ABC Wastewater Collection System Operator (Three ) III |
Complete Exam Questions Test Bank with Correct Answers
and Detailed Rationales | Latest Updated Edition 2026/2027
– Already Graded A+
Question 1
Turbidity in wastewater is caused by:
A. Color
B. Dissolved calcium
C. Hardness
D. Finely divided suspended material
Answer: D
Rationale: Turbidity in wastewater is caused by finely divided suspended material
that scatters light and gives the water a cloudy appearance.
Question 2
The gas most commonly associated with septic wastewater is:
A. Carbon dioxide
B. Carbon monoxide
C. Hydrogen sulfide
D. Methane
Answer: C
Rationale: Hydrogen sulfide is the gas most commonly associated with septic
wastewater, produced by bacterial reduction of sulfate compounds under anaerobic
conditions.
Question 3
How many cubic meters per second in 10 MGD?
A. 0.44
B. 1.44
C. 4.73
D. 24.62
pg. 1
,Answer: A
Rationale: 10 MGD = 10,000,000 gallons/day. Convert to m³/day (1 gallon =
0.003785 m³) = 37,850 m³/day. Divide by 86,400 seconds/day = 0.438 m³/s ≈ 0.44.
Question 4
Mechanical ventilation of a lift station is required to:
A. Lower temperatures to reduce proportion of hydrogen sulfide
B. Reduce chlorine demand
C. Reduce corrosion
D. Increase DO in raw wastewater
Answer: C
Rationale: Mechanical ventilation is required to reduce corrosion by removing
hydrogen sulfide gas and other corrosive gases from the lift station atmosphere.
Question 5
A wet well probe is usually used for determination(s) of level:
A. Approximate
B. Dual point
C. Continuous
D. Single point
Answer: D
Rationale: A wet well probe is usually used for single point determination of
level, providing on/off control for pumps.
Question 6
A pump is delivering at less than the expected rate of discharge. Which of the
causes listed below is incorrect?
A. Speed of motor too low
B. Pump not primed
C. Impeller clogged
D. Discharge head too low
Answer: D
Rationale: Discharge head too low would increase flow rate, not decrease it. The
other options all cause reduced discharge rates.
pg. 2
,Question 7
Metal pipes often fail because of:
A. Back siphonage
B. Browning movement
C. Galvanic action
D. Reverse osmosis
Answer: C
Rationale: Metal pipes often fail due to galvanic action, where dissimilar metals in
contact with an electrolyte create an electrochemical reaction causing corrosion.
Question 8
When a fire hydrant is operated, it should be:
A. Just opened enough to have a flow
B. Opened fully
C. Opened halfway
D. Regulated to flow required
Answer: B
Rationale: Fire hydrants should be opened fully when operated to prevent damage
to the valve and ensure proper flow.
Question 9
If the pump bearings on horizontal centrifugal pumps are over lubricated, the most
important effect is that:
A. Will result in smoother and more efficient operation of the pump
B. Will not make any difference in the operation of the pump
C. Will be wasted
D. Shaft or shaft sleeve will be damaged
Answer: D
Rationale: Over-lubrication can cause overheating and damage to the shaft or
shaft sleeve due to excessive pressure and friction.
Question 10
If packing is not maintained properly:
A. Cavitation damage will result
B. Impeller will corrode
pg. 3
, C. Loss of suction due to air being allowed to enter pump
D. Shaft or shaft sleeve will be damaged
Answer: C
Rationale: Improperly maintained packing allows air to enter the pump, causing
loss of suction and reduced pumping efficiency.
Question 11
In certain situations, a supervisor encourages the employees to make their own
decisions. This is considered to be:
A. Against the rules to follow past experiences in decision-making
B. Bad form since the supervisor eventually loses control
C. Highly desirable, since it encourages employee growth and frees the supervisor
for other tasks
D. Passing the buck
Answer: C
Rationale: Encouraging employees to make decisions is highly desirable as it
promotes employee growth, development, and frees the supervisor for other tasks.
Question 12
Successful communication requires mutual:
A. Agreement
B. Confusion
C. Transmission
D. Understanding
Answer: D
Rationale: Successful communication requires mutual understanding between the
sender and receiver of the message.
Question 13
When a great deal of authority is delegated on many levels, an organization may be
described as:
A. Authoritarian
B. Centralized
C. Decentralized
D. Unstructured
pg. 4
Complete Exam Questions Test Bank with Correct Answers
and Detailed Rationales | Latest Updated Edition 2026/2027
– Already Graded A+
Question 1
Turbidity in wastewater is caused by:
A. Color
B. Dissolved calcium
C. Hardness
D. Finely divided suspended material
Answer: D
Rationale: Turbidity in wastewater is caused by finely divided suspended material
that scatters light and gives the water a cloudy appearance.
Question 2
The gas most commonly associated with septic wastewater is:
A. Carbon dioxide
B. Carbon monoxide
C. Hydrogen sulfide
D. Methane
Answer: C
Rationale: Hydrogen sulfide is the gas most commonly associated with septic
wastewater, produced by bacterial reduction of sulfate compounds under anaerobic
conditions.
Question 3
How many cubic meters per second in 10 MGD?
A. 0.44
B. 1.44
C. 4.73
D. 24.62
pg. 1
,Answer: A
Rationale: 10 MGD = 10,000,000 gallons/day. Convert to m³/day (1 gallon =
0.003785 m³) = 37,850 m³/day. Divide by 86,400 seconds/day = 0.438 m³/s ≈ 0.44.
Question 4
Mechanical ventilation of a lift station is required to:
A. Lower temperatures to reduce proportion of hydrogen sulfide
B. Reduce chlorine demand
C. Reduce corrosion
D. Increase DO in raw wastewater
Answer: C
Rationale: Mechanical ventilation is required to reduce corrosion by removing
hydrogen sulfide gas and other corrosive gases from the lift station atmosphere.
Question 5
A wet well probe is usually used for determination(s) of level:
A. Approximate
B. Dual point
C. Continuous
D. Single point
Answer: D
Rationale: A wet well probe is usually used for single point determination of
level, providing on/off control for pumps.
Question 6
A pump is delivering at less than the expected rate of discharge. Which of the
causes listed below is incorrect?
A. Speed of motor too low
B. Pump not primed
C. Impeller clogged
D. Discharge head too low
Answer: D
Rationale: Discharge head too low would increase flow rate, not decrease it. The
other options all cause reduced discharge rates.
pg. 2
,Question 7
Metal pipes often fail because of:
A. Back siphonage
B. Browning movement
C. Galvanic action
D. Reverse osmosis
Answer: C
Rationale: Metal pipes often fail due to galvanic action, where dissimilar metals in
contact with an electrolyte create an electrochemical reaction causing corrosion.
Question 8
When a fire hydrant is operated, it should be:
A. Just opened enough to have a flow
B. Opened fully
C. Opened halfway
D. Regulated to flow required
Answer: B
Rationale: Fire hydrants should be opened fully when operated to prevent damage
to the valve and ensure proper flow.
Question 9
If the pump bearings on horizontal centrifugal pumps are over lubricated, the most
important effect is that:
A. Will result in smoother and more efficient operation of the pump
B. Will not make any difference in the operation of the pump
C. Will be wasted
D. Shaft or shaft sleeve will be damaged
Answer: D
Rationale: Over-lubrication can cause overheating and damage to the shaft or
shaft sleeve due to excessive pressure and friction.
Question 10
If packing is not maintained properly:
A. Cavitation damage will result
B. Impeller will corrode
pg. 3
, C. Loss of suction due to air being allowed to enter pump
D. Shaft or shaft sleeve will be damaged
Answer: C
Rationale: Improperly maintained packing allows air to enter the pump, causing
loss of suction and reduced pumping efficiency.
Question 11
In certain situations, a supervisor encourages the employees to make their own
decisions. This is considered to be:
A. Against the rules to follow past experiences in decision-making
B. Bad form since the supervisor eventually loses control
C. Highly desirable, since it encourages employee growth and frees the supervisor
for other tasks
D. Passing the buck
Answer: C
Rationale: Encouraging employees to make decisions is highly desirable as it
promotes employee growth, development, and frees the supervisor for other tasks.
Question 12
Successful communication requires mutual:
A. Agreement
B. Confusion
C. Transmission
D. Understanding
Answer: D
Rationale: Successful communication requires mutual understanding between the
sender and receiver of the message.
Question 13
When a great deal of authority is delegated on many levels, an organization may be
described as:
A. Authoritarian
B. Centralized
C. Decentralized
D. Unstructured
pg. 4
