Practice Test
1. Estimate the detention time for a rectangular basin that has a flow of 2.4 MDG. The basin is 30 feet long, 17 feet wide, and 9 feet deep. a. 15 min b. 20 min c. 25 min d. 30 min
2. Calculate the correct setting for a dry alum feeder in pounds per day if jar testing shows the optimum dose is 12 mg/L and plant flow is 5.4 MGD a. 500 lb/day b. 450 lb/day c. 540 lb/day d. 480 lb/day
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3. If plant flow averages 3.2 MGD, calculate how many pounds of polymer will be required to feed the plant at a dose of 2.1 mg/L for 14 days. a. 785 lb b. 625 lb c. 750 lb d. 830 lb
4. If 30 pounds of cationic polymer were consumed to treat 2.7 million gallons of water in a 24 hour period, what was the polymer dose in mg/L? a. 0.9 mg/L b. 1.1 mg/L c. 1.3 mg/L d. 1.5 mg/L
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Practice Test
5. How much liquid polymer that is a 7% solution should be added to a 200 gallon mix tank to produce a 0.5% solution? a. 12.5 gal b. 13.2 gal c. 14.3 gal d. 15.3 gal
6. A liquid alum solution used to treat water contains 643 mg of alum for each ml of solution. Jar testing shows that the optimum dose is 11 mg/L. Find the setting in ml/min for the alum feed pump if plant flow is 3 MGD. a. 125 ml/min b. 135 ml/min c. 145 ml/min d. 155 ml/min
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7. Calculate the volume of water in gallons of a tank with a diameter of 25 feet that has 12 feet of water in it. a. 41,039 gal b. 42,039 gal c. 43,039 gal d. 44,039 gal
8. How much does a 55 gallon drum weigh if it is full of water? (ignore the weight of the drum) a. 479 lb b. 469 lb c. 459 lb d. 449 lb
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Practice Test
9. Calculate the surface area of a circular clarifier with a 15 foot radius. a. 607 ft2 b. 707 ft2 c. 807 ft2 d. 997 ft2
10. How much copper sulfate is required to produce a concentration of 0.6 mg/L of copper in a 15 million gallon reservoir? (copper sulfate is 25% copper) a. 300 lb b. 400 lb c. 350 lb d. 75 lb
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11. Calculate the surface loading rate for a plant flowing 1.8 MGD and a sedimentation basin that measures 70 feet long by 30 feet wide. a. 12 gpm/ft2 b. 6 gpm/ft2 c. 0.6 gpm/ft2 d. 0.12 gpm/ft2
12. Find the weir loading rate in gpm/ft if plant flow is 1.2 MGD and the combined weir length is 30 feet. a. 28.7 gpm/ft b. 27.8 gpm/ft c. 23.4 gpm/ft d. 24.3 gpm/ft
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Practice Test
13. Calculate the filtration rate in gpm/ft2 for a treatment plant flowing 1.4 MGD with 540 ft2 of filter surface area. a. 1.4 gpm/ft2 b. 5.0 gpm/ft2 c. 4.2 gpm/ft2 d. 1.8 gpm/ft2
14. If there is 6 feet of head on a gravity filter, what is the pressure in psi on the filter surface? a. 2.6 psi b. 1.6 psi c. 3.6 psi d. 4.6 psi
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15. Calculate the upward force in lb on the bottom of an empty tank due to 4 feet of ground water above the tank bottom. The tank bottom has a surface area of 250 ft2. a. 45,400lb b. 54,500 lb c. 62,400 lb d. 74,800 lb
16. What percent of finished water is used for backwashing if 25,000 gallons is used for each 1.5 million gallons produced? a. 2.8 % b. 1.7% c. 3.4% d. 5.6%
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Practice Test
17. Calculate the flow rate in gpm of water flowing through an 18 inch pipe at 3 feet per second. a. 2,475 gpm b. 2,380 gpm c. 1,270 gpm d. 950 gpm
18. Estimate the flow velocity in a channel in which a float travels 30 feet in 15 seconds. a. 5 ft/sec b. 4 ft/sec c. 3 ft/sec d. 2 ft/sec
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19. If a chlorine cylinder weighs 1400 lb at 12:00 p.m. and later weighs 1380 lb at 8:00 p.m., find the dose in pounds per day. a. 40 lb/day b. 50 lb/day c. 60 lb/day d. 70 lb/day
20. What is the chlorine demand of water being treated with a dose of 2.5 mg/L chlorine and has a residual of 1.6 mg/L after 30 minutes? a. 4.1 mg/L b. 1.1 mg/L c. 0.9 mg/L d. 1.8 mg/L
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Practice Test
21. What is the wire to water efficiency of a pump if water HP is 8 and the power input is 11 HP? a. 66% b. 71 % c. 73% d. 78%
22. Find the Motor HP required if the water HP required is 40 HP and the pump efficiency is 75% and the motor efficiency is 88%. a. 59.8 HP b. 60.6 HP c. 61.4 HP d. 64.0 HP
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23. A temperature of 80oF is equivalent to how many degrees Celsius? a. 27oC b. 28oC c. 29oC d. 30oC
24. A temperature of 12oC is the same as how many degrees Fahrenheit? a. 44oF b. 54oF c. 64oF d. 34oF
25. How long should a 60 feet long sample with a pipe ¾ inch diameter be flushed with a flow of 0.5 gpm if you need to flush two line volumes before sampling? a. 2.5 min b. 3.25 min c. 5.5 min d. 4.5 min
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