CSLB General Building (B)Site Work, Foundations and ConcreteMedium
A crew is preparing to enter a 6-foot-deep trench to install a sewer lateral in Type C soil. According to Cal/OSHA excavation safety requirements, what must be provided before workers enter the trench?
- AContinuous ventilation fans at the trench opening
- BA ladder placed every 50 feet regardless of depth
- CA protective system such as shoring, shielding, or sloping
- DA spotter standing at the surface at all times
Show answer & explanationAnswer & explanation
Correct answer: C. A protective system such as shoring, shielding, or sloping
Cal/OSHA requires a protective system (shoring, trench box/shielding, or benching/sloping) for excavations 5 feet or deeper unless the excavation is made entirely in stable rock. A 6-foot trench in Type C soil clearly requires such protection.
Why the other options are wrong
- A. Ventilation is required for confined space or atmospheric hazards, not standard cave-in protection.
- B. Ladder spacing rules apply to means of egress but do not substitute for cave-in protection.
- D. A spotter may be used for equipment operations but does not satisfy protective system requirements.
Trench Shoring Requirement
Cal/OSHA mandates a protective system for trenches 5 feet or deeper unless the excavation is entirely in stable rock.
- 5-foot trigger depth for protective systems
- Options include shoring, shielding (trench boxes), or sloping/benching
- Type C soil is the least stable, requiring more conservative slopes
Memory trick: 5 feet down, protection's the crown.