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HomeMy WebLinkAboutDrainage_Analysis_Wed_Dec_20_2023_08-16-45 \\vhb.com\gbl\proj\Wethersfield\43380.00 CEH South Windsor\Reports\Stormwater Memo\Tennis Courts\43380.00_Drainage Memo - Tennis Courts.docx To:Christopher Hulk, PE FieldTurf Date:December 19, 2023 Project #: 43380.00 From:Steven J. Kochis, PE VHB Re:FieldTurf Tennis Court Drainage Ayers Road & Nevers Road South Windsor, Connecticut Site & Project Description South Windsor High School is located at 161 Nevers Road in South Windsor, Connecticut. The property contains the existing school buildings, associated parking and athletic fields. The project proposes seven (7) new tennis courts with a small parking area located southeast of the existing school. VHB prepared an analysis of existing and proposed conditions drainage conditions. NRCS Web Soil Survey lists the area as Udorthents-Urban Land Complex (Hydrologic Soil Group B), Enfield Silt Loam. 3-8% slopes (Hydrologic Soil Group B) and a small portion along Collins Crossing as Enfield Silt Loam, 3-8% Slopes (Hydrologic Soil Group B). Per available FEMA Map No. 09003C0381F dated 09/26/2008, the site is located within Zone X – 0.2% annual chance flood hazard areas of 1% annual chance flood with average depth less than one foot or with drainage areas of less than one square mile. A portion of the development lies within zone AE – Area with a base flood elevation of approximately 162.4. Existing Drainage Conditions Under existing conditions, the project area was analyzed as two (2) drainage areas that outlet to one design point (Plum Gulley Brook at Collins Crossing “DP-1”). See Figure 1 – Existing Drainage Conditions. Drainage Area C-1: This 1.13- acre catchment area consists of the frontage and western portion of the land between Collins Crossing and South Windsor High School Main Entrance off of Nevers Road. This area conveys stormwater runoff overland (west) through a grassed swale with stone check dams to DP-1. Drainage Area C-2: This 1.05-acre catchment area consists of the eastern portion of the land between Collins Crossing and South Windsor High School Main Entrance off of Nevers Road. Stormwater in this area is conveyed westerly overland to Plum Gulley Brook towards DP-1. Proposed Drainage Conditions The project proposes seven (7) new tennis courts with a small parking area of eight (8) spaces located southeast of the existing school. Two stormwater basins are proposed with emergency overflows that ultimately outlet into Plum Gulley Brook. Both have been designed to allow volumetric storage of stormwater runoff to promote retention and infiltration for water quality. Peak rates of runoff are attenuated from proposed conditions down to pre-development levels. An infiltration rate of 7 inches per hour into the native soil has been assumed in the hydrologic model by recommendation of FieldTurf. This assumption should be tested in the field and VHB provided the opportunity to Ref: FieldTurf – Tennis Courts - South Windsor, CT December 19, 2023 Page 2 \\vhb.com\gbl\proj\Wethersfield\43380.00 CEH South Windsor\Reports\Stormwater Memo\Tennis Courts\43380.00_Drainage Memo - Tennis Courts.docx adjust the stormwater design if/as needed upon completion. It is also recommended that a wetland study be performed within the development area for the possible presence of wetlands pertaining to the drainage ditch or Plum Gulley Brook as portions of the development may impact wetlands or upland review areas. Table 1 below displays the anticipated existing and proposed peak flows for the project area before and after site improvements. Figure 2 illustrates the proposed “post construction conditions for the project area. As shown the project area was analyzed as two (2) catchment areas that outlet to one design point (DP-1). Drainage Area C-1: This 0.68-acre catchment area consists of the proposed parking area and western portion of the site including the existing grassed swale with stone check dams. The parking lot will drain overland into a proposed Stormwater Basin (1P) which then outlets into the existing grassed swale which then outlets into Plum Gulley Brook (DP-1). Drainage Area C-2: This 1.49-acre catchment area consists of the proposed tennis courts. The courts will drain west and outlet into a proposed Stormwater Basin (2P) which then outlets towards Plum Gulley Brook (DP-1). The table (Table 1) below presents a summary of the existing and proposed conditions peak discharge rates: Design Point 2-year 10-year 25-year 100-year Design Point: DP1 Existing 0.7 2.9 4.6 7.6 Proposed 0.1 2.8 4.3 7.6 Water Quality Retention and infiltration of the required water quality volume is provided within the two proposed stormwater basins. Computations for the required water quality volume are enclosed herewith. Ref: FieldTurf – Tennis Courts - South Windsor, CT December 19, 2023 Page 3 \\vhb.com\gbl\proj\Wethersfield\43380.00 CEH South Windsor\Reports\Stormwater Memo\Tennis Courts\43380.00_Drainage Memo - Tennis Courts.docx Figures Figure 1: Existing Conditions Drainage Areas Figure 2: Proposed Conditions Drainage Areas Attachments Attachment 3: NOAA Precipitation Frequency Attachment 4: NRCS Hydrologic Soil Group Attachment 5: FEMA Flood Map Attachment 6: Water Quality Volume Computations Attachment 7: HydroCAD Existing Conditions Attachment 8: HydroCAD Proposed Conditions PLUM GULLEY BROOK ASP H A L T C U R B AS P H A L T C U R B AS P H A L T C U R B ASPHALT CURB ASPHALT CURB ASP H A L T C U R B ASPHALT CURB AS P H A L T C U R B AS P H A L T C U R B C O N C . W A L K ASPHALT C U R B ASPHALT CURB ASPHALT CURB AS P H A L T C U R B CO L L I N S C R O S S I N G GU A R D R A I L LP MHRIM=168.97 MHRIM=168.83 MHRIM=168.35 MHRIM=169.24 MHRIM=165.09 MHRIM=163.74 MHRIM=163.60 MHRIM=168.21 MHRIM=165.34 FH CBGR=166.66 CBGR=161.57INV=158.97(E)OUT=158.97(W) CBGR=164.64 CBGR=164.48 CBGR=162.85 CBGR=162.58 CBGR=162.95 CBGR=165.83 CBGR=166.84 CBGR=169.04 CBGR=170.82 CBGR=170.55 "DWS" "DWS" UPFRNT #3059 MHRIM=173.25 MHRIM=170.68 MHRIM=171.08 LP WV CBGR=164.72 CBGR=162.52 12"RCPINV=157.80 24"RCPINV=161.40 ASPHAL T W A L K CONCRETE WALK LAWN LAWN LA W N CONC. 72"RCPINV=159.48 12"RCPINV=161.59 12"RCPINV=161.82 BOT. CULV. =154.76 BR I C K BU I L D I N G BR I C K BU I L D I N G N.F.LESLIE M. COLLINS PLUM GULLEY BROOK TP 7 TP 6 ASPHALT CURB ASPHALT CURB ASPHALT CURB ASP H A L T C U R B AS P H A L T C U R B CH A I N L I N K F E N C E CH A I N L I N K F E N C E CHAIN LINK FENCE NEVERS ROAD CHAIN L I N K F E N C E MHRIM=167.00 WVWVWV WV CBGR=167.13CBGR=166.55 CH A I N L I N K F E N C E SHED SHED UP SHED LP LP LP CONCRETE WALK AS P H A L T W A L K LAWN CONC. ASPHALT CURB 10 0 ' U P L A N D R E V I E W A R E A 10 0 ' U P L A N D R E V I E W A R E A 704C 704B 306 702A 704B DP1 C-1 C-2 Legend SYMBOLS X LINETYPES DRAINAGE AREA DESIGNATION DRAINAGE AREA BOUNDARY TIME OF CONCENTRATION FLOW LINE SOIL TYPE BOUNDARY DPX DESIGN POINT 0 40 80 160 Feet SCS SOIL CLASSIFICATIONS 306 UDORTHENTS-URBAN LAND COMPLEX, HSG B 704B 704C ENFIELD SILT LOAM, 8-15% SLOPES, HSG B 702A TISBURY SILT LOAM, 0-3% SLOPES, HSG B/D ENFIELD SILT LOAM, 3-8% SLOPES, HSG B 704C 704B 306 702A 704B DP1 1P PLUM GULLEY BROOK AS P H A L T C U R B AS P H A L T C U R B ASP H A L T C U R B ASPHALT CURB ASPHALT CURB ASP H A L T C U R B ASPHALT CURB AS P H A L T C U R B AS P H A L T C U R B C O N C . W A L K ASPHALT C U R B ASPHALT CURB ASPHALT CURB AS P H A L T C U R B C O L L I N S C R O S S I N G GU A R D R A I L LP MHRIM=168.97 MHRIM=168.83 MHRIM=168.35 MHRIM=169.24 MHRIM=165.09 MHRIM=163.74 MHRIM=163.60 MHRIM=168.21 MHRIM=165.34 FH CBGR=166.66 CBGR=161.57INV=158.97(E)OUT=158.97(W) CBGR=164.64 CBGR=164.48 CBGR=162.85 CBGR=162.58 CBGR=162.95 CBGR=165.83 CBGR=166.84 CBGR=169.04 CBGR=170.82 CBGR=170.55 "DWS" "DWS" UPFRNT #3059 MHRIM=173.25 MHRIM=170.68 MHRIM=171.08 LP WV CBGR=164.72 CBGR=162.52 12"RCPINV=157.80 24"RCPINV=161.40 ASPHAL T W A L K CONCRETE WALK LAWN LAWN LA W N CONC. 72"RCPINV=159.48 12"RCPINV=161.59 12"RCPINV=161.82 BOT. CULV. =154.76 BR I C K BU I L D I N G BR I C K BU I L D I N G N.F.LESLIE M. COLLINS PLUM GULLEY BROOK TP 7 TP 6 ASPHALT CURB ASPHALT CURB ASPHALT CURB ASP H A L T C U R B AS P H A L T C U R B CH A I N L I N K F E N C E CH A I N L I N K F E N C E CHAIN LINK FENCE NEVERS ROAD CHAIN L I N K F E N C E MHRIM=167.00 WVWV WV WV CBGR=167.13CBGR=166.55 CH A I N L I N K F E N C E SHED SHED UP SHED LP LP LP CONCRETE WALK AS P H A L T W A L K LAWN CONC. ASPHALT CURB 10 0 ' U P L A N D R E V I E W A R E A 10 0 ' U P L A N D R E V I E W A R E A 3 12 54 (78 SEATS) C-1 C-2 2P Legend SYMBOLS X LINETYPES DRAINAGE AREA DESIGNATION DRAINAGE AREA BOUNDARY TIME OF CONCENTRATION FLOW LINE SOIL TYPE BOUNDARY DPX DESIGN POINT 0 40 80 160 Feet \\vhb.com\gbl\proj\Wethersfield\43380.00 CEH South Windsor\cad\ld\Eng\Tennis Courts\43380.00-PR Drainage - Tennis.dwg 12/19/2023 Figure 2Proposed Drainage Conditions FieldTurf - S. Windsor High Drainage Proposed Tennis Courts Ayers Road & Nevers Road, South Windsor, CT SCS SOIL CLASSIFICATIONS 306 UDORTHENTS-URBAN LAND COMPLEX, HSG B 704B 704C ENFIELD SILT LOAM, 8-15% SLOPES, HSG B 702A TISBURY SILT LOAM, 0-3% SLOPES, HSG B/D ENFIELD SILT LOAM, 3-8% SLOPES, HSG B Hydrologic Soil Group—State of Connecticut, Western Part Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 12/15/2023 Page 1 of 4 46 3 4 9 5 0 46 3 4 9 8 0 46 3 5 0 1 0 46 3 5 0 4 0 46 3 5 0 7 0 46 3 5 1 0 0 46 3 5 1 3 0 46 3 5 1 6 0 46 3 5 1 9 0 46 3 5 2 2 0 46 3 4 9 5 0 46 3 4 9 8 0 46 3 5 0 1 0 46 3 5 0 4 0 46 3 5 0 7 0 46 3 5 1 0 0 46 3 5 1 3 0 46 3 5 1 6 0 46 3 5 1 9 0 46 3 5 2 2 0 703090 703120 703150 703180 703210 703240 703270 703300 703120 703150 703180 703210 703240 703270 703300 41° 50' 34'' N 72 ° 3 3 ' 1 3 ' ' W 41° 50' 34'' N 72 ° 3 3 ' 4 ' ' W 41° 50' 25'' N 72 ° 3 3 ' 1 3 ' ' W 41° 50' 25'' N 72 ° 3 3 ' 4 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 18N WGS84 0 50 100 200 300 Feet 0 20 40 80 120 Meters Map Scale: 1:1,370 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 Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available 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 1:12,000. 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: State of Connecticut, Western Part Survey Area Data: Version 1, Sep 15, 2023 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jun 14, 2022—Oct 6, 2022 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. Hydrologic Soil Group—State of Connecticut, Western Part Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 12/15/2023 Page 2 of 4 Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 306 Udorthents-Urban land complex B 3.5 39.5% 702A Tisbury silt loam, 0 to 3 percent slopes B/D 0.5 5.0% 704B Enfield silt loam, 3 to 8 percent slopes B 2.1 23.2% 704C Enfield silt loam, 8 to 15 percent slopes B 2.9 32.3% Totals for Area of Interest 8.9 100.0% 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-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, 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 claypan 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 (A/D, B/D, or C/D), 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. Hydrologic Soil Group—State of Connecticut, Western Part Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 12/15/2023 Page 3 of 4 Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Hydrologic Soil Group—State of Connecticut, Western Part Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 12/15/2023 Page 4 of 4 National Flood Hazard Layer FIRMette 0 500 1,000 1,500 2,000250 Feet Ü SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT SPECIAL FLOODHAZARD AREAS Without Base Flood Elevation (BFE)Zone A, V, A99With BFE or DepthZone AE, AO, AH, VE, AR Regulatory Floodway 0.2% Annual Chance Flood Hazard, Areasof 1% annual chance flood with averagedepth less than one foot or with drainageareas of less than one square mileZone X Future Conditions 1% Annual Chance Flood HazardZone X Area with Reduced Flood Risk due to Levee. See Notes.Zone X Area with Flood Risk due to LeveeZone D NO SCREENArea of Minimal Flood Hazard Zone X Area of Undetermined Flood HazardZone D Channel, Culvert, or Storm Sewer Levee, Dike, or Floodwall Cross Sections with 1% Annual Chance 17.5 Water Surface Elevation Coastal Transect Coastal Transect Baseline Profile Baseline Hydrographic Feature Base Flood Elevation Line (BFE) Effective LOMRs Limit of Study Jurisdiction Boundary Digital Data Available No Digital Data Available Unmapped This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below.The basemap shown complies with FEMA's basemapaccuracy standards The flood hazard information is derived directly from theauthoritative NFHL web services provided by FEMA. This mapwas exported on 12/15/2023 at 2:17 PM and does notreflect changes or amendments subsequent to this date andtime. The NFHL and effective information may change orbecome superseded by new data over time. This map image is void if the one or more of the following map elements do not appear: basemap imagery, flood zone labels, legend, scale bar, map creation date, community identifiers, FIRM panel number, and FIRM effective date. Map images for unmapped and unmodernized areas cannot be used for regulatory purposes. Legend OTHER AREAS OF FLOOD HAZARD OTHER AREAS GENERAL STRUCTURES OTHER FEATURES MAP PANELS 8 B 20.2 The pin displayed on the map is an approximatepoint selected by the user and does not representan authoritative property location. 1:6,000 72°33'30"W 41°50'40"N 72°32'52"W 41°50'14"N Basemap Imagery Source: USGS National Map 2023 Project:By: AMK Date: 12/19/23 Location:Checked: SJK Date: Rainfall, P 1.0 in. 1.0 in. a Area, A 0.68 ac 1.50 ac b Impervious Cover Area 0.17 ac 1.00 ac c % Impervious, I 25 % 67 % Volumetric Runoff Coeff., R 0.279 0.653 d 0.016 ac-ft 0.081 ac-ft e 693 cf 3,549 cf a First one inch of rainfall; 2004 Connecticut Stormwater Quality Manual b Area tributary to the stormwater management basin c Impervious cover area tributary to the stormwater management basin d R=0.05+0.009*I; Section 7.4.1 from 2004 Connecticut Stormwater Quality Manual e WQV=P*R*A/12; Section 7.4.1 from 2004 Connecticut Stormwater Quality Manual Water Quality Volume, WQV Water Quality Volume Calculations South Windsor High School Tennis Court South Windsor, CT Basin Name C-1 C-2 VHB C-1 Subcat C-1 C-2 Subcat C-2 DP1 PLUM GULLEY BROOK Routing Diagram for 43380-EX DR Prepared by VHB, Inc, Printed 12/18/2023 HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Subcat Reach Pond Link 43380-EX DR Printed 12/18/2023Prepared by VHB, Inc Page 2HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (acres) CN Description (subcatchment-numbers) 2.067 61 >75% Grass cover, Good, HSG B (C-1, C-2) 0.080 74 >75% Grass cover, Good, HSG C (C-1) 0.035 98 Paved parking, HSG B (C-1, C-2) 0.000 98 Water Surface, 0% imp, HSG B (C-2) 2.182 62 TOTAL AREA 43380-EX DR Printed 12/18/2023Prepared by VHB, Inc Page 3HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Soil Listing (all nodes) Area (acres) Soil Group Subcatchment Numbers 0.000 HSG A 2.102 HSG B C-1, C-2 0.080 HSG C C-1 0.000 HSG D 0.000 Other 2.182 TOTAL AREA 43380-EX DR Printed 12/18/2023Prepared by VHB, Inc Page 4HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Ground Covers (all nodes) HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers 0.000 2.067 0.080 0.000 0.000 2.148 >75% Grass cover, Good C-1, C-2 0.000 0.035 0.000 0.000 0.000 0.035 Paved parking C-1, C-2 0.000 0.000 0.000 0.000 0.000 0.000 Water Surface, 0% imp C-2 0.000 2.102 0.080 0.000 0.000 2.182 TOTAL AREA Type III 24-hr 100 yr Rainfall=7.84"43380-EX DR Printed 12/18/2023Prepared by VHB, Inc Page 5HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Time span=0.00-36.00 hrs, dt=0.03 hrs, 1201 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=1.132 ac 2.71% Impervious Runoff Depth=3.54"Subcatchment C-1: Subcat C-1 Tc=10.0 min CN=63 Runoff=4.05 cfs 0.334 af Runoff Area=1.050 ac 0.37% Impervious Runoff Depth=3.32"Subcatchment C-2: Subcat C-2 Tc=10.0 min CN=61 Runoff=3.50 cfs 0.291 af Inflow=7.56 cfs 0.625 afLink DP1: PLUM GULLEY BROOK Primary=7.56 cfs 0.625 af Total Runoff Area = 2.182 ac Runoff Volume = 0.625 af Average Runoff Depth = 3.44" 98.42% Pervious = 2.148 ac 1.58% Impervious = 0.035 ac Type III 24-hr 100 yr Rainfall=7.84"43380-EX DR Printed 12/18/2023Prepared by VHB, Inc Page 6HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment C-1: Subcat C-1 Runoff = 4.05 cfs @ 12.15 hrs, Volume= 0.334 af, Depth= 3.54" Routed to Link DP1 : PLUM GULLEY BROOK Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 100 yr Rainfall=7.84" Area (ac) CN Description 1.021 61 >75% Grass cover, Good, HSG B 0.080 74 >75% Grass cover, Good, HSG C 0.031 98 Paved parking, HSG B 1.132 63 Weighted Average 1.101 97.29% Pervious Area 0.031 2.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment C-1: Subcat C-1 Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 4 3 2 1 0 Type III 24-hr 100 yr Rainfall=7.84" Runoff Area=1.132 ac Runoff Volume=0.334 af Runoff Depth=3.54" Tc=10.0 min CN=63 4.05 cfs Type III 24-hr 100 yr Rainfall=7.84"43380-EX DR Printed 12/18/2023Prepared by VHB, Inc Page 7HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment C-2: Subcat C-2 Runoff = 3.50 cfs @ 12.15 hrs, Volume= 0.291 af, Depth= 3.32" Routed to Link DP1 : PLUM GULLEY BROOK Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 100 yr Rainfall=7.84" Area (ac) CN Description 1.046 61 >75% Grass cover, Good, HSG B 0.004 98 Paved parking, HSG B 0.000 98 Water Surface, 0% imp, HSG B 1.050 61 Weighted Average 1.047 99.63% Pervious Area 0.004 0.37% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment C-2: Subcat C-2 Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 3 2 1 0 Type III 24-hr 100 yr Rainfall=7.84" Runoff Area=1.050 ac Runoff Volume=0.291 af Runoff Depth=3.32" Tc=10.0 min CN=61 3.50 cfs Type III 24-hr 100 yr Rainfall=7.84"43380-EX DR Printed 12/18/2023Prepared by VHB, Inc Page 8HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Link DP1: PLUM GULLEY BROOK Inflow Area = 2.182 ac, 1.58% Impervious, Inflow Depth = 3.44" for 100 yr event Inflow = 7.56 cfs @ 12.15 hrs, Volume= 0.625 af Primary = 7.56 cfs @ 12.15 hrs, Volume= 0.625 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Link DP1: PLUM GULLEY BROOK Inflow Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 8 7 6 5 4 3 2 1 0 Inflow Area=2.182 ac 7.56 cfs 7.56 cfs 43380-PR DR Printed 12/18/2023Prepared by VHB, Inc Page 1HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Rainfall Events Listing Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC 1 2 yr Type III 24-hr Default 24.00 1 3.13 2 2 10 yr Type III 24-hr Default 24.00 1 4.95 2 3 25 yr Type III 24-hr Default 24.00 1 6.09 2 4 100 yr Type III 24-hr Default 24.00 1 7.84 2 Type III 24-hr 2 yr Rainfall=3.13"43380-PR DR Printed 12/18/2023Prepared by VHB, Inc Page 2HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Pond 2P: Stormwater Basin 2 Inflow Area = 1.498 ac, 66.96% Impervious, Inflow Depth = 1.77" for 2 yr event Inflow = 3.20 cfs @ 12.08 hrs, Volume= 0.221 af Outflow = 0.41 cfs @ 12.69 hrs, Volume= 0.221 af, Atten= 87%, Lag= 36.7 min Discarded = 0.38 cfs @ 12.69 hrs, Volume= 0.220 af Primary = 0.03 cfs @ 12.69 hrs, Volume= 0.001 af Routed to Link DP1 : PLUM GULLEY BROOK Routing by Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Peak Elev= 162.04' @ 12.69 hrs Surf.Area= 2,686 sf Storage= 3,698 cf Plug-Flow detention time= 97.8 min calculated for 0.221 af (100% of inflow) Center-of-Mass det. time= 97.8 min ( 920.3 - 822.6 ) Volume Invert Avail.Storage Storage Description #1 160.00' 10,535 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 160.00 1,027 0 0 161.00 1,764 1,396 1,396 162.00 2,649 2,207 3,602 163.00 3,689 3,169 6,771 164.00 3,839 3,764 10,535 Device Routing Invert Outlet Devices #1 Primary 163.50'8.0' long x 2.0' 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 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 #2 Primary 162.00'16.0" W x 4.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Discarded 160.00'6.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 10.00' Discarded OutFlow Max=0.38 cfs @ 12.69 hrs HW=162.04' (Free Discharge) 3=Exfiltration ( Controls 0.38 cfs) Primary OutFlow Max=0.03 cfs @ 12.69 hrs HW=162.04' (Free Discharge) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) 2=Orifice/Grate (Orifice Controls 0.03 cfs @ 0.61 fps) Type III 24-hr 2 yr Rainfall=3.13"43380-PR DR Printed 12/18/2023Prepared by VHB, Inc Page 3HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Pond 2P: Stormwater Basin 2 Inflow Outflow Discarded Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 3 2 1 0 Inflow Area=1.498 ac Peak Elev=162.04' Storage=3,698 cf 3.20 cfs 0.41 cfs 0.38 cfs 0.03 cfs Type III 24-hr 10 yr Rainfall=4.95"43380-PR DR Printed 12/18/2023Prepared by VHB, Inc Page 4HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Pond 2P: Stormwater Basin 2 Inflow Area = 1.498 ac, 66.96% Impervious, Inflow Depth = 3.42" for 10 yr event Inflow = 6.10 cfs @ 12.07 hrs, Volume= 0.427 af Outflow = 2.12 cfs @ 12.34 hrs, Volume= 0.427 af, Atten= 65%, Lag= 16.1 min Discarded = 0.48 cfs @ 12.34 hrs, Volume= 0.313 af Primary = 1.64 cfs @ 12.34 hrs, Volume= 0.114 af Routed to Link DP1 : PLUM GULLEY BROOK Routing by Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Peak Elev= 162.76' @ 12.34 hrs Surf.Area= 3,437 sf Storage= 5,908 cf Plug-Flow detention time= 81.9 min calculated for 0.426 af (100% of inflow) Center-of-Mass det. time= 81.8 min ( 885.7 - 803.9 ) Volume Invert Avail.Storage Storage Description #1 160.00' 10,535 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 160.00 1,027 0 0 161.00 1,764 1,396 1,396 162.00 2,649 2,207 3,602 163.00 3,689 3,169 6,771 164.00 3,839 3,764 10,535 Device Routing Invert Outlet Devices #1 Primary 163.50'8.0' long x 2.0' 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 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 #2 Primary 162.00'16.0" W x 4.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Discarded 160.00'6.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 10.00' Discarded OutFlow Max=0.48 cfs @ 12.34 hrs HW=162.76' (Free Discharge) 3=Exfiltration ( Controls 0.48 cfs) Primary OutFlow Max=1.64 cfs @ 12.34 hrs HW=162.76' (Free Discharge) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) 2=Orifice/Grate (Orifice Controls 1.64 cfs @ 3.69 fps) Type III 24-hr 10 yr Rainfall=4.95"43380-PR DR Printed 12/18/2023Prepared by VHB, Inc Page 5HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Pond 2P: Stormwater Basin 2 Inflow Outflow Discarded Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 6 5 4 3 2 1 0 Inflow Area=1.498 ac Peak Elev=162.76' Storage=5,908 cf 6.10 cfs 2.12 cfs 0.48 cfs 1.64 cfs Type III 24-hr 25 yr Rainfall=6.09"43380-PR DR Printed 12/18/2023Prepared by VHB, Inc Page 6HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Pond 2P: Stormwater Basin 2 Inflow Area = 1.498 ac, 66.96% Impervious, Inflow Depth = 4.50" for 25 yr event Inflow = 7.93 cfs @ 12.07 hrs, Volume= 0.561 af Outflow = 2.76 cfs @ 12.34 hrs, Volume= 0.561 af, Atten= 65%, Lag= 15.8 min Discarded = 0.52 cfs @ 12.34 hrs, Volume= 0.362 af Primary = 2.23 cfs @ 12.34 hrs, Volume= 0.199 af Routed to Link DP1 : PLUM GULLEY BROOK Routing by Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Peak Elev= 163.26' @ 12.34 hrs Surf.Area= 3,728 sf Storage= 7,728 cf Plug-Flow detention time= 77.8 min calculated for 0.560 af (100% of inflow) Center-of-Mass det. time= 77.7 min ( 874.0 - 796.2 ) Volume Invert Avail.Storage Storage Description #1 160.00' 10,535 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 160.00 1,027 0 0 161.00 1,764 1,396 1,396 162.00 2,649 2,207 3,602 163.00 3,689 3,169 6,771 164.00 3,839 3,764 10,535 Device Routing Invert Outlet Devices #1 Primary 163.50'8.0' long x 2.0' 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 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 #2 Primary 162.00'16.0" W x 4.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Discarded 160.00'6.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 10.00' Discarded OutFlow Max=0.52 cfs @ 12.34 hrs HW=163.26' (Free Discharge) 3=Exfiltration ( Controls 0.52 cfs) Primary OutFlow Max=2.23 cfs @ 12.34 hrs HW=163.26' (Free Discharge) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) 2=Orifice/Grate (Orifice Controls 2.23 cfs @ 5.02 fps) Type III 24-hr 25 yr Rainfall=6.09"43380-PR DR Printed 12/18/2023Prepared by VHB, Inc Page 7HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Pond 2P: Stormwater Basin 2 Inflow Outflow Discarded Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 8 7 6 5 4 3 2 1 0 Inflow Area=1.498 ac Peak Elev=163.26' Storage=7,728 cf 7.93 cfs 2.76 cfs 0.52 cfs 2.23 cfs Type III 24-hr 100 yr Rainfall=7.84"43380-PR DR Printed 12/18/2023Prepared by VHB, Inc Page 8HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Pond 2P: Stormwater Basin 2 Inflow Area = 1.498 ac, 66.96% Impervious, Inflow Depth = 6.18" for 100 yr event Inflow = 10.72 cfs @ 12.07 hrs, Volume= 0.771 af Outflow = 5.83 cfs @ 12.19 hrs, Volume= 0.771 af, Atten= 46%, Lag= 7.1 min Discarded = 0.54 cfs @ 12.19 hrs, Volume= 0.424 af Primary = 5.29 cfs @ 12.19 hrs, Volume= 0.346 af Routed to Link DP1 : PLUM GULLEY BROOK Routing by Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Peak Elev= 163.75' @ 12.19 hrs Surf.Area= 3,802 sf Storage= 9,588 cf Plug-Flow detention time= 72.4 min calculated for 0.770 af (100% of inflow) Center-of-Mass det. time= 72.4 min ( 859.9 - 787.5 ) Volume Invert Avail.Storage Storage Description #1 160.00' 10,535 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 160.00 1,027 0 0 161.00 1,764 1,396 1,396 162.00 2,649 2,207 3,602 163.00 3,689 3,169 6,771 164.00 3,839 3,764 10,535 Device Routing Invert Outlet Devices #1 Primary 163.50'8.0' long x 2.0' 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 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 #2 Primary 162.00'16.0" W x 4.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Discarded 160.00'6.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 10.00' Discarded OutFlow Max=0.54 cfs @ 12.19 hrs HW=163.75' (Free Discharge) 3=Exfiltration ( Controls 0.54 cfs) Primary OutFlow Max=5.22 cfs @ 12.19 hrs HW=163.75' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 2.53 cfs @ 1.27 fps) 2=Orifice/Grate (Orifice Controls 2.69 cfs @ 6.05 fps) Type III 24-hr 100 yr Rainfall=7.84"43380-PR DR Printed 12/18/2023Prepared by VHB, Inc Page 9HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Pond 2P: Stormwater Basin 2 Inflow Outflow Discarded Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=1.498 ac Peak Elev=163.75' Storage=9,588 cf 10.72 cfs 5.83 cfs 0.54 cfs 5.29 cfs \\vhb.com\gbl\proj\Wethersfield\43380.00 CEH South Windsor\Reports\Stormwater Memo\43380.00_Drainage Memo REV 20231219.docx To: Christopher Hulk, PE FieldTurf Date: December 19, 2023 Project #: 43380.00 From:Steven J. Kochis, PE VHB Re: FieldTurf Athletic Field Drainage Ayers Road & Nevers Road South Windsor, Connecticut Site & Project Description South Windsor High School is located at 161 Nevers Road in South Windsor, Connecticut. The property contains the existing school buildings, associated parking and athletic fields. The project proposes a new synthetic turf field to replace an existing grass athletic field. The new field is proposed northwest of the existing field. VHB prepared an analysis of existing and proposed conditions drainage conditions. NRCS Web Soil Survey lists the existing field as Udorthents-Urban Land Complex (Hydrologic Soil Group B) and a small portion as Enfield Silt Loam, 8-15% Slopes (Hydrologic Soil Group B) and Haven-Urban Land Complex, 0-8% Slopes (Hydrologic Soil Group B). Per available FEMA Map No. 09003C0381F dated 09/26/2008, the site is located within Zone X – area of minimal flood hazard (no Special Flood Hazard Areas). Existing Drainage Conditions Under existing conditions, the project area was analyzed as two (2) drainage areas that outlet to two (2) design points. See Figure 1 – Existing Drainage Conditions. Drainage Area E-1: This 6.4- acre catchment area consists of a portion of the South Windsor Parks and Recreation parking, an existing grassed field west of South Windsor Parks and Recreation Building, portions of the existing South Windsor High School Baseball Field and the existing South Windsor High School tennis courts. This area conveys stormwater runoff overland to the southern property line adjacent to the existing tennis courts (DP1). Drainage Area E-2: This 2.3-acre catchment area consists of a portion of the South Windsor Parks and Recreation parking lot, the northern portion of the South Windsor High School Baseball Field and the grassed area adjacent to Ayers Road. Stormwater in this area is conveyed westerly overland to the western property line (DP2). Proposed Drainage Conditions A synthetic turf field is proposed, which will include no actual hardscape and a network of subsurface perforated drains within crushed stone. The proposed field area itself has been modelled as a stone reservoir for the subsurface stone. An outlet control structure incorporating an above-ground inlet will allow volumetric storage of stormwater runoff to promote retention and infiltration for water quality. A small basin is also proposed primarily to treat water quality from portions of the parking lot. Peak rates of runoff are attenuated from proposed conditions down to pre- development levels. An infiltration rate of 7 inches per hour into the native soil has been assumed in the hydrologic Ref: FieldTurf South Windsor, CT December 19, 2023 Page 2 \\vhb.com\gbl\proj\Wethersfield\43380.00 CEH South Windsor\Reports\Stormwater Memo\43380.00_Drainage Memo REV 20231219.docx model by recommendation of FieldTurf. This assumption should be tested in the field and VHB provided the opportunity to adjust the stormwater design if/as needed upon completion. It is also recommended that a wetland study be performed within the development area for the possible presence of wetlands. Table 1 below displays the anticipated existing and proposed peak flows for the project area before and after site improvements including underdrainage. Figure 2 illustrates the proposed “post construction conditions for the project area. As shown the project area was analyzed as four (4) catchment areas (two (2) drainage areas) that outlet to two (2) design points. Drainage Area P-1A: This 2.2-acre catchment area consists of the grassed area at the western property line. The area drains overland to the southern proposed stormwater basin (Pond 1P). Drainage Area P-1B: This 3.1-acre catchment area consists of a portion of the proposed parking expansion and the proposed field. Stormwater flows over the field being collected by the fields underdrainage and then is conveyed into the proposed stormwater basin (Pond 1P). Drainage Area P-1C: This 1.1-acre catchment area consists of the majority of the proposed parking area as well as a portion of the proposed field and the grassed area located south of the field. Stormwater is collected via catch basins within the parking field and conveyed to a flared end section which deposits the stormwater into a grassed swale and then into the proposed stormwater basin (Pond 1P), where it is combined with Drainage Area P-1B. Drainage Area P-2: This 2.3-acre catchment area consist of a portion of the existing and proposed parking area located along the road frontage as well as the grassed area proposed north of the field. Stormwater flows overland to the northwest corner of the property (DP2). The table (Table 1) below presents a summary of the existing and proposed conditions peak discharge rates: Design Point 2-year 10-year 100-year Design Point: DP1 Existing 3.6 12.2 29.1 Proposed 0.8 3.2 8.3 Design Point: DP2 Existing 2.6 6.4 12.9 Proposed 2.5 6.1 12.7 Water Quality Retention and infiltration of the required water quality volume is provided within the two proposed stormwater basins. Computations for the required water quality volume are enclosed herewith. Ref: FieldTurf South Windsor, CT December 19, 2023 Page 3 \\vhb.com\gbl\proj\Wethersfield\43380.00 CEH South Windsor\Reports\Stormwater Memo\43380.00_Drainage Memo REV 20231219.docx Figures Figure 1: Existing Conditions Drainage Areas Figure 2: Proposed Conditions Drainage Areas Attachments Attachment 3: NOAA Precipitation Frequency Attachment 4: NRCS Hydrologic Soil Group Attachment 5: FEMA Flood Map Attachment 6: Water Quality Volume Computations Attachment 7: HydroCAD Existing Conditions Attachment 8: HydroCAD Proposed Conditions 170 172 174 176 178 180 182 184 186 18 8 190 188 186 184 182 180 178 176 174 172 170 168 166 166168170 172 174 178 176 174 172 170 168 166 164 164 16 6 166 180 182 184 DP1 EX-1 EX-2 E-1 37E 704C 306 232B DP2 E-2 Legend SYMBOLS X LINETYPES DRAINAGE AREA DESIGNATION DRAINAGE AREA BOUNDARY TIME OF CONCENTRATION FLOW LINE SOIL TYPE BOUNDARY DPX DESIGN POINT 0 40 80 160 Feet \\vhb.com\gbl\proj\Wethersfield\43380.00 CEH South Windsor\cad\ld\Eng\433800-EX Drainage.dwg 12-13-2023 Figure 1Existing Drainage Conditions FieldTurf - S. Windsor High Drainage Ayers Road & Nevers Road, South Windsor, CT SCS SOIL CLASSIFICATIONS 306 UDORTHENTS-URBAN LAND COMPLEX, HSG B 232B HAVEN-URBAN LAND COMPLEX, 0-8% SLOPES, HSG B 704C ENFIELD SILT LOAM, 8-15% SLOPES, HSG B 308 UDORTHENTS, SMOOTHED, HSG B 37E MANCHESTER GRAVELLY SANDY LOAM, 15-45% SLOPES, HSG B 170 172 174 17 6 178 180 182 184 186 18 8 190 188 186 184 182 180 178 176 174 172 170 168 166 166168170 172 174 178 176 174 172 170 168 166 164 164 16 6 166 180 182 184 CCCC CCSASATT SA T C SA TTTTTTTTTTSASASASASASASASASACCCCCCCCCCC 37E 704C 306 232B DP1 DP2 P-1A P-2 1CP P-1C P-1B 1BP Legend SYMBOLS X LINETYPES DRAINAGE AREA DESIGNATION DRAINAGE AREA BOUNDARY TIME OF CONCENTRATION FLOW LINE SOIL TYPE BOUNDARY DRAINAGE PONDXP DPX DESIGN POINT 0 40 80 160 Feet \\vhb.com\gbl\proj\Wethersfield\43380.00 CEH South Windsor\cad\ld\Eng\433800-PR Drainage.dwg 12-19-2023 Figure 2Proposed Drainage Conditions FieldTurf - S. Windsor High Drainage Ayers Road & Nevers Road, South Windsor, CT SCS SOIL CLASSIFICATIONS 306 UDORTHENTS-URBAN LAND COMPLEX, HSG B 232B HAVEN-URBAN LAND COMPLEX, 0-8% SLOPES, HSG B 704C ENFIELD SILT LOAM, 8-15% SLOPES, HSG B 308 UDORTHENTS, SMOOTHED, HSG B 37E MANCHESTER GRAVELLY SANDY LOAM, 15-45% SLOPES, HSG B Project:By: AMK Date: 12/19/23 Location:Checked: SJK Date: Rainfall, P 1.0 in. 1.0 in. a Area, A 3.13 ac 1.08 ac b Impervious Cover Area 0.6 ac 0.6 ac c % Impervious, I 19 % 54 % Volumetric Runoff Coeff., R 0.221 0.533 d 0.058 ac-ft 0.048 ac-ft e 2,511 cf 2,087 cf a First one inch of rainfall; 2004 Connecticut Stormwater Quality Manual b Area tributary to the stormwater management basin c Impervious cover area tributary to the stormwater management basin d R=0.05+0.009*I; Section 7.4.1 from 2004 Connecticut Stormwater Quality Manual e WQV=P*R*A/12; Section 7.4.1 from 2004 Connecticut Stormwater Quality Manual Water Quality Volume, WQV Water Quality Volume Calculations South Windsor High School Field South Windsor, CT Basin Name PR-1B PR-1C VHB VHB EX-1 Subcat EX-1 EX-2 Subcat EX-2 1L DP-1 2L DP-2 Routing Diagram for 43380-EX DR Prepared by VHB, Inc, Printed 12/13/2023 HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Subcat Reach Pond Link 43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 2HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Rainfall Events Listing (selected events) Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC 1 2 yr Type III 24-hr Default 24.00 1 3.13 2 2 10 yr Type III 24-hr Default 24.00 1 4.95 2 3 100 yr Type III 24-hr Default 24.00 1 7.84 2 43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 3HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (acres) CN Description (subcatchment-numbers) 5.901 61 >75% Grass cover, Good, HSG B (EX-1, EX-2) 0.166 82 Dirt roads, HSG B (EX-1, EX-2) 2.649 98 Unconnected pavement, HSG B (EX-1, EX-2) 8.717 73 TOTAL AREA 43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 4HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Soil Listing (all nodes) Area (acres) Soil Group Subcatchment Numbers 0.000 HSG A 8.717 HSG B EX-1, EX-2 0.000 HSG C 0.000 HSG D 0.000 Other 8.717 TOTAL AREA 43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 5HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Ground Covers (all nodes) HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers 0.000 5.901 0.000 0.000 0.000 5.901 >75% Grass cover, Good EX-1, EX-2 0.000 0.166 0.000 0.000 0.000 0.166 Dirt roads EX-1, EX-2 0.000 2.649 0.000 0.000 0.000 2.649 Unconnected pavement EX-1, EX-2 0.000 8.717 0.000 0.000 0.000 8.717 TOTAL AREA Type III 24-hr 2 yr Rainfall=3.13"43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 6HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Time span=0.00-36.00 hrs, dt=0.03 hrs, 1201 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=6.449 ac 28.81% Impervious Runoff Depth=0.61"Subcatchment EX-1: Subcat EX-1 Tc=6.0 min UI Adjusted CN=66 Runoff=3.63 cfs 0.327 af Runoff Area=2.268 ac 34.90% Impervious Runoff Depth=1.05"Subcatchment EX-2: Subcat EX-2 Flow Length=381' Tc=6.0 min CN=75 Runoff=2.64 cfs 0.198 af Inflow=3.63 cfs 0.327 afLink 1L: DP-1 Primary=3.63 cfs 0.327 af Inflow=2.64 cfs 0.198 afLink 2L: DP-2 Primary=2.64 cfs 0.198 af Total Runoff Area = 8.717 ac Runoff Volume = 0.525 af Average Runoff Depth = 0.72" 69.61% Pervious = 6.067 ac 30.39% Impervious = 2.649 ac Type III 24-hr 2 yr Rainfall=3.13"43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 7HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment EX-1: Subcat EX-1 Runoff = 3.63 cfs @ 12.11 hrs, Volume= 0.327 af, Depth= 0.61" Routed to Link 1L : DP-1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 2 yr Rainfall=3.13" Area (ac) CN Adj Description 4.558 61 >75% Grass cover, Good, HSG B 0.033 82 Dirt roads, HSG B 1.858 98 Unconnected pavement, HSG B 6.449 72 66 Weighted Average, UI Adjusted 4.591 71.19% Pervious Area 1.858 28.81% Impervious Area 1.858 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment EX-1: Subcat EX-1 Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 4 3 2 1 0 Type III 24-hr 2 yr Rainfall=3.13" Runoff Area=6.449 ac Runoff Volume=0.327 af Runoff Depth=0.61" Tc=6.0 min UI Adjusted CN=66 3.63 cfs Type III 24-hr 2 yr Rainfall=3.13"43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 8HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment EX-2: Subcat EX-2 Runoff = 2.64 cfs @ 12.10 hrs, Volume= 0.198 af, Depth= 1.05" Routed to Link 2L : DP-2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 2 yr Rainfall=3.13" Area (ac) CN Description 1.343 61 >75% Grass cover, Good, HSG B 0.133 82 Dirt roads, HSG B 0.791 98 Unconnected pavement, HSG B 2.268 75 Weighted Average 1.476 65.10% Pervious Area 0.791 34.90% Impervious Area 0.791 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 4.3 50 0.0400 0.19 Sheet Flow, Grass: Short n= 0.150 P2= 3.13" 0.1 36 0.0830 4.64 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 0.3 85 0.1060 5.24 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 1.3 210 0.0285 2.72 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 6.0 381 Total Type III 24-hr 2 yr Rainfall=3.13"43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 9HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Subcatchment EX-2: Subcat EX-2 Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 2 1 0 Type III 24-hr 2 yr Rainfall=3.13" Runoff Area=2.268 ac Runoff Volume=0.198 af Runoff Depth=1.05" Flow Length=381' Tc=6.0 min CN=75 2.64 cfs Type III 24-hr 2 yr Rainfall=3.13"43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 10HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Link 1L: DP-1 Inflow Area = 6.449 ac, 28.81% Impervious, Inflow Depth = 0.61" for 2 yr event Inflow = 3.63 cfs @ 12.11 hrs, Volume= 0.327 af Primary = 3.63 cfs @ 12.11 hrs, Volume= 0.327 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Link 1L: DP-1 Inflow Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 4 3 2 1 0 Inflow Area=6.449 ac 3.63 cfs 3.63 cfs Type III 24-hr 2 yr Rainfall=3.13"43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 11HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Link 2L: DP-2 Inflow Area = 2.268 ac, 34.90% Impervious, Inflow Depth = 1.05" for 2 yr event Inflow = 2.64 cfs @ 12.10 hrs, Volume= 0.198 af Primary = 2.64 cfs @ 12.10 hrs, Volume= 0.198 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Link 2L: DP-2 Inflow Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 2 1 0 Inflow Area=2.268 ac 2.64 cfs 2.64 cfs Type III 24-hr 10 yr Rainfall=4.95"43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 12HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Time span=0.00-36.00 hrs, dt=0.03 hrs, 1201 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=6.449 ac 28.81% Impervious Runoff Depth=1.69"Subcatchment EX-1: Subcat EX-1 Tc=6.0 min UI Adjusted CN=66 Runoff=12.21 cfs 0.910 af Runoff Area=2.268 ac 34.90% Impervious Runoff Depth=2.41"Subcatchment EX-2: Subcat EX-2 Flow Length=381' Tc=6.0 min CN=75 Runoff=6.35 cfs 0.455 af Inflow=12.21 cfs 0.910 afLink 1L: DP-1 Primary=12.21 cfs 0.910 af Inflow=6.35 cfs 0.455 afLink 2L: DP-2 Primary=6.35 cfs 0.455 af Total Runoff Area = 8.717 ac Runoff Volume = 1.365 af Average Runoff Depth = 1.88" 69.61% Pervious = 6.067 ac 30.39% Impervious = 2.649 ac Type III 24-hr 10 yr Rainfall=4.95"43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 13HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment EX-1: Subcat EX-1 Runoff = 12.21 cfs @ 12.10 hrs, Volume= 0.910 af, Depth= 1.69" Routed to Link 1L : DP-1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 10 yr Rainfall=4.95" Area (ac) CN Adj Description 4.558 61 >75% Grass cover, Good, HSG B 0.033 82 Dirt roads, HSG B 1.858 98 Unconnected pavement, HSG B 6.449 72 66 Weighted Average, UI Adjusted 4.591 71.19% Pervious Area 1.858 28.81% Impervious Area 1.858 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment EX-1: Subcat EX-1 Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Type III 24-hr 10 yr Rainfall=4.95" Runoff Area=6.449 ac Runoff Volume=0.910 af Runoff Depth=1.69" Tc=6.0 min UI Adjusted CN=66 12.21 cfs Type III 24-hr 10 yr Rainfall=4.95"43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 14HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment EX-2: Subcat EX-2 Runoff = 6.35 cfs @ 12.09 hrs, Volume= 0.455 af, Depth= 2.41" Routed to Link 2L : DP-2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 10 yr Rainfall=4.95" Area (ac) CN Description 1.343 61 >75% Grass cover, Good, HSG B 0.133 82 Dirt roads, HSG B 0.791 98 Unconnected pavement, HSG B 2.268 75 Weighted Average 1.476 65.10% Pervious Area 0.791 34.90% Impervious Area 0.791 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 4.3 50 0.0400 0.19 Sheet Flow, Grass: Short n= 0.150 P2= 3.13" 0.1 36 0.0830 4.64 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 0.3 85 0.1060 5.24 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 1.3 210 0.0285 2.72 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 6.0 381 Total Type III 24-hr 10 yr Rainfall=4.95"43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 15HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Subcatchment EX-2: Subcat EX-2 Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 7 6 5 4 3 2 1 0 Type III 24-hr 10 yr Rainfall=4.95" Runoff Area=2.268 ac Runoff Volume=0.455 af Runoff Depth=2.41" Flow Length=381' Tc=6.0 min CN=75 6.35 cfs Type III 24-hr 10 yr Rainfall=4.95"43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 16HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Link 1L: DP-1 Inflow Area = 6.449 ac, 28.81% Impervious, Inflow Depth = 1.69" for 10 yr event Inflow = 12.21 cfs @ 12.10 hrs, Volume= 0.910 af Primary = 12.21 cfs @ 12.10 hrs, Volume= 0.910 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Link 1L: DP-1 Inflow Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=6.449 ac 12.21 cfs 12.21 cfs Type III 24-hr 10 yr Rainfall=4.95"43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 17HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Link 2L: DP-2 Inflow Area = 2.268 ac, 34.90% Impervious, Inflow Depth = 2.41" for 10 yr event Inflow = 6.35 cfs @ 12.09 hrs, Volume= 0.455 af Primary = 6.35 cfs @ 12.09 hrs, Volume= 0.455 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Link 2L: DP-2 Inflow Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 7 6 5 4 3 2 1 0 Inflow Area=2.268 ac 6.35 cfs 6.35 cfs Type III 24-hr 100 yr Rainfall=7.84"43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 18HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Time span=0.00-36.00 hrs, dt=0.03 hrs, 1201 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=6.449 ac 28.81% Impervious Runoff Depth=3.88"Subcatchment EX-1: Subcat EX-1 Tc=6.0 min UI Adjusted CN=66 Runoff=29.11 cfs 2.083 af Runoff Area=2.268 ac 34.90% Impervious Runoff Depth=4.90"Subcatchment EX-2: Subcat EX-2 Flow Length=381' Tc=6.0 min CN=75 Runoff=12.91 cfs 0.925 af Inflow=29.11 cfs 2.083 afLink 1L: DP-1 Primary=29.11 cfs 2.083 af Inflow=12.91 cfs 0.925 afLink 2L: DP-2 Primary=12.91 cfs 0.925 af Total Runoff Area = 8.717 ac Runoff Volume = 3.009 af Average Runoff Depth = 4.14" 69.61% Pervious = 6.067 ac 30.39% Impervious = 2.649 ac Type III 24-hr 100 yr Rainfall=7.84"43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 19HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment EX-1: Subcat EX-1 Runoff = 29.11 cfs @ 12.09 hrs, Volume= 2.083 af, Depth= 3.88" Routed to Link 1L : DP-1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 100 yr Rainfall=7.84" Area (ac) CN Adj Description 4.558 61 >75% Grass cover, Good, HSG B 0.033 82 Dirt roads, HSG B 1.858 98 Unconnected pavement, HSG B 6.449 72 66 Weighted Average, UI Adjusted 4.591 71.19% Pervious Area 1.858 28.81% Impervious Area 1.858 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment EX-1: Subcat EX-1 Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 Type III 24-hr 100 yr Rainfall=7.84" Runoff Area=6.449 ac Runoff Volume=2.083 af Runoff Depth=3.88" Tc=6.0 min UI Adjusted CN=66 29.11 cfs Type III 24-hr 100 yr Rainfall=7.84"43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 20HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment EX-2: Subcat EX-2 Runoff = 12.91 cfs @ 12.09 hrs, Volume= 0.925 af, Depth= 4.90" Routed to Link 2L : DP-2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 100 yr Rainfall=7.84" Area (ac) CN Description 1.343 61 >75% Grass cover, Good, HSG B 0.133 82 Dirt roads, HSG B 0.791 98 Unconnected pavement, HSG B 2.268 75 Weighted Average 1.476 65.10% Pervious Area 0.791 34.90% Impervious Area 0.791 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 4.3 50 0.0400 0.19 Sheet Flow, Grass: Short n= 0.150 P2= 3.13" 0.1 36 0.0830 4.64 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 0.3 85 0.1060 5.24 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 1.3 210 0.0285 2.72 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 6.0 381 Total Type III 24-hr 100 yr Rainfall=7.84"43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 21HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Subcatchment EX-2: Subcat EX-2 Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Type III 24-hr 100 yr Rainfall=7.84" Runoff Area=2.268 ac Runoff Volume=0.925 af Runoff Depth=4.90" Flow Length=381' Tc=6.0 min CN=75 12.91 cfs Type III 24-hr 100 yr Rainfall=7.84"43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 22HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Link 1L: DP-1 Inflow Area = 6.449 ac, 28.81% Impervious, Inflow Depth = 3.88" for 100 yr event Inflow = 29.11 cfs @ 12.09 hrs, Volume= 2.083 af Primary = 29.11 cfs @ 12.09 hrs, Volume= 2.083 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Link 1L: DP-1 Inflow Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 Inflow Area=6.449 ac 29.11 cfs 29.11 cfs Type III 24-hr 100 yr Rainfall=7.84"43380-EX DR Printed 12/13/2023Prepared by VHB, Inc Page 23HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Link 2L: DP-2 Inflow Area = 2.268 ac, 34.90% Impervious, Inflow Depth = 4.90" for 100 yr event Inflow = 12.91 cfs @ 12.09 hrs, Volume= 0.925 af Primary = 12.91 cfs @ 12.09 hrs, Volume= 0.925 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Link 2L: DP-2 Inflow Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=2.268 ac 12.91 cfs 12.91 cfs PR-1A PR-1A PR-1B PR-1B PR-1C PR-1C PR-2 PR-2 1BP Turf Reservoir 1P Stormwater Basin DP-1 DP-1 DP-2 DP-2 Routing Diagram for 43380-PR DR Prepared by VHB, Inc, Printed 12/19/2023 HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Subcat Reach Pond Link 43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 2HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Rainfall Events Listing (selected events) Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC 1 2 yr Type III 24-hr Default 24.00 1 3.13 2 2 10 yr Type III 24-hr Default 24.00 1 4.95 2 3 100 yr Type III 24-hr Default 24.00 1 7.84 2 43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 3HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (acres) CN Description (subcatchment-numbers) 4.383 61 >75% Grass cover, Good, HSG B (PR-1A, PR-1B, PR-1C, PR-2) 2.157 83 Fallow, crop residue, Good, HSG B (PR-1B) 0.180 96 Gravel surface, HSG B (PR-1A, PR-1B, PR-2) 1.894 98 Unconnected pavement, HSG B (PR-1A, PR-1B, PR-1C, PR-2) 0.102 98 Unconnected roofs, HSG B (PR-1A) 8.717 76 TOTAL AREA 43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 4HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Soil Listing (all nodes) Area (acres) Soil Group Subcatchment Numbers 0.000 HSG A 8.717 HSG B PR-1A, PR-1B, PR-1C, PR-2 0.000 HSG C 0.000 HSG D 0.000 Other 8.717 TOTAL AREA 43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 5HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Ground Covers (all nodes) HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers 0.000 4.383 0.000 0.000 0.000 4.383 >75% Grass cover, Good PR-1A, PR-1B, PR-1C, PR-2 0.000 2.157 0.000 0.000 0.000 2.157 Fallow, crop residue, Good PR-1B 0.000 0.180 0.000 0.000 0.000 0.180 Gravel surface PR-1A, PR-1B, PR-2 0.000 1.894 0.000 0.000 0.000 1.894 Unconnected pavement PR-1A, PR-1B, PR-1C, PR-2 0.000 0.102 0.000 0.000 0.000 0.102 Unconnected roofs PR-1A 0.000 8.717 0.000 0.000 0.000 8.717 TOTAL AREA Type III 24-hr 2 yr Rainfall=3.13"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 6HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Time span=0.00-36.00 hrs, dt=0.03 hrs, 1201 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=96,811 sf 7.72% Impervious Runoff Depth=0.49"Subcatchment PR-1A: PR-1A Flow Length=522' Tc=9.0 min UI Adjusted CN=63 Runoff=0.78 cfs 0.090 af Runoff Area=136,533 sf 15.37% Impervious Runoff Depth=1.48"Subcatchment PR-1B: PR-1B Tc=6.0 min UI Adjusted CN=82 Runoff=5.40 cfs 0.387 af Runoff Area=46,988 sf 53.68% Impervious Runoff Depth=1.41"Subcatchment PR-1C: PR-1C Tc=6.0 min CN=81 Runoff=1.77 cfs 0.127 af Runoff Area=99,364 sf 33.50% Impervious Runoff Depth=0.99"Subcatchment PR-2: PR-2 Tc=6.0 min CN=74 Runoff=2.49 cfs 0.189 af Peak Elev=172.50' Storage=133 cf Inflow=5.40 cfs 0.387 afPond 1BP: Turf Reservoir Discarded=5.38 cfs 0.387 af Primary=0.00 cfs 0.000 af Outflow=5.38 cfs 0.387 af Peak Elev=167.29' Storage=978 cf Inflow=1.77 cfs 0.127 afPond 1P: Stormwater Basin Discarded=0.57 cfs 0.127 af Primary=0.00 cfs 0.000 af Outflow=0.57 cfs 0.127 af Inflow=0.78 cfs 0.090 afLink DP-1: DP-1 Primary=0.78 cfs 0.090 af Inflow=2.49 cfs 0.189 afLink DP-2: DP-2 Primary=2.49 cfs 0.189 af Total Runoff Area = 8.717 ac Runoff Volume = 0.793 af Average Runoff Depth = 1.09" 77.10% Pervious = 6.720 ac 22.90% Impervious = 1.996 ac Type III 24-hr 2 yr Rainfall=3.13"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 7HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment PR-1A: PR-1A Runoff = 0.78 cfs @ 12.16 hrs, Volume= 0.090 af, Depth= 0.49" Routed to Link DP-1 : DP-1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 2 yr Rainfall=3.13" Area (sf) CN Adj Description 3,032 98 Unconnected pavement, HSG B 4,438 98 Unconnected roofs, HSG B 947 96 Gravel surface, HSG B 88,394 61 >75% Grass cover, Good, HSG B 96,811 64 63 Weighted Average, UI Adjusted 89,341 92.28% Pervious Area 7,470 7.72% Impervious Area 7,470 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 4.8 50 0.0300 0.17 Sheet Flow, Grass: Short n= 0.150 P2= 3.13" 0.4 66 0.0300 2.79 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 1.8 213 0.0150 1.97 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 2.0 193 0.0100 1.61 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 9.0 522 Total Type III 24-hr 2 yr Rainfall=3.13"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 8HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Subcatchment PR-1A: PR-1A Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type III 24-hr 2 yr Rainfall=3.13" Runoff Area=96,811 sf Runoff Volume=0.090 af Runoff Depth=0.49" Flow Length=522' Tc=9.0 min UI Adjusted CN=63 0.78 cfs Type III 24-hr 2 yr Rainfall=3.13"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 9HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment PR-1B: PR-1B Runoff = 5.40 cfs @ 12.09 hrs, Volume= 0.387 af, Depth= 1.48" Routed to Pond 1BP : Turf Reservoir Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 2 yr Rainfall=3.13" Area (sf) CN Adj Description 20,984 98 Unconnected pavement, HSG B 4,917 96 Gravel surface, HSG B 93,955 83 Fallow, crop residue, Good, HSG B 16,677 61 >75% Grass cover, Good, HSG B 136,533 83 82 Weighted Average, UI Adjusted 115,549 84.63% Pervious Area 20,984 15.37% Impervious Area 20,984 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment PR-1B: PR-1B Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 6 5 4 3 2 1 0 Type III 24-hr 2 yr Rainfall=3.13" Runoff Area=136,533 sf Runoff Volume=0.387 af Runoff Depth=1.48" Tc=6.0 min UI Adjusted CN=82 5.40 cfs Type III 24-hr 2 yr Rainfall=3.13"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 10HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment PR-1C: PR-1C Runoff = 1.77 cfs @ 12.09 hrs, Volume= 0.127 af, Depth= 1.41" Routed to Pond 1P : Stormwater Basin Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 2 yr Rainfall=3.13" Area (sf) CN Description 25,222 98 Unconnected pavement, HSG B 0 96 Gravel surface, HSG B 21,766 61 >75% Grass cover, Good, HSG B 46,988 81 Weighted Average 21,766 46.32% Pervious Area 25,222 53.68% Impervious Area 25,222 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment PR-1C: PR-1C Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 1 0 Type III 24-hr 2 yr Rainfall=3.13" Runoff Area=46,988 sf Runoff Volume=0.127 af Runoff Depth=1.41" Tc=6.0 min CN=81 1.77 cfs Type III 24-hr 2 yr Rainfall=3.13"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 11HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment PR-2: PR-2 Runoff = 2.49 cfs @ 12.10 hrs, Volume= 0.189 af, Depth= 0.99" Routed to Link DP-2 : DP-2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 2 yr Rainfall=3.13" Area (sf) CN Description 33,283 98 Unconnected pavement, HSG B 64,091 61 >75% Grass cover, Good, HSG B 1,990 96 Gravel surface, HSG B 99,364 74 Weighted Average 66,081 66.50% Pervious Area 33,283 33.50% Impervious Area 33,283 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment PR-2: PR-2 Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 2 1 0 Type III 24-hr 2 yr Rainfall=3.13" Runoff Area=99,364 sf Runoff Volume=0.189 af Runoff Depth=0.99" Tc=6.0 min CN=74 2.49 cfs Type III 24-hr 2 yr Rainfall=3.13"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 12HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Pond 1BP: Turf Reservoir Inflow Area = 3.134 ac, 15.37% Impervious, Inflow Depth = 1.48" for 2 yr event Inflow = 5.40 cfs @ 12.09 hrs, Volume= 0.387 af Outflow = 5.38 cfs @ 12.10 hrs, Volume= 0.387 af, Atten= 0%, Lag= 0.4 min Discarded = 5.38 cfs @ 12.10 hrs, Volume= 0.387 af Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Link DP-1 : DP-1 Routing by Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Peak Elev= 172.50' @ 12.10 hrs Surf.Area= 93,140 sf Storage= 133 cf Plug-Flow detention time= 0.4 min calculated for 0.387 af (100% of inflow) Center-of-Mass det. time= 0.4 min ( 837.7 - 837.3 ) Volume Invert Avail.Storage Storage Description #1 172.50' 37,256 cf Custom Stage Data (Irregular) Listed below (Recalc) 93,140 cf Overall x 40.0% Voids Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (cubic-feet) (cubic-feet) (sq-ft) 172.50 93,140 746.0 0 0 93,140 173.00 93,140 746.0 46,570 46,570 93,513 173.50 93,140 746.0 46,570 93,140 93,886 Device Routing Invert Outlet Devices #1 Primary 172.75'746.0' long x 2.0' 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 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 #2 Discarded 172.50'7.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 10.00' Discarded OutFlow Max=15.09 cfs @ 12.10 hrs HW=172.50' (Free Discharge) 2=Exfiltration ( Controls 15.09 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=172.50' (Free Discharge) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 2 yr Rainfall=3.13"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 13HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Pond 1BP: Turf Reservoir Inflow Outflow Discarded Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 6 5 4 3 2 1 0 Inflow Area=3.134 ac Peak Elev=172.50' Storage=133 cf 5.40 cfs 5.38 cfs 5.38 cfs 0.00 cfs Type III 24-hr 2 yr Rainfall=3.13"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 14HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Pond 1P: Stormwater Basin Inflow Area = 1.079 ac, 53.68% Impervious, Inflow Depth = 1.41" for 2 yr event Inflow = 1.77 cfs @ 12.09 hrs, Volume= 0.127 af Outflow = 0.57 cfs @ 12.44 hrs, Volume= 0.127 af, Atten= 68%, Lag= 20.8 min Discarded = 0.57 cfs @ 12.44 hrs, Volume= 0.127 af Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Link DP-1 : DP-1 Routing by Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Peak Elev= 167.29' @ 12.44 hrs Surf.Area= 3,482 sf Storage= 978 cf Plug-Flow detention time= 9.8 min calculated for 0.127 af (100% of inflow) Center-of-Mass det. time= 9.8 min ( 850.5 - 840.6 ) Volume Invert Avail.Storage Storage Description #1 167.00' 8,234 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 167.00 3,227 0 0 168.00 4,103 3,665 3,665 169.00 5,035 4,569 8,234 Device Routing Invert Outlet Devices #1 Primary 168.50'10.0' long x 5.0' 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 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 #2 Discarded 167.00'7.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 10.00' Discarded OutFlow Max=0.57 cfs @ 12.44 hrs HW=167.29' (Free Discharge) 2=Exfiltration ( Controls 0.57 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=167.00' (Free Discharge) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 2 yr Rainfall=3.13"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 15HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Pond 1P: Stormwater Basin Inflow Outflow Discarded Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 1 0 Inflow Area=1.079 ac Peak Elev=167.29' Storage=978 cf 1.77 cfs 0.57 cfs 0.57 cfs 0.00 cfs Type III 24-hr 2 yr Rainfall=3.13"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 16HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Link DP-1: DP-1 Inflow Area = 6.436 ac, 19.15% Impervious, Inflow Depth = 0.17" for 2 yr event Inflow = 0.78 cfs @ 12.16 hrs, Volume= 0.090 af Primary = 0.78 cfs @ 12.16 hrs, Volume= 0.090 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Link DP-1: DP-1 Inflow Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Inflow Area=6.436 ac 0.78 cfs 0.78 cfs Type III 24-hr 2 yr Rainfall=3.13"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 17HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Link DP-2: DP-2 Inflow Area = 2.281 ac, 33.50% Impervious, Inflow Depth = 0.99" for 2 yr event Inflow = 2.49 cfs @ 12.10 hrs, Volume= 0.189 af Primary = 2.49 cfs @ 12.10 hrs, Volume= 0.189 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Link DP-2: DP-2 Inflow Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 2 1 0 Inflow Area=2.281 ac 2.49 cfs 2.49 cfs Type III 24-hr 10 yr Rainfall=4.95"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 18HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Time span=0.00-36.00 hrs, dt=0.03 hrs, 1201 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=96,811 sf 7.72% Impervious Runoff Depth=1.48"Subcatchment PR-1A: PR-1A Flow Length=522' Tc=9.0 min UI Adjusted CN=63 Runoff=3.20 cfs 0.274 af Runoff Area=136,533 sf 15.37% Impervious Runoff Depth=3.03"Subcatchment PR-1B: PR-1B Tc=6.0 min UI Adjusted CN=82 Runoff=11.07 cfs 0.793 af Runoff Area=46,988 sf 53.68% Impervious Runoff Depth=2.94"Subcatchment PR-1C: PR-1C Tc=6.0 min CN=81 Runoff=3.70 cfs 0.264 af Runoff Area=99,364 sf 33.50% Impervious Runoff Depth=2.32"Subcatchment PR-2: PR-2 Tc=6.0 min CN=74 Runoff=6.16 cfs 0.442 af Peak Elev=172.51' Storage=272 cf Inflow=11.07 cfs 0.793 afPond 1BP: Turf Reservoir Discarded=11.04 cfs 0.793 af Primary=0.00 cfs 0.000 af Outflow=11.04 cfs 0.793 af Peak Elev=167.93' Storage=3,376 cf Inflow=3.70 cfs 0.264 afPond 1P: Stormwater Basin Discarded=0.66 cfs 0.264 af Primary=0.00 cfs 0.000 af Outflow=0.66 cfs 0.264 af Inflow=3.20 cfs 0.274 afLink DP-1: DP-1 Primary=3.20 cfs 0.274 af Inflow=6.16 cfs 0.442 afLink DP-2: DP-2 Primary=6.16 cfs 0.442 af Total Runoff Area = 8.717 ac Runoff Volume = 1.772 af Average Runoff Depth = 2.44" 77.10% Pervious = 6.720 ac 22.90% Impervious = 1.996 ac Type III 24-hr 10 yr Rainfall=4.95"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 19HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment PR-1A: PR-1A Runoff = 3.20 cfs @ 12.14 hrs, Volume= 0.274 af, Depth= 1.48" Routed to Link DP-1 : DP-1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 10 yr Rainfall=4.95" Area (sf) CN Adj Description 3,032 98 Unconnected pavement, HSG B 4,438 98 Unconnected roofs, HSG B 947 96 Gravel surface, HSG B 88,394 61 >75% Grass cover, Good, HSG B 96,811 64 63 Weighted Average, UI Adjusted 89,341 92.28% Pervious Area 7,470 7.72% Impervious Area 7,470 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 4.8 50 0.0300 0.17 Sheet Flow, Grass: Short n= 0.150 P2= 3.13" 0.4 66 0.0300 2.79 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 1.8 213 0.0150 1.97 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 2.0 193 0.0100 1.61 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 9.0 522 Total Type III 24-hr 10 yr Rainfall=4.95"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 20HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Subcatchment PR-1A: PR-1A Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 3 2 1 0 Type III 24-hr 10 yr Rainfall=4.95" Runoff Area=96,811 sf Runoff Volume=0.274 af Runoff Depth=1.48" Flow Length=522' Tc=9.0 min UI Adjusted CN=63 3.20 cfs Type III 24-hr 10 yr Rainfall=4.95"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 21HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment PR-1B: PR-1B Runoff = 11.07 cfs @ 12.09 hrs, Volume= 0.793 af, Depth= 3.03" Routed to Pond 1BP : Turf Reservoir Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 10 yr Rainfall=4.95" Area (sf) CN Adj Description 20,984 98 Unconnected pavement, HSG B 4,917 96 Gravel surface, HSG B 93,955 83 Fallow, crop residue, Good, HSG B 16,677 61 >75% Grass cover, Good, HSG B 136,533 83 82 Weighted Average, UI Adjusted 115,549 84.63% Pervious Area 20,984 15.37% Impervious Area 20,984 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment PR-1B: PR-1B Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 12 11 10 9 8 7 6 5 4 3 2 1 0 Type III 24-hr 10 yr Rainfall=4.95" Runoff Area=136,533 sf Runoff Volume=0.793 af Runoff Depth=3.03" Tc=6.0 min UI Adjusted CN=82 11.07 cfs Type III 24-hr 10 yr Rainfall=4.95"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 22HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment PR-1C: PR-1C Runoff = 3.70 cfs @ 12.09 hrs, Volume= 0.264 af, Depth= 2.94" Routed to Pond 1P : Stormwater Basin Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 10 yr Rainfall=4.95" Area (sf) CN Description 25,222 98 Unconnected pavement, HSG B 0 96 Gravel surface, HSG B 21,766 61 >75% Grass cover, Good, HSG B 46,988 81 Weighted Average 21,766 46.32% Pervious Area 25,222 53.68% Impervious Area 25,222 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment PR-1C: PR-1C Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 4 3 2 1 0 Type III 24-hr 10 yr Rainfall=4.95" Runoff Area=46,988 sf Runoff Volume=0.264 af Runoff Depth=2.94" Tc=6.0 min CN=81 3.70 cfs Type III 24-hr 10 yr Rainfall=4.95"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 23HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment PR-2: PR-2 Runoff = 6.16 cfs @ 12.09 hrs, Volume= 0.442 af, Depth= 2.32" Routed to Link DP-2 : DP-2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 10 yr Rainfall=4.95" Area (sf) CN Description 33,283 98 Unconnected pavement, HSG B 64,091 61 >75% Grass cover, Good, HSG B 1,990 96 Gravel surface, HSG B 99,364 74 Weighted Average 66,081 66.50% Pervious Area 33,283 33.50% Impervious Area 33,283 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment PR-2: PR-2 Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 6 5 4 3 2 1 0 Type III 24-hr 10 yr Rainfall=4.95" Runoff Area=99,364 sf Runoff Volume=0.442 af Runoff Depth=2.32" Tc=6.0 min CN=74 6.16 cfs Type III 24-hr 10 yr Rainfall=4.95"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 24HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Pond 1BP: Turf Reservoir Inflow Area = 3.134 ac, 15.37% Impervious, Inflow Depth = 3.03" for 10 yr event Inflow = 11.07 cfs @ 12.09 hrs, Volume= 0.793 af Outflow = 11.04 cfs @ 12.10 hrs, Volume= 0.793 af, Atten= 0%, Lag= 0.4 min Discarded = 11.04 cfs @ 12.10 hrs, Volume= 0.793 af Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Link DP-1 : DP-1 Routing by Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Peak Elev= 172.51' @ 12.10 hrs Surf.Area= 93,140 sf Storage= 272 cf Plug-Flow detention time= 0.4 min calculated for 0.792 af (100% of inflow) Center-of-Mass det. time= 0.4 min ( 817.1 - 816.7 ) Volume Invert Avail.Storage Storage Description #1 172.50' 37,256 cf Custom Stage Data (Irregular) Listed below (Recalc) 93,140 cf Overall x 40.0% Voids Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (cubic-feet) (cubic-feet) (sq-ft) 172.50 93,140 746.0 0 0 93,140 173.00 93,140 746.0 46,570 46,570 93,513 173.50 93,140 746.0 46,570 93,140 93,886 Device Routing Invert Outlet Devices #1 Primary 172.75'746.0' long x 2.0' 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 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 #2 Discarded 172.50'7.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 10.00' Discarded OutFlow Max=15.09 cfs @ 12.10 hrs HW=172.51' (Free Discharge) 2=Exfiltration ( Controls 15.09 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=172.50' (Free Discharge) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 10 yr Rainfall=4.95"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 25HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Pond 1BP: Turf Reservoir Inflow Outflow Discarded Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=3.134 ac Peak Elev=172.51' Storage=272 cf 11.07 cfs 11.04 cfs 11.04 cfs 0.00 cfs Type III 24-hr 10 yr Rainfall=4.95"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 26HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Pond 1P: Stormwater Basin Inflow Area = 1.079 ac, 53.68% Impervious, Inflow Depth = 2.94" for 10 yr event Inflow = 3.70 cfs @ 12.09 hrs, Volume= 0.264 af Outflow = 0.66 cfs @ 12.56 hrs, Volume= 0.264 af, Atten= 82%, Lag= 28.3 min Discarded = 0.66 cfs @ 12.56 hrs, Volume= 0.264 af Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Link DP-1 : DP-1 Routing by Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Peak Elev= 167.93' @ 12.56 hrs Surf.Area= 4,041 sf Storage= 3,376 cf Plug-Flow detention time= 35.6 min calculated for 0.264 af (100% of inflow) Center-of-Mass det. time= 35.6 min ( 855.1 - 819.5 ) Volume Invert Avail.Storage Storage Description #1 167.00' 8,234 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 167.00 3,227 0 0 168.00 4,103 3,665 3,665 169.00 5,035 4,569 8,234 Device Routing Invert Outlet Devices #1 Primary 168.50'10.0' long x 5.0' 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 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 #2 Discarded 167.00'7.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 10.00' Discarded OutFlow Max=0.66 cfs @ 12.56 hrs HW=167.93' (Free Discharge) 2=Exfiltration ( Controls 0.66 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=167.00' (Free Discharge) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 10 yr Rainfall=4.95"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 27HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Pond 1P: Stormwater Basin Inflow Outflow Discarded Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 4 3 2 1 0 Inflow Area=1.079 ac Peak Elev=167.93' Storage=3,376 cf 3.70 cfs 0.66 cfs 0.66 cfs 0.00 cfs Type III 24-hr 10 yr Rainfall=4.95"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 28HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Link DP-1: DP-1 Inflow Area = 6.436 ac, 19.15% Impervious, Inflow Depth = 0.51" for 10 yr event Inflow = 3.20 cfs @ 12.14 hrs, Volume= 0.274 af Primary = 3.20 cfs @ 12.14 hrs, Volume= 0.274 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Link DP-1: DP-1 Inflow Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 3 2 1 0 Inflow Area=6.436 ac 3.20 cfs 3.20 cfs Type III 24-hr 10 yr Rainfall=4.95"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 29HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Link DP-2: DP-2 Inflow Area = 2.281 ac, 33.50% Impervious, Inflow Depth = 2.32" for 10 yr event Inflow = 6.16 cfs @ 12.09 hrs, Volume= 0.442 af Primary = 6.16 cfs @ 12.09 hrs, Volume= 0.442 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Link DP-2: DP-2 Inflow Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 6 5 4 3 2 1 0 Inflow Area=2.281 ac 6.16 cfs 6.16 cfs Type III 24-hr 100 yr Rainfall=7.84"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 30HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Time span=0.00-36.00 hrs, dt=0.03 hrs, 1201 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=96,811 sf 7.72% Impervious Runoff Depth=3.54"Subcatchment PR-1A: PR-1A Flow Length=522' Tc=9.0 min UI Adjusted CN=63 Runoff=8.23 cfs 0.656 af Runoff Area=136,533 sf 15.37% Impervious Runoff Depth=5.71"Subcatchment PR-1B: PR-1B Tc=6.0 min UI Adjusted CN=82 Runoff=20.41 cfs 1.491 af Runoff Area=46,988 sf 53.68% Impervious Runoff Depth=5.59"Subcatchment PR-1C: PR-1C Tc=6.0 min CN=81 Runoff=6.90 cfs 0.503 af Runoff Area=99,364 sf 33.50% Impervious Runoff Depth=4.78"Subcatchment PR-2: PR-2 Tc=6.0 min CN=74 Runoff=12.70 cfs 0.909 af Peak Elev=172.55' Storage=1,934 cf Inflow=20.41 cfs 1.491 afPond 1BP: Turf Reservoir Discarded=15.10 cfs 1.491 af Primary=0.00 cfs 0.000 af Outflow=15.10 cfs 1.491 af Peak Elev=168.67' Storage=6,604 cf Inflow=6.90 cfs 0.503 afPond 1P: Stormwater Basin Discarded=0.77 cfs 0.455 af Primary=1.58 cfs 0.048 af Outflow=2.35 cfs 0.503 af Inflow=8.23 cfs 0.704 afLink DP-1: DP-1 Primary=8.23 cfs 0.704 af Inflow=12.70 cfs 0.909 afLink DP-2: DP-2 Primary=12.70 cfs 0.909 af Total Runoff Area = 8.717 ac Runoff Volume = 3.559 af Average Runoff Depth = 4.90" 77.10% Pervious = 6.720 ac 22.90% Impervious = 1.996 ac Type III 24-hr 100 yr Rainfall=7.84"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 31HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment PR-1A: PR-1A Runoff = 8.23 cfs @ 12.13 hrs, Volume= 0.656 af, Depth= 3.54" Routed to Link DP-1 : DP-1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 100 yr Rainfall=7.84" Area (sf) CN Adj Description 3,032 98 Unconnected pavement, HSG B 4,438 98 Unconnected roofs, HSG B 947 96 Gravel surface, HSG B 88,394 61 >75% Grass cover, Good, HSG B 96,811 64 63 Weighted Average, UI Adjusted 89,341 92.28% Pervious Area 7,470 7.72% Impervious Area 7,470 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 4.8 50 0.0300 0.17 Sheet Flow, Grass: Short n= 0.150 P2= 3.13" 0.4 66 0.0300 2.79 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 1.8 213 0.0150 1.97 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 2.0 193 0.0100 1.61 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 9.0 522 Total Type III 24-hr 100 yr Rainfall=7.84"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 32HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Subcatchment PR-1A: PR-1A Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 9 8 7 6 5 4 3 2 1 0 Type III 24-hr 100 yr Rainfall=7.84" Runoff Area=96,811 sf Runoff Volume=0.656 af Runoff Depth=3.54" Flow Length=522' Tc=9.0 min UI Adjusted CN=63 8.23 cfs Type III 24-hr 100 yr Rainfall=7.84"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 33HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment PR-1B: PR-1B Runoff = 20.41 cfs @ 12.09 hrs, Volume= 1.491 af, Depth= 5.71" Routed to Pond 1BP : Turf Reservoir Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 100 yr Rainfall=7.84" Area (sf) CN Adj Description 20,984 98 Unconnected pavement, HSG B 4,917 96 Gravel surface, HSG B 93,955 83 Fallow, crop residue, Good, HSG B 16,677 61 >75% Grass cover, Good, HSG B 136,533 83 82 Weighted Average, UI Adjusted 115,549 84.63% Pervious Area 20,984 15.37% Impervious Area 20,984 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment PR-1B: PR-1B Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Type III 24-hr 100 yr Rainfall=7.84" Runoff Area=136,533 sf Runoff Volume=1.491 af Runoff Depth=5.71" Tc=6.0 min UI Adjusted CN=82 20.41 cfs Type III 24-hr 100 yr Rainfall=7.84"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 34HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment PR-1C: PR-1C Runoff = 6.90 cfs @ 12.09 hrs, Volume= 0.503 af, Depth= 5.59" Routed to Pond 1P : Stormwater Basin Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 100 yr Rainfall=7.84" Area (sf) CN Description 25,222 98 Unconnected pavement, HSG B 0 96 Gravel surface, HSG B 21,766 61 >75% Grass cover, Good, HSG B 46,988 81 Weighted Average 21,766 46.32% Pervious Area 25,222 53.68% Impervious Area 25,222 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment PR-1C: PR-1C Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 7 6 5 4 3 2 1 0 Type III 24-hr 100 yr Rainfall=7.84" Runoff Area=46,988 sf Runoff Volume=0.503 af Runoff Depth=5.59" Tc=6.0 min CN=81 6.90 cfs Type III 24-hr 100 yr Rainfall=7.84"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 35HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment PR-2: PR-2 Runoff = 12.70 cfs @ 12.09 hrs, Volume= 0.909 af, Depth= 4.78" Routed to Link DP-2 : DP-2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Type III 24-hr 100 yr Rainfall=7.84" Area (sf) CN Description 33,283 98 Unconnected pavement, HSG B 64,091 61 >75% Grass cover, Good, HSG B 1,990 96 Gravel surface, HSG B 99,364 74 Weighted Average 66,081 66.50% Pervious Area 33,283 33.50% Impervious Area 33,283 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment PR-2: PR-2 Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Type III 24-hr 100 yr Rainfall=7.84" Runoff Area=99,364 sf Runoff Volume=0.909 af Runoff Depth=4.78" Tc=6.0 min CN=74 12.70 cfs Type III 24-hr 100 yr Rainfall=7.84"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 36HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Pond 1BP: Turf Reservoir Inflow Area = 3.134 ac, 15.37% Impervious, Inflow Depth = 5.71" for 100 yr event Inflow = 20.41 cfs @ 12.09 hrs, Volume= 1.491 af Outflow = 15.10 cfs @ 12.16 hrs, Volume= 1.491 af, Atten= 26%, Lag= 4.3 min Discarded = 15.10 cfs @ 12.16 hrs, Volume= 1.491 af Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Link DP-1 : DP-1 Routing by Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Peak Elev= 172.55' @ 12.16 hrs Surf.Area= 93,140 sf Storage= 1,934 cf Plug-Flow detention time= 0.6 min calculated for 1.490 af (100% of inflow) Center-of-Mass det. time= 0.6 min ( 799.5 - 798.8 ) Volume Invert Avail.Storage Storage Description #1 172.50' 37,256 cf Custom Stage Data (Irregular) Listed below (Recalc) 93,140 cf Overall x 40.0% Voids Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (cubic-feet) (cubic-feet) (sq-ft) 172.50 93,140 746.0 0 0 93,140 173.00 93,140 746.0 46,570 46,570 93,513 173.50 93,140 746.0 46,570 93,140 93,886 Device Routing Invert Outlet Devices #1 Primary 172.75'746.0' long x 2.0' 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 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 #2 Discarded 172.50'7.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 10.00' Discarded OutFlow Max=15.10 cfs @ 12.16 hrs HW=172.55' (Free Discharge) 2=Exfiltration ( Controls 15.10 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=172.50' (Free Discharge) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 100 yr Rainfall=7.84"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 37HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Pond 1BP: Turf Reservoir Inflow Outflow Discarded Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=3.134 ac Peak Elev=172.55' Storage=1,934 cf 20.41 cfs 15.10 cfs 15.10 cfs 0.00 cfs Type III 24-hr 100 yr Rainfall=7.84"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 38HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Pond 1P: Stormwater Basin Inflow Area = 1.079 ac, 53.68% Impervious, Inflow Depth = 5.59" for 100 yr event Inflow = 6.90 cfs @ 12.09 hrs, Volume= 0.503 af Outflow = 2.35 cfs @ 12.38 hrs, Volume= 0.503 af, Atten= 66%, Lag= 17.4 min Discarded = 0.77 cfs @ 12.38 hrs, Volume= 0.455 af Primary = 1.58 cfs @ 12.38 hrs, Volume= 0.048 af Routed to Link DP-1 : DP-1 Routing by Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Peak Elev= 168.67' @ 12.38 hrs Surf.Area= 4,724 sf Storage= 6,604 cf Plug-Flow detention time= 58.6 min calculated for 0.502 af (100% of inflow) Center-of-Mass det. time= 58.5 min ( 859.8 - 801.3 ) Volume Invert Avail.Storage Storage Description #1 167.00' 8,234 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 167.00 3,227 0 0 168.00 4,103 3,665 3,665 169.00 5,035 4,569 8,234 Device Routing Invert Outlet Devices #1 Primary 168.50'10.0' long x 5.0' 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 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 #2 Discarded 167.00'7.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 10.00' Discarded OutFlow Max=0.77 cfs @ 12.38 hrs HW=168.67' (Free Discharge) 2=Exfiltration ( Controls 0.77 cfs) Primary OutFlow Max=1.57 cfs @ 12.38 hrs HW=168.67' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 1.57 cfs @ 0.95 fps) Type III 24-hr 100 yr Rainfall=7.84"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 39HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Pond 1P: Stormwater Basin Inflow Outflow Discarded Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 7 6 5 4 3 2 1 0 Inflow Area=1.079 ac Peak Elev=168.67' Storage=6,604 cf 6.90 cfs 2.35 cfs 0.77 cfs 1.58 cfs Type III 24-hr 100 yr Rainfall=7.84"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 40HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Link DP-1: DP-1 Inflow Area = 6.436 ac, 19.15% Impervious, Inflow Depth = 1.31" for 100 yr event Inflow = 8.23 cfs @ 12.13 hrs, Volume= 0.704 af Primary = 8.23 cfs @ 12.13 hrs, Volume= 0.704 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Link DP-1: DP-1 Inflow Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 9 8 7 6 5 4 3 2 1 0 Inflow Area=6.436 ac 8.23 cfs 8.23 cfs Type III 24-hr 100 yr Rainfall=7.84"43380-PR DR Printed 12/19/2023Prepared by VHB, Inc Page 41HydroCAD® 10.20-3c s/n 01038 © 2023 HydroCAD Software Solutions LLC Summary for Link DP-2: DP-2 Inflow Area = 2.281 ac, 33.50% Impervious, Inflow Depth = 4.78" for 100 yr event Inflow = 12.70 cfs @ 12.09 hrs, Volume= 0.909 af Primary = 12.70 cfs @ 12.09 hrs, Volume= 0.909 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-36.00 hrs, dt= 0.03 hrs Link DP-2: DP-2 Inflow Primary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210 Fl o w ( c f s ) 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=2.281 ac 12.70 cfs 12.70 cfs