ABC Foundational Knowledge Assessment 3 — Questions and Answers
Question 1: An operator notices turbidity levels in the finished water are rising. What is the most appropriate first action?
- Increase coagulant dosage and monitor filter performance (Correct answer)
- Immediately shut down the plant
- Notify the media
- Reduce chlorine dosage
Correct answer: Increase coagulant dosage and monitor filter performance
Rising turbidity indicates coagulation or filtration issues; adjusting coagulant and monitoring filters is the standard corrective first step.
Question 2: Which parameter is the most direct indicator of microbial contamination risk in a treated water supply?
- Total coliform presence (Correct answer)
- Hardness level
- Iron concentration
- pH value
Correct answer: Total coliform presence
Total coliform bacteria are indicator organisms used to detect potential pathogen contamination in drinking water.
Question 3: In wastewater treatment, what is the main goal of the secondary treatment stage?
- Remove dissolved organic matter through biological processes (Correct answer)
- Remove large solids through screening
- Disinfect the effluent with chlorine
- Adjust the pH to neutral
Correct answer: Remove dissolved organic matter through biological processes
Secondary treatment uses biological processes such as activated sludge to reduce dissolved and suspended organic pollutants.
Question 4: A water system operator observes a sudden drop in system pressure. Which hazard should be investigated first?
- Potential backflow or cross-connection (Correct answer)
- Seasonal demand fluctuation
- Meter calibration error
- Pump speed variation
Correct answer: Potential backflow or cross-connection
A sudden pressure drop can allow backflow and contaminants to enter the distribution system, making cross-connection investigation the priority.
Question 5: Which disinfection byproduct (DBP) is most associated with chlorination of water containing natural organic matter?
- Trihalomethanes (THMs) (Correct answer)
- Fluoride compounds
- Nitrates
- Arsenic
Correct answer: Trihalomethanes (THMs)
Trihalomethanes form when chlorine reacts with natural organic matter in source water and are regulated under the SDWA.
Question 6: Which process is used to remove dissolved gases such as hydrogen sulfide from groundwater?
- Aeration (Correct answer)
- Coagulation
- Sedimentation
- Ion exchange
Correct answer: Aeration
Aeration exposes water to air, allowing volatile dissolved gases like hydrogen sulfide to escape from solution.
Question 7: What does the term 'MCL' stand for in the context of drinking water regulations?
- Maximum Contaminant Level (Correct answer)
- Minimum Chlorine Limit
- Maximum Coagulant Load
- Measured Compliance Level
Correct answer: Maximum Contaminant Level
MCL stands for Maximum Contaminant Level, the highest permissible concentration of a contaminant in public drinking water.
ABC Foundational Knowledge Assessment 3
An operator notices turbidity levels in the finished water are rising.
What is the most appropriate first action?