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Wastewater Collections Operator Class III Practice Exam 100 Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf
- What is the primary purpose of a wastewater collection system?
- To remove solids from wastewater
- To transport wastewater to a treatment facility
- To disinfect wastewater
- To store wastewater for reuse
Answer: B
Collection systems are designed mainly to convey wastewater safely and efficiently to a treatment plant.
- A manhole’s primary function in a gravity sewer system is to: 1 / 4
- Provide flow metering
- Serve as a sediment trap
- Provide access for inspection and maintenance
- Act as a pump station
Answer: C
Manholes allow operators to access sewer lines for cleaning, inspection, and emergency repairs.
- The minimum recommended velocity in a gravity sewer to prevent
solids deposition is:
- 0.5 fps
- 1.0 fps
- 2.0 fps
- 3.0 fps
Answer: C
Velocities of 2 fps or greater help keep solids suspended and reduce blockages.
- The type of sewer that carries only domestic and industrial wastewater
is called:
- Storm sewer
- Combined sewer 2 / 4
- Sanitary sewer
- Interceptor sewer
Answer: C
Sanitary sewers are dedicated to conveying wastewater without stormwater.
5. A combined sewer transports:
- Only rainfall runoff
- Only industrial waste
- Both wastewater and stormwater
- Groundwater only
Answer: C
Combined sewers collect both sanitary flow and stormwater in the same pipe.
6. Hydrogen sulfide (H₂S) gas is most likely to form in:
- High-velocity force mains
- Long, slow-moving sewer lines
- Recently cleaned sewer lines
- Lines with abundant oxygen
Answer: B 3 / 4
Slow flow conditions allow anaerobic bacteria to produce hydrogen sulfide gas.
7. The main health risk associated with H₂S gas is:
- Skin irritation
- Hearing loss
- Respiratory paralysis
- Eye damage
Answer: C
High concentrations of H₂S can cause rapid respiratory failure and death.
8. The portion of the sewer pipe where the wastewater flows is called the:
- Crown
- Spring line
- Invert
- Barrel
Answer: C
The invert is the lowest interior point of a sewer pipe where flow occurs.
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