AK Storm Drain Contractor Exam Questions
and Correct Answers (Verified Answers)
Plus Rationale 2027 Q&A| Instant
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1. What is the primary purpose of a storm drain system?
a. To supply potable water
b. To collect and convey stormwater runoff
c. To treat wastewater for reuse
d. To increase groundwater salinity
Answer: b. To collect and convey stormwater runoff
Rationale: Storm drain systems are designed to collect runoff
generated by rainfall or snowmelt and convey it safely to an
appropriate discharge point. They help reduce flooding, erosion,
ponding, and damage to roads and structures.
2. Before excavating for a storm drain installation, what should the
contractor do first?
,a. Begin trenching at the outlet
b. Remove all existing pavement
c. Locate and verify existing utilities
d. Install the catch basins
Answer: c. Locate and verify existing utilities
Rationale: Existing underground utilities must be identified before
excavation begins. Utility conflicts can cause service interruptions,
injuries, environmental releases, and costly project delays.
3. Which factor most directly affects the required capacity of a
storm drain?
a. Paint color of the pipe
b. Expected stormwater runoff
c. Contractor's office location
d. Type of construction trailer
Answer: b. Expected stormwater runoff
Rationale: Storm drain capacity must be adequate for the anticipated
runoff entering the system. Drainage calculations consider factors
such as rainfall intensity, drainage area, surface characteristics, and
applicable design criteria.
4. What is the purpose of a catch basin?
,a. To collect surface runoff and provide access to the drainage system
b. To increase domestic water pressure
c. To store drinking water
d. To ventilate a building
Answer: a. To collect surface runoff and provide access to the
drainage system
Rationale: Catch basins collect water from paved or graded surfaces
and direct it into storm drainage pipes. They can also provide access
for inspection and maintenance and may capture sediment and
debris.
5. Why is proper pipe slope important in a gravity storm drain?
a. It allows water to flow toward the outlet
b. It eliminates the need for pipe joints
c. It prevents all sediment from entering the system
d. It increases pipe wall thickness
Answer: a. It allows water to flow toward the outlet
Rationale: Gravity drainage depends on elevation differences to move
water. An appropriate slope helps maintain adequate hydraulic
performance and reduces the likelihood of standing water and
sediment accumulation.
, 6. Which instrument is commonly used to establish elevations and
grades during storm drain construction?
a. Pipe wrench
b. Level or laser level
c. Concrete vibrator
d. Torque wrench
Answer: b. Level or laser level
Rationale: Levels and laser instruments allow contractors to establish
and verify elevations, slopes, and invert grades. Accurate elevation
control is essential for gravity drainage systems.
7. What does the term “invert elevation” refer to?
a. The elevation of the top of a manhole
b. The elevation of the bottom inside surface of a pipe or channel
c. The elevation of surrounding pavement
d. The elevation of a property boundary
Answer: b. The elevation of the bottom inside surface of a pipe or
channel
Rationale: The invert is the lowest interior elevation of a pipe, conduit,
or drainage structure. Invert elevations are used to establish pipe
slopes and ensure proper connections between drainage structures.
and Correct Answers (Verified Answers)
Plus Rationale 2027 Q&A| Instant
Download Pdf
1. What is the primary purpose of a storm drain system?
a. To supply potable water
b. To collect and convey stormwater runoff
c. To treat wastewater for reuse
d. To increase groundwater salinity
Answer: b. To collect and convey stormwater runoff
Rationale: Storm drain systems are designed to collect runoff
generated by rainfall or snowmelt and convey it safely to an
appropriate discharge point. They help reduce flooding, erosion,
ponding, and damage to roads and structures.
2. Before excavating for a storm drain installation, what should the
contractor do first?
,a. Begin trenching at the outlet
b. Remove all existing pavement
c. Locate and verify existing utilities
d. Install the catch basins
Answer: c. Locate and verify existing utilities
Rationale: Existing underground utilities must be identified before
excavation begins. Utility conflicts can cause service interruptions,
injuries, environmental releases, and costly project delays.
3. Which factor most directly affects the required capacity of a
storm drain?
a. Paint color of the pipe
b. Expected stormwater runoff
c. Contractor's office location
d. Type of construction trailer
Answer: b. Expected stormwater runoff
Rationale: Storm drain capacity must be adequate for the anticipated
runoff entering the system. Drainage calculations consider factors
such as rainfall intensity, drainage area, surface characteristics, and
applicable design criteria.
4. What is the purpose of a catch basin?
,a. To collect surface runoff and provide access to the drainage system
b. To increase domestic water pressure
c. To store drinking water
d. To ventilate a building
Answer: a. To collect surface runoff and provide access to the
drainage system
Rationale: Catch basins collect water from paved or graded surfaces
and direct it into storm drainage pipes. They can also provide access
for inspection and maintenance and may capture sediment and
debris.
5. Why is proper pipe slope important in a gravity storm drain?
a. It allows water to flow toward the outlet
b. It eliminates the need for pipe joints
c. It prevents all sediment from entering the system
d. It increases pipe wall thickness
Answer: a. It allows water to flow toward the outlet
Rationale: Gravity drainage depends on elevation differences to move
water. An appropriate slope helps maintain adequate hydraulic
performance and reduces the likelihood of standing water and
sediment accumulation.
, 6. Which instrument is commonly used to establish elevations and
grades during storm drain construction?
a. Pipe wrench
b. Level or laser level
c. Concrete vibrator
d. Torque wrench
Answer: b. Level or laser level
Rationale: Levels and laser instruments allow contractors to establish
and verify elevations, slopes, and invert grades. Accurate elevation
control is essential for gravity drainage systems.
7. What does the term “invert elevation” refer to?
a. The elevation of the top of a manhole
b. The elevation of the bottom inside surface of a pipe or channel
c. The elevation of surrounding pavement
d. The elevation of a property boundary
Answer: b. The elevation of the bottom inside surface of a pipe or
channel
Rationale: The invert is the lowest interior elevation of a pipe, conduit,
or drainage structure. Invert elevations are used to establish pipe
slopes and ensure proper connections between drainage structures.
