STORM WATER MANAGEMENT INSPECTOR ACTUAL EXAM REVIEW
150 QUESTIONS AND CORRECT ANSWERS 2026 LATEST VERSION
OVERVIEW
This section of the exam focuses on site-level stormwater management practices and green
infrastructure techniques used to control runoff, reduce pollutant loads, and improve water
quality. It covers rooftop disconnection methods, including simple disconnection to pervious
areas and disconnection to alternative practices like soil compost-amended filter paths, rain
gardens, or cisterns, with their functions in reducing annual runoff volume and nutrient loads.
The exam reviews design and construction of vegetated filter strips, grass channels, check
dams, gravel diaphragms, and engineered level spreaders, emphasizing proper sequencing,
pretreatment, soil testing, and maintenance. It also addresses green infrastructure practices
such as vegetated rooftops, rainwater harvesting systems, and permeable pavement, detailing
construction layers, media, planting, and long-term care. Overall, the questions highlight
regulatory compliance, pollutant control, hydraulic considerations, and practical installation
and maintenance procedures for sustainable stormwater management.
What are the types of disconnection allowed for rooftop disconnection? - correct answer -1) simple
disconnection - rooftops and/or on-lot residential impervious surfaces are directed to pervious areas
2) disconnection leading to an alternative runoff reduction practice adjacent to the roof (ex: soil
compost amended filter path)
Why have a rooftop disconnection to an alternative practice? - correct answer --lot size too small
-filter width is too narrow
-need more water quality credit
Functions provided by simple rooftop disconnection - correct answer --annual runoff volume
reduction
-total phosphorus mass load removal
-total nitrogen mass load removal
Alternative rooftop disconnection types - correct 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? - correct 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 - correct 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 - correct 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 - correct 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 - correct answer -minimal; spring cleanup, regular mowing,
check dam repairs, and other methods of maintaining hydraulic efficiency
Grass channel design criteria - correct 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 - correct answer --check dams
-tree check dams
-grass filter strip
-gravel or stone diaphragm
-gravel or stone flow spreaders
Check dams - correct 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
150 QUESTIONS AND CORRECT ANSWERS 2026 LATEST VERSION
OVERVIEW
This section of the exam focuses on site-level stormwater management practices and green
infrastructure techniques used to control runoff, reduce pollutant loads, and improve water
quality. It covers rooftop disconnection methods, including simple disconnection to pervious
areas and disconnection to alternative practices like soil compost-amended filter paths, rain
gardens, or cisterns, with their functions in reducing annual runoff volume and nutrient loads.
The exam reviews design and construction of vegetated filter strips, grass channels, check
dams, gravel diaphragms, and engineered level spreaders, emphasizing proper sequencing,
pretreatment, soil testing, and maintenance. It also addresses green infrastructure practices
such as vegetated rooftops, rainwater harvesting systems, and permeable pavement, detailing
construction layers, media, planting, and long-term care. Overall, the questions highlight
regulatory compliance, pollutant control, hydraulic considerations, and practical installation
and maintenance procedures for sustainable stormwater management.
What are the types of disconnection allowed for rooftop disconnection? - correct answer -1) simple
disconnection - rooftops and/or on-lot residential impervious surfaces are directed to pervious areas
2) disconnection leading to an alternative runoff reduction practice adjacent to the roof (ex: soil
compost amended filter path)
Why have a rooftop disconnection to an alternative practice? - correct answer --lot size too small
-filter width is too narrow
-need more water quality credit
Functions provided by simple rooftop disconnection - correct answer --annual runoff volume
reduction
-total phosphorus mass load removal
-total nitrogen mass load removal
Alternative rooftop disconnection types - correct 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? - correct 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 - correct 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 - correct 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 - correct 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 - correct answer -minimal; spring cleanup, regular mowing,
check dam repairs, and other methods of maintaining hydraulic efficiency
Grass channel design criteria - correct 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 - correct answer --check dams
-tree check dams
-grass filter strip
-gravel or stone diaphragm
-gravel or stone flow spreaders
Check dams - correct 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
