CHST CHST - Construction Health and Safety Technician Excavation and Trenching Safety Questions and Answers 2

Question 1

At what depth must a registered professional engineer design a protective system for a trench according to OSHA standards?

Accepted Answer

20 feet

Answer

OSHA requires a protective system designed by a registered professional engineer for trenches 20 feet or deeper.

Question 2

Which soil type is considered the LEAST stable for excavation purposes under the OSHA soil classification system?

Accepted Answer

Type C

Answer

Type C soil is the least stable of the three soil classifications and includes granular soils such as gravel, sand, and loamy sand.

Question 3

How far from the edge of an excavation must spoil piles be kept according to OSHA regulations?

Accepted Answer

At least 2 feet

Answer

OSHA requires that spoil piles be kept at least 2 feet from the edge of an excavation to prevent materials from falling back into the trench.

Question 4

What is the maximum allowable slope ratio for Type B soil in an excavation less than 20 feet deep?

Accepted Answer

1-1/2H:1V

Answer

Type B soil requires a maximum allowable slope of 1-1/2 horizontal to 1 vertical (53 degrees) for excavations under 20 feet.

Question 5

Which of the following conditions would require reclassifying Type A soil to a lower classification?

Accepted Answer

The soil is subject to vibration from heavy traffic

Answer

Vibration from heavy traffic or other sources can destabilize Type A soil, requiring it to be reclassified to Type B or Type C.

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