Texas Wastewater Collection System
Operator Class III Exam With Actual
120 Questions & Verified Answers,Plus
Rationales/Expert Verified For
Guaranteed Pass Graded A+/
2025/2026 /Latest Update/Instant
Download Pdf
Texas Wastewater Collection System Operator Class III – Practice Exam
1. The primary purpose of a wastewater collection system is to:
a) Provide irrigation water for crops
b) Deliver potable water to homes
c) Convey wastewater to a treatment facility
d) Store stormwater for reuse
• The purpose of a collection system is to move wastewater safely from its source to a
treatment plant.
2. What is the main cause of hydrogen sulfide gas in wastewater collection systems?
a) High pH
b) Anaerobic conditions
c) Chlorination
d) High oxygen content
• Hydrogen sulfide is formed in anaerobic (no oxygen) conditions when sulfate-
reducing bacteria break down organic matter.
3. Which of the following is considered an infiltration source?
a) Kitchen sink
b) Bathtub drain
c) Toilet
d) Groundwater entering through pipe cracks
,• Infiltration is unwanted groundwater entering the sewer system through defects in
pipes or joints.
4. Which of the following is considered inflow?
a) Stormwater entering through a manhole cover
b) Groundwater seepage
c) Wastewater from toilets
d) Grease discharge from restaurants
• Inflow refers to direct stormwater entry into the sewer, such as from roof drains,
sump pumps, or manhole covers.
5. The recommended minimum velocity in a gravity sewer to prevent solids deposition
is:
a) 0.5 ft/sec
b) 1.0 ft/sec
c) 2.0 ft/sec
d) 5.0 ft/sec
• A velocity of at least 2.0 ft/sec is needed to keep solids in suspension and prevent
clogging.
6. The function of a manhole in a collection system is to:
a) Increase water pressure
b) Provide access for inspection and maintenance
c) Collect wastewater for reuse
d) Reduce odors
• Manholes allow entry into sewer lines for cleaning, repairs, and inspection.
7. Which type of sewer carries wastewater and stormwater in the same pipe?
a) Sanitary sewer
b) Combined sewer
c) Storm sewer
d) Pressure sewer
• Combined sewers carry both stormwater and wastewater together.
8. Which device is commonly used to prevent backflow in collection systems?
a) Bar screen
b) Pump impeller
c) Check valve
d) Flow meter
• Check valves allow flow in only one direction, preventing backflow.
, 9. What is the typical slope of a small-diameter gravity sewer line?
a) 0.01 ft/ft
b) 0.002–0.005 ft/ft
c) 0.1 ft/ft
d) 0.5 ft/ft
• Small sewer lines are usually laid at slopes of 0.2%–0.5% (0.002–0.005 ft/ft) to
maintain flow velocity.
10. A major safety hazard in manholes is:
a) Cold temperature
b) Toxic or explosive gases
c) High water pressure
d) Lack of lighting
• Manholes may contain hydrogen sulfide, methane, or low oxygen, which are serious
safety hazards.
11. The minimum oxygen concentration required for safe entry into a confined space is:
a) 10%
b) 19.5%
c) 25%
d) 35%
• OSHA standards require at least 19.5% oxygen for safe confined space entry.
12. What is the term for wastewater seeping out of defective sewers into the
surrounding soil?
a) Infiltration
b) Exfiltration
c) Inflow
d) Percolation
• Exfiltration is when sewage leaks outward from a sewer line into the soil.
13. What piece of equipment is used to measure flow in a collection system?
a) Check valve
b) Grinder
c) Bar screen
d) Flow meter
• Flow meters measure wastewater volume moving through a sewer.
14. Which of the following is a root control method?
a) Chlorination
Operator Class III Exam With Actual
120 Questions & Verified Answers,Plus
Rationales/Expert Verified For
Guaranteed Pass Graded A+/
2025/2026 /Latest Update/Instant
Download Pdf
Texas Wastewater Collection System Operator Class III – Practice Exam
1. The primary purpose of a wastewater collection system is to:
a) Provide irrigation water for crops
b) Deliver potable water to homes
c) Convey wastewater to a treatment facility
d) Store stormwater for reuse
• The purpose of a collection system is to move wastewater safely from its source to a
treatment plant.
2. What is the main cause of hydrogen sulfide gas in wastewater collection systems?
a) High pH
b) Anaerobic conditions
c) Chlorination
d) High oxygen content
• Hydrogen sulfide is formed in anaerobic (no oxygen) conditions when sulfate-
reducing bacteria break down organic matter.
3. Which of the following is considered an infiltration source?
a) Kitchen sink
b) Bathtub drain
c) Toilet
d) Groundwater entering through pipe cracks
,• Infiltration is unwanted groundwater entering the sewer system through defects in
pipes or joints.
4. Which of the following is considered inflow?
a) Stormwater entering through a manhole cover
b) Groundwater seepage
c) Wastewater from toilets
d) Grease discharge from restaurants
• Inflow refers to direct stormwater entry into the sewer, such as from roof drains,
sump pumps, or manhole covers.
5. The recommended minimum velocity in a gravity sewer to prevent solids deposition
is:
a) 0.5 ft/sec
b) 1.0 ft/sec
c) 2.0 ft/sec
d) 5.0 ft/sec
• A velocity of at least 2.0 ft/sec is needed to keep solids in suspension and prevent
clogging.
6. The function of a manhole in a collection system is to:
a) Increase water pressure
b) Provide access for inspection and maintenance
c) Collect wastewater for reuse
d) Reduce odors
• Manholes allow entry into sewer lines for cleaning, repairs, and inspection.
7. Which type of sewer carries wastewater and stormwater in the same pipe?
a) Sanitary sewer
b) Combined sewer
c) Storm sewer
d) Pressure sewer
• Combined sewers carry both stormwater and wastewater together.
8. Which device is commonly used to prevent backflow in collection systems?
a) Bar screen
b) Pump impeller
c) Check valve
d) Flow meter
• Check valves allow flow in only one direction, preventing backflow.
, 9. What is the typical slope of a small-diameter gravity sewer line?
a) 0.01 ft/ft
b) 0.002–0.005 ft/ft
c) 0.1 ft/ft
d) 0.5 ft/ft
• Small sewer lines are usually laid at slopes of 0.2%–0.5% (0.002–0.005 ft/ft) to
maintain flow velocity.
10. A major safety hazard in manholes is:
a) Cold temperature
b) Toxic or explosive gases
c) High water pressure
d) Lack of lighting
• Manholes may contain hydrogen sulfide, methane, or low oxygen, which are serious
safety hazards.
11. The minimum oxygen concentration required for safe entry into a confined space is:
a) 10%
b) 19.5%
c) 25%
d) 35%
• OSHA standards require at least 19.5% oxygen for safe confined space entry.
12. What is the term for wastewater seeping out of defective sewers into the
surrounding soil?
a) Infiltration
b) Exfiltration
c) Inflow
d) Percolation
• Exfiltration is when sewage leaks outward from a sewer line into the soil.
13. What piece of equipment is used to measure flow in a collection system?
a) Check valve
b) Grinder
c) Bar screen
d) Flow meter
• Flow meters measure wastewater volume moving through a sewer.
14. Which of the following is a root control method?
a) Chlorination
