CSLB Law & Business ExamSafetyMedium
A crew is working in a 12-foot trench for a utility installation. Cal/OSHA requires testing for hazardous atmospheres in trenches deeper than what threshold, where such atmospheres may reasonably be expected?
- A3 feet
- B4 feet
- C6 feet
- D10 feet
Show answer & explanationAnswer & explanation
Correct answer: B. 4 feet
Cal/OSHA excavation regulations require testing for oxygen deficiency and hazardous atmospheres in excavations deeper than 4 feet where such conditions could exist, such as near landfills, gas lines, or sewers.
Why the other options are wrong
- A. 3 feet is below the regulatory threshold.
- C. 6 feet is the threshold for protective systems, not atmospheric testing.
- D. 10 feet is unrelated to this specific requirement.
Atmospheric Testing Threshold
Excavations deeper than 4 feet where a hazardous atmosphere may exist require testing for oxygen content and toxic or flammable gases before entry.
- Applies near sewers, landfills, or gas lines
- Testing must continue as conditions change
- Ventilation or respiratory protection required if hazards are detected
Memory trick: Four feet down, test the air around