California Water Distribution D2 Exam Prep FREE Sample Exam

An operator needs both the free and the total chlorine of a distribution sample using DPD. How are the two values obtained?

By a single DPD reading, which reports free and total chlorine as the same number whenever the sample comes from a system that uses chlorine in any form at all

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By measuring free chlorine with DPD and estimating total chlorine from the chlorine dose applied at the plant, since total chlorine cannot be measured in the field

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By filtering the sample to remove the combined chlorine and then reading the filtrate twice, once for the free portion and once for the portion removed by the filter

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By DPD colorimetric readings for free chlorine and for total chlorine on the sample, with combined chlorine taken as the difference

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About how much available chlorine does calcium hypochlorite (HTH) contain?

About 5 to 10 percent

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About 25 percent

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About 65 to 70 percent

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Essentially 100 percent

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Which set contains only disadvantages or risks of chloramination?

Weaker and slower disinfection, a residual that disappears faster than free chlorine, and trihalomethane formation higher than with free chlorination of the same water

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Nitrification risk, complete inability to maintain any residual at dead ends, and a requirement to dechlorinate all water before it can be served to customers

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Taste or odor if di- or trichloramine forms, formation of ozone in the mains, and a residual that cannot be measured by any chlorine test available to operators

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Weaker and slower disinfection, nitrification risk, and taste or odor if di- or trichloramine forms

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An 18-inch transmission main (1.5 ft in diameter) carries 2,000 gallons per minute. What is the velocity of the water in the main?

5.05 ft/s

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2.52 ft/s

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4.46 ft/s

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1.26 ft/s

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A pressure gauge on a distribution main reads 31 psi. How many feet of head does that pressure represent?

13.42 ft

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71.61 ft

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62 ft

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93 ft

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To report the average rate at which water left a storage facility during a drawdown period, which approach is correct?

Divide the tank's total rated capacity by its age in years of service

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Read the static pressure at the base of the tank one single time

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Multiply the tank diameter by the depth of water inside the tank

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Divide the volume change by the time it took

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What does an in-line (continuous) chlorine analyzer do during normal operation?

It continuously samples the flowing water and reports the residual, alarming on out-of-range values

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It samples the water once a month and mails the result away

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It adds chlorine to the water whenever the flow increases so the residual never falls at peak demand

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It stores a day's flow so it can be analyzed the next morning

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Chemical solution is metered into a flow of 0.85 MGD at a booster station to deliver a dose of 3.1 mg/L. The product’s purity is 55 percent and each gallon of it weighs 9.6 lb. How many gallons per day must the feeder deliver?

4.16 gal/day

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2.29 gal/day

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7.92 gal/day

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1.85 gal/day

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What do the records of a fire hydrant testing program document?

Only the names of the crew members who attended the testing that day and signed the work order before leaving the site

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The water rates charged in the surrounding blocks

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The flow-test results and the condition found for each hydrant tested

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The age of the pavement around each hydrant

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Which list contains only recognized procedures for cleaning the inside of a water main?

Flushing, sandblasting the outside of the barrel, and repainting the hydrants

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Pigging, jetting the service laterals with a garden hose, and vacuuming the trench, none of which is a recognized way to clean the inside of a main in service

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Air scouring, ice pigging, and relining the street above the main

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Flushing, swabbing or pigging, air scouring, and ice pigging

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Water moves through a pipe 0.5 ft in diameter at 5.2 ft per second. How many gallons per minute is the pipe carrying at that velocity?

352.31 gpm

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1,030.50 gpm

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458.00 gpm

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61.23 gpm

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What is a presumptive result in water quality testing?

A final verified result that closes out the sample, with no further testing of any kind needed afterward

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A result the laboratory reports only after repeat sampling

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A preliminary positive indication from an initial test, before confirmation

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A negative result that presumes the water is safe

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California Water Distribution D2 Exam Prep FREE Sample Exam — Fixed Set

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