is a 20 page booklet describing pertinent OSHA standards in detail.
  • Sloping, Shoring, and Shielding, a one-day instructional program with classroom session and hands-on workshop. Available from NAC (Order No. 009863, $30), the package includes an instructor's manual, outline for field exercise/workshop and 60 slides.