Archive Notice - OSHA Archive

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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

June 26, 1985

This is in response to your memorandum on this subject of May 29, 1985.

While the standard is not too definitive as to where the sloping of the side of a trench on the five-foot plane should begin, sound engineering principles based on a scaled drawing of a cross section of a trench would indicate the necessity of removal of all the earth above the five-foot level, back to the imaginary line of the angle of repose, starting at the bottom of the trench and then sloping upward with the angle of repose. This is necessary to preclude the possibility of collapsing the unshored side of the trench by additional load that the five foot level method would superimpose on the side of the trench. Mr. Kurtz's interpretation to calculate the slope or angle of repose from the bottom of the trench is therefore correct. In regard to the three issues raised by the Dallas Area office, our response is as follows:

  1. Table P-1 does apply when determining slope in hard or compact soils.
  2. The angle of repose should be measured from the bottom of the trench.
  3. It is not our understanding that the courts have interpreted 29 CFR 1926.652(c) to mean that the slope should be measured from the five-foot level to grade.
Memorandum For:

Regional Administrator


ARA/Technical Support


JOHN B. MILES, JR., Director
Directorate of Field Operations


Request for Interpretation/Clarification of 29 CFR 1926.652(c)