DEQ STORMWATER MANAGEMENT
INSPECTOR FINAL EXAM REVIEW 2026
QUESTIONS AND ANSWERS FULLY VERIFIED
● Why have a rooftop disconnection to an alternative practice? Answer:
-lot size too small
-filter width is too narrow
-need more water quality credit
● Functions provided by simple rooftop disconnection Answer: -annual
runoff volume reduction
-total phosphorus mass load removal
-total nitrogen mass load removal
● Alternative rooftop disconnection types Answer: -soil compost-
amended filter path
-dry-well or french drain
-rain-garden//front yard bioretention
-rainwater harvesting//cistern
-stormwater planter
,● How does sheet flow to a vegetated filter strip or conserved open
space work? Answer: Filter strips are vegetated areas that treat sheet
flow delivered from adjacent impervious and managed turd areas by
slowing runoff velocities and allowing sediment and attached pollutants
to settle and/or be filtered by the vegetation
● Gravel diaphragm Answer: -pretreatment device
-maintains sheet flow
-not necessary if contributing drainage area is solely turf
-trench is 2 ft. wide and 1 ft. deep
-runs on same contour at top of filter strip
-drop at least 3 inches
-fabric between gravel and soil
● Engineered level spreader Answer: -forebay: max. 3ft. deep, transition
to 1 ft. at level spreader lip
-level spreader lip - concrete, wood, or prefabricated metal, with a well
anchored footer, or other accepted rigid, non-erodible material
-location: 3-6 inches above downstream natural grade to avoid turf
buildup
-3ft. of VDOT #3 stone, underlain by filter fabric just below spreader
-vegetated receiving area must be stabilized
,● Construction sequence for conserved open space Answer: - no
clearing, grading, heavy equipment
-protect area during construction
-prevent sediment discharge
-mark limits of disturbance
-drainage area stabilized
-grade with tracked vehicles
-install gravel diaphragm and/or level spreader
-mark filter boundaries
-keep vehicles out
-stockpile topsoil for later use
-divert construction runoff
-install gravel diaphragm and/or level spreader
-grade with tracked vehicles
-open to runoff once stabilized
● Maintenance of Vegetated Filter Strips Answer: minimal; spring
cleanup, regular mowing, check dam repairs, and other methods of
maintaining hydraulic efficiency
● Grass channel design criteria Answer: -the bottom width of the
channel should be between 4-8 feet wide
-the channel side-slopes should be 3H:1V or flatter
, -the maximum total contributing drainage area to any individual grass
channel is 5 acres
-the longitudinal slope of the channel is <4%
-max flow velocity of channel must be <1ft/sec during a 1 inch storm
event
-the dimensions of the channel should ensure that flow velocity is non-
erosive during the 2-yr and 10-yr design storm events and the 10-yr
design flow is contained within the channel
● Grass channel pretreatment Answer: -check dams
-tree check dams
-grass filter strip
-gravel or stone diaphragm
-gravel or stone flow spreaders
● Check dams Answer: -Purpose: break-up slopes and increase time
water stays in channel
max desired height 12-18 in
-averaging ponding depth: 12 in
-armoring may be needed downstream
-anchored into side slopes and bottom
-center weir to pass 10-year storm
-weep hole or similar drainage for dewatering, composed of
wood/concrete/stone/other non-erodible material
INSPECTOR FINAL EXAM REVIEW 2026
QUESTIONS AND ANSWERS FULLY VERIFIED
● Why have a rooftop disconnection to an alternative practice? Answer:
-lot size too small
-filter width is too narrow
-need more water quality credit
● Functions provided by simple rooftop disconnection Answer: -annual
runoff volume reduction
-total phosphorus mass load removal
-total nitrogen mass load removal
● Alternative rooftop disconnection types Answer: -soil compost-
amended filter path
-dry-well or french drain
-rain-garden//front yard bioretention
-rainwater harvesting//cistern
-stormwater planter
,● How does sheet flow to a vegetated filter strip or conserved open
space work? Answer: Filter strips are vegetated areas that treat sheet
flow delivered from adjacent impervious and managed turd areas by
slowing runoff velocities and allowing sediment and attached pollutants
to settle and/or be filtered by the vegetation
● Gravel diaphragm Answer: -pretreatment device
-maintains sheet flow
-not necessary if contributing drainage area is solely turf
-trench is 2 ft. wide and 1 ft. deep
-runs on same contour at top of filter strip
-drop at least 3 inches
-fabric between gravel and soil
● Engineered level spreader Answer: -forebay: max. 3ft. deep, transition
to 1 ft. at level spreader lip
-level spreader lip - concrete, wood, or prefabricated metal, with a well
anchored footer, or other accepted rigid, non-erodible material
-location: 3-6 inches above downstream natural grade to avoid turf
buildup
-3ft. of VDOT #3 stone, underlain by filter fabric just below spreader
-vegetated receiving area must be stabilized
,● Construction sequence for conserved open space Answer: - no
clearing, grading, heavy equipment
-protect area during construction
-prevent sediment discharge
-mark limits of disturbance
-drainage area stabilized
-grade with tracked vehicles
-install gravel diaphragm and/or level spreader
-mark filter boundaries
-keep vehicles out
-stockpile topsoil for later use
-divert construction runoff
-install gravel diaphragm and/or level spreader
-grade with tracked vehicles
-open to runoff once stabilized
● Maintenance of Vegetated Filter Strips Answer: minimal; spring
cleanup, regular mowing, check dam repairs, and other methods of
maintaining hydraulic efficiency
● Grass channel design criteria Answer: -the bottom width of the
channel should be between 4-8 feet wide
-the channel side-slopes should be 3H:1V or flatter
, -the maximum total contributing drainage area to any individual grass
channel is 5 acres
-the longitudinal slope of the channel is <4%
-max flow velocity of channel must be <1ft/sec during a 1 inch storm
event
-the dimensions of the channel should ensure that flow velocity is non-
erosive during the 2-yr and 10-yr design storm events and the 10-yr
design flow is contained within the channel
● Grass channel pretreatment Answer: -check dams
-tree check dams
-grass filter strip
-gravel or stone diaphragm
-gravel or stone flow spreaders
● Check dams Answer: -Purpose: break-up slopes and increase time
water stays in channel
max desired height 12-18 in
-averaging ponding depth: 12 in
-armoring may be needed downstream
-anchored into side slopes and bottom
-center weir to pass 10-year storm
-weep hole or similar drainage for dewatering, composed of
wood/concrete/stone/other non-erodible material
