Wastewater D License Exam ACTUAL
QUESTIONS AND CORRECT ANSWERS
How many PPB equals one PPM? - CORRECT ANSWERS One thousand parts per billion
equals one part per million
If the bubbler system air supply line at the wet well is clogged, what will this cause the pump to
do? - CORRECT ANSWERS Pressure build up in the supply line would signal more water
column then there really was, causing the pump to run longer than necessary, possibly not kick
off and run continually
If the bubbler system air supply line at the wet well has a hole in it above the water level, what
will this cause the pump to do? - CORRECT ANSWERS It would cause a low pressure
reading showing a lower water level then there really is, or possible not even kicking on the
pump
What is the best way to keep within the operating budget? - CORRECT ANSWERS keep
list of purchases and expenses to date during fiscal year
comparisons should be made with budget allocations to avoid excess purchases
review purchases monthly and compare to budget
If a diaphragm pump has 2 check valves open, what will the pump do? - CORRECT
ANSWERS It would not pump properly because 1 check valve should be shut while the
other is open
,A suction lift pump on the inlet side normally reads 2in of mercury on the psi vacuum gauge but
not reads 3in of mercury. What is the problem with the pump? - CORRECT ANSWERS A
higher vacuum than normal may indicate a partially plugged or restricted suction line.
A lower vacuum may indicate a higher wet well level or a worn pump impeller or wearing rings.
One mg per L equals how many pounds per 1 MG? - CORRECT ANSWERS 8.34
What is the proper way to put packing in a pump? - CORRECT ANSWERS cut the
packing rope about 45 degree angle, place around shaft, be sure to offset/stagger the next joint
from the previous
How many drips of water should you have coming out of a packing seal? - CORRECT
ANSWERS no drip on a mechanical seal
How many drips of water should you have coming out of a packing seal? 2 - CORRECT
ANSWERS what the operation and maintenance manual recommends
A one horsepower motor that runs on 110 volts using 10 amps has what efficiency? - CORRECT
ANSWERS most motors run from 80-95% efficiency
A motor that has 440 volt supply is usually what phase of power? - CORRECT
ANSWERS 3 phase
NPDES - CORRECT ANSWERS National Pollutant Discharge Elimination System
,the regulatory agency document issued by either a federal or state agency which is designed to
control all discharges of pollutants from point sources into US waterways - CORRECT
ANSWERS NPDES permit
What is the name of our operating permit? - CORRECT ANSWERS NPDES
What is the best way to promote safety in the workplace? - CORRECT ANSWERS the
supervisor needs to be safe and promote safety in such a manner to get the employees involved
What is normally used to raise the pH in sludge? - CORRECT ANSWERS lime
What is the common device used to measure the effluent of a lagoon? - CORRECT
ANSWERS v notch weir
What concentration of H2S is unsafe to humans? - CORRECT ANSWERS death in a few
minutes at 0.2%. Paralyzes respiratory center
What is the minimum O2 concentration that is safe for workers to enter a manhole? - CORRECT
ANSWERS If O2 is less than 19.5%, do not enter space without respiratory protection.
Normal air contains 20.93% of O2.
Normal air contains ______% of O2 - CORRECT ANSWERS 19.5%
What knob is turned to control the usage of chlorine applied? - CORRECT
ANSWERS rotameter
Can you store BOD at 4C for 48 hours? - CORRECT ANSWERS yes
, What is the minimum velocity of the water flow for a grit chamber and the maximum flow? -
CORRECT ANSWERS 1.0 feet per second minimum
1.5 feet per second optimum
2.0 feet per second maximum
How many mg/L equals one grain per gallon? - CORRECT ANSWERS 17.1 mg/L
Dissolved oxygen increases when the temperature __________ - CORRECT
ANSWERS decreases
You can tell if a clarifier scraper arm is working by what means? - CORRECT
ANSWERS the simplest is to visual check to see if the scum scraper arm is moving
properly
check into foam
If the sludge is thick or thin, then what does this tell you about the sludge scraper? - CORRECT
ANSWERS possible answer is the flights are damaged or the speed of the scrapers(flights)
need to be increased if sludge is too thick
or slowed down if the sludge is too thin
aging and maturing of a body of water - CORRECT ANSWERS eutrophication
eutrophication - CORRECT ANSWERS aging and maturing of a body of water
QUESTIONS AND CORRECT ANSWERS
How many PPB equals one PPM? - CORRECT ANSWERS One thousand parts per billion
equals one part per million
If the bubbler system air supply line at the wet well is clogged, what will this cause the pump to
do? - CORRECT ANSWERS Pressure build up in the supply line would signal more water
column then there really was, causing the pump to run longer than necessary, possibly not kick
off and run continually
If the bubbler system air supply line at the wet well has a hole in it above the water level, what
will this cause the pump to do? - CORRECT ANSWERS It would cause a low pressure
reading showing a lower water level then there really is, or possible not even kicking on the
pump
What is the best way to keep within the operating budget? - CORRECT ANSWERS keep
list of purchases and expenses to date during fiscal year
comparisons should be made with budget allocations to avoid excess purchases
review purchases monthly and compare to budget
If a diaphragm pump has 2 check valves open, what will the pump do? - CORRECT
ANSWERS It would not pump properly because 1 check valve should be shut while the
other is open
,A suction lift pump on the inlet side normally reads 2in of mercury on the psi vacuum gauge but
not reads 3in of mercury. What is the problem with the pump? - CORRECT ANSWERS A
higher vacuum than normal may indicate a partially plugged or restricted suction line.
A lower vacuum may indicate a higher wet well level or a worn pump impeller or wearing rings.
One mg per L equals how many pounds per 1 MG? - CORRECT ANSWERS 8.34
What is the proper way to put packing in a pump? - CORRECT ANSWERS cut the
packing rope about 45 degree angle, place around shaft, be sure to offset/stagger the next joint
from the previous
How many drips of water should you have coming out of a packing seal? - CORRECT
ANSWERS no drip on a mechanical seal
How many drips of water should you have coming out of a packing seal? 2 - CORRECT
ANSWERS what the operation and maintenance manual recommends
A one horsepower motor that runs on 110 volts using 10 amps has what efficiency? - CORRECT
ANSWERS most motors run from 80-95% efficiency
A motor that has 440 volt supply is usually what phase of power? - CORRECT
ANSWERS 3 phase
NPDES - CORRECT ANSWERS National Pollutant Discharge Elimination System
,the regulatory agency document issued by either a federal or state agency which is designed to
control all discharges of pollutants from point sources into US waterways - CORRECT
ANSWERS NPDES permit
What is the name of our operating permit? - CORRECT ANSWERS NPDES
What is the best way to promote safety in the workplace? - CORRECT ANSWERS the
supervisor needs to be safe and promote safety in such a manner to get the employees involved
What is normally used to raise the pH in sludge? - CORRECT ANSWERS lime
What is the common device used to measure the effluent of a lagoon? - CORRECT
ANSWERS v notch weir
What concentration of H2S is unsafe to humans? - CORRECT ANSWERS death in a few
minutes at 0.2%. Paralyzes respiratory center
What is the minimum O2 concentration that is safe for workers to enter a manhole? - CORRECT
ANSWERS If O2 is less than 19.5%, do not enter space without respiratory protection.
Normal air contains 20.93% of O2.
Normal air contains ______% of O2 - CORRECT ANSWERS 19.5%
What knob is turned to control the usage of chlorine applied? - CORRECT
ANSWERS rotameter
Can you store BOD at 4C for 48 hours? - CORRECT ANSWERS yes
, What is the minimum velocity of the water flow for a grit chamber and the maximum flow? -
CORRECT ANSWERS 1.0 feet per second minimum
1.5 feet per second optimum
2.0 feet per second maximum
How many mg/L equals one grain per gallon? - CORRECT ANSWERS 17.1 mg/L
Dissolved oxygen increases when the temperature __________ - CORRECT
ANSWERS decreases
You can tell if a clarifier scraper arm is working by what means? - CORRECT
ANSWERS the simplest is to visual check to see if the scum scraper arm is moving
properly
check into foam
If the sludge is thick or thin, then what does this tell you about the sludge scraper? - CORRECT
ANSWERS possible answer is the flights are damaged or the speed of the scrapers(flights)
need to be increased if sludge is too thick
or slowed down if the sludge is too thin
aging and maturing of a body of water - CORRECT ANSWERS eutrophication
eutrophication - CORRECT ANSWERS aging and maturing of a body of water
