NPDES EROSION AND SEDIMENT
CONTROL: NATIONAL POLLUTANT
DISCHARGE ELIMINATION SYSTEM, EXAM
2025/2026 WITH CORRECT/ACCURATE
ANSWERS
Best Management Practices (BMPs)
A combination of erosion control (preventing soil from moving) and sediment control (trapping soil
that does move) BMPs is necessary.
Control Description & Examples
Type
Erosion Protect the soil surface and prevent particles from
Controls becoming dislodged. Examples: Seeding, mulching,
sodding, erosion control blankets, riparian buffers,
preserving existing vegetation, and phased construction.
Sedime Trap sediment after it has eroded and before it leaves the
nt site. Examples: Silt fences, inlet protection, sediment
Controls traps, sediment basins, and check dams.
Minimum Standard 1 - CORRECT-ANSWERS--Stabilization
permanent or temporary soil stabilization shall be applied to denuded
areas within seven days after final grade is reached on any portion of the
site; temporary soil stabilization shall be applied within seven days to
denuded areas that may not be at final grade but will remain dormant for
,longer than 14 days; permanent stabilization shall be applied to areas that
are to be left dormant for more than one year
Site NOT at Final Grade - CORRECT-ANSWERS--- stabilize in 14 days
- temporarily seed
- mulch
- permanently stabilize if dormant > 1 year
Site at Final Grade - CORRECT-ANSWERS--- stabilize in 7 days
(recommended immediately)
- permanently or temporarily seed and mulch
- mulch/matting/straw
Minimum Standard 2 - CORRECT-ANSWERS--Stock Piles, Waste and Borrow
Areas
during construction, soil stock piles and borrow areas shall be stabilized or
protected with sediment trapping measures
mulch prevents erosion by protecting the surface from raindrop impact
and silt fence intercepts and detains from disturbed areas
Minimum Standard 3 - CORRECT-ANSWERS--Permanent Vegetation
permanent vegetation cover shall be established on denuded areas not
otherwise permanently stabilized (permanent vegetation shall not be
,considered established until a ground cover is achieved that is uniform,
mature enough to survive, and will inhibit erosion *there is no %
associated with this*)
reduce erosion and decrease sediment yield from disturbed area
this is the standard used to verify that a site is ready for release of bonds
or surety
Minimum Standard 4 - CORRECT-ANSWERS--First-Step Measures
Sediment basins and traps, perimeter dikes, sediment barriers and other
measures intended to trap sediment shall be constructed as a first step in
any land-disturbing activity and shall be made functional before upslope
land disturbance takes place
a certain amount of initial land disturbance may be required to provide
access for equipment to install the perimeter controls, but site clearing
and grading should be kept to a minimum until the perimeter controls are
in place
intercepts and detains small amounts of sediment from disturbed areas
during construction operation to prevent sediment from leaving the site
and decrease velocity of sheet flows and low-to-moderate level channel
flow
, Perimeter Controls - CORRECT-ANSWERS--assures that sediment does not
leave the perimeter of the land-disturbing area once site clearing,
grading, and construction commences
Examples: silt fences, sediment traps, sediment basins, construction
entrance, temporary diversions, diversions
Minimum Standard 5 - CORRECT-ANSWERS--Earthen Structure
Stabilization
stabilization measures shall be applied to earthen structures such as
dams, dikes, and diversions immediately after installation
reduce erosion and sedimentation and reduce damage from sediment and
runoff to downstream or off-site areas
Minimum Standard 6 - CORRECT-ANSWERS--Traps and Basins
sediment traps and basins shall be designed and constructed based upon
the total drainage area (not just disturbed area) to be served by the trap
or basin
Sediment Traps - CORRECT-ANSWERS--minimum storage capacity shall be
134 cubic yards per acre of drainage area and shall only control drainage
areas less than 3 acres
*stone outlet = trap*
CONTROL: NATIONAL POLLUTANT
DISCHARGE ELIMINATION SYSTEM, EXAM
2025/2026 WITH CORRECT/ACCURATE
ANSWERS
Best Management Practices (BMPs)
A combination of erosion control (preventing soil from moving) and sediment control (trapping soil
that does move) BMPs is necessary.
Control Description & Examples
Type
Erosion Protect the soil surface and prevent particles from
Controls becoming dislodged. Examples: Seeding, mulching,
sodding, erosion control blankets, riparian buffers,
preserving existing vegetation, and phased construction.
Sedime Trap sediment after it has eroded and before it leaves the
nt site. Examples: Silt fences, inlet protection, sediment
Controls traps, sediment basins, and check dams.
Minimum Standard 1 - CORRECT-ANSWERS--Stabilization
permanent or temporary soil stabilization shall be applied to denuded
areas within seven days after final grade is reached on any portion of the
site; temporary soil stabilization shall be applied within seven days to
denuded areas that may not be at final grade but will remain dormant for
,longer than 14 days; permanent stabilization shall be applied to areas that
are to be left dormant for more than one year
Site NOT at Final Grade - CORRECT-ANSWERS--- stabilize in 14 days
- temporarily seed
- mulch
- permanently stabilize if dormant > 1 year
Site at Final Grade - CORRECT-ANSWERS--- stabilize in 7 days
(recommended immediately)
- permanently or temporarily seed and mulch
- mulch/matting/straw
Minimum Standard 2 - CORRECT-ANSWERS--Stock Piles, Waste and Borrow
Areas
during construction, soil stock piles and borrow areas shall be stabilized or
protected with sediment trapping measures
mulch prevents erosion by protecting the surface from raindrop impact
and silt fence intercepts and detains from disturbed areas
Minimum Standard 3 - CORRECT-ANSWERS--Permanent Vegetation
permanent vegetation cover shall be established on denuded areas not
otherwise permanently stabilized (permanent vegetation shall not be
,considered established until a ground cover is achieved that is uniform,
mature enough to survive, and will inhibit erosion *there is no %
associated with this*)
reduce erosion and decrease sediment yield from disturbed area
this is the standard used to verify that a site is ready for release of bonds
or surety
Minimum Standard 4 - CORRECT-ANSWERS--First-Step Measures
Sediment basins and traps, perimeter dikes, sediment barriers and other
measures intended to trap sediment shall be constructed as a first step in
any land-disturbing activity and shall be made functional before upslope
land disturbance takes place
a certain amount of initial land disturbance may be required to provide
access for equipment to install the perimeter controls, but site clearing
and grading should be kept to a minimum until the perimeter controls are
in place
intercepts and detains small amounts of sediment from disturbed areas
during construction operation to prevent sediment from leaving the site
and decrease velocity of sheet flows and low-to-moderate level channel
flow
, Perimeter Controls - CORRECT-ANSWERS--assures that sediment does not
leave the perimeter of the land-disturbing area once site clearing,
grading, and construction commences
Examples: silt fences, sediment traps, sediment basins, construction
entrance, temporary diversions, diversions
Minimum Standard 5 - CORRECT-ANSWERS--Earthen Structure
Stabilization
stabilization measures shall be applied to earthen structures such as
dams, dikes, and diversions immediately after installation
reduce erosion and sedimentation and reduce damage from sediment and
runoff to downstream or off-site areas
Minimum Standard 6 - CORRECT-ANSWERS--Traps and Basins
sediment traps and basins shall be designed and constructed based upon
the total drainage area (not just disturbed area) to be served by the trap
or basin
Sediment Traps - CORRECT-ANSWERS--minimum storage capacity shall be
134 cubic yards per acre of drainage area and shall only control drainage
areas less than 3 acres
*stone outlet = trap*
