WASTEWATER CLASS 4 EXAM VIRGINIA
2025
In an electrical circuit, the grounding wire is indicated by which color? -
Answer ✔✔Green
According to the Ohms Law, which electrical unit measures pressure? -
Answer ✔✔Volts
According to the Ohms Law, which electrical unit measures resistance? -
Answer ✔✔Ohms
According to the Ohms Law, which electrical unit measures current? -
Answer ✔✔Amps
How do you convert cubic feet to gallons? - Answer ✔✔Multiply by
7.48
How do you convert gallons to pounds? - Answer ✔✔Multiply by 8.34
Calculate the SVI of your aeration basin when your 30-minute settleable
sample is 360 mL/L and your average mixed liquor suspended solids
concentration is 4000 mg/L. - Answer ✔✔90
,Solution:
360 x 1,000
------------- = 90
4,000
What is the most widely used dechlorination agent in a conventional
chlorine gas plant? - Answer ✔✔Sulfur Dioxide
What is the most prominent concern in failing to remove grit from the
wastewater? - Answer ✔✔Excessive wear and damage on mechanical
equipment
What is the chemical formula for Sulfuric Acid? - Answer ✔✔H2SO4
What is the ideal velocity in a grit channel, in feet per second? - Answer
✔✔1 fps
Conventional pump packing should be: - Answer ✔✔Tightened down to
a drip
In a primary clarifier, the expected performance for removing settleable
solids is 90-95% removal. What about the removal of suspended solids?
- Answer ✔✔50%
, When preparing a sample for laboratory analysis that involves acid and
water, how should the sample be poured? - Answer ✔✔Always pour the
acid into the water
You are tasked with recording a manual flow sample in an open channel.
Where will you position yourself, relative to the weir, to record the most
accurate measure of flow? - Answer ✔✔Behind the weir, 4 times the
maximum head of the weir
Why must a positive displacement pump never be started against a
closed discharge valve? - Answer ✔✔Excessive pressure may damage
the line, the pump, and the motor
A circular tank is 45 feet in diameter and has a depth of 10 feet. What is
the detention time in hours when the flow is 1.42 MGD? - Answer ✔✔2
hours
Solution:
0.785 x 45 x 45 x 10 x 7.48 x 24
----------------------------------- = 2.038
1,420,000
What is the most common device for measuring flow in an open
channel? - Answer ✔✔V-notch weir, then ultrasonic flowmeter.
2025
In an electrical circuit, the grounding wire is indicated by which color? -
Answer ✔✔Green
According to the Ohms Law, which electrical unit measures pressure? -
Answer ✔✔Volts
According to the Ohms Law, which electrical unit measures resistance? -
Answer ✔✔Ohms
According to the Ohms Law, which electrical unit measures current? -
Answer ✔✔Amps
How do you convert cubic feet to gallons? - Answer ✔✔Multiply by
7.48
How do you convert gallons to pounds? - Answer ✔✔Multiply by 8.34
Calculate the SVI of your aeration basin when your 30-minute settleable
sample is 360 mL/L and your average mixed liquor suspended solids
concentration is 4000 mg/L. - Answer ✔✔90
,Solution:
360 x 1,000
------------- = 90
4,000
What is the most widely used dechlorination agent in a conventional
chlorine gas plant? - Answer ✔✔Sulfur Dioxide
What is the most prominent concern in failing to remove grit from the
wastewater? - Answer ✔✔Excessive wear and damage on mechanical
equipment
What is the chemical formula for Sulfuric Acid? - Answer ✔✔H2SO4
What is the ideal velocity in a grit channel, in feet per second? - Answer
✔✔1 fps
Conventional pump packing should be: - Answer ✔✔Tightened down to
a drip
In a primary clarifier, the expected performance for removing settleable
solids is 90-95% removal. What about the removal of suspended solids?
- Answer ✔✔50%
, When preparing a sample for laboratory analysis that involves acid and
water, how should the sample be poured? - Answer ✔✔Always pour the
acid into the water
You are tasked with recording a manual flow sample in an open channel.
Where will you position yourself, relative to the weir, to record the most
accurate measure of flow? - Answer ✔✔Behind the weir, 4 times the
maximum head of the weir
Why must a positive displacement pump never be started against a
closed discharge valve? - Answer ✔✔Excessive pressure may damage
the line, the pump, and the motor
A circular tank is 45 feet in diameter and has a depth of 10 feet. What is
the detention time in hours when the flow is 1.42 MGD? - Answer ✔✔2
hours
Solution:
0.785 x 45 x 45 x 10 x 7.48 x 24
----------------------------------- = 2.038
1,420,000
What is the most common device for measuring flow in an open
channel? - Answer ✔✔V-notch weir, then ultrasonic flowmeter.
