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Epidemiologic Notes and Reports Worker Fatalities due to Excavation Cave-Ins

Worker fatalities due to excavation cave-ins in four states have recently been investigated by the National Institute for Occupational Safety and Health (NIOSH) as part of its Fatal Accident Circumstances and Epidemiology (FACE) project. Brief reports follow.

On February 25, 1985, a 22-year-old laborer in Georgia was manually digging a dry well and an 8-foot-deep trench for a drainage-pipe connection. One wall of the trench collapsed, covering him with 6 feet of soil. He was apparently dead at the scene. None of the walls in the excavated area were shored (braced) or sloped appropriately.

On March 24, 1985, a 45-year-old "lead man" on a construction crew in Arizona was shoveling loose dirt from the bottom of a 21-foot excavation. He was preparing it for the placement of a fabricated trench shield. As soil began falling from a side wall, the worker tried to leave the site, but the soil gave way, covering him. He died during surgery approximately 6 hours after the cave-in. The vertical walls of this excavation had not been shored.

On May 3, 1985, a 33-year-old field foreman on a construction site in Pennsylvania was standing in a vertical-walled excavation approximately 7 feet deep. One wall caved in, knocking him to the ground and burying him. Efforts to revive him at the scene were unsuccessful. The walls of the excavation had not been shored.

On August 8, 1985, a two-man crew in Ohio was using a backhoe* in an 11- to 12-foot-deep excavation to cut a lateral trench off an 8-inch sewer main. One of the crew, a 62-year-old laborer, was killed when the trench wall collapsed, covering him with 3 feet of soil. The sides of the trench had not been shored.

NIOSH investigators determined that neither the relevant Occupational Safety and Health Administration (OSHA) standards nor the NIOSH-recommended work practices for such excavations had been adhered to in any of these cases. The current OSHA standards** specify that:

  1. The walls and faces of all excavations in which employees are exposed to danger from moving ground shall be guarded by a shoring system, sloping of the ground, or some other equivalent means.

  2. Sides of trenches in unstable or soft material 5 feet or more in depth shall be shored, sheeted, braced, sloped, or otherwise supported by means of sufficient strength to protect employees working within them.

  3. Excavations (including trenches) adjacent to backfilled areas or subjected to vibrations from railroads, highway traffic, or operation of machinery shall have additional shoring and bracing precautions taken. NIOSH and the National Bureau of Standards (NBS) recommend that:

  4. Shoring systems or sloping of the walls be used in all excavations 5-24 feet deep in any type of soil, except solid, stable rock.

  5. Appropriate shoring, shielding, or sloping requirements for all excavations deeper than 24 feet (except those in unfractured rock) be determined by an engineer qualified to make these determinations.

  6. All employers engaged in excavation activities familiarize themselves with the provisions of the NBS/NIOSH document, Development of Draft Construction Safety Standards for Excavations (1) and implement them as safe work practices in conjunction with compliance to the existing OSHA standards. The investigations further determined that compliance with the

relevant OSHA standards or adherence to the NIOSH-recommended work practices regarding excavations would have reduced the inherent risk in each of the four reported fatal incidents. Reported by Injury Surveillance Br, Div of Safety Research, National Institute for Occupational Safety and Health, CDC.

Editorial Note

Editorial Note: Excavation cave-ins often cause serious and fatal injuries to U.S. workers. Analysis of workers' compensation claims for 1976-1981 (2) in the Supplementary Data System of the Bureau of Labor Statistics suggests that excavation cave-ins caused approximately 1,000 work-related injuries per year. Of these, approximately 140 resulted in permanent disability, and 75 were fatal. Thus, this type of incident is an important cause of occupational deaths, and accounts for nearly 1% of all work-related deaths reported annually in the United States.

To clarify prior OSHA regulations, NBS and NIOSH have developed recommendations establishing a requirement to provide protection in excavations 5 feet deep or greater, regardless of soil type. These recommendations also present a simplified soil-classification system for use in determining appropriate side-sloping requirements and for calculating the lateral soil pressures imposed on shoring systems.

The principal objective of investigations undertaken by NIOSH as part of its FACE project is to determine what factors allowed the fatality to occur and how such fatalities can be prevented. Whether an operation was in compliance with existing mandatory standards is only one of many variables that may have contributed to the fatality. Evidence of noncompliance in the four incidents described above suggests that employers are either (1) unaware of the existence of the OSHA standards or (2) misinterpreting the requirements of the standards. As an obvious first step in preventing such fatalities, all such operations should be done in full compliance with existing OSHA standards.

NIOSH urges safety and trade associations, underground-utility companies, and municipalities and other local governments responsible for underground-utility services, as well as state OSHA consultative services to bring these recommendations to the attention of employers engaged in excavations.

Suggestions, requests for additional information on safe work practices, or questions related to this announcement should be directed to Director, Division of Safety Research, National Institute for Occupational Safety and Health, 944 Chestnut Ridge Road, Morgantown, West Virginia 26505; telephone (304) 291-4595.

References

  1. National Institute for Occupational Safety and Health/National Bureau of Standards. Development of draft construction safety standards for excavations, Vols. I and II. NBSIR 83-2693, DHHS (NIOSH) publication no. 83-103.

  2. U.S. Department of Labor, Bureau of Labor Statistics. Supplementary data system. Unpublished injury and fatality data for 1976-1981. *An excavation machine with a mechanical arm that operates back toward the worker. **((29 CFR 1926.651 and 1926.652.



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