Trade Exam · Module 6
Trenching and Excavation
Trench collapse risks, soil types, competent person inspections, protective systems, spoil pile clearance, and the critical 811 locating requirement.
Key Takeaways
- Type A soil max slope 3/4:1 (53°); Type B 1:1 (45°); Type C 1.5:1 (34°).
- Unknown soil defaults to Type C; treat conservatively.
- Spoil piles minimum 2 feet from trench edge to prevent collapse.
- Heavy equipment must stay 5 feet from trench edge; vibration destabilizes walls.
- Competent person must inspect trench daily and before entry; visual observation alone is insufficient.
Why This Matters on the Exam
Trenching and excavation are inherently dangerous. Trench collapses cause the most job site fatalities in the construction industry. The C-36 exam expects you to know the rules for safe trenching, protective systems, and the competent person's role. This isn't just exam material—it's literally the difference between someone going home to their family or not. Questions test your understanding of collapse mechanisms and when specific protections are required.
What You Must Know
Here's the deal: trench collapse can happen fast and without warning. You need to know:
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