Excavation & Trenching
A cubic yard of soil weighs about as much as a car, so cave-ins are deadly — trenching has strict, well-tested rules.
Protective system: at 5 ft deep · Spoil setback: 2 ft from the edge · Egress: ladder/ramp within 25 ft (trenches ≥ 4 ft) · Inspection: competent person, daily and after rain · Least stable soil: Type C · Type C max slope: 1.5:1 (≈34°).
Before you dig
Locate underground utilities — call 811 (DigAlert in California) before breaking ground.
Protecting the trench
- Use a protective system at 5 feet: slope the walls back, shore them, or drop in a trench shield (box).
- Soil is classified Type A, B, or C (plus stable rock); Type C is the least stable and slopes back the most — 1.5:1.
- Keep spoil and equipment 2 feet from the edge, and provide egress within 25 feet in any trench 4 feet or deeper.
- A competent person inspects daily, after rain, and whenever conditions change, and can order everyone out. Test the air when a hazardous atmosphere could exist.
Practice: Excavation & Trenching
Frequently asked
At what depth does a trench need a protective system?
How far from the trench edge must excavated soil be kept?
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Construction fall protection: the 6-foot rule, guardrail heights and strength, personal fall arrest anchorages and arresting force, and hole covers — from OSHA 29 CFR 1926 Subpart M.
Read & practice →Ladders & Scaffolds
Ladder and scaffold safety: the 4:1 ladder angle, 3-foot rail extension, three points of contact, the 10-foot scaffold fall-protection rule, 4× load capacity, and competent-person inspections.
Read & practice →Electrical & Lockout/Tagout
Electrical safety on the jobsite: GFCIs and the assured-grounding program, the 10-foot overhead-line clearance, lockout/tagout, grounded or double-insulated tools, and treating conductors as energized.
Read & practice →PPE, Silica & Respiratory
Personal protective equipment and health hazards: employer-paid PPE, hard hats and eye protection, the 85 dBA noise action level, the 50 µg/m³ silica limit, dust controls, and respirator requirements.
Read & practice →Hazard Communication & Focus Four
Hazard communication and OSHA basics: Safety Data Sheets and their 16 sections, GHS labels and signal words, the Right-to-Know law, the Focus Four hazards, the General Duty Clause, and reporting deadlines.
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