AWWA Quality Control Procedures 3 — Questions and Answers
Question 1: Which document defines the written procedures, personnel responsibilities, and QA objectives for a water laboratory's quality program?
- Standard Methods manual
- Quality Assurance Project Plan (QAPP) (Correct answer)
- Chain-of-custody form
- Laboratory information management system (LIMS)
Correct answer: Quality Assurance Project Plan (QAPP)
A QAPP documents all quality assurance and quality control objectives, procedures, and responsibilities for a specific project or ongoing program.
Question 2: What is the acceptable chlorine residual range at the entry point to a distribution system under the Surface Water Treatment Rule?
- 0.0 mg/L minimum
- 0.2 mg/L minimum (Correct answer)
- 1.0 mg/L minimum
- 2.0 mg/L minimum
Correct answer: 0.2 mg/L minimum
The Surface Water Treatment Rule requires a detectable disinfectant residual (minimum 0.2 mg/L) at the entry point to the distribution system.
Question 3: In a water quality report, a result reported as '<0.005 mg/L' indicates the concentration is:
- Exactly 0.005 mg/L
- Below the method detection limit (Correct answer)
- Above the maximum contaminant level
- Within the optimal treatment range
Correct answer: Below the method detection limit
The less-than symbol indicates the analyte was not detected above the reporting limit, meaning the true value could be zero or any value below that threshold.
Question 4: Which AWWA standard provides guidance on the performance testing of water meters?
- AWWA B100
- AWWA C700 (Correct answer)
- AWWA C900
- AWWA M36
Correct answer: AWWA C700
AWWA C700 covers cold-water meters and includes accuracy and performance testing requirements for residential displacement meters.
Question 5: A turbidity spike in filtered water that exceeds 0.3 NTU most likely indicates:
- A calibration error in the turbidimeter
- A filter breakthrough or media problem (Correct answer)
- Normal diurnal variation
- Excessive chemical dosing
Correct answer: A filter breakthrough or media problem
A turbidity spike in filtered effluent often signals filter breakthrough, media cracking, or inadequate ripening, compromising particle removal.
Question 6: What is the primary reason water samples for microbiological testing must be collected in sterile containers with sodium thiosulfate?
- To preserve the pH of the sample
- To neutralize residual chlorine and prevent bacterial die-off (Correct answer)
- To maintain dissolved oxygen levels
- To prevent freezing during transport
Correct answer: To neutralize residual chlorine and prevent bacterial die-off
Sodium thiosulfate neutralizes residual chlorine, which would otherwise continue killing bacteria and cause falsely low counts.
Question 7: Under the Lead and Copper Rule, first-draw samples must be collected after water has stood motionless in plumbing for at least:
- 2 hours
- 6 hours (Correct answer)
- 8 hours
- 12 hours
Correct answer: 6 hours
First-draw samples must follow a minimum 6-hour stagnation period to maximize the opportunity for lead or copper to leach from plumbing materials.
AWWA Quality Control Procedures 3
Which document defines the written procedures, personnel responsibilities, and QA objectives for a water laboratory's quality program?