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STORMWATER_NARRATIVE_MAIN HOUSE900 New York 146 Clifton Park, NY 12065 (P) 518.371.7621 (F) 518.371.9540 edpllp.com STORMWATER MANAGEMENT NARRATIVE PROPOSED MAIN HOUSE WEST RESIDENCE TOWN OF QUEENSBURY, NY Prepared by: Environmental Design Partnership Clifton Park, NY 12065 MAY 2021 Stormwater Management Narrative Bay Parkway. Town of Queensbury, New York 900 New York 146 Clifton Park, NY 12065 (P) 518.371.7621 (F) 518.371.9540 edpllp.com 1.0 INTRODUCTION The applicant is proposing to demolish an existing residential building and construct a new single-family residence on an approximate 0.91 acre parcel. The project site is located to the north side of Bay Parkway, off of Assembly Point Rd north of the intersection with Ridge Rd, in the Town of Queensbury, New York. The proposed redevelopment will result in total soil disturbance on the order of 23,630 square feet and approximately 11,810 square feet of impervious surface which is an increase of 3,830 square feet from existing. A stormwater management system will be designed to provide reduction of the stormwater runoff rates and volumes in accordance with the Town of Queensbury Stormwater Management Regulations. The proposed project includes less than 1 acre of disturbance therefore is not required to gain coverage under NYSDEC SPDES permit. The proposed stormwater management system will include 1 rain garden with a total storage volume on the order of 1,229 cubic feet. This narrative presents a review of the design concepts and parameters of the stormwater management system for the proposed site improvements. The purpose of the stormwater management narrative is to assure that changes in the surface runoff characteristi cs, as a result of the proposed construction, will not adversely impact adjacent or downstream properties. On-site stormwater management will be implemented in accordance with the Town of Queensbury Stormwater Management Regulations, Chapter 147 of the Town Code, to accommodate runoff rate and volumes. 2.0 EXISTING SITE CONDITIONS The existing site consists of a single-family house, detached garage, several sheds, paved driveway and lawn area. The runoff flows to the north of the property eventually running into Lake George. The topography of the site is flat with the majority of the slopes around or below 5%. 2.1 Soil and Groundwater Conditions The NRCS Web Soil Survey identifies the primary soil groups within the area of the proposed site improvements to be SuB (Sutton Loam). The Soil Survey identifies SuB soil series as Hydrologic Soil Group (HSG) “B/D”. A hydraulic model of the preexisting site was prepared using the Hydrocad program. One (1) subcatchment was used to represent the existing drainage characteristics, see Figure 2. The existing parameters of topography, vegetation, slope and soil type are all incorporated into the predevelopment hydraulic model, the entire drainage area was modeled as “woods good” for the predevelopment model. The results for the existing condition model are summarized later in this report and have been included in Appendix A. Stormwater Management Narrative Bay Parkway. Town of Queensbury, New York 900 New York 146 Clifton Park, NY 12065 (P) 518.371.7621 (F) 518.371.9540 edpllp.com 3.0 POST DEVELOPMENT STORMWATER ANALYSIS Site improvements to the property consist of removal of a single-family house, detached garage, several sheds, paved driveway and construction of a single-family house and driveway. Stormwater management practices have been designed to provide filtration, infiltration capacity and attenuation of stormwater runoff from the site area. The proposed stormwater management system shall consist of one (1) rain garden. The rain garden has been designed to collect, attenuate and infiltrate the stormwater runoff from the driveway as well as from portions of the roof and lawn. The rain garden is designed to provide attenuation and infiltration of the contributing stormwater runoff. The rain garden has been designed with a planting soil media and a stone reservoir in order to allow for filtering of the contributing stormwater runoff. The rain garden has been sized accordingly to provide attenuation and infiltration of stormwater runoff for storms up to and including the 25-year design storm. Overflow from the rain garden will be directed to Lake George to follow pre development site conditions. 3.1 Town of Queensbury Stormwater Regulations The project consists of greater than 15,000 square feet of disturbance and therefore, according the Chapter 147 of the town code, is considered a major project. The proposed stormwater management has been designed in accordance with the Queensbury Town Code which requires that the volume of runoff for a ten-year storm shall be maintained after development and that the peak rate of runoff shall not be increased for the 25-year storm. The following tables summarize the stormwater modeling results. Table 1: 10-Year (3.51 inch) Design Storm Runoff Volume Design Point Predevelopment Runoff Volume (cf) Post-Development Runoff Volume (cf) 1 5,177 4,155 Table 2: 25-Year (4.25 inch) Design Storm Runoff Rate Design Point Predevelopment Runoff Rate (cfs) Post-Development Runoff Rate (cfs) 1 3.05 2.41 Stormwater Management Narrative Bay Parkway. Town of Queensbury, New York 900 New York 146 Clifton Park, NY 12065 (P) 518.371.7621 (F) 518.371.9540 edpllp.com 4.0 SUMMARY Development of the proposed site has changed the stormwater drainage characteristics of the site; impervious area was added and the site was re-graded to support the improvements. Changes to the stormwater drainage characteristics of the site have been evaluated in accordance with the Queensbury Town Code. The proposed stormwater management system will comply with the recommendations in these standards related to runoff volume and flow rate reduction. Through the implementation of acceptable stormwater management practices, the proposed project will not adversely affect adjacent or downstream properties. Prepared by: Evan Klein, E.I.T. Reviewed by: Brandon M. Ferguson, P.E. Stormwater Management Narrative Bay Parkway. Town of Queensbury, New York 900 New York 146 Clifton Park, NY 12065 (P) 518.371.7621 (F) 518.371.9540 edpllp.com 5.0 REFERENCES HydroCAD version 6.00, Applied Microcomputer Systems, Chocura, New Hampshire. 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, 2015. “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., 1982. “TR-20 Project Formulation-Hydrology, Technical Release No. 20”, U.S. Department of Agriculture, Soil Conservation Service, Hydrology Unit Division of Engi neering. Stormwater Management Narrative Bay Parkway. Town of Queensbury, New York 900 New York 146 Clifton Park, NY 12065 (P) 518.371.7621 (F) 518.371.9540 edpllp.com Figure 1: Site Location SITE LOCATION LANDS N/F OFO'KEEFESTEPSIPF465'± ALONG THE SHOREMEAN HIGH WATERELEVATION 320.20MEAN LOW WATERELEVATION OF 317.74 X X X X X X X X X X XXDECKGarageShedS H E D 2 STORY LOG HOMEDock DOCKCOVEREDBOAT LIFTPATIOG A Z E B O FF=324.45 30.0'METALCOVERINV. 4" PVC=321.66INV. 4" PVC=321.62Shed18" Beech14" Tree14" Spruce14" Spruce14" Spruce14" Cedar14" Spruce12" Spruce20" Cherry26" Ash16" SpruceIPFCIRSCIRSLandingUtility Pole 9'± to ShoreDockDeckIPFWood Fence Bench MarkRR Spike InUP NG 3Elev. = 328.74'327326326326325325325324323322320327 UPSteps Edge PlanterEdge Planter Edge P l a n te r Edge PlanterSteps Typ.320325 3 2 3 324326322 3223251" = 30'2Q:\WARREN\QUEENSBURY\BAY PARKWAY\106-108 WEST\05-DWG\Detailed Plans\FIGURES\STORMWATER MAIN HOUSE.dwg May 14, 2021 02:11:35PM, EHK PROPERTY ON LAKE GEORGE 106 BAY PARKWAY TOWN OF QUEENSBURY APRIL 27, 2021 WEST RESIDENCEPREDEVELOPMENT WARREN COUNTY, NEW YORK TAX MAP. No. 226.15-1-17900 Route 146 Clifton Park, New York 12065 edpllp.com(518) 371-7621 E N V I R O N M E N T A L D E S I G N P A R T N E R S H I P, L L P. LANDS N/F OFO'KEEFESTEPSIPF465'± ALONG THE SHOREMEAN HIGH WATERELEVATION 320.20MEAN LOW WATERELEVATION OF 317.74 X X X X X X X X X X XXS H E DDockDOCKCOVEREDBOAT LIFT18" Beech14" Tree14" Spruce14" Spruce14" Spruce14" Cedar14" Spruce12" Spruce20" Cherry26" Ash16" SpruceIPFCIRSCIRSLandingUtility Pole 9'± to ShoreDockDeckIPFWood Fence Bench MarkRR Spike InUP NG 3Elev. = 328.74'327326326326325325325324323322320327 UPSteps Edge PlanterEdge Planter Edge P l a n te r Edge PlanterSteps Typ.320325 3 2 3 324326322 3223251" = 30'3Q:\WARREN\QUEENSBURY\BAY PARKWAY\106-108 WEST\05-DWG\Detailed Plans\FIGURES\STORMWATER MAIN HOUSE.dwg May 14, 2021 02:11:50PM, EHK PROPERTY ON LAKE GEORGE 106 BAY PARKWAY TOWN OF QUEENSBURY APRIL 27, 2021 WEST RESIDENCEPOSTDEVELOPMENTWARREN COUNTY, NEW YORK TAX MAP. No. 226.15-1-17900 Route 146 Clifton Park, New York 12065 edpllp.com(518) 371-7621 E N V I R O N M E N T A L D E S I G N P A R T N E R S H I P, L L P. Stormwater Management Narrative Bay Parkway. Town of Queensbury, New York 900 New York 146 Clifton Park, NY 12065 (P) 518.371.7621 (F) 518.371.9540 edpllp.com Appendix A USDA Soil Survey Soil Map—Warren County, New York Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/14/2021 Page 1 of 3481418048142004814220481424048142604814280481430048143204814340481418048142004814220481424048142604814280481430048143204814340608450608470608490608510608530608550608570 608450 608470 608490 608510 608530 608550 608570 43° 28' 26'' N 73° 39' 33'' W43° 28' 26'' N73° 39' 27'' W43° 28' 21'' N 73° 39' 33'' W43° 28' 21'' N 73° 39' 27'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 18N WGS84 0 40 80 160 240 Feet 0 10 20 40 60 Meters Map Scale: 1:853 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:15,800. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Warren County, New York Survey Area Data: Version 20, Jun 11, 2020 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jun 10, 2015—Mar 29, 2017 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Soil Map—Warren County, New York Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/14/2021 Page 2 of 3 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI SuB Sutton loam, 3 to 8 percent slopes 2.0 57.0% W Water 1.5 43.0% Totals for Area of Interest 3.5 100.0% Soil Map—Warren County, New York Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/14/2021 Page 3 of 3 Stormwater Management Narrative Bay Parkway. Town of Queensbury, New York 900 New York 146 Clifton Park, NY 12065 (P) 518.371.7621 (F) 518.371.9540 edpllp.com Appendix B Predevelopment Stormwater Modeling Calculations S1 DP Routing Diagram for PREDEVELOPMENT MAIN HOUSE Prepared by {enter your company name here}, Printed 5/14/2021 HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Subcat Reach Pond Link PREDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 2HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Rainfall Events Listing Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC 1 1 YR Type II 24-hr Default 24.00 1 2.13 2 2 10 YR Type II 24-hr Default 24.00 1 3.51 2 3 25 YR Type II 24-hr Default 24.00 1 4.25 2 PREDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 3HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (sq-ft) CN Description (subcatchment-numbers) 43,200 77 Woods, Good, HSG D (S1) 43,200 77 TOTAL AREA PREDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 4HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Soil Listing (all nodes) Area (sq-ft) Soil Group Subcatchment Numbers 0 HSG A 0 HSG B 0 HSG C 43,200 HSG D S1 0 Other 43,200 TOTAL AREA PREDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 5HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Ground Covers (all nodes) HSG-A (sq-ft) HSG-B (sq-ft) HSG-C (sq-ft) HSG-D (sq-ft) Other (sq-ft) Total (sq-ft) Ground Cover Subcatchment Numbers 0 0 0 43,200 0 43,200 Woods, Good S 1 0 0 0 43,200 0 43,200 TOTAL AREA Type II 24-hr 1 YR Rainfall=2.13"PREDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 6HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Time span=0.00-80.00 hrs, dt=0.05 hrs, 1601 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=43,200 sf 0.00% Impervious Runoff Depth=0.52"Subcatchment S1: Flow Length=249' Tc=9.7 min CN=77 Runoff=0.73 cfs 1,871 cf Inflow=0.73 cfs 1,871 cfLink DP: Primary=0.73 cfs 1,871 cf Total Runoff Area = 43,200 sf Runoff Volume = 1,871 cf Average Runoff Depth = 0.52" 100.00% Pervious = 43,200 sf 0.00% Impervious = 0 sf Type II 24-hr 1 YR Rainfall=2.13"PREDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 7HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment S1: Runoff = 0.73 cfs @ 12.03 hrs, Volume= 1,871 cf, Depth= 0.52" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Type II 24-hr 1 YR Rainfall=2.13" Area (sf) CN Description 43,200 77 Woods, Good, HSG D 43,200 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 92 0.0380 0.19 Sheet Flow, Grass: Short n= 0.150 P2= 2.50" 0.2 8 0.0250 0.80 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.50" 0.1 15 0.0270 3.34 Shallow Concentrated Flow, Paved Kv= 20.3 fps 0.4 64 0.0270 2.46 Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps 1.0 70 0.0550 1.17 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 9.7 249 Total Summary for Link DP: Inflow Area = 43,200 sf, 0.00% Impervious, Inflow Depth = 0.52" for 1 YR event Inflow = 0.73 cfs @ 12.03 hrs, Volume= 1,871 cf Primary = 0.73 cfs @ 12.03 hrs, Volume= 1,871 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Type II 24-hr 10 YR Rainfall=3.51"PREDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 8HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Time span=0.00-80.00 hrs, dt=0.05 hrs, 1601 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=43,200 sf 0.00% Impervious Runoff Depth=1.44"Subcatchment S1: Flow Length=249' Tc=9.7 min CN=77 Runoff=2.18 cfs 5,177 cf Inflow=2.18 cfs 5,177 cfLink DP: Primary=2.18 cfs 5,177 cf Total Runoff Area = 43,200 sf Runoff Volume = 5,177 cf Average Runoff Depth = 1.44" 100.00% Pervious = 43,200 sf 0.00% Impervious = 0 sf Type II 24-hr 10 YR Rainfall=3.51"PREDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 9HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment S1: Runoff = 2.18 cfs @ 12.02 hrs, Volume= 5,177 cf, Depth= 1.44" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Type II 24-hr 10 YR Rainfall=3.51" Area (sf) CN Description 43,200 77 Woods, Good, HSG D 43,200 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 92 0.0380 0.19 Sheet Flow, Grass: Short n= 0.150 P2= 2.50" 0.2 8 0.0250 0.80 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.50" 0.1 15 0.0270 3.34 Shallow Concentrated Flow, Paved Kv= 20.3 fps 0.4 64 0.0270 2.46 Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps 1.0 70 0.0550 1.17 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 9.7 249 Total Summary for Link DP: Inflow Area = 43,200 sf, 0.00% Impervious, Inflow Depth = 1.44" for 10 YR event Inflow = 2.18 cfs @ 12.02 hrs, Volume= 5,177 cf Primary = 2.18 cfs @ 12.02 hrs, Volume= 5,177 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Type II 24-hr 25 YR Rainfall=4.25"PREDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 10HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Time span=0.00-80.00 hrs, dt=0.05 hrs, 1601 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=43,200 sf 0.00% Impervious Runoff Depth=2.01"Subcatchment S1: Flow Length=249' Tc=9.7 min CN=77 Runoff=3.05 cfs 7,234 cf Inflow=3.05 cfs 7,234 cfLink DP: Primary=3.05 cfs 7,234 cf Total Runoff Area = 43,200 sf Runoff Volume = 7,234 cf Average Runoff Depth = 2.01" 100.00% Pervious = 43,200 sf 0.00% Impervious = 0 sf Type II 24-hr 25 YR Rainfall=4.25"PREDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 11HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment S1: Runoff = 3.05 cfs @ 12.01 hrs, Volume= 7,234 cf, Depth= 2.01" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Type II 24-hr 25 YR Rainfall=4.25" Area (sf) CN Description 43,200 77 Woods, Good, HSG D 43,200 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 92 0.0380 0.19 Sheet Flow, Grass: Short n= 0.150 P2= 2.50" 0.2 8 0.0250 0.80 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.50" 0.1 15 0.0270 3.34 Shallow Concentrated Flow, Paved Kv= 20.3 fps 0.4 64 0.0270 2.46 Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps 1.0 70 0.0550 1.17 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 9.7 249 Total Summary for Link DP: Inflow Area = 43,200 sf, 0.00% Impervious, Inflow Depth = 2.01" for 25 YR event Inflow = 3.05 cfs @ 12.01 hrs, Volume= 7,234 cf Primary = 3.05 cfs @ 12.01 hrs, Volume= 7,234 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Table of ContentsPREDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC TABLE OF CONTENTS Project Reports 1 Routing Diagram 2 Rainfall Events Listing 3 Area Listing (all nodes) 4 Soil Listing (all nodes) 5 Ground Covers (all nodes) 1 YR Event 6 Node Listing 7 Subcat S1: 8 Link DP: 10 YR Event 8 Node Listing 9 Subcat S1: 10 Link DP: 25 YR Event 10 Node Listing 11 Subcat S1: 12 Link DP: Stormwater Management Narrative Bay Parkway. Town of Queensbury, New York 900 New York 146 Clifton Park, NY 12065 (P) 518.371.7621 (F) 518.371.9540 edpllp.com Appendix C Post-development Stormwater Modeling Calculations S1 S2 S3 1R (new Reach) 1P SMA #1 DP Routing Diagram for POSTDEVELOPMENT MAIN HOUSE Prepared by {enter your company name here}, Printed 5/14/2021 HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Subcat Reach Pond Link POSTDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 2HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Rainfall Events Listing Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC 1 1 YR Type II 24-hr Default 24.00 1 2.13 2 2 10 YR Type II 24-hr Default 24.00 1 3.51 2 3 25 YR Type II 24-hr Default 24.00 1 4.25 2 POSTDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 3HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (sq-ft) CN Description (subcatchment-numbers) 28,295 80 >75% Grass cover, Good, HSG D (S1, S2, S3) 7,341 98 Paved parking, HSG D (S1, S2, S3) 2,937 98 Roofs, HSG D (S2) 2,449 98 Unconnected roofs, HSG D (S1) 1,516 77 Woods, Good, HSG D (S2) 42,538 85 TOTAL AREA POSTDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 4HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Soil Listing (all nodes) Area (sq-ft) Soil Group Subcatchment Numbers 0 HSG A 0 HSG B 0 HSG C 42,538 HSG D S1, S2, S3 0 Other 42,538 TOTAL AREA POSTDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 5HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Ground Covers (all nodes) HSG-A (sq-ft) HSG-B (sq-ft) HSG-C (sq-ft) HSG-D (sq-ft) Other (sq-ft) Total (sq-ft) Ground Cover Subcatchment Numbers 0 0 0 28,295 0 28,295 >75% Grass cover, Good 0 0 0 7,341 0 7,341 Paved parking 0 0 0 2,937 0 2,937 Roofs 0 0 0 2,449 0 2,449 Unconnected roofs 0 0 0 1,516 0 1,516 Woods, Good 0 0 0 42,538 0 42,538 TOTAL AREA Type II 24-hr 1 YR Rainfall=2.13"POSTDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 6HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Time span=0.00-80.00 hrs, dt=0.05 hrs, 1601 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=15,172 sf 46.84% Impervious Runoff Depth=1.07"Subcatchment S1: Flow Length=94' Tc=11.7 min CN=88 Runoff=0.53 cfs 1,354 cf Runoff Area=24,492 sf 20.07% Impervious Runoff Depth=0.79"Subcatchment S2: Flow Length=98' Slope=0.0306 '/' Tc=9.2 min CN=83 Runoff=0.68 cfs 1,603 cf Runoff Area=2,874 sf 24.53% Impervious Runoff Depth=0.84"Subcatchment S3: Flow Length=52' Slope=0.0200 '/' Tc=6.6 min CN=84 Runoff=0.09 cfs 201 cf Avg. Flow Depth=0.00' Max Vel=1.30 fps Inflow=0.09 cfs 201 cfReach 1R: (new Reach) n=0.015 L=50.0' S=0.0800 '/' Capacity=1,364.86 cfs Outflow=0.09 cfs 201 cf Peak Elev=322.62' Storage=400 cf Inflow=0.62 cfs 1,555 cfPond 1P: SMA #1 Discarded=0.14 cfs 1,555 cf Primary=0.00 cfs 0 cf Outflow=0.14 cfs 1,555 cf Inflow=0.68 cfs 1,603 cfLink DP: Primary=0.68 cfs 1,603 cf Total Runoff Area = 42,538 sf Runoff Volume = 3,157 cf Average Runoff Depth = 0.89" 70.08% Pervious = 29,811 sf 29.92% Impervious = 12,727 sf Type II 24-hr 1 YR Rainfall=2.13"POSTDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 7HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment S1: Runoff = 0.53 cfs @ 12.04 hrs, Volume= 1,354 cf, Depth= 1.07" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Type II 24-hr 1 YR Rainfall=2.13" Area (sf) CN Description 8,065 80 >75% Grass cover, Good, HSG D 2,449 98 Unconnected roofs, HSG D 4,658 98 Paved parking, HSG D 15,172 88 Weighted Average 8,065 53.16% Pervious Area 7,107 46.84% Impervious Area 2,449 34.46% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.0 3 0.5000 2.19 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.50" 3.6 18 0.0110 0.08 Sheet Flow, Grass: Short n= 0.150 P2= 2.50" 0.4 15 0.0110 0.65 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.50" 6.8 42 0.0120 0.10 Sheet Flow, Grass: Short n= 0.150 P2= 2.50" 0.3 14 0.0120 0.67 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.50" 0.6 2 0.0120 0.06 Sheet Flow, Grass: Short n= 0.150 P2= 2.50" 11.7 94 Total Summary for Subcatchment S2: Runoff = 0.68 cfs @ 12.01 hrs, Volume= 1,603 cf, Depth= 0.79" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Type II 24-hr 1 YR Rainfall=2.13" Area (sf) CN Description 18,061 80 >75% Grass cover, Good, HSG D 2,937 98 Roofs, HSG D 1,978 98 Paved parking, HSG D 1,516 77 Woods, Good, HSG D 24,492 83 Weighted Average 19,577 79.93% Pervious Area 4,915 20.07% Impervious Area Type II 24-hr 1 YR Rainfall=2.13"POSTDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 8HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 9.2 98 0.0306 0.18 Sheet Flow, Grass: Short n= 0.150 P2= 2.50" Summary for Subcatchment S3: Runoff = 0.09 cfs @ 11.98 hrs, Volume= 201 cf, Depth= 0.84" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Type II 24-hr 1 YR Rainfall=2.13" Area (sf) CN Description 2,169 80 >75% Grass cover, Good, HSG D 0 98 Unconnected roofs, HSG D 705 98 Paved parking, HSG D 2,874 84 Weighted Average 2,169 75.47% Pervious Area 705 24.53% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.6 52 0.0200 0.13 Sheet Flow, Grass: Short n= 0.150 P2= 2.50" Summary for Reach 1R: (new Reach) Inflow Area = 2,874 sf, 24.53% Impervious, Inflow Depth = 0.84" for 1 YR event Inflow = 0.09 cfs @ 11.98 hrs, Volume= 201 cf Outflow = 0.09 cfs @ 12.00 hrs, Volume= 201 cf, Atten= 4%, Lag= 1.1 min Routing by Stor-Ind+Trans method, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Max. Velocity= 1.30 fps, Min. Travel Time= 0.6 min Avg. Velocity = 1.30 fps, Avg. Travel Time= 0.6 min Peak Storage= 4 cf @ 11.99 hrs Average Depth at Peak Storage= 0.00' , Surface Width= 50.00' Bank-Full Depth= 1.00' Flow Area= 50.0 sf, Capacity= 1,364.86 cfs 50.00' x 1.00' deep channel, n= 0.015 Brickwork Length= 50.0' Slope= 0.0800 '/' Inlet Invert= 327.00', Outlet Invert= 323.00' ‡ Type II 24-hr 1 YR Rainfall=2.13"POSTDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 9HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Summary for Pond 1P: SMA #1 Inflow Area = 18,046 sf, 43.29% Impervious, Inflow Depth = 1.03" for 1 YR event Inflow = 0.62 cfs @ 12.03 hrs, Volume= 1,555 cf Outflow = 0.14 cfs @ 11.85 hrs, Volume= 1,555 cf, Atten= 77%, Lag= 0.0 min Discarded = 0.14 cfs @ 11.85 hrs, Volume= 1,555 cf Primary = 0.00 cfs @ 0.00 hrs, Volume= 0 cf Routing by Stor-Ind method, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Peak Elev= 322.62' @ 12.30 hrs Surf.Area= 1,233 sf Storage= 400 cf Plug-Flow detention time= 16.0 min calculated for 1,554 cf (100% of inflow) Center-of-Mass det. time= 16.0 min ( 852.8 - 836.8 ) Volume Invert Avail.Storage Storage Description #1 321.50' 1,229 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim. Voids Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (%) (cubic-feet) (cubic-feet) (sq-ft) 321.50 1,233 238.0 0.0 0 0 1,233 322.00 1,233 238.0 40.0 247 247 1,352 323.00 1,233 238.0 20.0 247 493 1,590 323.50 1,722 251.0 100.0 735 1,229 2,110 Device Routing Invert Outlet Devices #1 Discarded 321.50'5.000 in/hr Exfiltration over Surface area #2 Primary 323.25'5.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Discarded OutFlow Max=0.14 cfs @ 11.85 hrs HW=321.54' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.14 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=321.50' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Link DP: Inflow Area = 42,538 sf, 29.92% Impervious, Inflow Depth = 0.45" for 1 YR event Inflow = 0.68 cfs @ 12.01 hrs, Volume= 1,603 cf Primary = 0.68 cfs @ 12.01 hrs, Volume= 1,603 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Type II 24-hr 10 YR Rainfall=3.51"POSTDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 10HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Time span=0.00-80.00 hrs, dt=0.05 hrs, 1601 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=15,172 sf 46.84% Impervious Runoff Depth=2.28"Subcatchment S1: Flow Length=94' Tc=11.7 min CN=88 Runoff=1.12 cfs 2,880 cf Runoff Area=24,492 sf 20.07% Impervious Runoff Depth=1.87"Subcatchment S2: Flow Length=98' Slope=0.0306 '/' Tc=9.2 min CN=83 Runoff=1.64 cfs 3,811 cf Runoff Area=2,874 sf 24.53% Impervious Runoff Depth=1.95"Subcatchment S3: Flow Length=52' Slope=0.0200 '/' Tc=6.6 min CN=84 Runoff=0.22 cfs 466 cf Avg. Flow Depth=0.00' Max Vel=1.30 fps Inflow=0.22 cfs 466 cfReach 1R: (new Reach) n=0.015 L=50.0' S=0.0800 '/' Capacity=1,364.86 cfs Outflow=0.21 cfs 466 cf Peak Elev=323.35' Storage=978 cf Inflow=1.31 cfs 3,346 cfPond 1P: SMA #1 Discarded=0.18 cfs 3,001 cf Primary=0.41 cfs 345 cf Outflow=0.59 cfs 3,346 cf Inflow=1.64 cfs 4,155 cfLink DP: Primary=1.64 cfs 4,155 cf Total Runoff Area = 42,538 sf Runoff Volume = 7,156 cf Average Runoff Depth = 2.02" 70.08% Pervious = 29,811 sf 29.92% Impervious = 12,727 sf Type II 24-hr 10 YR Rainfall=3.51"POSTDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 11HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment S1: Runoff = 1.12 cfs @ 12.03 hrs, Volume= 2,880 cf, Depth= 2.28" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Type II 24-hr 10 YR Rainfall=3.51" Area (sf) CN Description 8,065 80 >75% Grass cover, Good, HSG D 2,449 98 Unconnected roofs, HSG D 4,658 98 Paved parking, HSG D 15,172 88 Weighted Average 8,065 53.16% Pervious Area 7,107 46.84% Impervious Area 2,449 34.46% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.0 3 0.5000 2.19 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.50" 3.6 18 0.0110 0.08 Sheet Flow, Grass: Short n= 0.150 P2= 2.50" 0.4 15 0.0110 0.65 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.50" 6.8 42 0.0120 0.10 Sheet Flow, Grass: Short n= 0.150 P2= 2.50" 0.3 14 0.0120 0.67 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.50" 0.6 2 0.0120 0.06 Sheet Flow, Grass: Short n= 0.150 P2= 2.50" 11.7 94 Total Summary for Subcatchment S2: Runoff = 1.64 cfs @ 12.01 hrs, Volume= 3,811 cf, Depth= 1.87" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Type II 24-hr 10 YR Rainfall=3.51" Area (sf) CN Description 18,061 80 >75% Grass cover, Good, HSG D 2,937 98 Roofs, HSG D 1,978 98 Paved parking, HSG D 1,516 77 Woods, Good, HSG D 24,492 83 Weighted Average 19,577 79.93% Pervious Area 4,915 20.07% Impervious Area Type II 24-hr 10 YR Rainfall=3.51"POSTDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 12HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 9.2 98 0.0306 0.18 Sheet Flow, Grass: Short n= 0.150 P2= 2.50" Summary for Subcatchment S3: Runoff = 0.22 cfs @ 11.98 hrs, Volume= 466 cf, Depth= 1.95" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Type II 24-hr 10 YR Rainfall=3.51" Area (sf) CN Description 2,169 80 >75% Grass cover, Good, HSG D 0 98 Unconnected roofs, HSG D 705 98 Paved parking, HSG D 2,874 84 Weighted Average 2,169 75.47% Pervious Area 705 24.53% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.6 52 0.0200 0.13 Sheet Flow, Grass: Short n= 0.150 P2= 2.50" Summary for Reach 1R: (new Reach) Inflow Area = 2,874 sf, 24.53% Impervious, Inflow Depth = 1.95" for 10 YR event Inflow = 0.22 cfs @ 11.98 hrs, Volume= 466 cf Outflow = 0.21 cfs @ 12.00 hrs, Volume= 466 cf, Atten= 3%, Lag= 1.1 min Routing by Stor-Ind+Trans method, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Max. Velocity= 1.30 fps, Min. Travel Time= 0.6 min Avg. Velocity = 1.30 fps, Avg. Travel Time= 0.6 min Peak Storage= 8 cf @ 11.99 hrs Average Depth at Peak Storage= 0.00' , Surface Width= 50.00' Bank-Full Depth= 1.00' Flow Area= 50.0 sf, Capacity= 1,364.86 cfs 50.00' x 1.00' deep channel, n= 0.015 Brickwork Length= 50.0' Slope= 0.0800 '/' Inlet Invert= 327.00', Outlet Invert= 323.00' ‡ Type II 24-hr 10 YR Rainfall=3.51"POSTDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 13HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Summary for Pond 1P: SMA #1 Inflow Area = 18,046 sf, 43.29% Impervious, Inflow Depth = 2.22" for 10 YR event Inflow = 1.31 cfs @ 12.03 hrs, Volume= 3,346 cf Outflow = 0.59 cfs @ 12.18 hrs, Volume= 3,346 cf, Atten= 55%, Lag= 9.2 min Discarded = 0.18 cfs @ 12.18 hrs, Volume= 3,001 cf Primary = 0.41 cfs @ 12.18 hrs, Volume= 345 cf Routing by Stor-Ind method, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Peak Elev= 323.35' @ 12.18 hrs Surf.Area= 1,564 sf Storage= 978 cf Plug-Flow detention time= 32.4 min calculated for 3,344 cf (100% of inflow) Center-of-Mass det. time= 32.4 min ( 847.4 - 815.0 ) Volume Invert Avail.Storage Storage Description #1 321.50' 1,229 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim. Voids Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (%) (cubic-feet) (cubic-feet) (sq-ft) 321.50 1,233 238.0 0.0 0 0 1,233 322.00 1,233 238.0 40.0 247 247 1,352 323.00 1,233 238.0 20.0 247 493 1,590 323.50 1,722 251.0 100.0 735 1,229 2,110 Device Routing Invert Outlet Devices #1 Discarded 321.50'5.000 in/hr Exfiltration over Surface area #2 Primary 323.25'5.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Discarded OutFlow Max=0.18 cfs @ 12.18 hrs HW=323.35' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.18 cfs) Primary OutFlow Max=0.40 cfs @ 12.18 hrs HW=323.35' (Free Discharge) 2=Broad-Crested Rectangular Weir (Weir Controls 0.40 cfs @ 0.83 fps) Summary for Link DP: Inflow Area = 42,538 sf, 29.92% Impervious, Inflow Depth = 1.17" for 10 YR event Inflow = 1.64 cfs @ 12.01 hrs, Volume= 4,155 cf Primary = 1.64 cfs @ 12.01 hrs, Volume= 4,155 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Type II 24-hr 25 YR Rainfall=4.25"POSTDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 14HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Time span=0.00-80.00 hrs, dt=0.05 hrs, 1601 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=15,172 sf 46.84% Impervious Runoff Depth=2.96"Subcatchment S1: Flow Length=94' Tc=11.7 min CN=88 Runoff=1.44 cfs 3,745 cf Runoff Area=24,492 sf 20.07% Impervious Runoff Depth=2.50"Subcatchment S2: Flow Length=98' Slope=0.0306 '/' Tc=9.2 min CN=83 Runoff=2.18 cfs 5,112 cf Runoff Area=2,874 sf 24.53% Impervious Runoff Depth=2.59"Subcatchment S3: Flow Length=52' Slope=0.0200 '/' Tc=6.6 min CN=84 Runoff=0.29 cfs 621 cf Avg. Flow Depth=0.00' Max Vel=1.30 fps Inflow=0.29 cfs 621 cfReach 1R: (new Reach) n=0.015 L=50.0' S=0.0800 '/' Capacity=1,364.86 cfs Outflow=0.28 cfs 621 cf Peak Elev=323.43' Storage=1,107 cf Inflow=1.69 cfs 4,366 cfPond 1P: SMA #1 Discarded=0.19 cfs 3,524 cf Primary=1.00 cfs 842 cf Outflow=1.19 cfs 4,366 cf Inflow=2.41 cfs 5,953 cfLink DP: Primary=2.41 cfs 5,953 cf Total Runoff Area = 42,538 sf Runoff Volume = 9,477 cf Average Runoff Depth = 2.67" 70.08% Pervious = 29,811 sf 29.92% Impervious = 12,727 sf Type II 24-hr 25 YR Rainfall=4.25"POSTDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 15HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment S1: Runoff = 1.44 cfs @ 12.03 hrs, Volume= 3,745 cf, Depth= 2.96" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Type II 24-hr 25 YR Rainfall=4.25" Area (sf) CN Description 8,065 80 >75% Grass cover, Good, HSG D 2,449 98 Unconnected roofs, HSG D 4,658 98 Paved parking, HSG D 15,172 88 Weighted Average 8,065 53.16% Pervious Area 7,107 46.84% Impervious Area 2,449 34.46% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.0 3 0.5000 2.19 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.50" 3.6 18 0.0110 0.08 Sheet Flow, Grass: Short n= 0.150 P2= 2.50" 0.4 15 0.0110 0.65 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.50" 6.8 42 0.0120 0.10 Sheet Flow, Grass: Short n= 0.150 P2= 2.50" 0.3 14 0.0120 0.67 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.50" 0.6 2 0.0120 0.06 Sheet Flow, Grass: Short n= 0.150 P2= 2.50" 11.7 94 Total Summary for Subcatchment S2: Runoff = 2.18 cfs @ 12.01 hrs, Volume= 5,112 cf, Depth= 2.50" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Type II 24-hr 25 YR Rainfall=4.25" Area (sf) CN Description 18,061 80 >75% Grass cover, Good, HSG D 2,937 98 Roofs, HSG D 1,978 98 Paved parking, HSG D 1,516 77 Woods, Good, HSG D 24,492 83 Weighted Average 19,577 79.93% Pervious Area 4,915 20.07% Impervious Area Type II 24-hr 25 YR Rainfall=4.25"POSTDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 16HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 9.2 98 0.0306 0.18 Sheet Flow, Grass: Short n= 0.150 P2= 2.50" Summary for Subcatchment S3: Runoff = 0.29 cfs @ 11.98 hrs, Volume= 621 cf, Depth= 2.59" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Type II 24-hr 25 YR Rainfall=4.25" Area (sf) CN Description 2,169 80 >75% Grass cover, Good, HSG D 0 98 Unconnected roofs, HSG D 705 98 Paved parking, HSG D 2,874 84 Weighted Average 2,169 75.47% Pervious Area 705 24.53% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.6 52 0.0200 0.13 Sheet Flow, Grass: Short n= 0.150 P2= 2.50" Summary for Reach 1R: (new Reach) Inflow Area = 2,874 sf, 24.53% Impervious, Inflow Depth = 2.59" for 25 YR event Inflow = 0.29 cfs @ 11.98 hrs, Volume= 621 cf Outflow = 0.28 cfs @ 12.00 hrs, Volume= 621 cf, Atten= 3%, Lag= 1.1 min Routing by Stor-Ind+Trans method, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Max. Velocity= 1.30 fps, Min. Travel Time= 0.6 min Avg. Velocity = 1.30 fps, Avg. Travel Time= 0.6 min Peak Storage= 11 cf @ 11.99 hrs Average Depth at Peak Storage= 0.00' , Surface Width= 50.00' Bank-Full Depth= 1.00' Flow Area= 50.0 sf, Capacity= 1,364.86 cfs 50.00' x 1.00' deep channel, n= 0.015 Brickwork Length= 50.0' Slope= 0.0800 '/' Inlet Invert= 327.00', Outlet Invert= 323.00' ‡ Type II 24-hr 25 YR Rainfall=4.25"POSTDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} Page 17HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC Summary for Pond 1P: SMA #1 Inflow Area = 18,046 sf, 43.29% Impervious, Inflow Depth = 2.90" for 25 YR event Inflow = 1.69 cfs @ 12.02 hrs, Volume= 4,366 cf Outflow = 1.19 cfs @ 12.12 hrs, Volume= 4,366 cf, Atten= 30%, Lag= 5.9 min Discarded = 0.19 cfs @ 12.12 hrs, Volume= 3,524 cf Primary = 1.00 cfs @ 12.12 hrs, Volume= 842 cf Routing by Stor-Ind method, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Peak Elev= 323.43' @ 12.12 hrs Surf.Area= 1,646 sf Storage= 1,107 cf Plug-Flow detention time= 29.3 min calculated for 4,363 cf (100% of inflow) Center-of-Mass det. time= 29.3 min ( 836.8 - 807.5 ) Volume Invert Avail.Storage Storage Description #1 321.50' 1,229 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim. Voids Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (%) (cubic-feet) (cubic-feet) (sq-ft) 321.50 1,233 238.0 0.0 0 0 1,233 322.00 1,233 238.0 40.0 247 247 1,352 323.00 1,233 238.0 20.0 247 493 1,590 323.50 1,722 251.0 100.0 735 1,229 2,110 Device Routing Invert Outlet Devices #1 Discarded 321.50'5.000 in/hr Exfiltration over Surface area #2 Primary 323.25'5.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Discarded OutFlow Max=0.19 cfs @ 12.12 hrs HW=323.42' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.19 cfs) Primary OutFlow Max=0.94 cfs @ 12.12 hrs HW=323.42' (Free Discharge) 2=Broad-Crested Rectangular Weir (Weir Controls 0.94 cfs @ 1.11 fps) Summary for Link DP: Inflow Area = 42,538 sf, 29.92% Impervious, Inflow Depth = 1.68" for 25 YR event Inflow = 2.41 cfs @ 12.06 hrs, Volume= 5,953 cf Primary = 2.41 cfs @ 12.06 hrs, Volume= 5,953 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-80.00 hrs, dt= 0.05 hrs Table of ContentsPOSTDEVELOPMENT MAIN HOUSE Printed 5/14/2021Prepared by {enter your company name here} HydroCAD® 10.10-3a s/n 10197 © 2020 HydroCAD Software Solutions LLC TABLE OF CONTENTS Project Reports 1 Routing Diagram 2 Rainfall Events Listing 3 Area Listing (all nodes) 4 Soil Listing (all nodes) 5 Ground Covers (all nodes) 1 YR Event 6 Node Listing 7 Subcat S1: 8 Subcat S2: 9 Subcat S3: 9 Reach 1R: (new Reach) 9 Pond 1P: SMA #1 10 Link DP: 10 YR Event 10 Node Listing 11 Subcat S1: 12 Subcat S2: 13 Subcat S3: 13 Reach 1R: (new Reach) 13 Pond 1P: SMA #1 14 Link DP: 25 YR Event 14 Node Listing 15 Subcat S1: 16 Subcat S2: 17 Subcat S3: 17 Reach 1R: (new Reach) 17 Pond 1P: SMA #1 18 Link DP: