California Water Distribution D3 Exam Prep FREE Sample Exam

The free chlorine in a sample consists of the sum of which two chemical forms?

Chloramine plus ammonia

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Hypochlorous acid plus hypochlorite ion

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Hydrochloric acid plus chloride under the conditions described in this situation

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Ozone plus dissolved oxygen

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As part of a recoating estimate for a round tank 28 ft in diameter, the crew needs the interior side-wall area that stays submerged when the tank carries 12 ft of water. Compute that submerged wall area.

527.79 sq ft

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12,111.15 sq ft

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1,055.58 sq ft

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336.00 sq ft

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Heavy tuberculation has shrunk the open bore of a main, yet the system keeps pushing the same flow through it. Beyond the added roughness, why does head loss climb even further in this main?

The smaller bore slows the water down, and slow water drags against the pipe wall for a longer time before it can get through the narrowed reach of pipe

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The deposits give off heat as they grow, and warmer water always loses more head in a main

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The flow begins to run uphill through the deposits, adding elevation lift that was not there before

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The same flow squeezed through a smaller bore must move faster, and the higher velocity raises friction loss still more

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An atmospheric vacuum breaker protects a connection by doing what when supply pressure is lost?

Opening an air inlet that admits air and breaks the siphon before contaminated water can be drawn back

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Closing a spring-loaded check that seals the outlet against any pressure coming from downstream and holds it closed until a worker resets the assembly by hand

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Discharging water from a relief port until the downstream pressure falls below the supply pressure

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Raising the outlet above the flood rim of the fixture so a physical air gap is formed in the piping

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A well pump delivers 850 gpm against a total head of 118 ft at a pump efficiency of 74 percent. Calculate the brake horsepower required.

34.23 hp

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25.33 hp

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18.74 hp

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41.08 hp

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On a gas chlorinator, what operating loss will stop chlorine feed even when the cylinder still holds gas?

Loss of the paint finish on the outside of the cylinder

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A rise in the temperature of the room housing the feeder during a warm afternoon

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Loss of the vacuum that draws the gas through the chlorinator

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A change in the color of the solution in the sight glass

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When a replacement pump is being selected from manufacturers’ curves, what must its curve do at the station’s required duty?

Reach the highest shutoff head of any pump offered, regardless of the flow delivered at duty

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Stay below the system curve at every flow, so the pump is never asked to work very hard

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Pass through the required flow and head duty point

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Match the physical casing dimensions of the old pump, which guarantees the duty is met

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A cylindrical tank is 9 ft in diameter with a water depth of 11 ft. How many gallons of water does it hold?

1,307.94 gal

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5,231.77 gal

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698.94 gal

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10,463.54 gal

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A sampling crew arrives at a selected high-risk home and, out of habit, flushes the tap for several minutes before filling the lead and copper sample bottle. Why is that sample compromised?

The sample is fine because flushing is required before every sample of every kind in distribution work

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The sample is compromised only because the bottle was filled during daylight rather than at night

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Flushing improves the sample by removing the water that had contacted the household lead plumbing

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Lead and copper samples must be first-draw after standing in the plumbing

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Operators checking a transmission main read the master meter: 900 gallons per minute are passing through pipe whose inside bore is 1.25 ft across. From these readings, find how fast the water is traveling, in feet per second.

0.81 ft/s

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3.26 ft/s

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1.30 ft/s

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1.63 ft/s

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A contractor excavates a trench for a new main: 52 ft in length, 4 ft across, and 5 ft deep. Billing is per cubic yard of soil removed. How many cubic yards should appear on the bill?

1040.00 cubic yards

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19.26 cubic yards

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38.52 cubic yards

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77.04 cubic yards

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Which activity is a recognized source of organic contaminants in a water supply?

Groundwater dissolving calcium and magnesium out of limestone as it moves through the formation over many years

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Industrial discharges releasing organic chemicals into the water

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Corrosion of household plumbing slowly releasing dissolved metals into water standing in the pipes

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Rainwater picking up dissolved minerals from bare rock on hillsides far above the intake structure

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California Water Distribution D3 Exam Prep FREE Sample Exam — Fixed Set

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