Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

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

September 14, 1976

Mr. Kenneth G. May,
Agency Compliance Supervisor
The Great Lakes Construction Company
Box 09086 Pearlbrook Station
Cleveland, Ohio 44109

Subject: 1926.652 - Specific Trenching Requirements

Dear Mr. May:

This is in response to your letter of August 9, 1976 to Mr. Bowman of our Cleveland Area Office.

Whenever shoring is referenced, and used it must always start from the bottom of the trench.

Question #1: "1926.652(a) is applicable where employees are exposed to moving ground or cave-ins, in such cases banks over 5 feet must be shored, laid back as per Table P-1, or other equivalent means of protection."

You are correct, but you must also add the last sentence, "... Trenches less than 5 feet in depth shall also be effectively protected when examination of the ground indicates hazardous ground movement may be expected."

Question #2: "1926.652(b) is applicable in unstable or soft material with banks over 5 feet and in those cases, the sides must be shored, sheeted, or braced as per Table P-2 or sloped as per Table P-1, or otherwise supported."

You are correct, but the shoring, sheeting, bracing, etc. shall always start from the bottom of the trench.

Question #3: "1926.652(c) is applicable in hard or compact soil and in trenches over 5 feet in depth shall be shored or otherwise supported or sloped above the five-feet level to preclude collapse but not steeper than 1/2:1."

The imaginary slope line must start from the bottom of the trench. Sloping must start at a point of intersection of the imaginary slope line and a horizontal line at the 5 feet level. This point would be 2.5 feet away from the edge of the trench. All material above the 5 feet line and over to the stable slope shall be removed, since the sides of trenches in hard or compact soil, 5 feet or less in depth, will normally stand without further support. Another option would be to bench at each additional 5 foot level.

If you have any further questions, please feel free to call us on our toll-free number, 800-621-0523.

Very truly yours,

Nicholas DiArchangel
Acting Regional Administrator
for Occupational Safety and Health