Hazards Associated with Excavations

According to NIOSH Director Dr. J. Donald Millar, these deaths are entirely preventable. “It is appalling that workers continue to be buried alive in cave-ins.. Almost without exception, these deaths can be prevented with existing safety precautions. These are not accidents, but incidents that can both be anticipated and avoided,” said Millar.  Construction fatalities and injuries must not be accepted as an inevitable annual occurrence. Caution must be taken whenever workers are exposed to life-threatening hazards. Injuries and deaths can be prevented if employers and employees are aware of the hazards they face and ensure that proper precautions are taken.

Cave-in’s are the number 1 hazard in construction.  Several factors contribute to trench cave-ins. For example, soil stability is related so soil type and may be affected by changes in weather. In the spring, unshored trench walls, heavy from rain, can become unstable. Also, when damp soil is exposed to air during excavation, it can dry out and lose the ability to stand on its own, increasing the risk that it will slide into the trench. Other factors, such as proximity to highways, large machinery, backfilled areas or existing structures, can affect soil stability as well.

How can workers be protected?

To prevent trench cave-ins and additional worker fatalities, the Occupational Safety and Health Administration (OSHA) requires that one or more of the following precautions must be taken when working with trenches:

  • Utilize a shield or trench box system designed to protect workers in excavations.
  • Shore sides of excavations with timber or other materials to ensure that the earth does not collapse on workers who must enter them.
  • Slope the sides of excavations to reduce the “overburden” (weight and pressure exerted by large amounts of soil on the sides).
  • Secure sides by equivalent means, such as engineer-designed sheeting or bracing.

For more information on the OSHA standard intended to protect workers in excavations and trenches, see 29 CFR 1926.651 and .652.