Higley Letter Warren County Water Soil394 Schroon River Road, Warrensburg, NY 12885
Phone: 518-623-3119
Fax: 518-623-3519
nrowell123@nycap.rr.com
www.warrenswcd.org
June 17, 2020
Higley
23 Jay Road
Lake George, NY 12845
Dear Higley’s,
As requested, I am writing this letter in reference to my site visit on June 9, 2020 regarding the proposed
garage removal and planned conservation garden area. I have attached an aerial map and soils map of
the project location. You have only one soil type which is a Hinkley cobbly sandy loam. This soil type is
well suited for conservation gardens and the plant recommendations below grow well in areas that
experience periods of saturated soils.
Below are references and recommendations for each of the three conservation gardens we discussed
during our site visit.
Grassed filter or bioretention: It is recommended to grass this area to filter runoff prior to the rain
garden for ease of maintenance (catch debris in runoff). The recommended grass height for this practice
is 4-6 inches to slow and filter the stormwater runoff. The APA grass seed mix is a hardy mix that works
well in Warren County.
Rain garden: See the rain garden attachments and links below for design recommendations. I’ve also
listed a few recommended species below that are native and would do well in your location but there
are certainly many other native plant options.
Shrubs: Red Twig Dogwood, Buttonbush, Red Chokeberry, Common Elderberry, Witherod
Viburnum, American Cranberry, High Bush Blueberry, Winterberry, Ninebark
Perennials: Cutleaf Coneflower, Sensitive Fern, Blue Flag Iris, Cardinal Flower, Joe Pye Weed,
Blue Lobelia, Beebalm, Wild Columbine
Shoreline buffer: See the links below on shoreline buffers. Also, the south west corner of your shoreline
is a good example of a small shoreline buffer. This is the area we pointed out numerous hardy native
plants that work well in shoreline buffers.
Shrubs: Buttonbush, Red Twig Dogwood, Winterberry, Spicebush, River Birch, American
Cranberry, Ninebark, Red Chokeberry
LGA’s Lake Friendly Living https://www.lakegeorgeassociation.org/protect/lake-friendly-living/
LGA’s Shoreline Buffers https://www.lakegeorgeassociation.org/protect/lake-friendly-living/shoreline-
buffers-help-protect-lake-george/
LGA’s Rain Gardens https://www.lakegeorgeassociation.org/protect/lake-friendly-living/rain-gardens-
pretty-functional/
Projects in this location may require permits from the NYS Department of Environmental Conservation
(DEC), and the Town of Queensbury.
The recommended BMP’s and installation designs can be found in the New York State Standards and
Specifications for Erosion and Sediment Control book, also known as the NYS Blue Book
<http://www.dec.ny.gov/docs/water_pdf/2016nysstanec.pdf> and the NYS Stormwater Management
Design Manual < https://www.dec.ny.gov/chemical/29072.html>. I’ve attached practices from these
two documents to this letter. These are practices that we have utilized for numerous projects and they
are approved by the NYSDEC for use in their permit and grant projects.
Please contact me if you have any questions.
Sincerely,
Nick Rowell, CPESC
Natural Resources Specialist
NYS I TS G IS Prog ra m O ff ice, Westchester County/
Gr assed Filter
Rain Garden
Shoreline Buf f er
Hig ley Pro p e rty Re com m endations
HnC
W
W
NYS I TS G IS Prog ra m O ff ice, Westchester County/
Gr assed Filter
Rain Garden
Shoreline Buf f er
Hig ley Pro p e rty Re com m endations
Soils:HnCHinckley cobb ly sandy loamHydrologic So il Goup: A
New York State Stormwater Management Design Manual
Chapter 5: Green Infrastructure Practices
Section 5.3 Green Infrastructure Techniques
5.3.7 Rain Gardens
Description: The rain garden is a stormwater management practice intended to manage and treat small
volumes of stormwater runoff from impervious surfaces using a conditioned planting soil bed and planting
materials to filter runoff stored within a shallow depression. This practice is most commonly used in
residential land use settings. The method is a variation on bioretention and combines physical filtering and
adsorption with bio-geochemical processes to remove pollutants. Rain gardens are a simplified version of
bioretention and are designed as a passive filter system without an underdrain connected to the storm drain
system. A gravel drainage layer is typically used for dispersed infiltration. Rainwater is directed into the
garden from residential roof drains, driveways and other hard surfaces. The runoff temporarily ponds in the
garden and seeps into the soil over one to two days. The system consists of an inflow component, a shallow
ponding area over a planted soil bed, mulch layer, gravel filter chamber, attractive shrubs, grasses and
flowers, and an overflow mechanism to convey larger rain events to the storm drain system or receiving
waters (see Figures 5.42 and 5.43).
Figure 5.41 Profile of a typical rain garden
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Recommended Application of the Practice
The rain garden is suitable for townhouse, single family residential, and in some institutional settings such
as schoolyard projects, for treating small volumes of storm runoff from rooftops, driveways, and sidewalks.
Since rain gardens do not need to be tied directly into the storm drain system, they can be used to treat areas
that may be difficult to otherwise address due to inadequate head or other grading issues. Rain gardens are
designed as an “exfilter,” allowing rainwater to slowly seep through the soil. They have a prepared soil mix
and should be designed with a deeper gravel drainage layer chamber to improve treatment volume, and to
compensate for clays and fines washing into the area. Rain garden size can range from 40 - 300 square feet
for a residential area. Rain gardens can be integrated into a site with a high degree of flexibility and work
well in combination with other structural management systems, including porous pavement, infiltration
trenches, and swales.
Benefits
• Rain gardens can have many benefits when applied to redevelopment and infill projects in urban
settings. The most notable include:
• Pollutant treatment for residential rooftops and driveways, (solids, metals, nutrients and
hydrocarbons)
• Groundwater recharge augmentation
• Micro-scale habitat
Figure 5.42 Layout of typical rain gardens
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• Aesthetic improvement to turfgrass or otherwise hard urban surfaces (Figure 5.44)
• Ease of maintenance, coupling routine landscaping maintenance with effective stormwater
management control and reduced turfgrass maintenance
• Promotion of watershed education and stewardship
• Rain gardens require a modest land area to effectively capture and treat residential runoff from
storms up to approximately the 1-inch precipitation event.
Feasibility/Limitations
Rain gardens have some limitations, similar to bioretention, that restrict their application. The most notable
of these include:
• Steep slopes -
Rain gardens
require relatively
flat slopes to be
able to
accommodate
runoff filtering
through the
system. Some
design
modifications can
address this
constraint through
the use of berms
and timber or
block retaining
walls on moderate
slopes.
• Compacted and clay sub-soils - Sub-soils compacted by construction and heavy clay soils may
need more augmentation by mechanical means (deep tine aeration or deep ripping) to provide
appropriate infiltration or should be designed as a filter with under drains. A single rain garden
system should be designed to receive sheet flow runoff or shallow concentrated flow from an
impervious area or from a roof drain downspout with a total contributing drainage area equal to or
less than 1,000 square feet. Treatment of larger drainage areas should incorporate the design
elements of bioretention practices. Because the system works by filtration through a planting
media, runoff must enter at the surface.
• The rain garden must be sited in a location that allows overflow from the contributing drainage
area to sheet flow or be otherwise safely conveyed to the formal drainage system. Rain gardens
should be located downgradient and at least 10 feet from basement foundations.
• Rain gardens should not be located in areas with heavy tree cover, as the root systems will make
installation difficult and may be damaged by the excavation.
Figure 5.43 Rain gardens also have aesthetic value
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Section 5.3 Green Infrastructure Techniques
• Rain gardens cannot be used to treat parking lot or roadway runoff. Treatment of these areas and
other areas of increased pollutant loading should incorporate the design elements of a bioretention
practice.
Sizing and Design Criteria
Stormwater quantity reduction in rain gardens occurs via evaporation, transpiration, and infiltration, though
only the infiltration capacity of the soil and drainage system is considered for water quality sizing. The
storage volume of a rain garden is achieved within the gravel drainage layer bed, soil medium and ponding
area above the bed. The size should be determined using the water quality volume (WQv), calculated for the
drainage area contributing to the rain garden. The storage volume in the rain garden must be equal to or
greater than the water quality volume (WQv) in order to receive credit towards the runoff reduction volume.
Rain gardens without underdrains in good soils can reduce the total WQv. Those constructed on poor soils
cannot achieve runoff reduction more than 40% of total WQv. Instead of using an underdrain, it is
recommended to increase the surface area of the rain garden. The available volume in the garden is
determined by multiplying the volume of each layer by its porosity and adding the ponding volume. The
following sizing criteria is followed to arrive at the minimum surface area of the rain garden, based on the
required WQv:
WQv ≤ VSM + VDL + (DP x ARG)
VSM = ARG x DSM x nSM
VDL (optional) = ARG x DDL x nDL
where:
VSM = volume of the soil media [cubic feet]
VDL = volume of the gravel drainage layer [cubic feet]
ARG = rain garden surface area [square feet]
DSM = depth of the soil media, typically* 1.0 to 1.5 [feet]
DDL = depth of the drainage layer, minimum 0.5 [feet]
DP = depth of ponding above surface, maximum 0.5 feet [feet]
nSM = porosity of the soil media (≥ 20%)
nDL = porosity of the drainage layer (≥ 40%)
WQv = Water Quality Volume [cubic feet], as defined in Chapter 4
A simple example for sizing rain gardens based upon WQv is presented in Table 5.10.
*Maximum depth in soil types C and D is one foot.
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Required Elements
Siting: Rain gardens should be located as close as possible (without causing damage to structures) to the
impervious areas that they are intended to treat. Although some vegetated areas will drain to the rain garden,
they should be kept to a minimum to maximize the treatment of impervious areas. Rain gardens should be
located within approximately 30 feet of the downspout or impervious area treated. Rooftop conveyance to
the rain garden is through roof leaders directed to the area, with stone or splash blocks with dispersive stone
spreaders placed at the point of discharge into the rain garden to prevent erosion. Runoff from driveways
and other paved surfaces should be directed to the rain garden at a non-erosive rate through shallow swales,
or allowed to sheet flow across short distances (Figure 5.44).
Sizing: The following considerations should be given to design of the rain garden (after PA Stormwater
Design Manual, Bannerman 2003 and LID Center):
• Ponding depth above the rain garden bed should not exceed 6 inches. The recommended
maximum ponding depth of 6 inches provides surface storage of stormwater runoff, but is not too
deep to affect plant health, safety, or create an environment of stagnant conditions. On perfectly
flat sites, this depth is achieved through excavation of the rain garden and backfilling to the
appropriate level; on sloping sites, this depth can be achieved with the use of a berm on the
downslope edge, and excavation/backfill to the required level.
• Surface area is dependent upon storage volume requirements but should not exceed a loading ratio
of 5:1 (drainage area to infiltration area, where drainage area is assumed to be 100% impervious;
to the extent that the drainage area is not 100% impervious, the loading ratio may be modified).
• A length to width ratio of 2:1 with long axis perpendicular to slope and flow path is recommended.
Soil: The composition of the soil media should consist of 50%-70% sand (less than 5% clay content), 50%-
30% topsoil with an average of 5% organic material, such as compost or peat, free of stones, roots and woody
debris and animal waste.. The depth of the amended soil should be approximately 4 inches below the bottom
of the deepest root ball.
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Table 5.10 Rain Garden Simple Sizing Example
Given a 1,000 square foot impervious drainage area (e.g., rooftop), a rain garden design
has been proposed with a 200 square foot surface area, a soil layer depth of 12 inches, a
drainage layer depth of 6 inches, and an allowable ponding depth of 3 inches. Evaluate if
the proposed rain garden design satisfies site WQv requirements
Step 1: Calculate water quality volume using the following equation: 𝑊𝑊𝑊𝑊𝑊𝑊=(𝑃𝑃)(𝑅𝑅𝑊𝑊)𝐴𝐴12
where:
P = 90% rainfall number = 0.9 in
Rv = 0.05+0.009 (I) = 0.05+0.009(100) = 0.95
I = Percentage impervious area draining to site = 100%
A = Area draining to practice (treatment area) = 1,000 ft2 𝑊𝑊𝑊𝑊𝑊𝑊=(0.90)(0.95)1,00012 WQv = 71.25 ft3
Step 2: Solve for drainage layer and soil media storage volume:
VSM = ARG x DSM x PSM
VDL = ARG x DDL x PDL
where:
ARG = proposed rain garden surface area = 200 ft2
DSM = depth soil media = 12 inches = 1.0 ft
DDL = depth drainage layer = 6 inches = 0.5 ft
PSM = porosity of soil media = 0.20
PDL = porosity of drainage layer = 0.40
VSM = 200 ft2 x 1.0 ft x 0.20 = 40 ft3
VDL = 200 ft2 x 0.5 ft x 0.40 = 40 ft3
DP = ponding depth = 3 inches = 0.25 ft
WQv ≤ VSM+VDL+(DP x ARG) = 40 ft3 + 40 ft3 + (0.25 ft x 200 ft2)
WQv = 71.25 ft3 ≤ 130.0 ft3, OK
Therefore, the proposed design for treating an area of 1,000 ft2 exceeds the WQv
requirements. Since this is a contained rain garden without underdrains, the full WQv for
the contributing drainage area (71.25 ft3) is credited towards the runoff reduction volume
(Step 3)
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Construction Rain gardens should initially be dug out to a 24” depth, then backfilled with a 6-12 inch layer
of clean washed gravel (approximately 1.5-2.0 inch diameter rock), and filled back to the rain garden bed
depth with the design soil mix. When an underdrain is used, excavate to 30-36” depth, backfill with 12”
stone, fill with 18-24” design soil mix. Rain gardens should only be installed when surrounding landscapes
are stabilized and not subject to erosion.
Environmental/Landscaping Elements
The rain garden system relies on a successful native plant community to stabilize the ponding area, promote
infiltration, and uptake pollutants. To do that, plant species need to be selected that are adaptable to the
wet/dry conditions that will be present. The goal of planting the rain garden is to establish an attractive
planting bed with a mix of upland and wetland native shrubs, grasses and herbaceous plant material arranged
in a natural configuration starting from the more upland species at the outermost zone of the system to more
wetland species at the innermost zone. Plants shall be container-grown with a well-established root system,
planted on one-foot centers. Table 5.11 provides a representative list of suggested plant selections. Rain
gardens shall not be seeded as this takes too long to establish the desired root system, and seed may be
floated out with rain events. The same limitation is true for plugs. Shredded hardwood mulch should be
applied up to 2” to help keep soil in place.
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Maintenance
Rain gardens are intended to be relatively low maintenance. However, these practices may be subject to
sedimentation and invasive plant species which could create maintenance problems. If the recharge ability
is lost by accumulation of fine sediment, mosquito breeding may occur. Adequate arrangements for long-
term maintenance of these systems and updated inventories of their location are essential for the long-term
performance of these practices. Rain gardens should be treated as a component of the landscaping, with
routine maintenance specified through a legally binding maintenance agreement. Routine maintenance may
include the occasional replacement of plants, mulching, weeding and thinning to maintain the desired
appearance. Weeding and watering are essential the first year, and can be minimized with the use of a weed-
Table 5.11 Suggested Rain Garden Plant List
Shrubs Herbaceous Plants
Witch Hazel
Hamemelis virginiana
Cinnamon Fern
Osmunda cinnamomea
Winterberry
Ilex verticillata
Cutleaf Coneflower
Rudbeckia laciniata
Arrowwood
Viburnum dentatum
Woolgrass
Scirpus cyperinus
Brook-side Alder
Alnus serrulata
New England Aster
Aster novae-angliae
Red-Osier Dogwood
Cornus stolonifera
Fox Sedge
Carex vulpinoidea
Sweet Pepperbush
Clethra alnifolia
Spotted Joe-Pye Weed
Eupatorium maculatum
Switch Grass
Panicum virgatum
Great Blue Lobelia
Lobelia siphatica
Wild Bergamot
Monarda fistulosa
Red Milkweed
Asclepias incarnate
Adapted from NYSDM Bioretention Specifications, Bannerman,
Brooklyn Botanic Garden.
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free mulch layer. Studies have found that rain gardens, especially when native plants are used, are well
accepted if they appear orderly and well maintained. Homeowners and landscapers must be educated
regarding the purpose and maintenance requirements of the rain garden, so the desirable aspects of ponded
water are recognized and maintained.
Select lower growing species that stay upright. Keep plants pruned if they start to get “leggy” and floppy.
Cut off old flower heads after a plant is done blooming. Keeping the garden weeded is one of the most
important tasks, especially in the first couple of years while the native plants are establishing their root
systems. Once the rain garden has matured, the garden area should be free of bare areas except where
stepping stones are located.
Inspect for sediment accumulations or heavy organic matter where runoff enters the garden and remove as
necessary. The top few inches of planting soil should be removed and replaced when water ponds for more
than 48 hours. Blockages may cause diversion of flow around the garden. If the garden overflow device is
an earthen berm or lip, check for erosion and repair as soon as possible. If this continues, a harder armoring
of stone may be necessary. Make sure all appropriate elevations have been maintained, no settlement has
occurred and no low spots have been created.
References/Further Resources
Bannerman, Roger. 2003. Rain Gardens, a How-to Manual for Homeowners. University of Wisconsin.
PUB-WT-776.
Brooklyn Botanic Garden. 2004. Using Spectacular Wetland Plantings to Reduce Runoff.
Iowa Rain Garden Design and Installation Manual, 2008 www.iowastormwater.org
Low Impact Development Center, Inc. (LID) http://www.lid-
stormwater.net/intro/sitemap.htm#permpavers
Pennsylvania Stormwater Best Management Practices Manual. Draft 2005.
Rain Gardens, A hoe-to manual for homeowners, Wisconsin department of Natural Resources DNR
Publication PUB-WT-776 2003.
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5.3.2 Sheetflow to Riparian Buffers or Filter Strips
Description: Vegetated filter strips or undisturbed natural areas such as riparian buffers can be used to treat
and control stormwater runoff from some areas of a development. Vegetated filter strips (a.k.a., grassed filter
strips, filter strips, and grassed filters) are vegetated surfaces that are designed to treat sheet flow from
adjacent surfaces and remove pollutants through filtration and infiltration. Riparian reforestation can be
applied to existing impacted riparian area corridors.
Runoff can be directed towards riparian buffers and other undisturbed natural areas delineated in the initial
stages of site planning to infiltrate runoff, reduce runoff velocity and remove pollutants. Natural depressions
can be used to temporarily store (detain) and infiltrate water, particularly in areas with more permeable
(hydrologic soil groups A and B) soils.
The objective in using natural areas for stormwater infiltration is to intercept runoff before it has become
substantially concentrated and then distribute this flow evenly (as sheet flow) to the buffer or natural
conservation area. This can typically be accomplished using a level spreader, as seen in Figure 5.33. A
mechanism for the bypass of higher-flow events should be provided to reduce erosion or damage to a buffer
or undisturbed natural area. Recommended buffer widths for various uses are indicated in Figure 5.34.
Carefully constructed berms can be placed around natural depressions and below undisturbed vegetated areas
with porous soils to provide for additional runoff storage and/or infiltration of flows.
There are two design variants for sheet flow into filter strips and riparian buffers. The design, installation
and management of these design variants are quite different, as shown in Table 5.8.
Figure 5.32 Use of a level spreader with a riparian buffer
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Recommended Application of Practice
• Direct runoff towards undisturbed riparian buffers or filter strips, using sheet flow or a level
spreader to ensure sheet flow
• Use natural depressions for runoff storage
• Examine the slope, soils and vegetative cover of the buffer/filter strip
• Disconnect impervious areas to these areas
• Buffers may also be used as pretreatment
Table 5.8 The Two Design Variations of the Filter Strip and Vegetative Buffer
Design Issue Sheetflow to Riparian Buffer Sheetflow to Grass Filter
Strip
Soil and Ground Cover Undisturbed Soils and Native
Vegetation
Amended Soils and Dense Turf
Cover
Construction Stage Located Outside the Limits of
Disturbance and Protected by ESC
controls
Prevent Soil Compaction by
Heavy Equipment
Typical Application Adjacent Drainage to Stream Buffer
or Forest Conservation Area
Treat small areas of impervious
cover (e.g., 5,000 sf) close to
source
Compost Amendments No Yes
Boundary Spreader GD at top of filter GD at top of filter
PB at toe of filter
Boundary Zone 10 feet of level grass At 25 feet of level grass
Concentrated Flow ELS with 40 to 65 feet long level
spreader* per one cfs of low,
depending on width of conservation
area
ELS with 1ength of level
spreader per one cfs of flow
Maximum Slope, First Ten
Feet of Filter
Less than 4% Less than 2%
Maximum Overall Slope 6% 8%
GD: Gravel Diaphragm PB: Permeable Berm. ELS: Engineered Level Spreader, * See the NY
Standards and Specifications for Erosion and Sediment Control for the design of level spreaders
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Benefits
• Riparian buffers and undisturbed vegetated areas can be used to filter and infiltrate stormwater
runoff
• Natural depressions can provide inexpensive storage and detention of stormwater flows
• Can provide groundwater recharge
• Provides a valuable corridor for protection of stream or wetland and shoreline habitats
• Reduces the runoff volume that requires treatment and reduces SMP storage volume and size - See
Figure 5.35
• Saves cost and possible land consumption for SMPs
• Promotes protection of natural hydrologic balance that
maintains pre-developed groundwater recharge
characteristics
• Reduces pollutant load delivery to receiving waters that
will help meet water quality standard requirements
Feasibility /Limitations
• Require space – Use in areas where land is available
and land costs are not significantly high
• Will not be available to sites without riparian areas or
already forested riparian areas
Figure 5.34 Use of a vegetated filter
Figure 5.33 Preservation of buffers for various environmental quality goals
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• May be inappropriate in areas of higher pollutant loading due to direct infiltration of pollutants–
Integrate with other practices to ensure adequate treatment prior to discharge
• Channelization and premature failure can occur. This can be alleviated with proper design,
construction and maintenance
• Requires delineation, permanent protection of natural areas, and enforcement for buffer area
protections to be effective
• Sheet flow to a buffer is difficult to maintain and enforce
• Some sites may be too steep to effectively implement these practices
• Some residents may perceive natural buffer areas as potential nuisance areas for vermin and pests
• May be difficult to maintain minimum buffer distances and contributing flow paths
Required Elements
Filter Strip and Riparian Buffers to stream and wetland:
• Maximum contributing length shall be 150 feet for pervious and 75 feet for impervious surfaces
• Runoff shall enter the buffer as overland sheet flow; a flow spreader can be supplied to ensure
this, if average contributing slope criteria cannot be met (Note: a level spreader shall be used
between buffer slopes ranging between 3% and 15%; for buffer slopes beyond 15% this practice
cannot be applied)
• Minimum width of a vegetated filter strip or undisturbed riparian buffer shall be 50 feet for slopes
of 0% to 8%, 75 feet for slopes of 8% to 12% and 100 feet for slopes of 12 % to 15 %.
• Buffers must be fully vegetated.
• Siting and sizing of this practice should address WQv and runoff reduction requirements
and cannot result in overflow to undesignated areas.
Note: The NYS Freshwater Wetlands Act requires a 100-foot buffer for wetlands greater than 12.4 acres.
Applicants required to meet other regulatory requirements are still eligible to meet the stream and wetland
buffer credit provided the criteria cited above are also met.
Sizing and Design Criteria:
Subtract area draining by sheet flow to a riparian buffer or filter strip when computing the water quality
volume. See Figure 5.36. If the area draining contains impervious surface, the Rv value is reduced as well.
This practice is not applicable if the Disconnection of Rooftop Runoff or another area based practice is
already being applied to this area.
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• Maximum contributing length shall be 150 feet for pervious surfaces and 75 feet for impervious
cover
• In HSG C and D buffer length should be increased by 15%-20% respectively.
• For a combination of impervious cover (IC) and pervious cover (PC), use the following to
determine the maximum length of each contributing area:
• 150 – IC = contributing length of PC (maximum IC = 75, maximum PC =150).
Figure 5.35 Illustration of stream buffer practice. Site areas draining to stream buffer that meet the
specified criteria are removed from site area when calculating storage volumes for water quality.
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• Example: (75-IC)*2+IC= total of contributing length.
• The average contributing slope shall be 3% maximum unless a flow spreader is used
• Runoff shall enter the riparian corridor as overland sheet flow. A flow spreader can be supplied to
ensure this, or if average contributing slope criteria cannot be met
• Not applicable if overland flow filtration/groundwater recharge is already credited for the same
impervious cover
• Newly created riparian reforestation areas shall be maintained as a natural area
References/Further Resources
Center for Watershed Protection. 1998. Better Site Design: A Handbook for Changing Development Rules
in Your Community. Available from www.cwp.org
City of Portland, Oregon. September 2004. Stormwater Management Manual. Bureau of Environmental
Services, Portland, OR. Available from http://www.portlandonline.com/bes/
Prince George’s County, MD. June 1999. Low-Impact Development Design Strategies: An Integrated
Design Approach. Prince George’s County, Maryland, Department of Environmental Resources,
Largo, Maryland. Available from www.epa.gov
Virginia Department of Conservation and Recreation (VA DCR), Virginia DCR Stormwater Design
Specification No.2, "Sheet Flow To A Filter Strip or Conserved Open Space", Version 1.6, Dated
September 30, 2009.
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