CO Wastewater Systems Contractor Exam
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A|
Instant Download Pdf
1. What is the primary purpose of a wastewater collection system?
A. To increase drinking-water pressure
B. To store potable water
C. To convey wastewater from points of origin to treatment or
disposal facilities
D. To distribute treated water to buildings
Rationale: A wastewater collection system is designed to collect
sewage and other wastewater and convey it safely to a treatment
plant, disposal system, or other authorized facility. Proper conveyance
helps prevent public-health hazards, groundwater contamination, and
environmental damage.
, 2. Which force is most commonly used to move wastewater through
a conventional gravity sewer?
A. Air pressure
B. Pump pressure
C. Hydraulic pressure from a water main
D. Gravity
Rationale: Gravity sewers rely on elevation differences to move
wastewater downstream. Proper slope and pipe sizing are essential to
maintain adequate flow velocity and reduce sediment accumulation.
3. What is the primary function of a sewer manhole?
A. To disinfect wastewater
B. To increase sewer pressure
C. To provide access for inspection, maintenance, and changes in
alignment or elevation
D. To aerate drinking water
Rationale: Manholes provide personnel access to sewer lines for
inspection, cleaning, and maintenance. They are also commonly
located where sewer alignment, grade, or pipe size changes.
4. Which condition is most likely to cause excessive infiltration into a
wastewater collection system?
,A. Properly sealed pipe joints
B. Cracked sewer pipes or defective joints below the groundwater
table
C. Properly installed watertight manholes
D. Reduced rainfall
Rationale: Infiltration is groundwater entering a sewer system
through defects such as cracks, leaking joints, and deteriorated
structures. Excessive infiltration increases hydraulic loading on
downstream treatment facilities.
5. What is inflow in a wastewater collection system?
A. Groundwater entering through pipe cracks
B. Wastewater produced by industries
C. Water entering a sewer system through direct connections or
openings during rainfall or other events
D. Treated effluent returning to a treatment plant
Rationale: Inflow is water that enters a sanitary sewer from sources
such as roof drains, area drains, foundation drains, or improperly
connected stormwater systems. Unlike infiltration, inflow is generally
associated with direct surface-water connections or openings.
6. Why should stormwater generally be kept out of sanitary sewer
systems?
, A. It increases drinking-water quality
B. It prevents sewer pipes from flowing at all
C. It can overload collection and treatment facilities
D. It eliminates the need for wastewater treatment
Rationale: Stormwater can dramatically increase wastewater flows
during precipitation events. Excessive flow can cause sewer
surcharging, bypasses, treatment-process problems, and potentially
sanitary sewer overflows.
7. Which pipe material characteristic is particularly important for
wastewater sewer construction?
A. Ability to dissolve in water
B. Resistance to corrosion and chemical attack appropriate to the
service conditions
C. Maximum electrical conductivity
D. Ability to absorb wastewater
Rationale: Wastewater can contain corrosive chemicals and gases,
including compounds associated with hydrogen sulfide formation.
Sewer materials must be selected for compatibility with expected
chemical, structural, and hydraulic conditions.
8. What is the purpose of maintaining adequate slope in a gravity
sewer?
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A|
Instant Download Pdf
1. What is the primary purpose of a wastewater collection system?
A. To increase drinking-water pressure
B. To store potable water
C. To convey wastewater from points of origin to treatment or
disposal facilities
D. To distribute treated water to buildings
Rationale: A wastewater collection system is designed to collect
sewage and other wastewater and convey it safely to a treatment
plant, disposal system, or other authorized facility. Proper conveyance
helps prevent public-health hazards, groundwater contamination, and
environmental damage.
, 2. Which force is most commonly used to move wastewater through
a conventional gravity sewer?
A. Air pressure
B. Pump pressure
C. Hydraulic pressure from a water main
D. Gravity
Rationale: Gravity sewers rely on elevation differences to move
wastewater downstream. Proper slope and pipe sizing are essential to
maintain adequate flow velocity and reduce sediment accumulation.
3. What is the primary function of a sewer manhole?
A. To disinfect wastewater
B. To increase sewer pressure
C. To provide access for inspection, maintenance, and changes in
alignment or elevation
D. To aerate drinking water
Rationale: Manholes provide personnel access to sewer lines for
inspection, cleaning, and maintenance. They are also commonly
located where sewer alignment, grade, or pipe size changes.
4. Which condition is most likely to cause excessive infiltration into a
wastewater collection system?
,A. Properly sealed pipe joints
B. Cracked sewer pipes or defective joints below the groundwater
table
C. Properly installed watertight manholes
D. Reduced rainfall
Rationale: Infiltration is groundwater entering a sewer system
through defects such as cracks, leaking joints, and deteriorated
structures. Excessive infiltration increases hydraulic loading on
downstream treatment facilities.
5. What is inflow in a wastewater collection system?
A. Groundwater entering through pipe cracks
B. Wastewater produced by industries
C. Water entering a sewer system through direct connections or
openings during rainfall or other events
D. Treated effluent returning to a treatment plant
Rationale: Inflow is water that enters a sanitary sewer from sources
such as roof drains, area drains, foundation drains, or improperly
connected stormwater systems. Unlike infiltration, inflow is generally
associated with direct surface-water connections or openings.
6. Why should stormwater generally be kept out of sanitary sewer
systems?
, A. It increases drinking-water quality
B. It prevents sewer pipes from flowing at all
C. It can overload collection and treatment facilities
D. It eliminates the need for wastewater treatment
Rationale: Stormwater can dramatically increase wastewater flows
during precipitation events. Excessive flow can cause sewer
surcharging, bypasses, treatment-process problems, and potentially
sanitary sewer overflows.
7. Which pipe material characteristic is particularly important for
wastewater sewer construction?
A. Ability to dissolve in water
B. Resistance to corrosion and chemical attack appropriate to the
service conditions
C. Maximum electrical conductivity
D. Ability to absorb wastewater
Rationale: Wastewater can contain corrosive chemicals and gases,
including compounds associated with hydrogen sulfide formation.
Sewer materials must be selected for compatibility with expected
chemical, structural, and hydraulic conditions.
8. What is the purpose of maintaining adequate slope in a gravity
sewer?
