NPDES EXAM QUESTIONS AND CORRECT
ANSWERS | NEW 2026/2027 UPDATE | GRADED
A+.
Erosion - ANSWER is the process by which the land surface is worn away by
the action of wind, water, and gravity.
Sedimentation - ANSWER is the settling out of soil particles transported by
water and wind.
Four process of overland erosion are? - ANSWER Splash, sheet, rill, and gully
erosion.
Four principle factors influencing soil erosion are? - ANSWER Soil
characteristics, vegetative cover, topography, and climate.
List three physical effect of erosion and sedimentation: - ANSWER Increased
flooding reduced hydraulic capacity in rivers, and streams; increased
maintenance of stormwater systems.; increased water treatments cost; and
decreased recreational value.
List three biological effect of erosion and sedimentation: - ANSWER Reduced
light for aquatic plants; clogs fish gills; impairs spawning; disrupts food chain;
blankets bottom, suppresses aquatic life; and disrupts ecosystem.
Planning the development to fit the terrain using the particular: - ANSWER
Topography; soils; drainage patterns; natural vegetation of the site; and
minimize the extent of the area exposed at one time and the duration of
exposure.
,Perimeter Control Practices - ANSWER What you apply to protect the
disturbed area from off-site runoff and to protect off-site areas from sediment
damage.
Erosion Control Practices - ANSWER What you apply to prevent excessive on-
site damage.
Keep runoff velocities _____ and _______ runoff on the site - ANSWER Low
and retain
Soil erosion can be classified as 2 types. What are they? - ANSWER Wind and
Water.
What are the two sources of Soil erosion. - ANSWER Natural and Manmade
Water erosion can be classified as two type of erosions. What are they? -
ANSWER Overland and Stream/Channel erosion.
Soils in the Type A hydrologic group have ____ infiltration rates and ____
runoff potential even when thoroughly wetted. - ANSWER high and low
Soils in the Type D hydrologic group have very ____ infiltration rates and ____
runoff potential when thoroughly wetted. - ANSWER low and high
What is the rainfall erosion index? - ANSWER The rainfall erosion index is the
only factor in the Universal Soil Loss Equation which is beyond the developer's
control.
When do you stabilize disturbed areas after final grading to prevent raindrop
impacts from causing erosion. - ANSWER Immediately
, Storage of paints, solvents, cements, pesticides, acids, or other potentially
polluting chemicals is no big deal because they are only stored temporarily and
get used up quickly. (True / False). - ANSWER False
The public needs to understand that dust is just a normal part of construction.
(True / False). - ANSWER False
A temporary gravel construction entrance must extend the full width of the
entrance. It must be at least ____ feet long and at least ____ inches thick.
Aggregate should be ____ in. stone or FDOT No. ____ stone. Prior to installing
the gravel, a ____ should be placed on the ground to simplify installation and
maintenance. - ANSWER 50, 6, 2" or FDOT No.1, and geotextile
Maintenance of a temporary gravel construction entrance should be performed
when void spaces are full of ____ - ANSWER Sediment
The maximum drainage area for a silt fence under sheet flow conditions is ____
acre per 100 feet of barrier length. - ANSWER ¼
What is the average usable life of a silt fence? - ANSWER 6 months
For proper installation of a silt fence, a trench ____ inches deep and ____ inches
wide must be excavated. This will allow the ____ inches of fabric to extend into
the ground for backfilling and compaction. - ANSWER 4", 4", 8"
What is the maximum drainage area for an inlet protection device? - ANSWER
1 acre
When constructing a silt fence drop inlet sediment filter, a trench ____ inches
deep and ____ inches wide must be excavated to allow ____ inches of the fabric
to extend into the trench. - ANSWER 4", 4", 8"
Stakes shall be __" x __" by __ feet long and a 2" x 4" frame will be constructed
________ for proper stability. - ANSWER 2", 4", 3', around the top of the
stakes
The purpose of a sediment trap is to (filter/detain) turbid water. - ANSWER
ANSWERS | NEW 2026/2027 UPDATE | GRADED
A+.
Erosion - ANSWER is the process by which the land surface is worn away by
the action of wind, water, and gravity.
Sedimentation - ANSWER is the settling out of soil particles transported by
water and wind.
Four process of overland erosion are? - ANSWER Splash, sheet, rill, and gully
erosion.
Four principle factors influencing soil erosion are? - ANSWER Soil
characteristics, vegetative cover, topography, and climate.
List three physical effect of erosion and sedimentation: - ANSWER Increased
flooding reduced hydraulic capacity in rivers, and streams; increased
maintenance of stormwater systems.; increased water treatments cost; and
decreased recreational value.
List three biological effect of erosion and sedimentation: - ANSWER Reduced
light for aquatic plants; clogs fish gills; impairs spawning; disrupts food chain;
blankets bottom, suppresses aquatic life; and disrupts ecosystem.
Planning the development to fit the terrain using the particular: - ANSWER
Topography; soils; drainage patterns; natural vegetation of the site; and
minimize the extent of the area exposed at one time and the duration of
exposure.
,Perimeter Control Practices - ANSWER What you apply to protect the
disturbed area from off-site runoff and to protect off-site areas from sediment
damage.
Erosion Control Practices - ANSWER What you apply to prevent excessive on-
site damage.
Keep runoff velocities _____ and _______ runoff on the site - ANSWER Low
and retain
Soil erosion can be classified as 2 types. What are they? - ANSWER Wind and
Water.
What are the two sources of Soil erosion. - ANSWER Natural and Manmade
Water erosion can be classified as two type of erosions. What are they? -
ANSWER Overland and Stream/Channel erosion.
Soils in the Type A hydrologic group have ____ infiltration rates and ____
runoff potential even when thoroughly wetted. - ANSWER high and low
Soils in the Type D hydrologic group have very ____ infiltration rates and ____
runoff potential when thoroughly wetted. - ANSWER low and high
What is the rainfall erosion index? - ANSWER The rainfall erosion index is the
only factor in the Universal Soil Loss Equation which is beyond the developer's
control.
When do you stabilize disturbed areas after final grading to prevent raindrop
impacts from causing erosion. - ANSWER Immediately
, Storage of paints, solvents, cements, pesticides, acids, or other potentially
polluting chemicals is no big deal because they are only stored temporarily and
get used up quickly. (True / False). - ANSWER False
The public needs to understand that dust is just a normal part of construction.
(True / False). - ANSWER False
A temporary gravel construction entrance must extend the full width of the
entrance. It must be at least ____ feet long and at least ____ inches thick.
Aggregate should be ____ in. stone or FDOT No. ____ stone. Prior to installing
the gravel, a ____ should be placed on the ground to simplify installation and
maintenance. - ANSWER 50, 6, 2" or FDOT No.1, and geotextile
Maintenance of a temporary gravel construction entrance should be performed
when void spaces are full of ____ - ANSWER Sediment
The maximum drainage area for a silt fence under sheet flow conditions is ____
acre per 100 feet of barrier length. - ANSWER ¼
What is the average usable life of a silt fence? - ANSWER 6 months
For proper installation of a silt fence, a trench ____ inches deep and ____ inches
wide must be excavated. This will allow the ____ inches of fabric to extend into
the ground for backfilling and compaction. - ANSWER 4", 4", 8"
What is the maximum drainage area for an inlet protection device? - ANSWER
1 acre
When constructing a silt fence drop inlet sediment filter, a trench ____ inches
deep and ____ inches wide must be excavated to allow ____ inches of the fabric
to extend into the trench. - ANSWER 4", 4", 8"
Stakes shall be __" x __" by __ feet long and a 2" x 4" frame will be constructed
________ for proper stability. - ANSWER 2", 4", 3', around the top of the
stakes
The purpose of a sediment trap is to (filter/detain) turbid water. - ANSWER
