California Water Distribution D4 Exam Prep FREE Sample Exam

Winter water is cold and disinfection is slower, but a contact tank cannot be held longer this week because the system needs its storage back for supply security each morning. The residual, however, has room to rise within its normal operating band. What is the chief operator’s soundest way to protect the disinfection credit?

Accept the lower credit, because cold water also preserves the residual longer

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Raise the residual during the hold so the residual-times-time product is restored at the shorter contact time

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Warm the tank contents with the building heating system before each hold period and keep them warm until the tank returns to service each morning

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Credit the tank with summer contact-time values until the weather turns warmer

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The crew disinfecting a coastal well will chlorinate from the liquid product on the truck: sodium hypochlorite at 10% available chlorine, weighing 9.8 lb per gallon. The job covers 0.09 MG of water and the foreman has set the dose at 26 mg/L. How many gallons of the liquid product must the crew draw?

16.58 gallons

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23.90 gallons

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21.75 gallons

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19.91 gallons

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Before cleaning, a main at a set flow had a steep hydraulic gradient. After the main is cleaned and the same flow is restored, its gradient is noticeably flatter. What is the sound conclusion?

Cleaning reduced the friction in the main, so less head is now consumed per unit length at that flow

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Cleaning raised the friction in the main, and the flatter line is only an error in the new gauge readings

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The gradient change proves the main's diameter was permanently enlarged by the cleaning equipment used

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No conclusion is possible, because a gradient measured after cleaning can never be compared with one before

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What do accumulated run-time records for pumps and motors primarily enable a chief operator to do?

Prove that a pump has never operated outside its warranty period

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Schedule inspections, lubrication, and overhauls by actual use rather than by guesswork or breakdown

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Replace the need for any pressure or flow testing of the equipment

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Set the retail water rate charged to customers served by the station under all operating conditions the station will ever be expected to see

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A well pump must deliver 620 gallons per minute against a total head of 140 feet. Its efficiency at that duty is 72 percent. Calculate the brake horsepower required.

25.36 hp

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30.44 hp

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36.62 hp

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21.92 hp

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Under the Lead and Copper Rule, an action-level exceedance is judged on what basis?

The 90th-percentile value of the tap samples, compared against the action level

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The single highest tap sample collected anywhere in the system during the round

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The average of every tap sample collected during the monitoring round

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The result from the sample collected closest to the treatment plant entry point

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A confirmed result establishes a maximum contaminant level violation. A sample taken weeks later is below the level. What is the status of the violation?

It stands — the violation must still be addressed through the required notification and correction, despite the later lower result

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It is cancelled automatically, because any later passing result erases an earlier violation

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It never existed, because the later result is the most recent information about the system

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It converts into a secondary-standard issue, because time has passed since the confirmed result, because the newest laboratory report is always the one that decides whether a violation ever existed in the first place

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A Grade D4 distribution operator is planning continuing education for the upcoming renewal and wants the total for the full cycle. The certificate renews on a 3-year cycle — how many contact hours in total must be completed during that cycle?

12 contact hours per 3-year renewal cycle, which is the requirement associated with the lowest distribution grade level in California

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16 contact hours per 3-year renewal cycle, which is the requirement associated with the second distribution grade level in California

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24 contact hours per 3-year renewal cycle, which is the requirement associated with the third distribution grade level in California

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36 contact hours per 3-year renewal cycle

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A planning study projects a population of 72,500 people using 120 gallons per person per day. What is the estimated future water need?

6.04 MGD

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8.70 MGD

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9.60 MGD

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7.25 MGD

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A recently lined main has picked up loose sediment and stale water after a repair shutdown, and the lining must not be damaged by aggressive scraping. Which cleaning choice is proportionate?

Drive a hard pig through the lined section repeatedly until the walls are scraped bare, because lining damage is an acceptable cost of cleaning

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Use air scouring at maximum intensity as the first step, before trying any gentler method on a main whose deposits are loose and light

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Cut out the lined section and replace it, because loose sediment after a shutdown can never be removed by any cleaning method available

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Flush the main with system water to carry out the loose material without attacking the lining

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A crew verifying a new source meter runs water through a short test spool fitted with a velocity probe. The spool’s cross-section measures 0.85 sq ft and the probe reads 2.35 ft/s. How much water is the spool passing, in gallons per minute?

448.80 gpm

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896.46 gpm

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1,346.40 gpm

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2.00 gpm

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Which description fits a confined aquifer?

It lies open to the ground surface along its whole length, so rain anywhere above it enters the formation immediately

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It is a layer of clay at the surface that stores water tightly and is pumped directly as the producing formation

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It is sandwiched between low-permeability layers, and its water is under pressure within the formation

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It has no confining beds and no pressure, so a well in it can never rise above the top of the formation

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California Water Distribution D4 Exam Prep FREE Sample Exam — Fixed Set

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