AZ A-12 Sewers, Drains & Pipe
Laying Contractor Exam Questions
And Correct Answers (Verified
Answers) Plus Rationale2026 Q&A|
Instant Download Pdf
1. Which of the following is the primary purpose of a sewer system?
A. Supply drinking water
B. Collect and convey wastewater
C. Provide irrigation
D. Generate hydroelectric power
Rationale: The main purpose of a sewer system is to collect
wastewater from homes and businesses and convey it to treatment
facilities.
2. What is the minimum slope recommended for a 4-inch diameter sewer
pipe to ensure proper flow?
A. 1/16 inch per foot
B. 1/32 inch per foot
C. 1/4 inch per foot
D. 1/2 inch per foot
Rationale: A 1/4 inch per foot slope is standard for 4-inch sewer pipes
to maintain self-cleansing velocity.
3. Which pipe material is most commonly used for residential sewer
lateral lines?
A. Cast iron
B. Steel
C. PVC
D. Concrete
, Rationale: PVC is preferred due to its durability, corrosion
resistance, and ease of installation.
4. What is the primary function of a manhole in a sewer system?
A. Treat wastewater
B. Provide access for inspection and maintenance
C. Increase water pressure
D. Prevent pipe corrosion
Rationale: Manholes allow workers to inspect, clean, and maintain
sewer lines safely.
5. When connecting a sewer pipe to a building’s plumbing, the pipe
should have:
A. A vertical alignment
B. A continuous downward slope
C. A horizontal alignment
D. A slope of at least 1 inch per foot
Rationale: Sewer pipes must have a continuous downward slope to
allow gravity flow.
6. What is the standard depth range for residential sewer laterals?
A. 6–12 inches
B. 1–2 feet
C. 18–36 inches
D. 4–5 feet
Rationale: Residential sewer lines are typically buried 18–36 inches
to prevent freezing and ensure proper flow.
7. Which type of joint is most commonly used for PVC sewer pipes?
A. Threaded
B. Welded
C. Bell-and-spigot with solvent cement
D. Flanged
Rationale: Bell-and-spigot joints with solvent cement provide a
watertight, flexible connection.
8. What is the purpose of a cleanout in a sewer system?
A. Treat wastewater
B. Allow access for clearing blockages
C. Vent gases
D. Connect multiple pipes
, Rationale: Cleanouts give direct access to sewer lines for clearing
obstructions.
9. What is the typical spacing between manholes in a residential sewer
line?
A. 50–100 feet
B. 100–150 feet
C. 300–400 feet
D. 500–600 feet
Rationale: Manholes are generally spaced 300–400 feet apart to
allow access while minimizing cost.
10. For a sewer pipe installation under a road, what must be done
before backfilling?
A. Only compact the soil
B. Paint the pipe
C. Perform a pressure or leak test
D. Install a valve
Rationale: Testing under roads ensures the pipe is properly sealed
and can handle loads before backfilling.
11. What is the most common cause of sewer pipe blockages?
A. Broken pipe
B. Excess slope
C. Grease and debris buildup
D. Heavy rainfall
Rationale: Grease, hair, and other debris often accumulate and cause
clogs.
12. Which method is typically used to install large-diameter sewer
pipes under highways without excavation?
A. Open trench
B. Bore and jack
C. Sliplining
D. Open-cut
Rationale: Bore and jack allows installation of pipes beneath roads
with minimal surface disruption.
13. What is the minimum pipe diameter for a gravity sewer main in a
residential subdivision?
A. 4 inches
B. 8 inches
Laying Contractor Exam Questions
And Correct Answers (Verified
Answers) Plus Rationale2026 Q&A|
Instant Download Pdf
1. Which of the following is the primary purpose of a sewer system?
A. Supply drinking water
B. Collect and convey wastewater
C. Provide irrigation
D. Generate hydroelectric power
Rationale: The main purpose of a sewer system is to collect
wastewater from homes and businesses and convey it to treatment
facilities.
2. What is the minimum slope recommended for a 4-inch diameter sewer
pipe to ensure proper flow?
A. 1/16 inch per foot
B. 1/32 inch per foot
C. 1/4 inch per foot
D. 1/2 inch per foot
Rationale: A 1/4 inch per foot slope is standard for 4-inch sewer pipes
to maintain self-cleansing velocity.
3. Which pipe material is most commonly used for residential sewer
lateral lines?
A. Cast iron
B. Steel
C. PVC
D. Concrete
, Rationale: PVC is preferred due to its durability, corrosion
resistance, and ease of installation.
4. What is the primary function of a manhole in a sewer system?
A. Treat wastewater
B. Provide access for inspection and maintenance
C. Increase water pressure
D. Prevent pipe corrosion
Rationale: Manholes allow workers to inspect, clean, and maintain
sewer lines safely.
5. When connecting a sewer pipe to a building’s plumbing, the pipe
should have:
A. A vertical alignment
B. A continuous downward slope
C. A horizontal alignment
D. A slope of at least 1 inch per foot
Rationale: Sewer pipes must have a continuous downward slope to
allow gravity flow.
6. What is the standard depth range for residential sewer laterals?
A. 6–12 inches
B. 1–2 feet
C. 18–36 inches
D. 4–5 feet
Rationale: Residential sewer lines are typically buried 18–36 inches
to prevent freezing and ensure proper flow.
7. Which type of joint is most commonly used for PVC sewer pipes?
A. Threaded
B. Welded
C. Bell-and-spigot with solvent cement
D. Flanged
Rationale: Bell-and-spigot joints with solvent cement provide a
watertight, flexible connection.
8. What is the purpose of a cleanout in a sewer system?
A. Treat wastewater
B. Allow access for clearing blockages
C. Vent gases
D. Connect multiple pipes
, Rationale: Cleanouts give direct access to sewer lines for clearing
obstructions.
9. What is the typical spacing between manholes in a residential sewer
line?
A. 50–100 feet
B. 100–150 feet
C. 300–400 feet
D. 500–600 feet
Rationale: Manholes are generally spaced 300–400 feet apart to
allow access while minimizing cost.
10. For a sewer pipe installation under a road, what must be done
before backfilling?
A. Only compact the soil
B. Paint the pipe
C. Perform a pressure or leak test
D. Install a valve
Rationale: Testing under roads ensures the pipe is properly sealed
and can handle loads before backfilling.
11. What is the most common cause of sewer pipe blockages?
A. Broken pipe
B. Excess slope
C. Grease and debris buildup
D. Heavy rainfall
Rationale: Grease, hair, and other debris often accumulate and cause
clogs.
12. Which method is typically used to install large-diameter sewer
pipes under highways without excavation?
A. Open trench
B. Bore and jack
C. Sliplining
D. Open-cut
Rationale: Bore and jack allows installation of pipes beneath roads
with minimal surface disruption.
13. What is the minimum pipe diameter for a gravity sewer main in a
residential subdivision?
A. 4 inches
B. 8 inches
