CPWM Utility Systems 5 — Questions and Answers
Question 1: What is the primary regulatory standard for lead and copper in drinking water under the EPA's Lead and Copper Rule?
- Maximum contaminant level (MCL) of 5 ppb for lead
- Action level of 15 ppb for lead at the 90th percentile of tap samples (Correct answer)
- Treatment technique requiring zero lead in all samples
- Secondary standard of 1.3 ppm for copper in finished water
Correct answer: Action level of 15 ppb for lead at the 90th percentile of tap samples
The Lead and Copper Rule establishes an action level of 15 ppb for lead; if exceeded at the 90th percentile of tap samples, utilities must take corrective action.
Question 2: A public works department is planning a new water storage tank. Which siting consideration is MOST critical for maintaining adequate system pressure?
- Proximity to the treatment plant
- Tank overflow elevation relative to the pressure zone's required service pressure (Correct answer)
- Distance from the nearest fire hydrant
- Soil bearing capacity for tank foundation
Correct answer: Tank overflow elevation relative to the pressure zone's required service pressure
The overflow elevation determines the hydraulic grade line for the pressure zone; the tank must be sited high enough to provide minimum required pressure (typically 35-40 psi) at the highest service point.
Question 3: Which type of sewer system is specifically designed to carry ONLY stormwater runoff?
- Combined sewer system
- Sanitary sewer system
- Municipal separate storm sewer system (MS4) (Correct answer)
- Force main system
Correct answer: Municipal separate storm sewer system (MS4)
MS4s are designed exclusively to convey stormwater from impervious surfaces to receiving waters and are regulated under NPDES Phase I and Phase II permits.
Question 4: A gas distribution system experiences a sudden pressure drop across a large service area. What is the FIRST action a public works manager should take?
- Increase regulator station output pressure immediately
- Initiate emergency response, isolate the affected area, and check for leaks or main breaks (Correct answer)
- Notify customers to reduce gas usage
- Wait 30 minutes to see if pressure normalizes
Correct answer: Initiate emergency response, isolate the affected area, and check for leaks or main breaks
Sudden system-wide pressure loss suggests a major leak or main break; immediate emergency response to isolate and investigate protects public safety above all other priorities.
Question 5: What is the purpose of a 'valve exercising program' in a water distribution system?
- To install new valves in aging pipeline segments
- To regularly operate valves to ensure they function properly and can be closed during emergencies (Correct answer)
- To test pressure ratings of distribution valves annually
- To flush sediment from dead-end mains
Correct answer: To regularly operate valves to ensure they function properly and can be closed during emergencies
Valve exercising programs periodically turn each valve to ensure it operates correctly and can be fully closed when needed during main breaks or planned shutdowns.
Question 6: Under the EPA's Combined Sewer Overflow (CSO) Control Policy, what is the maximum number of overflow events per year considered acceptable under the 'nine minimum controls'?
- The policy targets no more than 4 overflow events per year
- The nine minimum controls do not set a specific frequency limit but require maximum use of existing systems (Correct answer)
- Overflows are limited to 2 events during design storm events
- No more than 1 overflow event per 5-year recurrence interval is allowed
Correct answer: The nine minimum controls do not set a specific frequency limit but require maximum use of existing systems
The nine minimum controls are operational best management practices that maximize use of existing collection systems but do not establish a specific numeric overflow frequency limit.
Question 7: Which pump configuration is MOST appropriate when a lift station needs to continue operating if one pump fails?
- Single large pump sized for peak flow
- Duplex pump arrangement with one pump as standby (Correct answer)
- Series pumps to maximize pressure
- Variable speed pumps without redundancy
Correct answer: Duplex pump arrangement with one pump as standby
A duplex (two-pump) arrangement with one lead and one standby pump ensures continued operation during pump failure or maintenance, which is critical for wastewater lift stations.
CPWM Utility Systems 5
What is the primary regulatory standard for lead and copper in drinking water under the EPA's Lead and Copper Rule?