Excavation and Trenching Safety Flashcards

Under OSHA 29 CFR 1926 Subpart P, who is qualified to classify soil at an excavation site?

Answer: A competent person with soil classification training

OSHA requires a competent person — one who can identify hazards and has authority to correct them — to classify soil using visual and manual tests.

Which soil test involves rolling a moist soil sample into a thread and observing if it crumbles?

Answer: Thread test

The thread test (dry strength test) checks cohesion by rolling soil into a 1/8-inch thread; if it holds, the soil has higher cohesion.

A trench 6 feet deep is being excavated in Type B soil. What is the maximum allowable slope ratio?

Answer: 1H:1V

Type B soil requires a 1H:1V (45°) slope per OSHA 29 CFR 1926 Appendix B.

What is the minimum distance spoil piles must be kept from the edge of an excavation?

Answer: 2 feet

OSHA 1926.651(j)(2) requires spoil piles and equipment to be kept at least 2 feet from excavation edges to prevent cave-in from surcharge loads.

When is a stairway, ladder, or ramp required in an excavation?

Answer: When workers must enter an excavation 4 feet or more in depth

OSHA 1926.651(c)(2) requires a means of egress (ladder, stairway, or ramp) for any excavation 4 feet or deeper.

Which condition would cause an excavation previously classified as Type A soil to be reclassified?

Answer: Previously disturbed soil is discovered beneath the surface

Previously disturbed soil cannot be classified as Type A; its prior disturbance reduces cohesion and stability.

A rescue retrieval system for permit-required confined spaces adjacent to a trench must be capable of retrieving workers without requiring rescuers to:

Answer: Enter the confined space

OSHA 1910.146(k)(3) requires non-entry rescue systems so rescuers can retrieve workers without entering the hazardous space themselves.