24 Collection System Maintenance Grade 4
Exam Questions and Answers Plus
Rationales
1. What is the primary purpose of a sewer collection system?
a) Provide drinking water
b) Control stormwater flooding
c) Transport wastewater to treatment facilities
d) Supply water for irrigation
The collection system’s main function is to carry wastewater from
homes and businesses to a treatment plant safely.
2. What is the typical minimum slope for a gravity sewer main?
a) 0.1%
b) 0.5%
c) 1.0%
d) 2.0%
A minimum slope ensures that wastewater flows by gravity
without stagnating.
3. Which type of pipe is commonly used in collection systems for
residential areas?
a) Copper
b) Steel
c) PVC
d) Asbestos cement
, PVC is preferred for its durability, corrosion resistance, and ease of
installation.
4. What is the primary cause of grease blockages in sewer lines?
a) Soil movement
b) Tree roots
c) Improper disposal of fats, oils, and grease
d) High water velocity
Fats, oils, and grease solidify in pipes, restricting flow.
5. What is the first step in inspecting a sewer line?
a) Reviewing maps and records
b) Flushing the line with water
c) Jet cleaning
d) Installing a bypass pump
Understanding the system layout helps identify potential problem
areas before physical inspection.
6. Which tool is used for internal inspection of sewer pipes?
a) Backhoe
b) Pipe wrench
c) CCTV camera
d) Rodder
CCTV cameras allow visual inspection of pipe conditions and
defects.
7. What is the main purpose of a manhole in a collection system?
a) Store wastewater
b) Provide access for inspection and maintenance
c) Treat sewage
d) Control water pressure
, Manholes provide entry points for maintenance, cleaning, and
inspection of the sewer lines.
8. What is the effect of inflow and infiltration (I/I) on a sewer
system?
a) Reduces flow
b) Increases water quality
c) Increases flow and can overload treatment facilities
d) Prevents blockages
Groundwater or stormwater entering the system can exceed
design capacity, causing overflows.
9. How often should routine cleaning of a gravity sewer main be
performed?
a) Every 10 years
b) As needed based on inspection or at least annually
c) Every 5 years
d) Only when a blockage occurs
Regular cleaning prevents blockages and reduces maintenance
costs over time.
10. Which type of flow is typical in a sewer pipe during dry
weather?
a) Supercritical flow
b) Turbulent flow
c) Partially full flow
d) Laminar flow
Gravity sewers rarely flow full; wastewater flows partially full
under normal conditions.
, 11. What is the purpose of a sewer flow monitoring program?
a) Detect pipe cracks
b) Measure pipe slope
c) Identify areas of high flow, infiltration, or blockages
d) Control odors
Flow monitoring helps prioritize maintenance and detect problems
early.
12. Which chemical can be used to prevent root intrusion in
sewers?
a) Sodium hypochlorite
b) Hydrochloric acid
c) Root-killing foams or foaming herbicides
d) Phosphoric acid
Foaming herbicides can kill roots inside pipes without damaging
infrastructure.
13. What is the recommended method to remove a grease
buildup in a sewer line?
a) Mechanical auger only
b) High-pressure water flushing
c) Combination of mechanical rodding and jetting
d) Acid treatment
Mechanical and high-pressure water cleaning effectively remove
grease without damaging pipes.
14. Which sign indicates a potential blockage in a sewer main?
a) Clear water in drains
b) Slow drainage or sewer backup
c) Odor-free manholes
Exam Questions and Answers Plus
Rationales
1. What is the primary purpose of a sewer collection system?
a) Provide drinking water
b) Control stormwater flooding
c) Transport wastewater to treatment facilities
d) Supply water for irrigation
The collection system’s main function is to carry wastewater from
homes and businesses to a treatment plant safely.
2. What is the typical minimum slope for a gravity sewer main?
a) 0.1%
b) 0.5%
c) 1.0%
d) 2.0%
A minimum slope ensures that wastewater flows by gravity
without stagnating.
3. Which type of pipe is commonly used in collection systems for
residential areas?
a) Copper
b) Steel
c) PVC
d) Asbestos cement
, PVC is preferred for its durability, corrosion resistance, and ease of
installation.
4. What is the primary cause of grease blockages in sewer lines?
a) Soil movement
b) Tree roots
c) Improper disposal of fats, oils, and grease
d) High water velocity
Fats, oils, and grease solidify in pipes, restricting flow.
5. What is the first step in inspecting a sewer line?
a) Reviewing maps and records
b) Flushing the line with water
c) Jet cleaning
d) Installing a bypass pump
Understanding the system layout helps identify potential problem
areas before physical inspection.
6. Which tool is used for internal inspection of sewer pipes?
a) Backhoe
b) Pipe wrench
c) CCTV camera
d) Rodder
CCTV cameras allow visual inspection of pipe conditions and
defects.
7. What is the main purpose of a manhole in a collection system?
a) Store wastewater
b) Provide access for inspection and maintenance
c) Treat sewage
d) Control water pressure
, Manholes provide entry points for maintenance, cleaning, and
inspection of the sewer lines.
8. What is the effect of inflow and infiltration (I/I) on a sewer
system?
a) Reduces flow
b) Increases water quality
c) Increases flow and can overload treatment facilities
d) Prevents blockages
Groundwater or stormwater entering the system can exceed
design capacity, causing overflows.
9. How often should routine cleaning of a gravity sewer main be
performed?
a) Every 10 years
b) As needed based on inspection or at least annually
c) Every 5 years
d) Only when a blockage occurs
Regular cleaning prevents blockages and reduces maintenance
costs over time.
10. Which type of flow is typical in a sewer pipe during dry
weather?
a) Supercritical flow
b) Turbulent flow
c) Partially full flow
d) Laminar flow
Gravity sewers rarely flow full; wastewater flows partially full
under normal conditions.
, 11. What is the purpose of a sewer flow monitoring program?
a) Detect pipe cracks
b) Measure pipe slope
c) Identify areas of high flow, infiltration, or blockages
d) Control odors
Flow monitoring helps prioritize maintenance and detect problems
early.
12. Which chemical can be used to prevent root intrusion in
sewers?
a) Sodium hypochlorite
b) Hydrochloric acid
c) Root-killing foams or foaming herbicides
d) Phosphoric acid
Foaming herbicides can kill roots inside pipes without damaging
infrastructure.
13. What is the recommended method to remove a grease
buildup in a sewer line?
a) Mechanical auger only
b) High-pressure water flushing
c) Combination of mechanical rodding and jetting
d) Acid treatment
Mechanical and high-pressure water cleaning effectively remove
grease without damaging pipes.
14. Which sign indicates a potential blockage in a sewer main?
a) Clear water in drains
b) Slow drainage or sewer backup
c) Odor-free manholes
