NEW MEXICO GF-9 UTILITY LINES EXAM
120-Question Practice Exam with Answers & Rationales
1. Under OSHA excavation standards, a trench is generally defined as a narrow
excavation where the depth is greater than the width, and the width does not
exceed:
A. 5 feet
B. 15 feet
C. 25 feet
D. 50 feet
Correct Answer: B
Rationale: OSHA defines a trench as an excavation that is deeper than it is wide, with a
width at the bottom not exceeding 15 feet, distinguishing it from a general excavation.
2. At what depth does OSHA generally require a protective system (shoring,
shielding, or sloping) for a trench?
A. 2 feet or more
B. 5 feet or more
C. 10 feet or more
D. 20 feet or more
Correct Answer: B
Rationale: OSHA requires a protective system for trenches 5 feet or deeper, unless the
excavation is entirely in stable rock; a competent person may also require protection at
shallower depths if hazards are present.
,3. Who is responsible for classifying soil type before selecting a trench protective
system?
A. Any laborer on site
B. A competent person
C. The equipment rental company
D. The property owner
Correct Answer: B
Rationale: OSHA requires that a competent person, who has training to identify hazards
and the authority to correct them, classify the soil (Type A, B, or C) to determine the
appropriate protective system.
4. Which soil type under OSHA classification is generally the most stable,
allowing the steepest safe slope?
A. Type C
B. Type B
C. Type A
D. Type D (there is no Type D)
Correct Answer: C
Rationale: Type A soil is the most cohesive and stable of the three OSHA soil
classifications, allowing a steeper maximum slope than Type B or Type C soils.
5. Spoil piles (excavated soil) should be placed at least how far from the edge of a
trench?
A. 1 foot
B. 2 feet
C. 6 inches
D. There is no required distance
Correct Answer: B
Rationale: OSHA requires spoil, materials, and equipment to be kept at least 2 feet back
from the edge of a trench to prevent them from falling or rolling into the excavation and
to reduce surcharge loading on the trench wall.
,6. What is the primary purpose of a trench box (shield)?
A. To protect workers by preventing trench walls from collapsing onto them
B. To measure trench depth
C. To pump groundwater out of the trench
D. To compact the backfill
Correct Answer: A
Rationale: A trench box, or shield, is a protective structure designed to withstand the
force of a cave-in and protect workers inside it; it protects workers rather than preventing
the collapse itself, which distinguishes it from shoring.
7. How often must a competent person inspect a trench for hazardous
conditions?
A. Only at the start of the project
B. Daily before work begins, and as needed throughout the shift, especially after a
rainstorm or other hazard-increasing event
C. Once per week
D. Only if a worker requests it
Correct Answer: B
Rationale: OSHA requires daily inspections by a competent person before work begins
and additional inspections after any event that could increase hazards, such as rainfall,
vibration, or changes in the excavation.
8. What is required for safe access and egress from a trench that is 4 feet or
deeper?
A. No access requirement exists
B. A stairway, ladder, ramp, or other safe means of exit located within 25 feet of
workers
C. A rope only
D. Workers must climb the trench walls
Correct Answer: B
Rationale: OSHA requires a safe means of egress, such as a ladder, stairway, or ramp,
within 25 feet of lateral travel for any trench 4 feet or deeper to allow workers to exit
quickly in an emergency.
, 9. Atmospheric testing is required in a trench or excavation when:
A. It is never required for utility trenches
B. There is a reasonable possibility of an oxygen deficiency or hazardous
atmosphere, such as near landfills or gas lines
C. Only when the trench exceeds 50 feet in length
D. Only during winter months
Correct Answer: B
Rationale: Atmospheric testing for oxygen levels and hazardous gases is required when
conditions suggest a hazardous atmosphere may exist, such as excavations near
landfills, buried gas lines, or areas with poor air circulation.
10. What is the maximum allowable slope for Type C soil under OSHA's simple
slope option?
A. 3/4:1 (53 degrees)
B. 1:1 (45 degrees)
C. 1.5:1 (34 degrees)
D. Vertical (90 degrees)
Correct Answer: C
Rationale: Under OSHA's simple slope method, Type C soil, the least stable
classification, requires the flattest maximum slope of 1.5 horizontal to 1 vertical
(approximately 34 degrees) to prevent collapse.
11. Before beginning excavation work, a contractor is required to contact the
one-call/utility notification center to:
A. Request a work permit only
B. Have existing underground utilities located and marked to prevent damage or
injury
C. Schedule an inspection with the state licensing board
D. Obtain a weather forecast
Correct Answer: B
Rationale: Calling the state one-call center (811) before digging allows utility companies
to mark the approximate location of buried gas, electric, water, and communication
lines, reducing the risk of strikes that can cause injury, service outages, or fines.
120-Question Practice Exam with Answers & Rationales
1. Under OSHA excavation standards, a trench is generally defined as a narrow
excavation where the depth is greater than the width, and the width does not
exceed:
A. 5 feet
B. 15 feet
C. 25 feet
D. 50 feet
Correct Answer: B
Rationale: OSHA defines a trench as an excavation that is deeper than it is wide, with a
width at the bottom not exceeding 15 feet, distinguishing it from a general excavation.
2. At what depth does OSHA generally require a protective system (shoring,
shielding, or sloping) for a trench?
A. 2 feet or more
B. 5 feet or more
C. 10 feet or more
D. 20 feet or more
Correct Answer: B
Rationale: OSHA requires a protective system for trenches 5 feet or deeper, unless the
excavation is entirely in stable rock; a competent person may also require protection at
shallower depths if hazards are present.
,3. Who is responsible for classifying soil type before selecting a trench protective
system?
A. Any laborer on site
B. A competent person
C. The equipment rental company
D. The property owner
Correct Answer: B
Rationale: OSHA requires that a competent person, who has training to identify hazards
and the authority to correct them, classify the soil (Type A, B, or C) to determine the
appropriate protective system.
4. Which soil type under OSHA classification is generally the most stable,
allowing the steepest safe slope?
A. Type C
B. Type B
C. Type A
D. Type D (there is no Type D)
Correct Answer: C
Rationale: Type A soil is the most cohesive and stable of the three OSHA soil
classifications, allowing a steeper maximum slope than Type B or Type C soils.
5. Spoil piles (excavated soil) should be placed at least how far from the edge of a
trench?
A. 1 foot
B. 2 feet
C. 6 inches
D. There is no required distance
Correct Answer: B
Rationale: OSHA requires spoil, materials, and equipment to be kept at least 2 feet back
from the edge of a trench to prevent them from falling or rolling into the excavation and
to reduce surcharge loading on the trench wall.
,6. What is the primary purpose of a trench box (shield)?
A. To protect workers by preventing trench walls from collapsing onto them
B. To measure trench depth
C. To pump groundwater out of the trench
D. To compact the backfill
Correct Answer: A
Rationale: A trench box, or shield, is a protective structure designed to withstand the
force of a cave-in and protect workers inside it; it protects workers rather than preventing
the collapse itself, which distinguishes it from shoring.
7. How often must a competent person inspect a trench for hazardous
conditions?
A. Only at the start of the project
B. Daily before work begins, and as needed throughout the shift, especially after a
rainstorm or other hazard-increasing event
C. Once per week
D. Only if a worker requests it
Correct Answer: B
Rationale: OSHA requires daily inspections by a competent person before work begins
and additional inspections after any event that could increase hazards, such as rainfall,
vibration, or changes in the excavation.
8. What is required for safe access and egress from a trench that is 4 feet or
deeper?
A. No access requirement exists
B. A stairway, ladder, ramp, or other safe means of exit located within 25 feet of
workers
C. A rope only
D. Workers must climb the trench walls
Correct Answer: B
Rationale: OSHA requires a safe means of egress, such as a ladder, stairway, or ramp,
within 25 feet of lateral travel for any trench 4 feet or deeper to allow workers to exit
quickly in an emergency.
, 9. Atmospheric testing is required in a trench or excavation when:
A. It is never required for utility trenches
B. There is a reasonable possibility of an oxygen deficiency or hazardous
atmosphere, such as near landfills or gas lines
C. Only when the trench exceeds 50 feet in length
D. Only during winter months
Correct Answer: B
Rationale: Atmospheric testing for oxygen levels and hazardous gases is required when
conditions suggest a hazardous atmosphere may exist, such as excavations near
landfills, buried gas lines, or areas with poor air circulation.
10. What is the maximum allowable slope for Type C soil under OSHA's simple
slope option?
A. 3/4:1 (53 degrees)
B. 1:1 (45 degrees)
C. 1.5:1 (34 degrees)
D. Vertical (90 degrees)
Correct Answer: C
Rationale: Under OSHA's simple slope method, Type C soil, the least stable
classification, requires the flattest maximum slope of 1.5 horizontal to 1 vertical
(approximately 34 degrees) to prevent collapse.
11. Before beginning excavation work, a contractor is required to contact the
one-call/utility notification center to:
A. Request a work permit only
B. Have existing underground utilities located and marked to prevent damage or
injury
C. Schedule an inspection with the state licensing board
D. Obtain a weather forecast
Correct Answer: B
Rationale: Calling the state one-call center (811) before digging allows utility companies
to mark the approximate location of buried gas, electric, water, and communication
lines, reducing the risk of strikes that can cause injury, service outages, or fines.
