Question 1003 of 229 · California Water Distribution Operator Exam
Under the AWWA C651 slug method, which dose and contact time apply?
Exactly one answer is correct.
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Correct answer to question 1003
- D: 100 mg/L held for at least 3 hours
Explanation
A slug of 100 mg/L chlorine moves slowly through the main so every part sees it for at least 3 hours. The 25 mg/L, 24-hour pairing belongs to the continuous-feed and tablet methods.
More questions: Disinfection
- 1004After the 24-hour contact period of the continuous-feed method, what free chlorine residual must remain in the main?
- 1005Why should a new main be flushed before the disinfectant is added?
- 1006Heavily chlorinated water flushed from a main must be dechlorinated before it reaches a storm drain or creek. Which chemical is commonly used?
- 1007Approximately what percentage of available chlorine does calcium hypochlorite (HTH) contain?
- 1008Which form of chlorine is 100 percent available chlorine?
- 1009A chlorine dose of 3.0 mg/L produces a free chlorine residual of 0.8 mg/L after the contact time. What is the chlorine demand?