An excavation is 7 feet deep in Type A soil with evidence of previous excavation. What protective system is required under Cal/OSHA?
Correct Answer
A) Protective system required due to previous excavation
Cal/OSHA Section 1541.1 requires protective systems when excavations show evidence of previous excavation, regardless of soil type, as this creates unstable conditions even in otherwise stable Type A soil.
Why This Is the Correct Answer
Under Cal/OSHA Section 1541.1, evidence of previous excavation in the same area compromises soil integrity and downclassifies the soil from Type A. Even though Type A soil normally allows sloping or may not require protection at certain depths, prior disturbance creates fissures and weakened zones that mandate a protective system regardless of apparent soil classification.
Why the Other Options Are Wrong
Option B: Daily inspection only
Daily inspection alone is insufficient when evidence of previous excavation exists. Inspection identifies hazards but does not protect workers from cave-in. A physical protective system (shoring, sloping, or trench box) is required.
Option C: No protection required in Type A soil
Type A soil does not automatically exempt workers from protection. The critical factor here is the evidence of previous excavation, which triggers protection requirements. This exception overrides the general Type A rules.
Option D: Sloping at 3/4:1 maximum
Sloping at 3/4:1 is the maximum allowed slope for Type A soil under normal conditions. However, when previous excavation is evident, the soil can no longer be classified as Type A — it must be reclassified as Type C (the most conservative), requiring 1.5:1 sloping or a trench protective system.
Memory Technique
Type A + Prior Dig = No Longer Type A. Think: 'Previously excavated = previously compromised.' The ground has been disturbed, so trust it less and protect more.
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A construction crew is working outdoors in Fresno when the temperature reaches 97°F. Under Cal/OSHA heat illness prevention requirements, what is the minimum frequency for providing preventive cool-down rest periods?
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