Distance from excavation sidewalls as cave-in protection

December 2, 1991

Mr. Dennis E. Palmer, P.E.
Vice President
Barr Engineering Company
[Recipient address omitted]

Dear Mr. Palmer:

This is in response to your letter requesting an interpretation of the Occupational Safety and Health Administration standards addressing excavations. I apologize for the delay in responding to your inquiry.

In your letter, you asked whether distance alone was adequate to protect employees from the hazards of cave-ins. We reviewed the situation discussed in your letter and determined that at the times your employee maintained a distance of at least two times the height of the vertical sidewall from the toe of the sidewall, the employee was not exposed to the hazards of cave-in. Therefore, no additional protective system was necessary. However, when distance alone is relied upon to protect employees from the hazards of cave-in, all employees entering the excavation must be instructed not to enter the danger zone and a warning system must be provided to prevent workers from entering the danger zone inadvertently. Roping off the area or adequately marking the area with cones, flags or other highly visible means are examples of acceptable warning systems.

Please be advised that it is the responsibility of a competent person to determine, based on the conditions existing at each site, the distance away from the highwall necessary to protect the workers and the warning system necessary to adequately warn workers of the hazardous area.

If we can be of any additional assistance, please contact Roy F. Gurnham or Dale R. Cavanaugh of my staff in the Office of Construction and Maritime Compliance Assistance at (202)235-8136.

Sincerely,
Patricia K. Clark
Director
Directorate of Compliance Programs

[The requester’s April 3 letter and two OSHA internal review memoranda reproduced on the source page are omitted here.]