OSHA 10-Hour Construction ReviewExcavationsHard
An excavation is planned near an existing building foundation. Which of the following is the most important consideration to prevent undermining the adjacent structure?
- AUtilizing a protective system designed to support the adjacent structure.
- BMaintaining a minimum 2-foot clearance for spoil piles from the trench edge.
- CImplementing a dewatering system to control groundwater.
- DEnsuring proper access and egress points are available.
Show answer & explanationAnswer & explanation
Correct answer: A. Utilizing a protective system designed to support the adjacent structure.
When excavating near existing structures, the primary risk is undermining their foundations, which can lead to collapse. A protective system specifically designed by a competent person or registered professional engineer to support the adjacent structure's foundation is crucial to prevent this. While other options are important for trench safety, they don't directly address the structural integrity of the adjacent building.
Why the other options are wrong
- B. Spoil pile clearance prevents surcharge loads on the trench walls, which is important, but a direct structural support system is necessary for preventing undermining of an adjacent foundation.
- C. Dewatering helps with trench stability and worker safety, but it's a secondary measure compared to direct structural support when an adjacent foundation is at risk.
- D. Access and egress are for worker safety within the trench, not for protecting adjacent structures.
Adjacent Structure Protection
When an excavation is near an existing structure, protective systems must be implemented to ensure the stability of the structure's foundation and prevent undermining or collapse.
- Crucial when excavating near buildings, walls, or utilities.
- Protective system must be specifically designed.
- Often requires shoring or underpinning for the structure.
- Design by competent person or RPE is critical.
Memory trick: Structures Need Solid Support