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Standard Interpretations
09/30/2004 - Permissibility of using average excavation depth to determine protective system requirements for the excavation.
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• Standard Number: 1926.650; 1926.652(a)(1)(ii); 1926.652(a)(1); 1926.652(b); 1926.652(c)

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 http://www.osha.gov.


September 30, 2004

Mr. Richard Johnston
Director of Loss
Hausmann Johnson Insurance
700 Regent Street
P.O. Box 259408
Madison, WI 53725-9408

Re: 29 CFR 1926.652(a)(1)(ii); whether averaging excavation depth is permitted for determining whether the protective requirements of §1926.652 apply.

Dear Mr. Johnston:

This is in response to your letter dated July 16, 2004, to the Occupational Safety and Health Administration (OSHA). You requested that OSHA address how measurements should be made when establishing the depth of an excavation pursuant to §1926.652(a)(1)(ii).

We have paraphrased your question as follows:

Question: Scenario: Equally spaced measurements are taken along the area of the trench that employees will be in. Some parts of a trench are more than 5 feet deep, while other parts are less than 5 feet deep. The average of those measurements is less than 5 feet. Would that establish that cave-in protection under 1926.652(a)(1) is not required?

Answer
No. Section 29 CFR 1926.652(a)(1) states:
(a) Protection of employees in excavations. (1) Each employee in an excavation shall be protected from cave-ins by an adequate protective system designed in accordance with paragraph (b) or (c) of this section except when:
* * *
(ii) Excavations are less than 5 feet (1.52 m) in depth and examination of the ground by a competent person provides no indication of a potential cave-in.
In §1926.650, the standard defines "excavation" as:
any man-made cut, cavity, trench, or depression in an earth surface, formed by earth removal.
No minimum length was included in the definition. That is consistent with the fact that the danger of a cave-in an excavation 5 feet or more in depth does not significantly vary based on its length. Consequently, in a trench, at all points where the excavation is 5 feet or more (except in stable rock), cave-in protection is required.1 In a trench that varies above and below 5 feet along its length, there will be places in the trench where protective measures will be required and areas where they will not be required. The less than 5-foot average in your scenario for measurements taken at points along the excavation would not fall under the exemption of §1926.652(a)(1)(ii) because protective measures are required at each point where the excavation is 5 feet or deeper, or at each point less than 5 feet where there is evidence of a potential cave-in.

If you need any information on this matter, please contact us by fax at: U.S. Department of Labor, Directorate of Construction Office of Construction Standards and Guidance, (202) 693-1689. You may also contact us by mail at the above office, Room N3468, 200 Constitution Avenue, N.W., Washington, D.C. 20210, although there may be a delay in our receiving correspondence by mail.

Sincerely,


Russell B. Swanson, Director
Directorate of Construction

1 Even in those areas of the trench that are less than 5 feet in depth, a protective system would be required, unless examination of the ground by a competent person did not reveal any indication of a potential cave-in. [ back to text ]

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