Protective Systems
45 min · Suggested lesson, discussion and practice time
Objectives
- Choose sloping, benching, shoring or shielding.
- Understand soil types A, B, C and stable rock.
Key points
- Required at 5 feet or deeper unless in stable rock; under 5 feet if a competent person sees cave-in potential.
- Maximum allowable slopes (Appendix B): Type A 3/4:1 (53°), Type B 1:1 (45°), Type C 1-1/2:1 (34°).
- Trench boxes and shoring follow the manufacturer's tabulated data — keep it on site.
- 20 feet or deeper: design by a registered professional engineer.
Field scenario
You're digging an 8-foot sewer trench in previously disturbed soil (Type C). The box is too short. What are your options?
Review questions
Practice review only — not a final exam, recorded completion or certificate.