UMC Operations and Maintenance 3 — Questions and Answers
Question 1: When performing confined space entry in a utility vault, what must be done FIRST?
- Enter quickly to minimize exposure time
- Test the atmosphere for oxygen, flammable gases, and toxic vapors (Correct answer)
- Turn off all lighting to conserve power
- Remove all PPE to allow freer movement
Correct answer: Test the atmosphere for oxygen, flammable gases, and toxic vapors
Atmospheric testing for oxygen levels, combustible gases, and toxic contaminants is the first required step before any confined space entry.
Question 2: What is the purpose of flushing water distribution mains?
- Increase system pressure
- Remove sediment, biofilm, and stale water to maintain water quality (Correct answer)
- Test for leaks in pipe joints
- Calibrate flow meters
Correct answer: Remove sediment, biofilm, and stale water to maintain water quality
Flushing distribution mains removes accumulated sediment, biofilm, and stagnant water that can degrade water quality and customer satisfaction.
Question 3: Which type of pump is most commonly used to move wastewater in lift stations?
- Reciprocating piston pump
- Peristaltic pump
- Centrifugal pump (Correct answer)
- Diaphragm pump
Correct answer: Centrifugal pump
Centrifugal pumps are the most common pump type in wastewater lift stations due to their reliability and ability to handle solids-laden liquids.
Question 4: What does BOD stand for in wastewater treatment?
- Basic Oxygen Demand
- Biological Oxygen Demand (Correct answer)
- Bacterial Output Density
- Baseline Organic Distribution
Correct answer: Biological Oxygen Demand
BOD (Biochemical Oxygen Demand) measures the amount of dissolved oxygen consumed by biological processes when decomposing organic matter in water.
Question 5: A utility is experiencing frequent main breaks in a specific zone. Which approach BEST addresses the root cause?
- Increase pressure throughout the system
- Conduct pipe condition assessment and prioritize rehabilitation (Correct answer)
- Add more chlorine to prevent corrosion
- Hire more repair crews
Correct answer: Conduct pipe condition assessment and prioritize rehabilitation
Systematic pipe condition assessment identifies deteriorated infrastructure and guides targeted rehabilitation or replacement to reduce break frequency.
Question 6: What is the primary hazard associated with hydrogen sulfide (H₂S) in sewer systems?
- It causes pipe corrosion only
- It is highly toxic and can cause rapid incapacitation at low concentrations (Correct answer)
- It increases wastewater pH
- It accelerates biological treatment
Correct answer: It is highly toxic and can cause rapid incapacitation at low concentrations
H₂S is immediately dangerous to life and health at concentrations above 100 ppm and can cause rapid loss of consciousness and death.
Question 7: Which document outlines the step-by-step procedures for safely isolating equipment for maintenance?
- Capital Improvement Plan
- Lockout/Tagout (LOTO) procedure (Correct answer)
- Consumer Confidence Report
- Asset Management Plan
Correct answer: Lockout/Tagout (LOTO) procedure
Lockout/Tagout (LOTO) procedures ensure that equipment is properly de-energized and isolated before maintenance, protecting workers from unexpected startup.
UMC Operations and Maintenance 3
When performing confined space entry in a utility vault, what must be done FIRST?