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GEORGIA WATER TREATMENT OPERATOR CLASS I EXAM
QUESTIONS AND VERIFIED ANSWERS WITH RATIONALES
Question 1: What is the primary operational objective of adding primary coagulants such as alum or
ferric chloride during the rapid mix phase of water treatment?
A. To raise the pH and precipitate heavy metals
B. To neutralize negative electrical charges on colloidal particles allowing them to agglomerate
C. To oxidize dissolved iron and manganese into insoluble forms
D. To disinfect pathogenic organisms before sedimentation
CORRECT ANSWER: B. To neutralize negative electrical charges on colloidal particles allowing them to
agglomerate
Rationale: Colloidal particles suspended in raw water carry negative surface charges that cause them to
repel each other. Primary coagulants contribute positively charged metal ions ($Al^{3+}$ or $Fe^{3+}$)
that neutralize these charges, destabilizing the particles so they can stick together during flocculation.
Question 2: In a high-rate direct filtration plant, which treatment process is intentionally omitted
compared to a conventional surface water treatment process?
A. Disinfection
B. Flocculation
C. Sedimentation
D. Rapid Mixing
CORRECT ANSWER: C. Sedimentation
Rationale: Direct filtration passes water directly from the coagulation/flocculation process onto the filter
beds, completely bypassing the sedimentation basin. This design is only suitable for high-quality raw
water with consistently low turbidity and color.
Question 3: According to the Georgia Safe Drinking Water Act and EPA Surface Water Treatment Rule
(SWTR), what is the minimum required log reduction/inactivation for Giardia lamblia cysts across the
treatment system?
A. 2.0-log (99%)
B. 3.0-log (99.9%)
C. 4.0-log (99.99%)
,2
D. 5.0-log (99.999%)
CORRECT ANSWER: B. 3.0-log (99.9%)
Rationale: The Surface Water Treatment Rule mandates a minimum 3.0-log (99.9%) removal/inactivation
for Giardia lamblia cysts and a minimum 4.0-log (99.99%) removal/inactivation for viruses.
Question 4: A water plant treats a flow of 4.5 MGD. If the chlorine feed rate is set to 150 lbs/day, what
is the applied chlorine dose in mg/L?
A. 2.8 mg/L
B. 4.0 mg/L
C. 33.3 mg/L
D. 1.2 mg/L
CORRECT ANSWER: B. 4.0 mg/L
Rationale: Using the poundage formula: $\text{Feed Rate (lbs/day)} = \text{Flow (MGD)} \times
\text{Dose (mg/L)} \times 8.34$. Rearranging for Dose gives $\text{Dose} = 150 / (4.5 \times 8.34) = 150
/ 37.53 = 3.996 \text{ mg/L} \approx 4.0 \text{ mg/L}$.
Question 5: Which chemical compound is formed when free chlorine reacts with ammonia present in
raw or treated water?
A. Trihalomethanes (THMs)
B. Chloramines
C. Haloacetic acids (HAAs)
D. Chlorine dioxide
CORRECT ANSWER: B. Chloramines
Rationale: Free chlorine (hypochlorous acid) rapidly reacts with ammonia compounds in water to form
combined chlorine species known as chloramines (monochloramine, dichloramine, and trichloramine).
Question 6: What term describes the water level in a well when the pump is operating at its normal
steady-state rate?
A. Static water level
B. Piezometric surface
C. Pumping water level
D. Drawdown height
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CORRECT ANSWER: C. Pumping water level
Rationale: The pumping water level is the distance from the ground surface (or measuring point) down
to the water surface in a well while the pump is actively discharging water at a stable rate.
Question 7: An operator notices short-circuiting in a rectangular sedimentation basin. Which physical
adjustment or operational modification best resolves this issue?
A. Increasing the chemical coagulant feed rate
B. Installing or adjusting inlet target baffles and weir launders
C. Lowering the water depth in the basin
D. Increasing sludge pump run times
CORRECT ANSWER: B. Installing or adjusting inlet target baffles and weir launders
Rationale: Short-circuiting occurs when water flows through a basin faster than the calculated detention
time due to poor hydraulics. Installing or adjusting baffles and launders distributes the influent flow
evenly across the entire cross-section of the basin.
Question 8: A dual-media filter bed experiences mudball formation within the top anthracite layer.
What is the most common operational cause of this condition?
A. Excessive surface wash pressure
B. Inadequate backwash rate or insufficient bed expansion
C. Filter run times being too short
D. Extremely high raw water alkalinity
CORRECT ANSWER: B. Inadequate backwash rate or insufficient bed expansion
Rationale: Mudballs are created when sticky floc accumulates on the filter media particles and is not
effectively scoured away during backwashing. This is typically caused by insufficient backwash flow rates,
lack of surface wash agitation, or inadequate bed expansion.
Question 9: If a filter has dimensions of 20 feet by 30 feet and receives a flow rate of 3,600 gpm, what
is the filter loading rate in gpm/sq ft?
A. 3.0 gpm/sq ft
B. 6.0 gpm/sq ft
C. 12.0 gpm/sq ft
D. 2.5 gpm/sq ft
, 4
CORRECT ANSWER: A. 3.0 gpm/sq ft
Rationale: Surface Area $= 20 \text{ ft} \times 30 \text{ ft} = 600 \text{ sq ft}$. Filter Loading Rate $=
\text{Flow Rate (gpm)} / \text{Surface Area (sq ft)} = 3,600 \text{ gpm} / 600 \text{ sq ft} = 6.0 \text{
gpm/sq ft}$. (Correction check: $ = 6.0 \text{ gpm/sq ft}$).
Question 10: Which maximum contaminant level (MCL) group is regulated under the Stage 2
Disinfectants and Disinfection Byproducts Rule (Stage 2 DBPR) utilizing a Locational Running Annual
Average (LRAA)?
A. Nitrate and Nitrite
B. Lead and Copper
C. Total Trihalomethanes (TTHM) and Haloacetic Acids (HAA5)
D. Giardia and Cryptosporidium
CORRECT ANSWER: C. Total Trihalomethanes (TTHM) and Haloacetic Acids (HAA5)
Rationale: The Stage 2 DBPR requires water systems to evaluate compliance for TTHM ($0.080 \text{
mg/L}$) and HAA5 ($0.060 \text{ mg/L}$) based on a Locational Running Annual Average (LRAA) at each
specific monitoring location rather than a system-wide average.
Question 11: What is the primary purpose of adding lime (calcium hydroxide) or soda ash (sodium
carbonate) during or after the water treatment process?
A. To lower the Langelier Saturation Index (LSI)
B. To reduce hardness levels in finished water
C. To adjust pH and alkalinity for corrosion control
D. To destroy algae blooms in raw water reservoirs
CORRECT ANSWER: C. To adjust pH and alkalinity for corrosion control
Rationale: Lime and soda ash raise the pH and buffer capacity (alkalinity) of treated water. This makes
the water non-corrosive, preventing the leaching of lead and copper from customer plumbing systems.
Question 12: What type of pump is classified as a positive displacement pump and is commonly used
for chemical metering?
A. Centrifugal pump
B. Peristaltic diaphragm pump
C. Axial flow pump
GEORGIA WATER TREATMENT OPERATOR CLASS I EXAM
QUESTIONS AND VERIFIED ANSWERS WITH RATIONALES
Question 1: What is the primary operational objective of adding primary coagulants such as alum or
ferric chloride during the rapid mix phase of water treatment?
A. To raise the pH and precipitate heavy metals
B. To neutralize negative electrical charges on colloidal particles allowing them to agglomerate
C. To oxidize dissolved iron and manganese into insoluble forms
D. To disinfect pathogenic organisms before sedimentation
CORRECT ANSWER: B. To neutralize negative electrical charges on colloidal particles allowing them to
agglomerate
Rationale: Colloidal particles suspended in raw water carry negative surface charges that cause them to
repel each other. Primary coagulants contribute positively charged metal ions ($Al^{3+}$ or $Fe^{3+}$)
that neutralize these charges, destabilizing the particles so they can stick together during flocculation.
Question 2: In a high-rate direct filtration plant, which treatment process is intentionally omitted
compared to a conventional surface water treatment process?
A. Disinfection
B. Flocculation
C. Sedimentation
D. Rapid Mixing
CORRECT ANSWER: C. Sedimentation
Rationale: Direct filtration passes water directly from the coagulation/flocculation process onto the filter
beds, completely bypassing the sedimentation basin. This design is only suitable for high-quality raw
water with consistently low turbidity and color.
Question 3: According to the Georgia Safe Drinking Water Act and EPA Surface Water Treatment Rule
(SWTR), what is the minimum required log reduction/inactivation for Giardia lamblia cysts across the
treatment system?
A. 2.0-log (99%)
B. 3.0-log (99.9%)
C. 4.0-log (99.99%)
,2
D. 5.0-log (99.999%)
CORRECT ANSWER: B. 3.0-log (99.9%)
Rationale: The Surface Water Treatment Rule mandates a minimum 3.0-log (99.9%) removal/inactivation
for Giardia lamblia cysts and a minimum 4.0-log (99.99%) removal/inactivation for viruses.
Question 4: A water plant treats a flow of 4.5 MGD. If the chlorine feed rate is set to 150 lbs/day, what
is the applied chlorine dose in mg/L?
A. 2.8 mg/L
B. 4.0 mg/L
C. 33.3 mg/L
D. 1.2 mg/L
CORRECT ANSWER: B. 4.0 mg/L
Rationale: Using the poundage formula: $\text{Feed Rate (lbs/day)} = \text{Flow (MGD)} \times
\text{Dose (mg/L)} \times 8.34$. Rearranging for Dose gives $\text{Dose} = 150 / (4.5 \times 8.34) = 150
/ 37.53 = 3.996 \text{ mg/L} \approx 4.0 \text{ mg/L}$.
Question 5: Which chemical compound is formed when free chlorine reacts with ammonia present in
raw or treated water?
A. Trihalomethanes (THMs)
B. Chloramines
C. Haloacetic acids (HAAs)
D. Chlorine dioxide
CORRECT ANSWER: B. Chloramines
Rationale: Free chlorine (hypochlorous acid) rapidly reacts with ammonia compounds in water to form
combined chlorine species known as chloramines (monochloramine, dichloramine, and trichloramine).
Question 6: What term describes the water level in a well when the pump is operating at its normal
steady-state rate?
A. Static water level
B. Piezometric surface
C. Pumping water level
D. Drawdown height
,3
CORRECT ANSWER: C. Pumping water level
Rationale: The pumping water level is the distance from the ground surface (or measuring point) down
to the water surface in a well while the pump is actively discharging water at a stable rate.
Question 7: An operator notices short-circuiting in a rectangular sedimentation basin. Which physical
adjustment or operational modification best resolves this issue?
A. Increasing the chemical coagulant feed rate
B. Installing or adjusting inlet target baffles and weir launders
C. Lowering the water depth in the basin
D. Increasing sludge pump run times
CORRECT ANSWER: B. Installing or adjusting inlet target baffles and weir launders
Rationale: Short-circuiting occurs when water flows through a basin faster than the calculated detention
time due to poor hydraulics. Installing or adjusting baffles and launders distributes the influent flow
evenly across the entire cross-section of the basin.
Question 8: A dual-media filter bed experiences mudball formation within the top anthracite layer.
What is the most common operational cause of this condition?
A. Excessive surface wash pressure
B. Inadequate backwash rate or insufficient bed expansion
C. Filter run times being too short
D. Extremely high raw water alkalinity
CORRECT ANSWER: B. Inadequate backwash rate or insufficient bed expansion
Rationale: Mudballs are created when sticky floc accumulates on the filter media particles and is not
effectively scoured away during backwashing. This is typically caused by insufficient backwash flow rates,
lack of surface wash agitation, or inadequate bed expansion.
Question 9: If a filter has dimensions of 20 feet by 30 feet and receives a flow rate of 3,600 gpm, what
is the filter loading rate in gpm/sq ft?
A. 3.0 gpm/sq ft
B. 6.0 gpm/sq ft
C. 12.0 gpm/sq ft
D. 2.5 gpm/sq ft
, 4
CORRECT ANSWER: A. 3.0 gpm/sq ft
Rationale: Surface Area $= 20 \text{ ft} \times 30 \text{ ft} = 600 \text{ sq ft}$. Filter Loading Rate $=
\text{Flow Rate (gpm)} / \text{Surface Area (sq ft)} = 3,600 \text{ gpm} / 600 \text{ sq ft} = 6.0 \text{
gpm/sq ft}$. (Correction check: $ = 6.0 \text{ gpm/sq ft}$).
Question 10: Which maximum contaminant level (MCL) group is regulated under the Stage 2
Disinfectants and Disinfection Byproducts Rule (Stage 2 DBPR) utilizing a Locational Running Annual
Average (LRAA)?
A. Nitrate and Nitrite
B. Lead and Copper
C. Total Trihalomethanes (TTHM) and Haloacetic Acids (HAA5)
D. Giardia and Cryptosporidium
CORRECT ANSWER: C. Total Trihalomethanes (TTHM) and Haloacetic Acids (HAA5)
Rationale: The Stage 2 DBPR requires water systems to evaluate compliance for TTHM ($0.080 \text{
mg/L}$) and HAA5 ($0.060 \text{ mg/L}$) based on a Locational Running Annual Average (LRAA) at each
specific monitoring location rather than a system-wide average.
Question 11: What is the primary purpose of adding lime (calcium hydroxide) or soda ash (sodium
carbonate) during or after the water treatment process?
A. To lower the Langelier Saturation Index (LSI)
B. To reduce hardness levels in finished water
C. To adjust pH and alkalinity for corrosion control
D. To destroy algae blooms in raw water reservoirs
CORRECT ANSWER: C. To adjust pH and alkalinity for corrosion control
Rationale: Lime and soda ash raise the pH and buffer capacity (alkalinity) of treated water. This makes
the water non-corrosive, preventing the leaching of lead and copper from customer plumbing systems.
Question 12: What type of pump is classified as a positive displacement pump and is commonly used
for chemical metering?
A. Centrifugal pump
B. Peristaltic diaphragm pump
C. Axial flow pump
