OSHA 10-Hour Construction ReviewExcavationsMedium
A utility crew is installing new conduit in an area where the excavation will be 7 feet deep. Due to limited space, sloping is not feasible, and the soil is considered Type C. What is the most appropriate protective system for this scenario?
- AUse a combination of sloping and benching.
- BInstall a hydraulic shoring system to support the trench walls.
- CUtilize a trench shield (trench box) for worker protection.
- DEmploy a benching system with a 1:1 slope.
Show answer & explanationAnswer & explanation
Correct answer: B. Install a hydraulic shoring system to support the trench walls.
Given that sloping is not feasible due to limited space, and the soil is Type C (least stable), an active support system is required. A hydraulic shoring system directly supports the trench walls, preventing collapse, and is suitable for tight spaces where sloping is impractical. A trench shield only protects workers inside, not the trench itself, and benching is a form of sloping and thus also not feasible.
Why the other options are wrong
- A. Combination of sloping and benching is still a form of sloping and would not be feasible due to limited space.
- C. A trench shield protects workers but does not prevent the trench walls from collapsing, which is crucial in unstable Type C soil with limited space.
- D. Benching is a form of sloping and is explicitly stated as 'not feasible' due to space constraints. Also, 1:1 slope is too steep for Type C soil.
Shoring for Confined Excavations
In excavations with limited space or unstable soil where sloping is impractical, shoring systems provide active structural support to prevent cave-ins.
- Shoring is effective in tight spaces.
- Essential for unstable soil types (e.g., Type C).
- Hydraulic shoring allows for safe installation from above the trench.
Memory trick: Tight spot? SHORE it up!