Preventing Cave-Ins And Other Excavation Disasters
If you are not using protective systems or equipment while working in trenches or excavations, you are at risk.
A 45-year-old construction “lead man” was shoveling loose dirt from the bottom of a 21-foot-deep unshored, vertical-walled excavation to accommodate placement of a fabricated trench shield. Soil began falling from a side wall; as the worker attempted to leave the site, the soil gave way, entirely covering and killing him.
This is just one of many cases noted in the Fatal Accident Circumstances and Epidemiology Project of the National Institute for Occupational Safety and Health. In case after case, none of the excavations were found to incorporate the following protective measures specified in applicable OSHA Standards:
- The walls and faces of all excavations in which employees are exposed to danger from moving ground should be guarded by a shoring system, sloping of the ground or some other equivalent means.
- Sides of trenches in unstable or soft material, five feet or more in depth, should be shored, sheeted, braced, sloped or otherwise supported by means of sufficient strength to protect employees working within them.
- Excavations (including trenches) adjacent to backfilled areas or subjected to vibrations from railroads, highway traffic or operation of machinery should be reinforced with additional shoring and bracing.
- Those working with excavations from 5 to 24 feet deep in Type A or Type B soils or 5 to 15 feet deep in Type C soil should either equip the trench with a shoring system capable of supporting the lateral soil pressure, cut the trench back to the steepest allowable slope for the type of soil or use a combination of both measures.
All excavations are hazardous because they are inherently unstable. If they are restricted spaces, they present the additional risks of oxygen depletion, toxic fumes and water accumulation. If you are not using protective systems while working in trenches or excavations at your site, you are in danger of suffocating, inhaling toxic materials, fire, drowning or being crushed by a cave-in.
