Underground Utility Contractor License
Exam Questions And Correct Answers
With Rationales
1. What is the primary purpose of shoring in a trench?
a) To speed up excavation
b) To provide drainage
c) To prevent soil collapse
d) To hold utility lines in place
Shoring prevents trench wall collapse, protecting workers from cave-
ins.
2. Which OSHA regulation governs trenching and excavation safety?
a) 1926.350
b) 1926 Subpart P
, c) 1910.134
d) 1926 Subpart N
OSHA 1926 Subpart P specifically addresses trenching and excavation
standards.
3. The minimum distance a spoil pile must be kept from the edge of a
trench is:
a) 1 foot
b) 3 feet
c) 2 feet
d) 5 feet
Spoil piles must be kept at least 2 feet away to reduce the risk of
material falling back into the trench.
4. What is the typical minimum cover depth for a potable water main?
a) 12 inches
b) 18 inches
c) 24 inches
d) 36 inches
Water mains are usually buried a minimum of 36 inches deep to
protect against freezing and surface loads.
5. Which of the following pipe materials is most resistant to corrosion?
a) Ductile iron
b) Steel
c) Concrete
, d) PVC
PVC (polyvinyl chloride) is naturally corrosion resistant, making it
ideal for underground utilities.
6. When dewatering a trench, what method is commonly used to lower
the groundwater table?
a) Sump pumping
b) Water jetting
c) Well points
d) Hydrovac
Well points create a temporary groundwater control system around
the excavation.
7. What is the maximum allowable trench depth without protective
systems if the soil is stable?
a) 3 feet
b) 4 feet
c) 5 feet
d) 6 feet
OSHA requires protective systems for trenches deeper than 5 feet
unless excavations are in stable rock.
8. The primary function of a thrust block is to:
a) Support trench walls
b) Prevent groundwater intrusion
c) Increase pipe flexibility
, d) Resist pipe movement due to pressure surges
Thrust blocks counteract the force of pressurized water at bends and
fittings.
9. Before beginning excavation near existing utilities, a contractor must
first:
a) Contact OSHA
b) Obtain a permit
c) Call the local utility locating service (e.g., 811)
d) Notify the fire department
Calling 811 ensures underground utilities are marked to prevent
accidental damage.
10. The bedding material beneath a pipe is typically composed of:
a) Topsoil
b) Clay
c) Sand or gravel
d) Peat
Sand or gravel provides a stable base and proper support for pipes.
11. Which backfill material is best for preventing pipe damage?
a) Large stones
b) Construction debris
c) Fine granular soil
d) Organic material
Exam Questions And Correct Answers
With Rationales
1. What is the primary purpose of shoring in a trench?
a) To speed up excavation
b) To provide drainage
c) To prevent soil collapse
d) To hold utility lines in place
Shoring prevents trench wall collapse, protecting workers from cave-
ins.
2. Which OSHA regulation governs trenching and excavation safety?
a) 1926.350
b) 1926 Subpart P
, c) 1910.134
d) 1926 Subpart N
OSHA 1926 Subpart P specifically addresses trenching and excavation
standards.
3. The minimum distance a spoil pile must be kept from the edge of a
trench is:
a) 1 foot
b) 3 feet
c) 2 feet
d) 5 feet
Spoil piles must be kept at least 2 feet away to reduce the risk of
material falling back into the trench.
4. What is the typical minimum cover depth for a potable water main?
a) 12 inches
b) 18 inches
c) 24 inches
d) 36 inches
Water mains are usually buried a minimum of 36 inches deep to
protect against freezing and surface loads.
5. Which of the following pipe materials is most resistant to corrosion?
a) Ductile iron
b) Steel
c) Concrete
, d) PVC
PVC (polyvinyl chloride) is naturally corrosion resistant, making it
ideal for underground utilities.
6. When dewatering a trench, what method is commonly used to lower
the groundwater table?
a) Sump pumping
b) Water jetting
c) Well points
d) Hydrovac
Well points create a temporary groundwater control system around
the excavation.
7. What is the maximum allowable trench depth without protective
systems if the soil is stable?
a) 3 feet
b) 4 feet
c) 5 feet
d) 6 feet
OSHA requires protective systems for trenches deeper than 5 feet
unless excavations are in stable rock.
8. The primary function of a thrust block is to:
a) Support trench walls
b) Prevent groundwater intrusion
c) Increase pipe flexibility
, d) Resist pipe movement due to pressure surges
Thrust blocks counteract the force of pressurized water at bends and
fittings.
9. Before beginning excavation near existing utilities, a contractor must
first:
a) Contact OSHA
b) Obtain a permit
c) Call the local utility locating service (e.g., 811)
d) Notify the fire department
Calling 811 ensures underground utilities are marked to prevent
accidental damage.
10. The bedding material beneath a pipe is typically composed of:
a) Topsoil
b) Clay
c) Sand or gravel
d) Peat
Sand or gravel provides a stable base and proper support for pipes.
11. Which backfill material is best for preventing pipe damage?
a) Large stones
b) Construction debris
c) Fine granular soil
d) Organic material
