An excavation is 15 feet deep in Type A soil. Instead of sloping, the contractor chooses to use a trench box. What is the minimum requirement for the trench box installation?
Correct Answer
D) All of the above
Trench boxes must extend at least 18 inches above the bottom of the excavation, be installed under supervision of a competent person, and meet manufacturer specifications which require professional engineer certification.
Why This Is the Correct Answer
All three requirements are mandatory for trench box installation according to OSHA standards. The box must extend 18 inches above the bottom of the excavation to protect workers from cave-ins, must be installed by a competent person who can identify hazards and take corrective action, and must be certified by a professional engineer to ensure it meets structural requirements for the specific soil conditions and depth. Since all individual requirements (A, B, and C) are correct, option D 'All of the above' is the correct answer.
Why the Other Options Are Wrong
Memory Technique
Remember 'ICE': 18 inches above bottom, Installed by competent person, Engineer certified - all three requirements must be met for trench boxes
Reference Hint
OSHA Construction Standards 29 CFR 1926 Subpart P - Excavations, specifically sections 1926.652 (protective systems) and 1926.95 (competent person requirements)
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