Texas Wastewater Operator Class D Exam Prep FREE Sample Exam

A wastewater operator license remains valid for what period of time before renewal comes due?

One year only

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Two years only

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Five years only

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Three years

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While crews are cleaning up a wastewater spill, a reporter asks an operator on site what caused it and how much spilled. The cause is not yet known. What is the most appropriate response?

Offer a best guess about the likely cause so the news story can run on time tonight anyway

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State a spill volume figure even though it has not been measured

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Decline to speculate and refer the reporter to the utility's designated spokesperson

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Tell the reporter that no spill occurred

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What does the average daily flow of a treatment plant describe?

The total flow received over a period divided by the number of days in that period

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The highest flow rate that the plant reaches during any single hour of operation

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The flow that happens to be measured at exactly midnight on each day of the period

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The rated flow capacity that is printed on the nameplate of the plant's largest pump

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A force main loses capacity over several weeks, pump run times lengthen, and the trouble traces to the highest point on the profile. What appurtenance at that high point addresses the cause?

A gate valve left partly closed at the low point

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An air release valve that vents trapped air from the high point

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A cleanout cap on the nearest lateral

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A check valve installed at the pump discharge only and nowhere else on the run

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Grit and solids keep building up on the floor of the screen channel ahead of the bars, narrowing the channel between cleanings. What flow condition causes that?

Approach velocity too low to keep the material carried through the channel

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Approach velocity high enough to scour the channel clean than the design flow of the plant

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Bar spacing wider than the channel itself

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Rake cycles running more often than designed

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Three mechanics will service a clarifier drive together, and the equipment must stay de-energized until every one of them is clear. How does a group lockout accomplish that?

The shift supervisor holds the only lock key in a desk drawer and promises the crew he will not start it until they report back to him in person

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Each worker applies a personal lock to a multi-lock device, so the equipment cannot be re-energized until all locks are removed

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One lock is applied and each worker keeps a photograph of it

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The breaker is taped open and a note is left on the panel

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A rectangular primary tank measures 28 ft long by 14 ft wide, and the wastewater in it is 7.5 ft deep. How many gallons does it hold?

21,991.20 gallons

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2,940 gallons

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29,321.60 gallons

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10,995.60 gallons

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A pond cell is found to be losing level faster than evaporation explains, and a crack is suspected in its liner. Why is repairing the liner a water-quality priority?

A leaking liner lets pond wastewater seep downward where it can contaminate groundwater supplies

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A leaking liner lets groundwater flow upward and dilute the pond contents beyond permit limits

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A leaking liner mainly wastes treated water that the plant had planned to sell for irrigation

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A leaking liner allows algae to escape the pond and take root in the surrounding native grasses

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A return rate is left low all weekend. On Monday the clarifier sludge smells septic and chunks of it are rising to the surface. What caused this?

Sludge sat too long in the clarifier, turned septic, and gas lifted pieces of it

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The sludge settled too well over the weekend and became too heavy to pump out

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Fresh influent diluted the contents of the clarifier more than usual that week

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The clarifier received far too much return flow all weekend from the basin

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A laboratory report lists an effluent result in milligrams per liter and a sludge cake result as a percent. An operator comparing the two numbers directly would be making what mistake?

Reading the report from the top down instead of from the bottom up

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Comparing results from two samples that were collected on different days

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Using a report that the laboratory printed rather than wrote out by hand

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Ignoring the units, which describe different kinds of quantities that cannot be compared as written

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Which statement about chlorine dioxide as a wastewater disinfectant is correct?

It is the only disinfectant that leaves a chlorine residual in stored effluent

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It disinfects by light energy, so its output falls as its lamps age

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It must be stored as a pressurized gas in cylinders between uses

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It remains effective over a wider range of pH values than free chlorine does

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An effluent filter is placed after secondary treatment at a plant that needs a cleaner discharge. What is its primary job?

To add back a chlorine residual that the secondary treatment step removed

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To remove suspended solids that carried over from secondary treatment

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To grow a new biological population to replace the secondary process

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To thicken waste sludge before it is sent to digestion

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Texas Wastewater Operator Class D Exam Prep FREE Sample Exam — Fixed Set

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