North Carolina Wastewater Collection System
Operator — Grade I Questions And Correct
Answers (Verified Answers) Plus Rationales
2026 Q&A | Instant Download Pdf
1. What is the primary purpose of a wastewater collection system?
a. To treat wastewater
b. To transport wastewater to a treatment facility
c. To filter solids
d. To disinfect water
b. To transport wastewater to a treatment facility
The collection system’s main role is conveyance, not treatment.
2. What does I/I stand for in collection systems?
a. Internal inspection
b. Intake infiltration
c. Inflow and infiltration
d. Inlet inspection
c. Inflow and infiltration
I/I refers to unwanted water entering the system.
3. A manhole typically provides:
a. Treatment of wastewater
b. Access for inspection and maintenance
c. Odor control only
d. Water sampling only
, b. Access for inspection and maintenance
Manholes are built for system access.
4. A sewer with a diameter less than 24 inches is classified as a:
a. Interceptor sewer
b. Force main
c. Lateral or branch sewer
d. Trunk sewer
c. Lateral or branch sewer
Laterals are small-diameter pipes connecting customers to mains.
5. What is the minimum recommended slope for gravity sewers?
a. 0%
b. 0.1%
c. 0.5%
d. 2%
c. 0.5%
To maintain flow velocity and prevent settling of solids.
6. What is the typical purpose of a cleanout?
a. Air release
b. Odor monitoring
c. Access for cleaning equipment
d. Sampling
c. Access for cleaning equipment
Cleanouts allow rods or jetting equipment to enter pipes.
7. Force mains operate under:
a. Gravity flow
b. Atmospheric pressure
c. Negative pressure
, d. Pressure created by pumps
d. Pressure created by pumps
Force mains require pumps to move wastewater.
8. Hydrogen sulfide gas is known for its odor of:
a. Ammonia
b. Rotten eggs
c. Chlorine
d. Vinegar
b. Rotten eggs
H₂S smells like rotten eggs and is toxic.
9. Which safety device monitors dangerous gas levels before
entering a confined space?
a. Altimeter
b. Gas detector
c. Flow meter
d. Hygrometer
b. Gas detector
Atmospheric testing is required for safe entry.
10. Manhole steps should be replaced if they show:
a. Slight discoloration
b. Loose or corroded metal
c. Paint fading
d. Surface dust
b. Loose or corroded metal
Damaged steps pose fall hazards.
11. The best method to control root intrusion is:
a. Adding gravel
Operator — Grade I Questions And Correct
Answers (Verified Answers) Plus Rationales
2026 Q&A | Instant Download Pdf
1. What is the primary purpose of a wastewater collection system?
a. To treat wastewater
b. To transport wastewater to a treatment facility
c. To filter solids
d. To disinfect water
b. To transport wastewater to a treatment facility
The collection system’s main role is conveyance, not treatment.
2. What does I/I stand for in collection systems?
a. Internal inspection
b. Intake infiltration
c. Inflow and infiltration
d. Inlet inspection
c. Inflow and infiltration
I/I refers to unwanted water entering the system.
3. A manhole typically provides:
a. Treatment of wastewater
b. Access for inspection and maintenance
c. Odor control only
d. Water sampling only
, b. Access for inspection and maintenance
Manholes are built for system access.
4. A sewer with a diameter less than 24 inches is classified as a:
a. Interceptor sewer
b. Force main
c. Lateral or branch sewer
d. Trunk sewer
c. Lateral or branch sewer
Laterals are small-diameter pipes connecting customers to mains.
5. What is the minimum recommended slope for gravity sewers?
a. 0%
b. 0.1%
c. 0.5%
d. 2%
c. 0.5%
To maintain flow velocity and prevent settling of solids.
6. What is the typical purpose of a cleanout?
a. Air release
b. Odor monitoring
c. Access for cleaning equipment
d. Sampling
c. Access for cleaning equipment
Cleanouts allow rods or jetting equipment to enter pipes.
7. Force mains operate under:
a. Gravity flow
b. Atmospheric pressure
c. Negative pressure
, d. Pressure created by pumps
d. Pressure created by pumps
Force mains require pumps to move wastewater.
8. Hydrogen sulfide gas is known for its odor of:
a. Ammonia
b. Rotten eggs
c. Chlorine
d. Vinegar
b. Rotten eggs
H₂S smells like rotten eggs and is toxic.
9. Which safety device monitors dangerous gas levels before
entering a confined space?
a. Altimeter
b. Gas detector
c. Flow meter
d. Hygrometer
b. Gas detector
Atmospheric testing is required for safe entry.
10. Manhole steps should be replaced if they show:
a. Slight discoloration
b. Loose or corroded metal
c. Paint fading
d. Surface dust
b. Loose or corroded metal
Damaged steps pose fall hazards.
11. The best method to control root intrusion is:
a. Adding gravel
