ADEQ WASTEWATER TREATMENT
OPERATOR GRADE 1 EXAM
2026/2027 Academic Year
Arizona Department of Environmental Quality
110 Multiple-Choice Questions (100 Scored + 10 Pre-Test)
180 Minutes | Passing Score: 70-75%
100% Verified | Graded A+
, ADEQ Wastewater Treatment Operator Grade 1 Exam
EXAM INSTRUCTIONS
1. This examination consists of 110 multiple-choice questions. Questions 1–100 are scored; Questions 101–
110 are pre-test items and are not included in your final score.
2. You have 180 minutes (3 hours) to complete the examination.
3. Each question has four answer options (A, B, C, D). Select the ONE best answer for each question.
4. The passing score is 70–75%, depending on exam form difficulty.
5. A basic calculator is permitted. Programmable calculators, cell phones, and electronic devices are NOT
allowed.
6. Reference materials, notes, and textbooks are NOT permitted during the examination.
7. Answer all questions. There is no penalty for guessing.
8. Mark your answers on the provided answer sheet. Ensure each mark is dark and complete.
9. If you need to change an answer, erase the previous mark completely.
10. Notify the proctor immediately if you have any questions about exam procedures.
DOMAIN DISTRIBUTION
1. Wastewater Collection & Conveyance: 15 questions
2. Preliminary & Primary Treatment Processes: 18 questions
3. Biological Treatment Fundamentals: 22 questions
4. Solids Handling & Disposal: 12 questions
5. Disinfection & Effluent Management: 12 questions
6. Mathematics & Process Control Calculations: 10 questions
7. Safety & Regulatory Compliance: 7 questions
8. Laboratory Procedures & Sampling: 6 questions
9. Maintenance & Troubleshooting: 4 questions
10. Scenario-Based Application: 4 questions
TOTAL: 110 questions
EXAMINATION QUESTIONS
Q1. What is the minimum self-cleaning velocity recommended for gravity sanitary sewers to
prevent solids deposition?
[Wastewater Collection & Conveyance]
A) 0.3 m/s (1.0 ft/s)
B) 0.6 m/s (2.0 ft/s)
C) 1.0 m/s (3.3 ft/s)
D) 1.5 m/s (5.0 ft/s)
Correct Answer: B — 0.6 m/s (2.0 ft/s)
Rationale: A minimum velocity of 0.6 m/s (2.0 ft/s) at half-full or full flow is the industry standard to
keep solids in suspension and prevent deposition in gravity sewers. Lower velocities allow settleable
solids to accumulate, leading to blockages and odor complaints.
Q2. In a force main, what is the primary function of an air release valve?
[Wastewater Collection & Conveyance]
A) To relieve excess pressure during surge events
B) To allow air to enter the pipe when draining
C) To release accumulated air pockets at high points in the pipeline
D) To regulate the flow rate of the pump station
Correct Answer: C — To release accumulated air pockets at high points in the pipeline
Rationale: Air release valves are installed at high points in force mains to automatically expel trapped
air that accumulates during operation. Trapped air reduces the effective cross-section of the pipe,
increases head loss, and can cause pump cycling or reduced capacity.
2
, ADEQ Wastewater Treatment Operator Grade 1 Exam
Q3. Which type of pump is most commonly used in wastewater lift stations?
[Wastewater Collection & Conveyance]
A) Centrifugal (submersible)
B) Progressive cavity
C) Piston
D) Diaphragm
Correct Answer: A — Centrifugal (submersible)
Rationale: Submersible centrifugal pumps are the most common choice for wastewater lift stations
because they can handle solids, are relatively easy to install and maintain, and operate efficiently over a
wide range of flow conditions. Their sealed motor design also eliminates the need for a separate dry
well.
Q4. Infiltration in a sewer system refers to:
[Wastewater Collection & Conveyance]
A) Groundwater entering the sewer through defective joints or cracks
B) Storm water directly connected to the sanitary sewer
C) Industrial discharge entering through manhole covers
D) Rainwater entering through roof drains connected to the sewer
Correct Answer: A — Groundwater entering the sewer through defective joints or cracks
Rationale: Infiltration is defined as groundwater that enters the sewer system through defective pipes,
pipe joints, connections, or manhole walls. It differs from inflow, which is surface water that enters
through direct connections such as roof drains or manhole covers.
Q5. What is the typical maximum spacing between manholes on straight runs of sewer less
than 600 mm (24 in.) in diameter?
[Wastewater Collection & Conveyance]
A) 60 m (200 ft)
B) 120 m (400 ft)
C) 180 m (600 ft)
D) 240 m (800 ft)
Correct Answer: B — 120 m (400 ft)
Rationale: Standard engineering practice recommends manholes at intervals not exceeding 120 m
(400 ft) for sewers less than 600 mm in diameter to provide access for cleaning, inspection, and
maintenance. Larger sewers may have greater spacing allowances.
Q6. Which method is most effective for controlling root intrusion in sewer lines?
[Wastewater Collection & Conveyance]
A) Applying herbicides to the sewer line
B) Chemical root control with copper sulfate
C) Mechanical cutting combined with chemical treatment
D) Increasing the sewer flow velocity
Correct Answer: C — Mechanical cutting combined with chemical treatment
Rationale: Mechanical cutting removes existing roots, and subsequent chemical treatment (such as
dichlobenil or metam-sodium) prevents regrowth. This combined approach is more effective than either
method alone because cutting alone allows regrowth, and chemicals alone cannot effectively penetrate
dense root masses.
Q7. During a manhole inspection, which of the following indicates potential structural
failure?
[Wastewater Collection & Conveyance]
A) Surface rust on the ladder rungs
B) Minor groundwater seepage at the base
3
OPERATOR GRADE 1 EXAM
2026/2027 Academic Year
Arizona Department of Environmental Quality
110 Multiple-Choice Questions (100 Scored + 10 Pre-Test)
180 Minutes | Passing Score: 70-75%
100% Verified | Graded A+
, ADEQ Wastewater Treatment Operator Grade 1 Exam
EXAM INSTRUCTIONS
1. This examination consists of 110 multiple-choice questions. Questions 1–100 are scored; Questions 101–
110 are pre-test items and are not included in your final score.
2. You have 180 minutes (3 hours) to complete the examination.
3. Each question has four answer options (A, B, C, D). Select the ONE best answer for each question.
4. The passing score is 70–75%, depending on exam form difficulty.
5. A basic calculator is permitted. Programmable calculators, cell phones, and electronic devices are NOT
allowed.
6. Reference materials, notes, and textbooks are NOT permitted during the examination.
7. Answer all questions. There is no penalty for guessing.
8. Mark your answers on the provided answer sheet. Ensure each mark is dark and complete.
9. If you need to change an answer, erase the previous mark completely.
10. Notify the proctor immediately if you have any questions about exam procedures.
DOMAIN DISTRIBUTION
1. Wastewater Collection & Conveyance: 15 questions
2. Preliminary & Primary Treatment Processes: 18 questions
3. Biological Treatment Fundamentals: 22 questions
4. Solids Handling & Disposal: 12 questions
5. Disinfection & Effluent Management: 12 questions
6. Mathematics & Process Control Calculations: 10 questions
7. Safety & Regulatory Compliance: 7 questions
8. Laboratory Procedures & Sampling: 6 questions
9. Maintenance & Troubleshooting: 4 questions
10. Scenario-Based Application: 4 questions
TOTAL: 110 questions
EXAMINATION QUESTIONS
Q1. What is the minimum self-cleaning velocity recommended for gravity sanitary sewers to
prevent solids deposition?
[Wastewater Collection & Conveyance]
A) 0.3 m/s (1.0 ft/s)
B) 0.6 m/s (2.0 ft/s)
C) 1.0 m/s (3.3 ft/s)
D) 1.5 m/s (5.0 ft/s)
Correct Answer: B — 0.6 m/s (2.0 ft/s)
Rationale: A minimum velocity of 0.6 m/s (2.0 ft/s) at half-full or full flow is the industry standard to
keep solids in suspension and prevent deposition in gravity sewers. Lower velocities allow settleable
solids to accumulate, leading to blockages and odor complaints.
Q2. In a force main, what is the primary function of an air release valve?
[Wastewater Collection & Conveyance]
A) To relieve excess pressure during surge events
B) To allow air to enter the pipe when draining
C) To release accumulated air pockets at high points in the pipeline
D) To regulate the flow rate of the pump station
Correct Answer: C — To release accumulated air pockets at high points in the pipeline
Rationale: Air release valves are installed at high points in force mains to automatically expel trapped
air that accumulates during operation. Trapped air reduces the effective cross-section of the pipe,
increases head loss, and can cause pump cycling or reduced capacity.
2
, ADEQ Wastewater Treatment Operator Grade 1 Exam
Q3. Which type of pump is most commonly used in wastewater lift stations?
[Wastewater Collection & Conveyance]
A) Centrifugal (submersible)
B) Progressive cavity
C) Piston
D) Diaphragm
Correct Answer: A — Centrifugal (submersible)
Rationale: Submersible centrifugal pumps are the most common choice for wastewater lift stations
because they can handle solids, are relatively easy to install and maintain, and operate efficiently over a
wide range of flow conditions. Their sealed motor design also eliminates the need for a separate dry
well.
Q4. Infiltration in a sewer system refers to:
[Wastewater Collection & Conveyance]
A) Groundwater entering the sewer through defective joints or cracks
B) Storm water directly connected to the sanitary sewer
C) Industrial discharge entering through manhole covers
D) Rainwater entering through roof drains connected to the sewer
Correct Answer: A — Groundwater entering the sewer through defective joints or cracks
Rationale: Infiltration is defined as groundwater that enters the sewer system through defective pipes,
pipe joints, connections, or manhole walls. It differs from inflow, which is surface water that enters
through direct connections such as roof drains or manhole covers.
Q5. What is the typical maximum spacing between manholes on straight runs of sewer less
than 600 mm (24 in.) in diameter?
[Wastewater Collection & Conveyance]
A) 60 m (200 ft)
B) 120 m (400 ft)
C) 180 m (600 ft)
D) 240 m (800 ft)
Correct Answer: B — 120 m (400 ft)
Rationale: Standard engineering practice recommends manholes at intervals not exceeding 120 m
(400 ft) for sewers less than 600 mm in diameter to provide access for cleaning, inspection, and
maintenance. Larger sewers may have greater spacing allowances.
Q6. Which method is most effective for controlling root intrusion in sewer lines?
[Wastewater Collection & Conveyance]
A) Applying herbicides to the sewer line
B) Chemical root control with copper sulfate
C) Mechanical cutting combined with chemical treatment
D) Increasing the sewer flow velocity
Correct Answer: C — Mechanical cutting combined with chemical treatment
Rationale: Mechanical cutting removes existing roots, and subsequent chemical treatment (such as
dichlobenil or metam-sodium) prevents regrowth. This combined approach is more effective than either
method alone because cutting alone allows regrowth, and chemicals alone cannot effectively penetrate
dense root masses.
Q7. During a manhole inspection, which of the following indicates potential structural
failure?
[Wastewater Collection & Conveyance]
A) Surface rust on the ladder rungs
B) Minor groundwater seepage at the base
3
