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Wastewater Collections Operator Class II 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 disinfect wastewater before treatment
- To convey wastewater to a treatment facility
- To remove solids from wastewater
- To pump effluent to receiving waters
Rationale: Collection systems exist mainly to transport wastewater to
treatment facilities.
- What is the typical slope range for gravity sewer lines?
A. 0.001%–0.003%
B. 0.05%–0.1% 1 / 3
C. 0.5%–2.0%
D. 3%–5%
Rationale: Gravity sewers require enough slope to maintain flow velocity
and prevent settling.
3. The term I&I refers to:
- Internal inspection
- Industrial infiltration
- Inflow and infiltration
- Internal inflow
Rationale: I&I refers to clean water entering the system through defects
and improper connections.
4. Hydrogen sulfide gas is most likely to form in:
- High-velocity sewers
- Long, flat sewer sections with low oxygen
- Pressurized force mains
- New PVC sewer lines
Rationale: Stagnant, anaerobic wastewater promotes H₂S generation.
- Which device measures sewer flow rate?
- Pitot gauge
- Weir box
- Parshall flume
- Datalogger 2 / 3
Rationale: Parshall flumes are commonly used for open-channel
wastewater flow measurement.
6. A manhole drop connection is used when:
- There is insufficient soil support
- Flow must be pumped
- There is a large difference in sewer pipe elevations
- The sewer is under pressure
Rationale: Drops prevent high-velocity falls inside manholes.
7. A force main is defined as:
- A gravity-fed sewer
- A pressurized sewer line using pumps
- A line conveying stormwater
- A vacuum-driven sewer
Rationale: Force mains use pumps to move wastewater under pressure.
- The recommended minimum velocity in a sewer to prevent solids
deposition is:
- 0.5 ft/s
- 1.0 ft/s
- 2.0 ft/s
- 5.0 ft/s
Rationale: Self-cleaning velocities of approximately 2 ft/s help prevent
settling.
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