TEXAS WASTEWATER CLASS C NEWEST 2024-2025 ACTUAL EXAM COMPLETE QUESTIONS AND CORRECT
DETAILED ANSWERS
What device(s) can be used as an emergency shut-off for the drive unit of a circular clarifier? - (answer)
Shear Pins
You are the operator-on-duty. The alarm for the fire detector in the Belt Filter Press Control Room goes
off. What type of fire extinguisher would you take to respond to this alarm? - (answer) Class C
When working in an area with two or more floor coverings (for example, grating and checker-plate), be
sure that they are always _____. - (answer) Secured together
When working in confined spaces where flammable gases may be present, use only toolsmade of -
(answer) A non sparking alloy
A treatment plant should have a valve exercise program in which all plant valves are exercised (opened
and closed) - (answer) Once a year
Immediate first aid for burns is to? - (answer) Flood with cold water
Recommended personal hygiene practices to minimize the risk of being infected by wastewater
pathogens include - (answer) Changing out of your work clothes and showering before leaving work
What is the best protection against the risk of exposure to infections and disease at a wastewater plant?
- (answer) Personal Hygenie
Regarding fire extinguisher training in the workplace. The employer must provide what? - (answer) A
written and practiced emergency action plan.
The combination of methane and which other gas can be very combustible? - (answer) Oxygen
In what location of the sewer manhole would methane gas be found? - (answer) At the top
,TEXAS WASTEWATER CLASS C NEWEST 2024-2025 ACTUAL EXAM COMPLETE QUESTIONS AND CORRECT
DETAILED ANSWERS
Which type of fire is safe for a pressurized water extinguisher or water hose to be used on? - (answer)
Brush
Mixing dry granular chlorine (HTH) with petroleum products can cause which of the following? -
(answer) Create a fire or explosive condition
The fusible plugs found on a 150lb cylinders and one-ton chlorinecontainers are designed to melt at
what temperature range? - (answer) 158-165 degrees Fahrenheit
In the event of a large leak of chlorine is occurring, what is the first action the operator should take? -
(answer) Immediately notify local fire and police departments
A Class C type fire involves? - (answer) Electrical equipment
A common fire extinguisher is AB or ABC type. What is the media contained inside these fire
extinguishers? - (answer) Dry Powder
This toxic gas impairs one's sense of smell rapidly at high concentrations as it paralyses the respiratory
organs. At lower concentrations it has a rotten egg odor. - (answer) Hydrogen Sulfide Gas
Coliform bacteria are: - (answer) More resistant to chlorination than pathogenic bacteria
Coliform bacteria are: - (answer) Indicators
E. Coli results must always be higher or lower than fecal coliform results? - (answer) Lower
Waterborne diseases and illnesses common to the wastewater industryinclude dysentery, hepatitis,
polio, typhoid, and what other disease? - (answer) Cholera
How many fusible plugs are in a 1 ton chlorine container? - (answer) 6
,TEXAS WASTEWATER CLASS C NEWEST 2024-2025 ACTUAL EXAM COMPLETE QUESTIONS AND CORRECT
DETAILED ANSWERS
What is the proper amount of oxygen to enter a confined space? - (answer) 19.5% - 23.5%
Which safety procedure can prevent accidental re-energizing of electrical energy while maintaining a
piece of equipment? - (answer) Use proper LO/TO procedures
If a leak of liquid chlorine occurs, one part of the liquid chlorine can expand to how many parts of
gaseous chlorine at room temperature and average barometric pressure? - (answer) 457 parts of gas.
Chlorine gas is how many times heavier than air? - (answer) 2.5 times
Methane gas is lighter than air - (answer) True
A pump's seal water pressure should be set at - (answer) 5 to 10 psi more than the pump operating
discharge pressure
What does a gradual increase in the bearing temperature of a centrifugal blower indicate? - (answer)
There is a problem with the bearing lubrication or connection
How often should the packing on a gate valve be replaced? - (answer) As required
What is surging in a centrifugal blower? - (answer) When the blower's discharge pressure is less than
the aeration system's backpressure
Pumps are often required to bring wastewater into a treatment plant. What types of pumps are typically
used to lift influent wastewater? - (answer) Centrifugal
If a centrifugal pump loses its prime after starting, what is the most probable cause? - (answer) Air
leaks into the pump through stuffing boxes
, TEXAS WASTEWATER CLASS C NEWEST 2024-2025 ACTUAL EXAM COMPLETE QUESTIONS AND CORRECT
DETAILED ANSWERS
The casing surrounding a pump impeller that collects the water discharged by the impeller is called a
__________. - (answer) Volute
A _____ is installed on the pump discharge piping to prevent water from flowing back across a pump
when it is off. - (answer) Check Valve
Why are check valves used in conjunction with centrifugal pumps? - (answer) To prevent water in the
suction line from flowing back into the wetwell
What separates the impeller from the volute and prevents backflow in a centrifugal pump? - (answer)
Wear Rings
Cavitation is the formation and collapse of a gas pocket or bubble on the blade of a pump's impeller. -
(answer) True
Bar screens must be cleaned frequently to prevent (choose the most correct answer) - (answer) Excess
head loss (slowing down the water moving through the pipe)
What is an air-gap device used for? - (answer) Backflow prevention
Flow - (answer) The amount of fluid to be pumped
Head - (answer) The extent or distance to which fluid is to be exported.
The discharge of a centrifugal pump: - (answer) Decreases with the increase of head, and increases
with the decrease in head
In a centrifugal pump, leakage is prevented by - (answer) Wear rings
Valves should be closed slowly to prevent: - (answer) Water Hammer
DETAILED ANSWERS
What device(s) can be used as an emergency shut-off for the drive unit of a circular clarifier? - (answer)
Shear Pins
You are the operator-on-duty. The alarm for the fire detector in the Belt Filter Press Control Room goes
off. What type of fire extinguisher would you take to respond to this alarm? - (answer) Class C
When working in an area with two or more floor coverings (for example, grating and checker-plate), be
sure that they are always _____. - (answer) Secured together
When working in confined spaces where flammable gases may be present, use only toolsmade of -
(answer) A non sparking alloy
A treatment plant should have a valve exercise program in which all plant valves are exercised (opened
and closed) - (answer) Once a year
Immediate first aid for burns is to? - (answer) Flood with cold water
Recommended personal hygiene practices to minimize the risk of being infected by wastewater
pathogens include - (answer) Changing out of your work clothes and showering before leaving work
What is the best protection against the risk of exposure to infections and disease at a wastewater plant?
- (answer) Personal Hygenie
Regarding fire extinguisher training in the workplace. The employer must provide what? - (answer) A
written and practiced emergency action plan.
The combination of methane and which other gas can be very combustible? - (answer) Oxygen
In what location of the sewer manhole would methane gas be found? - (answer) At the top
,TEXAS WASTEWATER CLASS C NEWEST 2024-2025 ACTUAL EXAM COMPLETE QUESTIONS AND CORRECT
DETAILED ANSWERS
Which type of fire is safe for a pressurized water extinguisher or water hose to be used on? - (answer)
Brush
Mixing dry granular chlorine (HTH) with petroleum products can cause which of the following? -
(answer) Create a fire or explosive condition
The fusible plugs found on a 150lb cylinders and one-ton chlorinecontainers are designed to melt at
what temperature range? - (answer) 158-165 degrees Fahrenheit
In the event of a large leak of chlorine is occurring, what is the first action the operator should take? -
(answer) Immediately notify local fire and police departments
A Class C type fire involves? - (answer) Electrical equipment
A common fire extinguisher is AB or ABC type. What is the media contained inside these fire
extinguishers? - (answer) Dry Powder
This toxic gas impairs one's sense of smell rapidly at high concentrations as it paralyses the respiratory
organs. At lower concentrations it has a rotten egg odor. - (answer) Hydrogen Sulfide Gas
Coliform bacteria are: - (answer) More resistant to chlorination than pathogenic bacteria
Coliform bacteria are: - (answer) Indicators
E. Coli results must always be higher or lower than fecal coliform results? - (answer) Lower
Waterborne diseases and illnesses common to the wastewater industryinclude dysentery, hepatitis,
polio, typhoid, and what other disease? - (answer) Cholera
How many fusible plugs are in a 1 ton chlorine container? - (answer) 6
,TEXAS WASTEWATER CLASS C NEWEST 2024-2025 ACTUAL EXAM COMPLETE QUESTIONS AND CORRECT
DETAILED ANSWERS
What is the proper amount of oxygen to enter a confined space? - (answer) 19.5% - 23.5%
Which safety procedure can prevent accidental re-energizing of electrical energy while maintaining a
piece of equipment? - (answer) Use proper LO/TO procedures
If a leak of liquid chlorine occurs, one part of the liquid chlorine can expand to how many parts of
gaseous chlorine at room temperature and average barometric pressure? - (answer) 457 parts of gas.
Chlorine gas is how many times heavier than air? - (answer) 2.5 times
Methane gas is lighter than air - (answer) True
A pump's seal water pressure should be set at - (answer) 5 to 10 psi more than the pump operating
discharge pressure
What does a gradual increase in the bearing temperature of a centrifugal blower indicate? - (answer)
There is a problem with the bearing lubrication or connection
How often should the packing on a gate valve be replaced? - (answer) As required
What is surging in a centrifugal blower? - (answer) When the blower's discharge pressure is less than
the aeration system's backpressure
Pumps are often required to bring wastewater into a treatment plant. What types of pumps are typically
used to lift influent wastewater? - (answer) Centrifugal
If a centrifugal pump loses its prime after starting, what is the most probable cause? - (answer) Air
leaks into the pump through stuffing boxes
, TEXAS WASTEWATER CLASS C NEWEST 2024-2025 ACTUAL EXAM COMPLETE QUESTIONS AND CORRECT
DETAILED ANSWERS
The casing surrounding a pump impeller that collects the water discharged by the impeller is called a
__________. - (answer) Volute
A _____ is installed on the pump discharge piping to prevent water from flowing back across a pump
when it is off. - (answer) Check Valve
Why are check valves used in conjunction with centrifugal pumps? - (answer) To prevent water in the
suction line from flowing back into the wetwell
What separates the impeller from the volute and prevents backflow in a centrifugal pump? - (answer)
Wear Rings
Cavitation is the formation and collapse of a gas pocket or bubble on the blade of a pump's impeller. -
(answer) True
Bar screens must be cleaned frequently to prevent (choose the most correct answer) - (answer) Excess
head loss (slowing down the water moving through the pipe)
What is an air-gap device used for? - (answer) Backflow prevention
Flow - (answer) The amount of fluid to be pumped
Head - (answer) The extent or distance to which fluid is to be exported.
The discharge of a centrifugal pump: - (answer) Decreases with the increase of head, and increases
with the decrease in head
In a centrifugal pump, leakage is prevented by - (answer) Wear rings
Valves should be closed slowly to prevent: - (answer) Water Hammer
