AR CA C-42 Sanitation Systems Contractor
Exam Questions and Correct Answers
(Verified Answers) Plus Rationale 2027
Q&A| Instant Download Pdf
Question 1
What is the primary purpose of a sanitary sewer system?
A. To transport stormwater from streets and parking lots
B. To distribute potable water to buildings
C. To collect and convey wastewater to an appropriate treatment or
disposal facility
D. To increase groundwater levels around buildings
Rationale: A sanitary sewer system collects wastewater from
plumbing fixtures, buildings, and other approved sources and conveys
it to a treatment facility or authorized disposal system. Stormwater
,drainage is generally handled by a separate system to prevent
unnecessary hydraulic loading on sanitary sewers.
Question 2
Which component is commonly installed at changes in direction, grade,
or alignment in a sanitary sewer to provide access for inspection and
maintenance?
A. Backwater valve
B. Manhole
C. Water meter
D. Pressure regulator
Rationale: A manhole provides access to underground sewer piping
for inspection, cleaning, maintenance, and certain repairs. It is
commonly placed at junctions and changes in direction, grade, or pipe
size, subject to applicable design requirements.
Question 3
What is the primary function of a septic tank?
A. To disinfect all wastewater before discharge
B. To increase the pressure of wastewater
C. To remove all dissolved contaminants
,D. To separate solids and provide primary treatment through settling
and anaerobic processes
Rationale: A septic tank allows heavier solids to settle as sludge and
lighter materials to float as scum. Anaerobic microorganisms partially
break down organic matter. The effluent still requires further
treatment, typically through an approved soil absorption system or
another authorized treatment process.
Question 4
Why is proper bedding important when installing underground sewer
pipe?
A. It eliminates the need for pipe testing.
B. It prevents all groundwater infiltration.
C. It provides uniform support and helps prevent excessive
deformation or settlement.
D. It increases the wastewater flow rate regardless of pipe slope.
Rationale: Properly selected and placed bedding supports the pipe
barrel, helps maintain the specified grade, and reduces concentrated
loads. Poor bedding can cause differential settlement, joint
displacement, pipe deformation, and eventual leakage or blockage.
, Question 5
What does the term “invert elevation” refer to in sewer construction?
A. The elevation of the top of a manhole cover
B. The elevation of the surrounding finished pavement
C. The elevation of the inside bottom of a pipe or channel
D. The elevation of the groundwater table
Rationale: The invert is the lowest interior point of a pipe or channel.
Invert elevations are used to establish sewer grades, connect
structures, and verify that wastewater can flow in the intended
direction.
Question 6
What is the primary purpose of maintaining an appropriate slope in a
gravity sewer?
A. To maintain constant water pressure
B. To eliminate the need for access structures
C. To provide adequate flow while limiting conditions that promote
solids deposition or excessive flow velocity
D. To ensure that the sewer remains completely full at all times
Exam Questions and Correct Answers
(Verified Answers) Plus Rationale 2027
Q&A| Instant Download Pdf
Question 1
What is the primary purpose of a sanitary sewer system?
A. To transport stormwater from streets and parking lots
B. To distribute potable water to buildings
C. To collect and convey wastewater to an appropriate treatment or
disposal facility
D. To increase groundwater levels around buildings
Rationale: A sanitary sewer system collects wastewater from
plumbing fixtures, buildings, and other approved sources and conveys
it to a treatment facility or authorized disposal system. Stormwater
,drainage is generally handled by a separate system to prevent
unnecessary hydraulic loading on sanitary sewers.
Question 2
Which component is commonly installed at changes in direction, grade,
or alignment in a sanitary sewer to provide access for inspection and
maintenance?
A. Backwater valve
B. Manhole
C. Water meter
D. Pressure regulator
Rationale: A manhole provides access to underground sewer piping
for inspection, cleaning, maintenance, and certain repairs. It is
commonly placed at junctions and changes in direction, grade, or pipe
size, subject to applicable design requirements.
Question 3
What is the primary function of a septic tank?
A. To disinfect all wastewater before discharge
B. To increase the pressure of wastewater
C. To remove all dissolved contaminants
,D. To separate solids and provide primary treatment through settling
and anaerobic processes
Rationale: A septic tank allows heavier solids to settle as sludge and
lighter materials to float as scum. Anaerobic microorganisms partially
break down organic matter. The effluent still requires further
treatment, typically through an approved soil absorption system or
another authorized treatment process.
Question 4
Why is proper bedding important when installing underground sewer
pipe?
A. It eliminates the need for pipe testing.
B. It prevents all groundwater infiltration.
C. It provides uniform support and helps prevent excessive
deformation or settlement.
D. It increases the wastewater flow rate regardless of pipe slope.
Rationale: Properly selected and placed bedding supports the pipe
barrel, helps maintain the specified grade, and reduces concentrated
loads. Poor bedding can cause differential settlement, joint
displacement, pipe deformation, and eventual leakage or blockage.
, Question 5
What does the term “invert elevation” refer to in sewer construction?
A. The elevation of the top of a manhole cover
B. The elevation of the surrounding finished pavement
C. The elevation of the inside bottom of a pipe or channel
D. The elevation of the groundwater table
Rationale: The invert is the lowest interior point of a pipe or channel.
Invert elevations are used to establish sewer grades, connect
structures, and verify that wastewater can flow in the intended
direction.
Question 6
What is the primary purpose of maintaining an appropriate slope in a
gravity sewer?
A. To maintain constant water pressure
B. To eliminate the need for access structures
C. To provide adequate flow while limiting conditions that promote
solids deposition or excessive flow velocity
D. To ensure that the sewer remains completely full at all times
