WATER OPERATOR LEVEL "C" CERTIFICATION: EXAM
STUDY QUESTIONS WITH COMPLETE SOLUTIONS
1) What is an Ampere? -- Answer ✔✔ a unit of measurement for current
2) what is usually indicated when at sample point "A" in a water main a high DO reading
is obtained, and at sample point "B" downstream, the DO reading is substantially
lower? -- Answer ✔✔ corrosion
3) when is THM formation more likely to occur? -- Answer ✔✔ spring and fall
4) with what material is hydrochloric acid highly reactive? -- Answer ✔✔ metals
5) sand drying beds are similar in construction to ? -- Answer ✔✔ gravity sand filters
6) calculate the langlier index where the PH = 8.8, and the PHs is 8.3 -- Answer ✔✔
+0.5
,7) a positive langlier index is _______. -- Answer ✔✔ scale forming
8) what do we call a detailed description of all underground features discovered during
well drilling? -- Answer ✔✔ geological log
9) what information is need to calculate the PHs for the langlier index? -- Answer ✔✔
temp, TDS, Alkalinity, Calcium hardness
10) what process is commonly used to remove volatile organics from water? -- Answer
✔✔ polyphosphates
11) how often must a water system test for radionuclides? -- Answer ✔✔ 3 yrs
12) calculate the amount of water needed to backwash a 360 sq ft dilter at 9000 gpm.
the backwash duration is 8 minutes. -- Answer ✔✔ 72,000 gal
13) in January a 6 ppm Cl2 dosage produced a 2.0 ppm residual. In July an 8 ppm dosage
produced a 1.5 ppm residual. what is most likely the cause for the lower chlorine
residual? -- Answer ✔✔ increase in water temperature
14) why is recarbonation necessary when lime softening is used to reduce excessive
hydroxide hardness? -- Answer ✔✔ reduce the scale forming tendencies of the
supersaturated H2O
,15) In hot water systems, scaling is a problem because _________ is less soluble in hot
H2O than it is in cold H2O. -- Answer ✔✔ calcium carbonate
16) what is the primary purpose of filters in a WTP? -- Answer ✔✔ lower turbidity
17) a WTP meets or exceeds all treatment parameters. It has started to receive
customer complaints concerning red water in the distribution system. Polyphosphate
is being used in the treatment process. what is most likely causing the red water? --
Answer ✔✔ polyphosphate reverted to orthophosphate
18) a well pump is rated at 6000 gpm at 85% efficiency. the well is 15' long, 12' wide, and
10' deep. if the pump takes 10 minutes to lower the well 5 feet, does it pump higher
or lower than rated? -- Answer ✔✔ 73 gpm, higher
19) what will happen if the recirculation rate for a solid contact unit is too high? --
Answer ✔✔ overflow of slurry to filter
20) if a water sample tests positive for coliform, what action must be taken by the water
system? -- Answer ✔✔ repeat sample 24 hours after notification
21) Many samples for MCL compliance are taken in the distribution system. what sample
is taken where the water enters the distribution system? -- Answer ✔✔ turbidity
22) when taking a hardness test, the titration should be completed within 5 min. An
inhibitor reagent should be used when metal ion interference causes an indistinct
, end point, and _________. -- Answer ✔✔ a sample volume should be selected
which requires less than 15 ml of EDTA titrant.
23) to control THM formation, alternate disinfectants are used including ozone, chlorine
dioxide, and _______. -- Answer ✔✔ chloramines.
24) to insure membrane longevity and slow down hydrolysis, RO plants add _____? --
Answer ✔✔ acid
25) the recovery rate of a membrane softening plant is limited by what two factors? --
Answer ✔✔ desired product h2o quality and mineral content
26) media loss is caused by high backwash rate and air bubbles caused by? -- Answer ✔✔
air binding
27) when alum dosage is decreased, lime dosage may? -- Answer ✔✔ decrease
28) what will happen if the brine valve in an RO unit is fully closed? -- Answer ✔✔ 100%
recovery and damage to the membranes
29) the plant operator is having difficulty maintaining the sludge blanked in the solids
contact unit. what action is needed? -- Answer ✔✔ adjust recirculation rate
30) how often must the standby generator be operated? -- Answer ✔✔ 4hrs
continuously under load, once a month
STUDY QUESTIONS WITH COMPLETE SOLUTIONS
1) What is an Ampere? -- Answer ✔✔ a unit of measurement for current
2) what is usually indicated when at sample point "A" in a water main a high DO reading
is obtained, and at sample point "B" downstream, the DO reading is substantially
lower? -- Answer ✔✔ corrosion
3) when is THM formation more likely to occur? -- Answer ✔✔ spring and fall
4) with what material is hydrochloric acid highly reactive? -- Answer ✔✔ metals
5) sand drying beds are similar in construction to ? -- Answer ✔✔ gravity sand filters
6) calculate the langlier index where the PH = 8.8, and the PHs is 8.3 -- Answer ✔✔
+0.5
,7) a positive langlier index is _______. -- Answer ✔✔ scale forming
8) what do we call a detailed description of all underground features discovered during
well drilling? -- Answer ✔✔ geological log
9) what information is need to calculate the PHs for the langlier index? -- Answer ✔✔
temp, TDS, Alkalinity, Calcium hardness
10) what process is commonly used to remove volatile organics from water? -- Answer
✔✔ polyphosphates
11) how often must a water system test for radionuclides? -- Answer ✔✔ 3 yrs
12) calculate the amount of water needed to backwash a 360 sq ft dilter at 9000 gpm.
the backwash duration is 8 minutes. -- Answer ✔✔ 72,000 gal
13) in January a 6 ppm Cl2 dosage produced a 2.0 ppm residual. In July an 8 ppm dosage
produced a 1.5 ppm residual. what is most likely the cause for the lower chlorine
residual? -- Answer ✔✔ increase in water temperature
14) why is recarbonation necessary when lime softening is used to reduce excessive
hydroxide hardness? -- Answer ✔✔ reduce the scale forming tendencies of the
supersaturated H2O
,15) In hot water systems, scaling is a problem because _________ is less soluble in hot
H2O than it is in cold H2O. -- Answer ✔✔ calcium carbonate
16) what is the primary purpose of filters in a WTP? -- Answer ✔✔ lower turbidity
17) a WTP meets or exceeds all treatment parameters. It has started to receive
customer complaints concerning red water in the distribution system. Polyphosphate
is being used in the treatment process. what is most likely causing the red water? --
Answer ✔✔ polyphosphate reverted to orthophosphate
18) a well pump is rated at 6000 gpm at 85% efficiency. the well is 15' long, 12' wide, and
10' deep. if the pump takes 10 minutes to lower the well 5 feet, does it pump higher
or lower than rated? -- Answer ✔✔ 73 gpm, higher
19) what will happen if the recirculation rate for a solid contact unit is too high? --
Answer ✔✔ overflow of slurry to filter
20) if a water sample tests positive for coliform, what action must be taken by the water
system? -- Answer ✔✔ repeat sample 24 hours after notification
21) Many samples for MCL compliance are taken in the distribution system. what sample
is taken where the water enters the distribution system? -- Answer ✔✔ turbidity
22) when taking a hardness test, the titration should be completed within 5 min. An
inhibitor reagent should be used when metal ion interference causes an indistinct
, end point, and _________. -- Answer ✔✔ a sample volume should be selected
which requires less than 15 ml of EDTA titrant.
23) to control THM formation, alternate disinfectants are used including ozone, chlorine
dioxide, and _______. -- Answer ✔✔ chloramines.
24) to insure membrane longevity and slow down hydrolysis, RO plants add _____? --
Answer ✔✔ acid
25) the recovery rate of a membrane softening plant is limited by what two factors? --
Answer ✔✔ desired product h2o quality and mineral content
26) media loss is caused by high backwash rate and air bubbles caused by? -- Answer ✔✔
air binding
27) when alum dosage is decreased, lime dosage may? -- Answer ✔✔ decrease
28) what will happen if the brine valve in an RO unit is fully closed? -- Answer ✔✔ 100%
recovery and damage to the membranes
29) the plant operator is having difficulty maintaining the sludge blanked in the solids
contact unit. what action is needed? -- Answer ✔✔ adjust recirculation rate
30) how often must the standby generator be operated? -- Answer ✔✔ 4hrs
continuously under load, once a month
