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Seismic blasting holes left charged before firing

Summary An OSHA region asked about seismic exploration charges placed in a national forest but not fired immediately. OSHA said the described charged, capped, and stemmed holes ordinarily did not violate the cited construction blasting provisions. It required the firing ends to be identified and concealed until firing and the blast to occur at a suitable time.
Document
Federal opinion letter
Agency
Occupational Safety and Health Administration (OSHA)
Document number
1981-02-03
Date issued
February 3, 1981
Status
Active
Status last verified October 10, 2026
Topics
Workplace Safety OSHA 1926 Blasting
Source
View the official document

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About this page: The full text below is the official document from Occupational Safety and Health Administration (OSHA). Ezel adds the plain-English summary and tracks the document's status. The official source linked on this page is authoritative for any reliance.

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.

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