3 ZBA - EDP Report ENVIRONMENTAL DESIGN 900 New VOM146C1ibePaN.NY13085
PARTNERSHIP, LLP. (146 CliftonPa ,NY1065
STORMWATER MANAGEMENT NARRATIVE
PROPOSED
SITE IMPROVEMENTS FOR
SANDERS RESIDENCE
TOWN OF QUEENSBURY, NY
Prepared by:
Environmental Design Partnership
Clifton Park, NY 12065
January 2020
Slormwater Management NanotWe
Sanders Residence ENVIRONMENTAL DESIGN
Town of Chmensfiory,New York edb PARTNERSHIP,LLP.
1.0 INTRODUCTION
The Sanders are proposing a second-floor addition to their two-bedroom residence on an existing
0.45+1-acre parcel. The project site is located to the north west side of Birdsall Road,with
frontage on Glen Lake,in the Town of Queensbury,New York. The proposed site improvements
will consist of a new second-floor to the dwelling,replacement septic system,new landscaped
features and stormwater management devices. The proposed development will result in soil
disturbance on the order of 3,895 square feet and the addition of approximately 142 square feet
of impervious surface
A stormwater management system will be designed to provide reduction in the stormwater
runoff rates and volumes in accordance with the Town of Queensbury Storr awater Management
Regulations. The proposed project is a single-family dwelling resulting in less than 5,000 SF of
disturbance with less than 1,000 SF added impervious cover and therefore is not required to gain
coverage under NYSDEC SPDES permit.The proposed stormwater management devices will
include multiple landscaped garden areas,and one drip edge infiltration trench.
This narrative presents a review and comparison of the existing site conditions and proposed site
conditions,as well as proposed design concepts to address increased impervious area for the
proposed site improvements. The purpose of the stormwater management narrative is to assure
that changes in the surface runoff characteristics, as a result of the proposed construction,will
not adversely impact adjacent or downstream properties.
2.0 EXISTING SITE CONDITIONS
The existing site consists of mostly developed residential type area with a two story wood frame
house,three car garage, asphalt drive and parking surface,a well-kept grassed front lawn area,a
deck off the rear of the house with a series of steps that traverse down the steep slopes on the
western portion of the property to the shoreline of Glen Lake, and a recently renovated dock.
The topography of the eastern half of the site(front yard&driveway area)is relatively flat with
the steepest slope within the driveway on the order of 4%. This portion of the property appears to
drain to the south-western corner of the site,and down Birdsall road.
The topography of the western half of the site(house,deck,and shoreline)are steeper with
slopes in excess of 30%.A series of steps and retaining walls we featured here to provide access
to the shoreline.This portion of the property drains downslope towards Glen Lake.
2.1 Soil and Groundwater Conditions
The USDA Natural Resources Conservation Service Soil Survey identifies the two primary soil
groups within the area of the proposed site improvements to be Hinckley cobbly sandy loam
(HnQ and Hinckley-plainfield complex(HpE). Where the soils onsite consist of sandy loam
with large cobbles. The Soil Survey identifies both soil series as Hydrologic Soil Group(HSG)
900 New Yolk 146 Clinon Park,NY 1"65 (P)518.371.7621 mlpllp cam
Stomrxawr Management Narra0ve
Sanders Residence ENVIRONMENTAL DESIGN
Town of Queensbury,New York ab PARTNERSHIP,LLPar
"A". Group A soils have a high infiltration rate and consist of deep,well drained to excessively
drained sands.
Soil test pits were dug on the project site by Redbud Development on November 22,2019 and
logged by Environmental Design Partnership. The soils encountered in these pits consisted of
brown medium-coarse sand to a depth greater than 72",which are consistent with Hydraulic Soil
Group"A"soils. No evidence of seasonal high groundwater was observed in the pits.
Percolation tests were also performed on the project site and observed by Environmental Design
Partnership. Percolation rates were on the order of 3-4 minutes per inch.
3.0 POST DEVELOPMENT STORMWATER ANALYSIS
Site improvements to the property will consist of a new second-floor added to the dwelling,a
replacement septic system,new landscaped features and stormwater management devices.
Stormwater management practices have been designed to provide filtration,infiltration capacity
Rod attenuation of stormwater runoff from the proposed impervious surfaces on the site. The
proposed stormwater management devices shall include multiple landscaped garden areas,and 1
drip edge infiltration trench.
The drip edge infiltration trench will be installed along the eastern and southern sides of the
dwelling and will capture runoff from the proposed front porch,dwelling rooftop,and proposed
rear screened porch. This device is an improvement from the existing conditions on the project
site. Runoff from the existing structure impervious area currently sheet flows to Glen Lake
without treatment. The drip edge infiltration will provide filtration,infiltration capacity,and
attenuation of stormwater runoff from the rooftop and porches.
Also incorporated in the proposed site design is an improved landscaped area located on the
steep slopes that lead down to the Glen Lake shoreline. The landscape plans include a number of
vegetated areas and improved walls and stairs surrounded by soil beds and plantings that will
provide attenuation and promote filtration of surface runoff. These landscape garden areas will
use a variation of bioretention with physical filtering and absorption to remove pollutants from
the runoff prior to flowing to Glen Lake.The existing shoreline does not feature these improved
landscaped areas and therefore these areas will act as an improvement to the existing conditions
with the proposed negligible increase in impervious area.
4.0 SUMMARY
Development of the proposed site will slightly change the stormwater drainage characteristics of
the site; approximately 142 square feet of impervious area will be added and the site will be re-
graded and landscaped to support the proposed improvements. Changes to the stormwater
drainage characteristics of the site have been evaluated. The proposed stormwater management
devices consisting of drip edge infiltration and landscaped garden areas will comply with the
recommendations related to runoff volume and flow rate reduction compared to existing site
NO New York 146 Clifton Park,NY 1200 (P)518.371,7621 eapllp.com
Sbrmwatar Management Narrative
T.nat neaide b PARTNEENVIRORSHIP,L 0ES10N
Town Sande.Resid n.e New York PARTNERSHIP,LLP.
conditions. Through the implementation of acceptable stotmwater management practices,the
proposed project will not adversely affect adjacent or downstream properties.
Prepared by:
Nicholas Zeglen
Reviewed by:
Clark Wilkinson,P.E.
NO New York 146 CliRon Park,NY 120M (P)518,371.7621 edpllp.c xn
Slormwater Management Narraaw
Sanders Residence ENVIRONMENT&DESIGN
Town of Ooeenabury,New York ecb PNRTNERSNIP,LLP.
5.0 REFERENCES
NYSDEC, 1990. "Technical and Operational Guidance Series(5.1.8)Stormwater Management
Guidelines for New Development',New York State Department of Environmental Conservation,
Division of Water.
NYSDEC, 1992. "Reducing the Impacts of Stormwater Runoff from New Development',New
York State Department of Environmental Conservation,Division of Water.
NYSDEC,2010. "New York State Stormwater Management Design Manual",Center for
Watershed Protection,Ellicott City,MD.
Rawls, W.J., Brakensiek,D.L.,and Saxton,K. E., 1982. "Estimation of Soil Properties",
Transactions of the American Society of Agricultural Engineers,Vol. 25,No. J,pp. 1316-1320.
S.C.S., 1988. "Soil Survey of Warren County,New York",U.S. Department of Agriculture,Soil
Conservation Service.
Said New York 1G6 CIIRon Park,NY 12065 (P)518.371.7621 eEPIIP.com
Slormwater Management Narrative
Sanders Residence ENVIRONMENTAL DESIGN
Town of Qucensbury,New York PARTNERSHIP,I.I.P.
Figure 1: Site Location
SITE
LOCATION
Qn a'-300 600r1
900 Nara,York 146 Clifton Park,NY 12065 (P)518.371.7621 e0pllp.com
SWMMWr Management Narrative
Sanders Residence ENVIRONMENTAL DESIGN
Town of Queensbuq,New York Ceb PARTNERSNIR LLP.
Appendix A
USDA Soil Survey
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Hydrologic Soil Group—Warren County,New York
Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres In AOl Pennon AO1
HnC Hinckley cobbty,sandy A 0.2 28.7%
loam,8 to 15 percent
slopes
HpE Hinckley-Plainfield A 0.4 71.3%
complex,steep
Totals for Area of Interest 0.6 100.0%
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet,and receive
precipitation from long-durafion storms.
The soils in the United States are assigned to four groups(A, B, C,and D)and
three dual classes(AID, BID, and C/D).The groups are defined as follows:
Group A. Soils having a high infiltration rate(low runoff potential)when
thoroughly wet.These consist mainly of deep,well drained to excessively
drained sands or gravelly sands.These soils have a high rate of water
transmission. ,
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well
drained soils that have moderately fine texture to moderately coarse texture.
These soils have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet.These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of
water transmission.
Group D.Soils having a very slow infiltration rate(high runoff potential)when
thoroughly wet.These consist chiefly of clays that have a high shrink-swell
potential,soils that have a high water table, soils that have a playpen or clay
layer at or near the surface,and soils that are shallow over nearly impervious
material. These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group(AID, BID, or VD),the first letter is
for drained areas and the second is for undrained areas. Only the soils that in
their natural condition are in group D are assigned to dual classes.
Natural Resources Wab Soil Surrey 1113Q020
Co rsemadon Service Natural Cooperative Son Survey Page 3 of 4
Hytkologic Soil Gmup—Wanen County,New VoM
Rating Options
Aggregation Method:Dominant Condition
Component Percent Cutoff.None Specified
Tie-break Rule:Higher
p5W NaWml Resources VJeb Soil Survey
Conservation Service National Coopengive Soil Survey Paapege 4 4 o off 4
4