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TCEQ Class C Surface Water Operator Exam
QUESTIONS AND DETAILED SOLUTIONS JUST
RELEASED
TCEQ Class C Surface Water Operator Exam
(With Answers & Rationales)
1. A surface water treatment plant operator is preparing to add alum to the raw water. What is the
primary purpose of this chemical addition?
A) To disinfect the water and kill pathogens
B) To neutralize electrical charges on particles, causing them to clump together
C) To raise the pH of the water to alkaline levels
D) To remove dissolved minerals from the water
Answer: B – Alum (aluminum sulfate) is a coagulant that neutralizes the negative electrical charges on
colloidal particles, allowing them to aggregate into larger floc for removal .
2. A new operator notices that the rapid mix basin is not operating properly. Why is rapid mixing critical
in the treatment process?
A) It provides settling time for large particles
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B) It ensures uniform dispersion of coagulants throughout the water
C) It adds chlorine to the water
D) It removes pathogens by UV light
Answer: B – Rapid mix basins ensure immediate and uniform dispersion of coagulants before floc
formation begins, which is essential for effective particle destabilization .
3. During a filter run, the effluent turbidity begins to rise despite normal filter operation. What is the
most likely cause of "filter breakthrough"?
A) The filter is operating at too low a flow rate
B) The filter media has become exhausted or is not adequately removing particles
C) The backwash cycle was too long
D) The pH is too high
Answer: B – Filter breakthrough occurs when the filter media can no longer effectively trap particles,
often due to media exhaustion, improper backwashing, or excessive loading .
4. An operator needs to calculate chemical feed dosage. The plant is treating 1.0 MGD and requires a
coagulant dosage of 2.0 mg/L. Using 8.34 lb/gal, how many pounds of chemical will be fed per day?
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A) 8.34 lbs
B) 16.68 lbs
C) 4.17 lbs
D) 33.36 lbs
Answer: B – Formula: Flow (MGD) × Dose (mg/L) × 8.34 = lbs/day. 1.0 × 2.0 × 8.34 = 16.68 lbs/day .
5. A filter has a flow rate of 500 GPM and a surface area of 100 square feet. What is the filtration rate in
GPM/sq ft?
A) 2 GPM/sq ft
B) 3 GPM/sq ft
C) 5 GPM/sq ft
D) 10 GPM/sq ft
Answer: C – Filtration Rate = Flow (GPM) / Area (sq ft). = 5 GPM/sq ft .
6. A treatment plant operator is monitoring the coagulation process and notices poor floc formation.
Which pH range should be targeted for optimal alum coagulation?
A) 3.0–4.5
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B) 5.5–7.5
C) 8.0–9.5
D) 10.0–12.0
Answer: B – Alum works best in a slightly acidic to neutral pH range (5.5–7.5) to maximize floc formation
and coagulation efficiency .
7. What is the typical detention time for a sedimentation basin in a surface water treatment plant?
A) 30 minutes
B) 1 hour
C) 2–4 hours
D) 8–12 hours
Answer: C – Sedimentation basins typically have a detention time of 2–4 hours to allow adequate
settling of floc particles .
8. The primary goal of the coagulation, sedimentation, and filtration processes is to remove which
contaminant?
A) Dissolved minerals
TCEQ Class C Surface Water Operator Exam
QUESTIONS AND DETAILED SOLUTIONS JUST
RELEASED
TCEQ Class C Surface Water Operator Exam
(With Answers & Rationales)
1. A surface water treatment plant operator is preparing to add alum to the raw water. What is the
primary purpose of this chemical addition?
A) To disinfect the water and kill pathogens
B) To neutralize electrical charges on particles, causing them to clump together
C) To raise the pH of the water to alkaline levels
D) To remove dissolved minerals from the water
Answer: B – Alum (aluminum sulfate) is a coagulant that neutralizes the negative electrical charges on
colloidal particles, allowing them to aggregate into larger floc for removal .
2. A new operator notices that the rapid mix basin is not operating properly. Why is rapid mixing critical
in the treatment process?
A) It provides settling time for large particles
, Page 2 of 123
B) It ensures uniform dispersion of coagulants throughout the water
C) It adds chlorine to the water
D) It removes pathogens by UV light
Answer: B – Rapid mix basins ensure immediate and uniform dispersion of coagulants before floc
formation begins, which is essential for effective particle destabilization .
3. During a filter run, the effluent turbidity begins to rise despite normal filter operation. What is the
most likely cause of "filter breakthrough"?
A) The filter is operating at too low a flow rate
B) The filter media has become exhausted or is not adequately removing particles
C) The backwash cycle was too long
D) The pH is too high
Answer: B – Filter breakthrough occurs when the filter media can no longer effectively trap particles,
often due to media exhaustion, improper backwashing, or excessive loading .
4. An operator needs to calculate chemical feed dosage. The plant is treating 1.0 MGD and requires a
coagulant dosage of 2.0 mg/L. Using 8.34 lb/gal, how many pounds of chemical will be fed per day?
, Page 3 of 123
A) 8.34 lbs
B) 16.68 lbs
C) 4.17 lbs
D) 33.36 lbs
Answer: B – Formula: Flow (MGD) × Dose (mg/L) × 8.34 = lbs/day. 1.0 × 2.0 × 8.34 = 16.68 lbs/day .
5. A filter has a flow rate of 500 GPM and a surface area of 100 square feet. What is the filtration rate in
GPM/sq ft?
A) 2 GPM/sq ft
B) 3 GPM/sq ft
C) 5 GPM/sq ft
D) 10 GPM/sq ft
Answer: C – Filtration Rate = Flow (GPM) / Area (sq ft). = 5 GPM/sq ft .
6. A treatment plant operator is monitoring the coagulation process and notices poor floc formation.
Which pH range should be targeted for optimal alum coagulation?
A) 3.0–4.5
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B) 5.5–7.5
C) 8.0–9.5
D) 10.0–12.0
Answer: B – Alum works best in a slightly acidic to neutral pH range (5.5–7.5) to maximize floc formation
and coagulation efficiency .
7. What is the typical detention time for a sedimentation basin in a surface water treatment plant?
A) 30 minutes
B) 1 hour
C) 2–4 hours
D) 8–12 hours
Answer: C – Sedimentation basins typically have a detention time of 2–4 hours to allow adequate
settling of floc particles .
8. The primary goal of the coagulation, sedimentation, and filtration processes is to remove which
contaminant?
A) Dissolved minerals
