Trenching & Excavation Safety
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& Verified Answers, Plus Explained
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1. What is the maximum allowable slope for a Type C soil in a trench
less than 20 feet deep?
A) 1:1
B) 1:1.5
C) 1:0.75
D) 1:2
A) 1:1
Type C soil is the least stable; OSHA requires a 1:1 slope for
trenches under 20 feet deep to prevent cave-ins.
2. Which soil type is considered the most stable in trenching
operations?
A) Type A
B) Type B
C) Type C
D) Sand
A) Type A
Type A soils are cohesive and stable, like clay, making them the
safest for vertical trench walls.
,3. What is the primary cause of trenching and excavation fatalities?
A) Equipment accidents
B) Cave-ins
C) Falls
D) Hazardous atmospheres
B) Cave-ins
Cave-ins account for the majority of trenching fatalities due to
sudden collapse of trench walls.
4. What is the minimum protective measure required for a trench 6
feet deep?
A) No protection needed
B) Sloping, shoring, or shielding
C) Only shoring
D) Only shielding
B) Sloping, shoring, or shielding
OSHA requires protective systems for trenches 5 feet or deeper
unless the excavation is in stable rock.
5. How often must an excavation be inspected by a competent
person?
A) Once per week
B) Daily
C) Before each shift and after any hazard-increasing event
D) Only when employees complain
C) Before each shift and after any hazard-increasing event
Trenches must be inspected by a competent person daily and
after rain, vibrations, or other events that may affect stability.
6. What is the role of a competent person in trench safety?
A) Operate equipment
B) Inspect trenches and determine soil type
, C) Only provide PPE
D) Train employees once a year
B) Inspect trenches and determine soil type
A competent person can identify hazards, soil classification, and
protective systems.
7. What is the maximum allowable depth for a trench without
protective systems?
A) 4 feet
B) 5 feet
C) 6 feet
D) 10 feet
B) 5 feet
Trenches less than 5 feet may be unprotected if the soil is stable;
deeper trenches require protection.
8. Which of the following is NOT a protective system?
A) Sloping
B) Shoring
C) Shielding
D) Barricading
D) Barricading
Barricading prevents access but does not prevent trench
collapse, so it is not a protective system.
9. What type of hazard does water accumulation in a trench create?
A) Electrocution
B) Cave-in and drowning risk
C) Fire hazard
D) Noise hazard
B) Cave-in and drowning risk
Specialist Exam With Actual Questions
& Verified Answers, Plus Explained
Rationales/Expert Verified For
Guaranteed 100% Pass 2026/Latest
Update/Instant Download Pdf
1. What is the maximum allowable slope for a Type C soil in a trench
less than 20 feet deep?
A) 1:1
B) 1:1.5
C) 1:0.75
D) 1:2
A) 1:1
Type C soil is the least stable; OSHA requires a 1:1 slope for
trenches under 20 feet deep to prevent cave-ins.
2. Which soil type is considered the most stable in trenching
operations?
A) Type A
B) Type B
C) Type C
D) Sand
A) Type A
Type A soils are cohesive and stable, like clay, making them the
safest for vertical trench walls.
,3. What is the primary cause of trenching and excavation fatalities?
A) Equipment accidents
B) Cave-ins
C) Falls
D) Hazardous atmospheres
B) Cave-ins
Cave-ins account for the majority of trenching fatalities due to
sudden collapse of trench walls.
4. What is the minimum protective measure required for a trench 6
feet deep?
A) No protection needed
B) Sloping, shoring, or shielding
C) Only shoring
D) Only shielding
B) Sloping, shoring, or shielding
OSHA requires protective systems for trenches 5 feet or deeper
unless the excavation is in stable rock.
5. How often must an excavation be inspected by a competent
person?
A) Once per week
B) Daily
C) Before each shift and after any hazard-increasing event
D) Only when employees complain
C) Before each shift and after any hazard-increasing event
Trenches must be inspected by a competent person daily and
after rain, vibrations, or other events that may affect stability.
6. What is the role of a competent person in trench safety?
A) Operate equipment
B) Inspect trenches and determine soil type
, C) Only provide PPE
D) Train employees once a year
B) Inspect trenches and determine soil type
A competent person can identify hazards, soil classification, and
protective systems.
7. What is the maximum allowable depth for a trench without
protective systems?
A) 4 feet
B) 5 feet
C) 6 feet
D) 10 feet
B) 5 feet
Trenches less than 5 feet may be unprotected if the soil is stable;
deeper trenches require protection.
8. Which of the following is NOT a protective system?
A) Sloping
B) Shoring
C) Shielding
D) Barricading
D) Barricading
Barricading prevents access but does not prevent trench
collapse, so it is not a protective system.
9. What type of hazard does water accumulation in a trench create?
A) Electrocution
B) Cave-in and drowning risk
C) Fire hazard
D) Noise hazard
B) Cave-in and drowning risk
