1. What is the minimum cover depth required for water mains in North
Carolina?
A. 18 inches
B. 24 inches
C. 30 inches
D. 36 inches
Answer: D. 36 inches
Explanation: NC standards require at least 36 inches of cover for water mains to
prevent freezing and damage.
2. Which pipe material is most commonly used for modern water
distribution systems?
A. Cast iron
B. Ductile iron
C. PVC
D. Asbestos-cement
Answer: C. PVC
Explanation: PVC is widely used due to cost-effectiveness, corrosion resistance,
and ease of installation.
3. When laying sewer mains, what is the standard minimum slope for 8-
inch diameter pipe?
A. 0.2%
B. 0.3%
C. 0.4%
D. 0.5%
Answer: B. 0.3%
Explanation: According to design standards, 8-inch sewers require a minimum
slope of 0.003 ft/ft (0.3%).
4. What is the primary purpose of a thrust block in a water line system?
A. Control water pressure
B. Anchor fittings against hydraulic forces
C. Prevent backflow
D. Reduce pipe vibration
Answer: B. Anchor fittings against hydraulic forces
,5. Which type of valve is commonly used for isolating sections of a water
distribution main?
A. Butterfly valve
B. Gate valve
C. Check valve
D. Ball valve
Answer: B. Gate valve
6. What test pressure is typically applied to water mains during hydrostatic
testing in NC?
A. 50 psi
B. 100 psi
C. 150 psi
D. 200 psi
Answer: C. 150 psi
7. In trench safety, what is the maximum depth at which a trench must be
shored or sloped if no protective system is used?
A. 3 feet
B. 4 feet
C. 5 feet
D. 6 feet
Answer: C. 5 feet
Explanation: OSHA standards require protective systems at trenches deeper
than 5 feet.
8. What is the main function of an air release valve in water transmission
lines?
A. Prevent backflow
B. Remove trapped air
C. Increase pressure
D. Reduce noise
Answer: B. Remove trapped air
9. Which agency regulates water line construction standards in North
Carolina?
A. OSHA
B. NCDEQ (Department of Environmental Quality)
C. DOT
D. NFPA
Answer: B. NCDEQ
10. What is the standard minimum horizontal separation between water
and sewer lines in NC?
,A. 5 feet
B. 7.5 feet
C. 10 feet
D. 15 feet
Answer: C. 10 feet
Explanation: NC code requires 10 feet separation unless special construction
methods are used.
11. Which pipe joint is most resistant to leakage under pressure?
A. Bell-and-spigot
B. Mechanical joint
C. Push-on joint
D. Welded joint
Answer: D. Welded joint
12. What is the purpose of a manhole in a sewer system?
A. Maintain water pressure
B. Provide access for inspection and maintenance
C. Increase velocity
D. Reduce odors
Answer: B. Provide access for inspection and maintenance
13. A “blowoff” assembly is installed at the low points of water mains to:
A. Relieve pressure
B. Drain water from the main
C. Release air
D. Stop flow
Answer: B. Drain water from the main
14. Which test is performed to ensure sewer lines are watertight?
A. Hydrostatic test
B. Air pressure test
C. Vacuum test
D. Dye test
Answer: B. Air pressure test
15. What is the maximum spacing between fire hydrants in urban areas of
NC?
A. 300 feet
B. 400 feet
C. 500 feet
, D. 600 feet
Answer: C. 500 feet
16. In a water distribution system, what does C-factor represent?
A. Corrosion resistance
B. Flow capacity of a pipe
C. Pressure rating
D. Chemical durability
Answer: B. Flow capacity of a pipe
17. The bedding material for PVC pipe should be:
A. Clay
B. Sand or crushed stone
C. Topsoil
D. Asphalt millings
Answer: B. Sand or crushed stone
18. What type of pipe is most commonly used for gravity sewer lines?
A. Ductile iron
B. PVC
C. Steel
D. Copper
Answer: B. PVC
19. What is the typical pressure range for municipal water distribution
systems?
A. 10–30 psi
B. 20–40 psi
C. 40–80 psi
D. 100–150 psi
Answer: C. 40–80 psi
20. The term “invert elevation” in sewer construction refers to:
A. Top of the pipe
B. Inside bottom of the pipe
C. Ground surface above pipe
D. Depth of manhole
Answer: B. Inside bottom of the pipe
Carolina?
A. 18 inches
B. 24 inches
C. 30 inches
D. 36 inches
Answer: D. 36 inches
Explanation: NC standards require at least 36 inches of cover for water mains to
prevent freezing and damage.
2. Which pipe material is most commonly used for modern water
distribution systems?
A. Cast iron
B. Ductile iron
C. PVC
D. Asbestos-cement
Answer: C. PVC
Explanation: PVC is widely used due to cost-effectiveness, corrosion resistance,
and ease of installation.
3. When laying sewer mains, what is the standard minimum slope for 8-
inch diameter pipe?
A. 0.2%
B. 0.3%
C. 0.4%
D. 0.5%
Answer: B. 0.3%
Explanation: According to design standards, 8-inch sewers require a minimum
slope of 0.003 ft/ft (0.3%).
4. What is the primary purpose of a thrust block in a water line system?
A. Control water pressure
B. Anchor fittings against hydraulic forces
C. Prevent backflow
D. Reduce pipe vibration
Answer: B. Anchor fittings against hydraulic forces
,5. Which type of valve is commonly used for isolating sections of a water
distribution main?
A. Butterfly valve
B. Gate valve
C. Check valve
D. Ball valve
Answer: B. Gate valve
6. What test pressure is typically applied to water mains during hydrostatic
testing in NC?
A. 50 psi
B. 100 psi
C. 150 psi
D. 200 psi
Answer: C. 150 psi
7. In trench safety, what is the maximum depth at which a trench must be
shored or sloped if no protective system is used?
A. 3 feet
B. 4 feet
C. 5 feet
D. 6 feet
Answer: C. 5 feet
Explanation: OSHA standards require protective systems at trenches deeper
than 5 feet.
8. What is the main function of an air release valve in water transmission
lines?
A. Prevent backflow
B. Remove trapped air
C. Increase pressure
D. Reduce noise
Answer: B. Remove trapped air
9. Which agency regulates water line construction standards in North
Carolina?
A. OSHA
B. NCDEQ (Department of Environmental Quality)
C. DOT
D. NFPA
Answer: B. NCDEQ
10. What is the standard minimum horizontal separation between water
and sewer lines in NC?
,A. 5 feet
B. 7.5 feet
C. 10 feet
D. 15 feet
Answer: C. 10 feet
Explanation: NC code requires 10 feet separation unless special construction
methods are used.
11. Which pipe joint is most resistant to leakage under pressure?
A. Bell-and-spigot
B. Mechanical joint
C. Push-on joint
D. Welded joint
Answer: D. Welded joint
12. What is the purpose of a manhole in a sewer system?
A. Maintain water pressure
B. Provide access for inspection and maintenance
C. Increase velocity
D. Reduce odors
Answer: B. Provide access for inspection and maintenance
13. A “blowoff” assembly is installed at the low points of water mains to:
A. Relieve pressure
B. Drain water from the main
C. Release air
D. Stop flow
Answer: B. Drain water from the main
14. Which test is performed to ensure sewer lines are watertight?
A. Hydrostatic test
B. Air pressure test
C. Vacuum test
D. Dye test
Answer: B. Air pressure test
15. What is the maximum spacing between fire hydrants in urban areas of
NC?
A. 300 feet
B. 400 feet
C. 500 feet
, D. 600 feet
Answer: C. 500 feet
16. In a water distribution system, what does C-factor represent?
A. Corrosion resistance
B. Flow capacity of a pipe
C. Pressure rating
D. Chemical durability
Answer: B. Flow capacity of a pipe
17. The bedding material for PVC pipe should be:
A. Clay
B. Sand or crushed stone
C. Topsoil
D. Asphalt millings
Answer: B. Sand or crushed stone
18. What type of pipe is most commonly used for gravity sewer lines?
A. Ductile iron
B. PVC
C. Steel
D. Copper
Answer: B. PVC
19. What is the typical pressure range for municipal water distribution
systems?
A. 10–30 psi
B. 20–40 psi
C. 40–80 psi
D. 100–150 psi
Answer: C. 40–80 psi
20. The term “invert elevation” in sewer construction refers to:
A. Top of the pipe
B. Inside bottom of the pipe
C. Ground surface above pipe
D. Depth of manhole
Answer: B. Inside bottom of the pipe
