CHST Excavation and Trenching Safety 4

Question 1

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

Accepted Answer

A competent person with soil classification training

Answer

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

Question 2

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

Accepted Answer

Thread test

Answer

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.

Question 3

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

Accepted Answer

1H:1V

Answer

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

Question 4

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

Accepted Answer

2 feet

Answer

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.

Question 5

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

Accepted Answer

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

Answer

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

CHST - Construction Health and Safety Technician Practice Test