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What is a possible cause of a back siphonage condition in a water line?
A leak in the water line
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The Chlorine dosage minus the Chlorine demand equals what?
Total chlorine residual
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What are four characteristics of a pump curve?
Capacity (gpm), total dynamic head, brake horsepower, pump efficiency
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What is the log removal or inactivation required for viruses?
4.0 log
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Most colloidal material from the raw water should be removed by what- method in a properly designed and operated treatment plant?
Disinfection
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Which is the most likely to occur if the finished water pH is too high?
Scaling in mains
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At what temperature does water achieve the greatest density?
4 degrees C
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"The process wherein electrostatic forces cause a chemical bridging of enmeshment of colloidal particles into discrete, visible, suspended particle that will readily settle under the influence of gravity", best describes:
Flocculation
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After rehabilitation, a pipeline segment should be disinfected, flushed, and:
Tested for bacteria
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The main sources of hardness in water are:
Calcium and magnesium
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Noncarbonate hardness equals:
Total hardness minus total alkalinity
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What can interfere with the chlorine residual in the distribution system?
Turbidity, temperature of water, organics, ammonia
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Which of the following violations for the National Interim Primary Drinking Water Regulations require public notification?
- Failure to monitor
- MCL violation
- Failure to comply with an approved test procedure
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Which chemical is commonly used to remove noncarbonate hardness?
Sodium carbonate
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What should be done if greater than 3% of total water production is used for filter backwashing?
Improve filter influent water quality
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Which is the approved method for chlorine testing?
DPD
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What type of meter measures turbidity?
Nephelometric
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Which gas increases during aeration?
Oxygen
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When placing a new main in service, what is the last test performed?
Flow
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What chemical is used for recarbonation?
Carbon dioxide
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In an ion exchange system, what is the purpose of the rinse cycle?
Remove unused salt
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At what temperature will the fusible plugs in a chlorine cylinder melt?
71 to 74 degrees C
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How many samples must be collected after a positive coliform test?
4
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One use of polyphosphate in water treatment is:
Keeps iron and manganese in solution
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As the temperature of the water is decreased, what will occur?
Viscosity will increase, CaOH solubility will increase
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What problem would likely occur if a well screen were not properly gravel packed?
Erosion
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A 5 ml water sample showed 43 colonies. What is the reported value?
860 colonies/100 ml
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What is the recommended free chlorine residual for the farthest point in the distribution system?
0.20 mg/L
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Which of the following conditions can improper backwashing cause?
Mudball formation and/or gravel displacement
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The primary function of a clarifier is:
Permit floc to settle
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Which bacteria are used as an indicator in water testing?
Coliform
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Which valve should be used to slowly refill a dry rapid sand filter?
Backwash
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As a pump moves water from the clearwell to elevated storage, the level in the clearwell drops 8 feet. What happens to the pump head?
Increases by 8 feet
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What would the operator expect to see if the lime dosage is twice what is required for softening?
Incrustation will increase
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Which of the following chlorine chemicals is not used for disinfection?
Dichloromethane
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The primary function of a flocculator is:
Build floc
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What is the most common type of valve used in water distribution systems?
Gate valves
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Which one of the following causes black staining?
Manganese
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What is the MCL for Nitrate-Nitrogen in drinking water?
10 mg/l
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Double the required alum dosage will result in what?
Lowering the pH
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What is the effect of slow flocculator tip speed?
Premature settling
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If a system has a regular bacteria sample show total coliform positive, what must be done within 24 hours?
Collect repeat samples
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"The addition of a chemical to a colloidal dispersion resulting in particle destabilization by a reduction of the forces tending to deep the particles apart" best describes:
Coagulation
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The main function of a rapid sand filter is:
Straining
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Which of the following is the most effective disinfectant?
Free available chlorine
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The term for the pressure against which a pump must operate is:
Head
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What is the optimum fluoride level for finished water in Ohio?
1.0 mg/l
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Which is not used for softening?
Ferric sulfate
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Where should potassium permanganate, KMnO4, be applied?
Raw water
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Where is the best location to store a self contained breathin apparatus?
In the closest adjacent room
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