Excavation Techniques, Trenching, and Material Handling
Excavation Techniques, Trenching, and Material Handling
This domain tests planning the dig, controlling depth and slope, keeping the trench stable, and handling spoil and materials safely.
Core rules
- Plan before digging: locate utilities, set the excavation line and bench, define spoil and access routes.
- Trench protection: slope, bench, or shore according to soil and the standard; provide a ladder within 25 ft (7.6 m) of travel; keep equipment away from the edge.
- Keep spoil and materials at least 2 ft (0.6 m) from the edge; do not undercut walls.
- Watch water, tension cracks, subsidence, and spoil loading; stop if the trench changes.
- Bucket technique: curl rather than crowd; maintain grade; avoid digging with teeth sideways.
- Material handling: know the load weight and radius; use rated lifting points and tag lines; never lift people.
- Backfill in lifts and compact as specified.
Worked example
A trench is 1.2 m wide, 2.5 m deep, and 20 m long. Reasoning: in-place volume = 1.2 × 2.5 × 20 = 60 m³. With 20% swell, spoil = 60 × 1.20 = 72 m³. That volume cannot be piled at the edge; plan trucks or a spoil zone outside the 2 ft setback before digging.
Traps
- Undercutting the trench wall.
- Placing spoil at the edge.
- Using bucket teeth as a lifting hook.
- Digging below a marked utility without hand excavation.