AZ L-83 Stormwater Systems 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 stormwater drainage system?
a. To increase groundwater contamination
b. To prevent all rainfall from entering soil
c. To collect, convey, control, and discharge stormwater safely
d. To eliminate the need for site grading
Rationale: A stormwater system is designed to manage runoff
generated by rainfall. Proper systems collect water from developed
surfaces, convey it through pipes or channels, control flow where
necessary, and discharge it in a manner that minimizes flooding,
erosion, and other impacts.
2. Which site condition generally produces the greatest amount of
stormwater runoff?
,a. Dense grass
b. Forested soil
c. Mulched landscape
d. Impervious pavement
Rationale: Pavement prevents rainfall from infiltrating into the soil,
causing a larger percentage of precipitation to become surface runoff.
Impervious surfaces such as concrete and asphalt therefore contribute
substantially to stormwater flow.
3. What is the primary function of a catch basin?
a. Increase soil permeability
b. Collect surface runoff and allow sediment and debris to settle
c. Pressurize a stormwater pipe
d. Treat drinking water
Rationale: Catch basins collect runoff entering through surface inlets.
Their sump can retain sediment and debris before water enters the
downstream drainage system, helping protect pipes and other
components.
4. Which component is commonly used to provide access to an
underground storm drain?
,a. Backflow preventer
b. Pressure regulator
c. Manhole or maintenance access structure
d. Water meter
Rationale: Manholes and similar access structures allow personnel to
inspect, clean, maintain, and sometimes repair underground
stormwater piping. They are particularly important at changes in
direction, grade, size, or pipe configuration.
5. What does the term “runoff” refer to?
a. Water that evaporates from pavement
b. Water stored permanently in a tank
c. Water flowing over or through a surface as a result of precipitation
d. Water supplied through a potable distribution system
Rationale: Runoff is precipitation that does not infiltrate, evaporate, or
otherwise remain on the site. It travels across surfaces or through
drainage systems toward a receiving location.
6. Which factor has a major effect on the quantity of stormwater
runoff from a developed site?
a. Building paint color
b. Impervious surface area
, c. Interior ceiling height
d. Type of electrical service
Rationale: Increasing impervious area generally decreases infiltration
and increases both the volume and rate of runoff. Site design therefore
considers roofs, parking lots, sidewalks, roads, and other impervious
surfaces.
7. What is the purpose of a storm drain inlet grate?
a. To increase pipe pressure
b. To prevent rainfall from reaching the ground
c. To allow runoff to enter the drainage system while limiting large
debris entry
d. To disinfect stormwater
Rationale: Grates provide an opening through which surface runoff can
enter an inlet. Their design also helps prevent large objects and debris
from entering the underground drainage system.
8. Why should stormwater pipes be installed with appropriate
slope?
a. To prevent all groundwater infiltration
b. To make pipes heavier
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A| Instant
Download Pdf
1. What is the primary purpose of a stormwater drainage system?
a. To increase groundwater contamination
b. To prevent all rainfall from entering soil
c. To collect, convey, control, and discharge stormwater safely
d. To eliminate the need for site grading
Rationale: A stormwater system is designed to manage runoff
generated by rainfall. Proper systems collect water from developed
surfaces, convey it through pipes or channels, control flow where
necessary, and discharge it in a manner that minimizes flooding,
erosion, and other impacts.
2. Which site condition generally produces the greatest amount of
stormwater runoff?
,a. Dense grass
b. Forested soil
c. Mulched landscape
d. Impervious pavement
Rationale: Pavement prevents rainfall from infiltrating into the soil,
causing a larger percentage of precipitation to become surface runoff.
Impervious surfaces such as concrete and asphalt therefore contribute
substantially to stormwater flow.
3. What is the primary function of a catch basin?
a. Increase soil permeability
b. Collect surface runoff and allow sediment and debris to settle
c. Pressurize a stormwater pipe
d. Treat drinking water
Rationale: Catch basins collect runoff entering through surface inlets.
Their sump can retain sediment and debris before water enters the
downstream drainage system, helping protect pipes and other
components.
4. Which component is commonly used to provide access to an
underground storm drain?
,a. Backflow preventer
b. Pressure regulator
c. Manhole or maintenance access structure
d. Water meter
Rationale: Manholes and similar access structures allow personnel to
inspect, clean, maintain, and sometimes repair underground
stormwater piping. They are particularly important at changes in
direction, grade, size, or pipe configuration.
5. What does the term “runoff” refer to?
a. Water that evaporates from pavement
b. Water stored permanently in a tank
c. Water flowing over or through a surface as a result of precipitation
d. Water supplied through a potable distribution system
Rationale: Runoff is precipitation that does not infiltrate, evaporate, or
otherwise remain on the site. It travels across surfaces or through
drainage systems toward a receiving location.
6. Which factor has a major effect on the quantity of stormwater
runoff from a developed site?
a. Building paint color
b. Impervious surface area
, c. Interior ceiling height
d. Type of electrical service
Rationale: Increasing impervious area generally decreases infiltration
and increases both the volume and rate of runoff. Site design therefore
considers roofs, parking lots, sidewalks, roads, and other impervious
surfaces.
7. What is the purpose of a storm drain inlet grate?
a. To increase pipe pressure
b. To prevent rainfall from reaching the ground
c. To allow runoff to enter the drainage system while limiting large
debris entry
d. To disinfect stormwater
Rationale: Grates provide an opening through which surface runoff can
enter an inlet. Their design also helps prevent large objects and debris
from entering the underground drainage system.
8. Why should stormwater pipes be installed with appropriate
slope?
a. To prevent all groundwater infiltration
b. To make pipes heavier
