CME CME Water & Wastewater Systems 1 — Questions and Answers
Question 1: What design standard is most commonly used for potable water distribution system hydraulics in the US?
- AWWA Manual M31
- ASCE 7
- Ten States Standards (Recommended Standards for Water Works) (Correct answer)
- NFPA 13
Correct answer: Ten States Standards (Recommended Standards for Water Works)
The Ten States Standards (Recommended Standards for Water Works) is the most widely used guidance document for potable water system design across the Midwest and Northeast US.
Question 2: Which federal regulation sets the primary drinking water standards that municipal water systems must meet?
- Clean Water Act
- Safe Drinking Water Act (SDWA) (Correct answer)
- Resource Conservation and Recovery Act
- National Environmental Policy Act
Correct answer: Safe Drinking Water Act (SDWA)
The Safe Drinking Water Act authorizes EPA to set National Primary Drinking Water Regulations (NPDWRs) that municipal water systems must comply with.
Question 3: What is the minimum residual chlorine level (free chlorine) EPA recommends maintaining throughout a distribution system?
- 0.01 mg/L
- 0.2 mg/L (Correct answer)
- 1.0 mg/L
- 2.0 mg/L
Correct answer: 0.2 mg/L
EPA recommends maintaining at least 0.2 mg/L free chlorine residual throughout the distribution system to prevent microbial contamination.
Question 4: What does the Hazen-Williams equation calculate in water distribution design?
- Pump power requirements
- Head loss due to friction in pipes carrying water (Correct answer)
- Water treatment chemical doses
- Reservoir storage volume
Correct answer: Head loss due to friction in pipes carrying water
The Hazen-Williams equation is an empirical formula used to calculate friction head loss in water-carrying pipes for distribution system design.
Question 5: What is the primary purpose of a water system's storage tank (elevated or ground-level)?
- Chemical treatment of water
- Equalize diurnal demand fluctuations and provide emergency fire flow storage (Correct answer)
- Pump station surge control only
- Backflow prevention
Correct answer: Equalize diurnal demand fluctuations and provide emergency fire flow storage
Water storage tanks equalize daily demand variations, maintain system pressure, and provide reserve capacity for fire fighting and emergencies.
Question 6: Under the Lead and Copper Rule (LCR), what action level for lead triggers required system mitigation?
- 0 µg/L (any detection)
- 5 µg/L
- 15 µg/L (Correct answer)
- 50 µg/L
Correct answer: 15 µg/L
The EPA Lead and Copper Rule sets an action level of 15 µg/L (ppb) for lead; if exceeded at 10% of sampled taps, utilities must take corrective action.
CME CME Water & Wastewater Systems 1
What design standard is most commonly used for potable water distribution system hydraulics in the US?