AWWA Operational Efficiency and Maintenance 3 — Questions and Answers
Question 1: In a SCADA-monitored pumping station, an alarm indicates a motor's current draw has increased 15% without a change in flow output. What does this most likely indicate?
- A faulty current sensor
- Mechanical binding or increased friction in the pump (Correct answer)
- Increased demand downstream
- A partially closed discharge valve
Correct answer: Mechanical binding or increased friction in the pump
Increased current draw without increased flow output typically indicates mechanical problems such as bearing wear, impeller rubbing, or seal friction.
Question 2: What is the purpose of conducting a pressure zone analysis in a water distribution system?
- To determine the optimal chlorine dosage for each zone
- To identify areas of excessive pressure that may cause main breaks or leaks (Correct answer)
- To calculate the total volume stored in elevated tanks
- To establish billing rates for different service areas
Correct answer: To identify areas of excessive pressure that may cause main breaks or leaks
Pressure zone analysis identifies areas with pressures that exceed pipe ratings, increasing the risk of main breaks, leaks, and customer complaints.
Question 3: Which AWWA standard addresses the installation and maintenance of fire hydrants?
- AWWA C502 (Correct answer)
- AWWA C651
- AWWA C900
- AWWA M17
Correct answer: AWWA C502
AWWA C502 covers dry-barrel fire hydrants, including design, materials, and installation requirements.
Question 4: A utility tracks its Infrastructure Leakage Index (ILI). A value of 1.0 indicates what about the system?
- The system is losing 100% more water than unavoidable losses
- The system has zero real losses
- Current real losses equal the theoretical minimum unavoidable losses (Correct answer)
- The system meets the 10% maximum NRW benchmark
Correct answer: Current real losses equal the theoretical minimum unavoidable losses
An ILI of 1.0 means the system's actual real losses equal the Unavoidable Annual Real Losses (UARL), representing theoretical best performance.
Question 5: When performing a hydrant flow test, the hydrant nearest the test point is called the:
- Residual hydrant (Correct answer)
- Flow hydrant
- Static hydrant
- Control hydrant
Correct answer: Residual hydrant
The residual hydrant is the closest hydrant to the test point where pressure is measured during flow from the flow hydrant(s).
Question 6: What is the primary advantage of variable frequency drives (VFDs) in water pumping operations?
- They eliminate the need for pressure relief valves
- They allow pumps to operate at variable speeds, matching output to demand and saving energy (Correct answer)
- They increase the maximum flow capacity of existing pumps
- They prevent water hammer by slowing pump start-up only
Correct answer: They allow pumps to operate at variable speeds, matching output to demand and saving energy
VFDs enable pumps to run at the speed needed to meet actual demand, significantly reducing energy consumption compared to constant-speed pumps with throttling control.
Question 7: Which condition would most likely require an emergency main break repair crew to be dispatched immediately?
- A pressure reading 5 psi below normal at a monitoring station
- A main break causing street flooding and service loss to a hospital (Correct answer)
- A routine meter replacement that cannot be scheduled during business hours
- A fire hydrant with a slow drip from the cap
Correct answer: A main break causing street flooding and service loss to a hospital
Service loss to critical facilities like hospitals combined with street flooding represents both a public safety hazard and a critical service disruption requiring immediate response.
AWWA Operational Efficiency and Maintenance 3
In a SCADA-monitored pumping station, an alarm indicates a motor's current draw has increased 15% without a change in flow output.
What does this most likely indicate?