CHST CHST - Construction Health and Safety Technician Excavation and Trenching Safety Questions and Answers 2 — Questions and Answers
Question 1: At what depth must a registered professional engineer design a protective system for a trench according to OSHA standards?
- 15 feet
- 20 feet (Correct answer)
- 25 feet
- 10 feet
Correct answer: 20 feet
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?
- Type A
- Type B
- Type C (Correct answer)
- Stable rock
Correct answer: Type C
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?
- At least 1 foot
- At least 2 feet (Correct answer)
- At least 3 feet
- At least 4 feet
Correct answer: At least 2 feet
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?
- 3/4H:1V
- 1H:1V
- 1-1/2H:1V (Correct answer)
- 2H:1V
Correct answer: 1-1/2H:1V
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?
- Soil is completely dry
- The excavation is less than 10 feet deep
- The soil is subject to vibration from heavy traffic (Correct answer)
- Soil has been undisturbed for over a year
Correct answer: The soil is subject to vibration from heavy traffic
Vibration from heavy traffic or other sources can destabilize Type A soil, requiring it to be reclassified to Type B or Type C.
Question 6: When using a trench box or shield, how far above the surrounding grade must the top of the shield extend?
- The shield does not need to extend above grade
- At least 6 inches
- At least 12 inches
- At least 18 inches (Correct answer)
Correct answer: At least 18 inches
Trench shields must extend at least 18 inches above the surrounding grade to provide adequate protection from surface hazards and falling materials.
CHST CHST - Construction Health and Safety Technician Excavation and Trenching Safety Questions and Answers 2
At what depth must a registered professional engineer design a protective system for a trench according to OSHA standards?