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157 Excavation Safety: Basic
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Appropriate Protective System Designs

Method 2: Shoring

Shoring requires the use of tabulated data such as tables and charts approved by a registered professional engineer to design excavation.

Timber, aluminum, or other suitable material may also be used in the construction of shoring systems
Timber, aluminum, or other suitable material may also be used in the construction of shoring systems.

The data must be in writing and must include enough explanatory information, including the criteria for making a selection and the limits on the use of the data, for the user to make a selection.

At least one copy of the data, including the identity of the registered professional engineer who approved it, must be kept at the worksite during the construction of the protective system.

Trench box system with ladder
Trench box with ladder. Notice space between the box side and trench face.

After the system is completed, the data can then be stored away from the jobsite. However, a copy must be provided upon request to the Assistant Secretary of Labor for OSHA.

Method 3: Trench Box or Shield

In this method, you would use a trench box or shield designed or approved by a registered professional engineer. Timber, aluminum, or other suitable material may also be used in the construction. OSHA standards permit the use of a trench shield if it provides the same level of protection as the appropriate shoring system.

Employers can choose the most practical method for the particular circumstance, but that system must meet the required performance criteria. The standard doesn't require a protective system when an excavation is made entirely in stable rock or is less than five feet deep. However, in this case, a competent person must examine the ground and find no indication of a potential cave-in.

Knowledge Check Choose the best answer for the question.

2-6. OSHA requires a protective system unless an excavation is _____.