OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

February 3, 1981

MEMORANDUM FOR:    CURTIS A. FOSTER
                  REGIONAL ADMINISTRATOR

THRU:              JOHN MILES
                  FIELD COORDINATOR

FROM:              BRUCE HILLENBRAND
                  ACTING DIRECTOR, FEDERAL COMPLIANCE
                    AND STATE PROGRAMS

SUBJECT:           Request for Interpretation of 29 CFR 1926.900(e)
                  and 29 CFR 1926.905(g)

Seismic exploration performed by qualified private contractors in a National Forest would normally not be in violation of 29 CFR 1926.900(e) or 29 CFR 1926.905(g) when the blasting hole is charged, capped and stemmed, but not immediately fired. Normally, the force of the blast, upon detonation of such blasting holes, will be restricted and will thus not pose a hazard to employees in the area. However, the ends of the firing system shall be identified and concealed until time of firing. The firing of the charges should be accomplished in a suitable (as defined in 29 CFR 1926.32(r)) time.