During excavation work, you encounter a trench that is 12 feet deep and 6 feet wide in Type B soil. The trench will be open for 3 weeks. What is the most appropriate protective system?
Correct Answer
D) Hydraulic shoring system
For a deep, narrow trench open for extended periods, a hydraulic shoring system provides the most practical and safe protection while allowing efficient work access.
Why This Is the Correct Answer
CORRECT_ANSWER - A hydraulic shoring system is the most appropriate choice for this scenario because the 12-foot depth and 6-foot width make sloping impractical due to space constraints. The 3-week duration requires a robust, adjustable system that can be safely installed and removed while providing continuous protection. Hydraulic shores can be quickly installed in narrow trenches and provide excellent support for Type B soil conditions over extended periods.
Why the Other Options Are Wrong
Option A: Sloping at 1:1 ratio
Sloping at 1:1 ratio would require sloping back 12 feet on each side, creating a trench opening of 30 feet wide (6 + 12 + 12), which is often impractical due to space limitations, utility conflicts, and excessive excavation costs.
Option B: No protection needed if workers stay near ladder
While benching is acceptable for Type B soil, the 6-foot width is too narrow to effectively implement benching systems, and the 3-week duration makes this less practical than hydraulic shoring for ongoing work access.
Memory Technique
Use 'HANDS' - Hydraulic for All Narrow Deep Situations. When width is limited but depth is great, hydraulic shoring gives you the best of both worlds: protection and workspace.
Reference Hint
OSHA 29 CFR 1926 Subpart P - Excavations, specifically 1926.652 Requirements for protective systems
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