TCEQ Wastewater Collection
System Operator Class II — Form B
Exam Questions and Correct
Answers with Detailed Rationales |
2026/2027 Edition | Exam Prep
Study Guide PDF
1. What is the primary purpose of a wastewater collection
system?
A. To treat wastewater before discharge
B. To store potable water
C. To transport wastewater from points of origin to a treatment
facility
D. To disinfect drinking water
Answer: C. To transport wastewater from points of origin to a
treatment facility
Rationale: A wastewater collection system is designed primarily
to collect and convey sewage from homes, businesses, and other
sources to a wastewater treatment facility. Treatment generally
occurs after the wastewater reaches the treatment plant. Proper
collection prevents sewage backups, overflows, and
environmental contamination.
2. Which condition is most likely to cause excessive infiltration
into a wastewater collection system?
,A. Properly sealed manhole covers
B. Cracked or deteriorated sewer pipes below the groundwater
table
C. New PVC service connections
D. Properly graded sewer lines
Answer: B. Cracked or deteriorated sewer pipes below the
groundwater table
Rationale: Infiltration is groundwater that enters a sanitary sewer
through defects such as cracks, broken joints, deteriorated
manholes, and defective pipe connections. When groundwater
levels are above defects in the collection system, hydrostatic
pressure can force water into the sewer.
3. What is the primary difference between infiltration and
inflow?
A. Infiltration enters through structural defects, while inflow
enters through direct connections or openings
B. Infiltration occurs only during dry weather
C. Inflow occurs only through cracked pipes
D. There is no difference between them
Answer: A. Infiltration enters through structural defects, while
inflow enters through direct connections or openings
Rationale: Infiltration generally comes from groundwater entering
through cracks, joints, porous materials, or other defects. Inflow is
typically stormwater that enters directly through sources such as
roof drains, yard drains, storm sewer connections, or improperly
sealed manholes. Both can increase hydraulic loading at a
wastewater treatment facility.
, 4. Which sewer condition is most associated with hydrogen
sulfide generation?
A. High dissolved oxygen
B. Aerobic conditions throughout the pipe
C. Septic conditions caused by prolonged wastewater detention
D. Excessive chlorine residual
Answer: C. Septic conditions caused by prolonged wastewater
detention
Rationale: Hydrogen sulfide can develop when wastewater
becomes septic under anaerobic conditions. Low flow, long
detention times, warm temperatures, and excessive organic
loading can promote sulfate-reducing biological activity.
Hydrogen sulfide is also associated with odor problems and
corrosion of concrete sewer structures.
5. What is the main purpose of maintaining adequate velocity
in a gravity sewer?
A. To increase groundwater infiltration
B. To prevent solids from settling in the pipe
C. To eliminate the need for manholes
D. To increase wastewater temperature
Answer: B. To prevent solids from settling in the pipe
Rationale: Adequate flow velocity helps maintain a self-cleansing
condition by keeping suspended solids moving through the sewer.
If velocity is too low for extended periods, solids may settle,
eventually causing deposits, reduced capacity, odors, and
blockages.
, 6. A sewer line has a significant amount of grease buildup.
Which cleaning method is commonly effective for removing
accumulated grease?
A. High-pressure water jetting
B. Increasing pipe slope
C. Installing an air-release valve
D. Reducing flow velocity
Answer: A. High-pressure water jetting
Rationale: High-pressure water jetting can effectively scour
grease and other deposits from sewer walls. The appropriate
nozzle, pressure, flow rate, and cleaning procedure should be
selected based on pipe size, material, condition, and the type of
obstruction. Operators should also consider where the loosened
material will go after cleaning.
7. What is the primary function of a manhole in a wastewater
collection system?
A. To chlorinate wastewater
B. To provide access for inspection, maintenance, and changes in
alignment or elevation
C. To increase drinking-water pressure
D. To remove dissolved contaminants
Answer: B. To provide access for inspection, maintenance,
and changes in alignment or elevation
Rationale: Manholes provide controlled access to underground
sewer lines. They are commonly located where sewer alignment,
grade, pipe size, or direction changes and at intervals that allow
inspection and maintenance. Properly maintained manholes are
important for collection-system reliability and worker safety.
System Operator Class II — Form B
Exam Questions and Correct
Answers with Detailed Rationales |
2026/2027 Edition | Exam Prep
Study Guide PDF
1. What is the primary purpose of a wastewater collection
system?
A. To treat wastewater before discharge
B. To store potable water
C. To transport wastewater from points of origin to a treatment
facility
D. To disinfect drinking water
Answer: C. To transport wastewater from points of origin to a
treatment facility
Rationale: A wastewater collection system is designed primarily
to collect and convey sewage from homes, businesses, and other
sources to a wastewater treatment facility. Treatment generally
occurs after the wastewater reaches the treatment plant. Proper
collection prevents sewage backups, overflows, and
environmental contamination.
2. Which condition is most likely to cause excessive infiltration
into a wastewater collection system?
,A. Properly sealed manhole covers
B. Cracked or deteriorated sewer pipes below the groundwater
table
C. New PVC service connections
D. Properly graded sewer lines
Answer: B. Cracked or deteriorated sewer pipes below the
groundwater table
Rationale: Infiltration is groundwater that enters a sanitary sewer
through defects such as cracks, broken joints, deteriorated
manholes, and defective pipe connections. When groundwater
levels are above defects in the collection system, hydrostatic
pressure can force water into the sewer.
3. What is the primary difference between infiltration and
inflow?
A. Infiltration enters through structural defects, while inflow
enters through direct connections or openings
B. Infiltration occurs only during dry weather
C. Inflow occurs only through cracked pipes
D. There is no difference between them
Answer: A. Infiltration enters through structural defects, while
inflow enters through direct connections or openings
Rationale: Infiltration generally comes from groundwater entering
through cracks, joints, porous materials, or other defects. Inflow is
typically stormwater that enters directly through sources such as
roof drains, yard drains, storm sewer connections, or improperly
sealed manholes. Both can increase hydraulic loading at a
wastewater treatment facility.
, 4. Which sewer condition is most associated with hydrogen
sulfide generation?
A. High dissolved oxygen
B. Aerobic conditions throughout the pipe
C. Septic conditions caused by prolonged wastewater detention
D. Excessive chlorine residual
Answer: C. Septic conditions caused by prolonged wastewater
detention
Rationale: Hydrogen sulfide can develop when wastewater
becomes septic under anaerobic conditions. Low flow, long
detention times, warm temperatures, and excessive organic
loading can promote sulfate-reducing biological activity.
Hydrogen sulfide is also associated with odor problems and
corrosion of concrete sewer structures.
5. What is the main purpose of maintaining adequate velocity
in a gravity sewer?
A. To increase groundwater infiltration
B. To prevent solids from settling in the pipe
C. To eliminate the need for manholes
D. To increase wastewater temperature
Answer: B. To prevent solids from settling in the pipe
Rationale: Adequate flow velocity helps maintain a self-cleansing
condition by keeping suspended solids moving through the sewer.
If velocity is too low for extended periods, solids may settle,
eventually causing deposits, reduced capacity, odors, and
blockages.
, 6. A sewer line has a significant amount of grease buildup.
Which cleaning method is commonly effective for removing
accumulated grease?
A. High-pressure water jetting
B. Increasing pipe slope
C. Installing an air-release valve
D. Reducing flow velocity
Answer: A. High-pressure water jetting
Rationale: High-pressure water jetting can effectively scour
grease and other deposits from sewer walls. The appropriate
nozzle, pressure, flow rate, and cleaning procedure should be
selected based on pipe size, material, condition, and the type of
obstruction. Operators should also consider where the loosened
material will go after cleaning.
7. What is the primary function of a manhole in a wastewater
collection system?
A. To chlorinate wastewater
B. To provide access for inspection, maintenance, and changes in
alignment or elevation
C. To increase drinking-water pressure
D. To remove dissolved contaminants
Answer: B. To provide access for inspection, maintenance,
and changes in alignment or elevation
Rationale: Manholes provide controlled access to underground
sewer lines. They are commonly located where sewer alignment,
grade, pipe size, or direction changes and at intervals that allow
inspection and maintenance. Properly maintained manholes are
important for collection-system reliability and worker safety.
