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HomeMy WebLinkAboutDrainage Report 06.11.25 Gramercy – Areas E & F Drainage Report SW Corner of Keystone Pkwy & 126th St Carmel, IN 46032 Original: June 11, 2025 Prepared For: Buckingham Companies 941 N Meridian St Indianapolis, IN 46204 Prepared By: Kimley-Horn and Associates, Inc. 500 East 96th Street, Suite 300 Indianapolis, IN 46240 Contact: Alex Stephens, P.E. Phone: (317) 218-9560 KH Project Number: 170291005 Buckingham Gramercy – Areas A, B, & C Page 2 June 23, 2025 Table of Contents 1.0. Introduction ................................................................................................. 3 2.0. Existing Conditions ....................................................................................... 3 3.0. Proposed Conditions .................................................................................... 4 5.0 Appendices .................................................................................................. 6 Appendix A: Project Site Maps ................................................................................................................... 7 Appendix B: Existing Conditions ................................................................................................................. 8 Appendix C: Proposed Conditions .............................................................................................................. 9 Appendix D: Proposed Storm Sewer Design ............................................................................................. 10 Appendix E: Stormwater Quality Design .................................................................................................. 11 Appendix F: Previous Report Excerpts ..................................................................................................... 12 Buckingham Gramercy – Areas E & F Page 3 June 23, 2025 Project Summary Project Name: Gramercy – Areas E & F Location: Golfview Dr & Kinzer Ave, Carmel, IN 46032 Report Type: Drainage Report Reviewing Agency: City of Carmel Storm Sewer Sizing: Rational Method Detention Basin Sizing: USDA NRCS TR-55 Stormwater Quality: Hydrodynamic Separator, Underground Detention Isolator Row, Dry Detention Basin Design Standards: City of Carmel Stormwater Technical Manual 1.0. Introduction Kimley-Horn and Associates, Inc. has been retained by Buckingham Companies to prepare construction documents and provide civil engineering services for the proposed Gramercy – Areas E & F which includes the construction of 22 building pads for future townhouse buildings, associated drive aisles, hardscape improvements, and infrastructure on a ±8.51 -acre project in the city of Carmel, Hamilton County, Indiana. The site is located at the intersection of Golfview Drive and Kinzer Ave. Water quality for the project will be provided by a combination of a hydrodynamic separator, an isolator row in an underground detention system, and a dry detention pond. The proposed stormwater quality and quantity measures were designed to meet the requirements of the current City of Carmel Stormwater Technical Manual. 2.0. Existing Conditions FEMA According to FEMA Flood Insurance Rate Maps 18097C0226G and 18057C0228G dated November 19, 2014 provided in Appendix A, the site resides within “Zone X” which corresponds to areas determined to be outside of the 0.2% annual chance floodplain. Soil Characteristics Per the United States Geological Survey’s (USGS) Natural Resources Conservation Service (NRCS) Web Soil Survey, the site soil consists primarily of Crosby silt loam, fine-loamy subsoil-Urban land complex, 0 to 2 percent slopes (YcIA), Miami silt Loam-Urban land complex, 2 to 6 percent slopes (YmsB2), Miami clay loam-Urban land complex, 6 to 12 percent slopes, severely eroded (YmdC3), Urban land-Miami silt loam complex, 2 to 6 percent slopes eroded (UkbB2), and Urban land- Brookston complex, 0 to 2 percent slopes (UbaA). Refer to Appendix A for the NRCS Web Soil Survey soil report. Existing Site Features The existing site is currently developed as open green space that surrounds existing apartment buildings. The site also has associated drive aisles, existing hardscape, and parking spaces. A portion of the existing Kinzer Avenue right-of-way is also included in the project site, which is collected by inlets on Kinzer and Buckingham Gramercy – Areas E & F Page 4 June 23, 2025 detained in a swale to the east of the road. The majority of the site drains via shallow concentrated flow to existing storm infrastructure that outfalls into an existing swale located east of Kinzer Ave. The swale ultimately leads to a large box culvert that crosses under Keystone Ave. An aerial of the project site is included in Appendix A. Refer to Appendix B for additional information regarding the existing drainage patterns for the site. The table below indicates the existing runoff from the site for the 2-Year, 10-Year, and 100-Year storm events using HydroCAD stormwater modeling. Refer to Appendix B for the existing drainage calculations. Existing Release Rates Storm Event Discharge Rate (cfs) 2-YR 5.82 10-YR 11.24 100-YR 24.52 Table 1: Existing Discharge Rates 3.0. Proposed Conditions The proposed project includes the construction of 22 building pads for future townhouse buildings, associated drive aisles, hardscape improvements, and infrastructure on a ±8.51 acre project in the city of Carmel, Indiana. Proposed onsite private storm inlets and sewers have been designed for Pod E & F to carry site drainage from the pavement, roof, drive aisles, and grassed areas to the provided detention systems. For Pod F an onsite underground detention system has been provided to detain drainage before discharging to the proposed dry detention pond via storm sewer. Pod E drainage will be discharged directly into the dry detention pond. The portion of Kinzer Ave that discharges to the east in the existing condition will be collected and detained as part of Area E. The on-site dry detention basin discharges into the existing storm sewer culvert east of the project site. Refer to Appendix C for a proposed drainage area map. Refer to Appendix D for a proposed storm sewer drainage area map. Offsite runoff will be collected from the north side of Area F, as well as the existing wet detention pond on the west side of Kinzer Ave. This offsite runoff will be routed through the dry detention pond as bypass over the spillway. The table below summarizes the previously calculated detention analysis for the existing wet detention pond. Excerpts from the Gramercy Section 2, 3, & 4 Drainage Report by Stoeppelworth and Associates, Inc which details the existing pond have been included in Appendix F. Storm Event 2-Year 10-Year 100-Year Overall Release Rate for Existing Wet Pond 1.316 cfs 1.737 cfs 5.455 cfs Per the City of Carmel’s redevelopment standards, the site’s proposed 100-year release rate must be reduced to a rate equal to or below the existing 10-year release rate. Additionally, the site’s proposed 10- Buckingham Gramercy – Areas E & F Page 5 June 23, 2025 year release rate must be reduced to a rate equal to or below the existing 2-year release rate. The table below summarizes the proposed and allowable runoff from the site using the SCS Curve Number method and HydroCAD modeling. Storm Event Allowable Discharge (cfs) Proposed Discharge (cfs) Peak Elevation (ft) 10-YR 5.82 5.69 832.74’ 100-YR 11.24 10.61 834.15’ Table 2: Allowable and Proposed Discharge Rates Stormwater Quality Per the City of Carmel’s Stormwater Technical Standards, two water quality BMPs are required in series to treat the 1” rainfall event. Site runoff from Pod E shall be treated by a hydrodynamic separator prior to entering the proposed dry detention pond. Site runoff from Pod F shall be treated by an isolator row in an underground detention system prior to entering the hydrodynamic separator and proposed dry detention pond. The proposed dry detention pond will be planted with native grasses and shrubs. Refer to Appendix E for Stormwater Quality Design. Conclusions The proposed drainage design for this project has been designed to meet the intent of the City of Carmel Stormwater Technical Standards. No adverse impacts are anticipated to affect any adjacent or downstream properties. Buckingham Gramercy – Areas E & F Page 6 June 23, 2025 5.0 Appendices Buckingham Gramercy – Areas A, B, & C June 23, 2025 Appendix A: Project Site Maps 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 FLOOD HAZARD AREAS Without Base Flood Elevation (BFE) Zone A, V, A99 With BFE or Depth Zone AE, AO, AH, VE, AR Regulatory Floodway 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 Zone X Future Conditions 1% Annual Chance Flood Hazard Zone X Area with Reduced Flood Risk due to Levee. See Notes.Zone X Area with Flood Risk due to Levee Zone D NO SCREEN Area of Minimal Flood Hazard Zone X Area of Undetermined Flood Hazard Zone 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 basemap accuracy standards The flood hazard information is derived directly from the authoritative NFHL web services provided by FEMA. This map was exported on 5/13/2025 at 6:12 PM and does not reflect changes or amendments subsequent to this date and time. The NFHL and effective information may change or become 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 approximate point selected by the user and does not represent an authoritative property location. 1:6,000 86°7'18"W 39°58'8"N 86°6'40"W 39°57'41"N Basemap Imagery Source: USGS National Map 2023 PROJECT AREA Hydrologic Soil Group—Hamilton County, Indiana Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/13/2025 Page 1 of 4 44 2 4 0 8 0 44 2 4 1 4 0 44 2 4 2 0 0 44 2 4 2 6 0 44 2 4 3 2 0 44 2 4 3 8 0 44 2 4 4 4 0 44 2 4 5 0 0 44 2 4 5 6 0 44 2 4 0 8 0 44 2 4 1 4 0 44 2 4 2 0 0 44 2 4 2 6 0 44 2 4 3 2 0 44 2 4 3 8 0 44 2 4 4 4 0 44 2 4 5 0 0 44 2 4 5 6 0 575200 575260 575320 575380 575440 575500 575560 575200 575260 575320 575380 575440 575500 575560 39° 58' 5'' N 86 ° 7 ' 1 1 ' ' W 39° 58' 5'' N 86 ° 6 ' 5 4 ' ' W 39° 57' 47'' N 86 ° 7 ' 1 1 ' ' W 39° 57' 47'' N 86 ° 6 ' 5 4 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 16N WGS84 0 100 200 400 600 Feet 0 35 70 140 210 Meters Map Scale: 1:2,620 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 1:15,800. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Hamilton County, Indiana Survey Area Data: Version 25, Aug 27, 2024 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Mar 1, 2024—Jul 1, 2024 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—Hamilton County, Indiana Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/13/2025 Page 2 of 4 Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI UbaA Urban land-Brookston complex, 0 to 2 percent slopes 0.4 2.6% UkbB2 Urban land-Miami silt loam complex, 2 to 6 percent slopes, eroded 0.1 0.6% YclA Crosby silt loam, fine- loamy subsoil-Urban land complex, 0 to 2 percent slopes C/D 8.1 52.0% YmdC3 Miami clay loam-Urban land complex, 6 to 12 percent slopes, severely eroded C 1.8 11.7% YmsB2 Miami silt loam-Urban land complex, 2 to 6 percent slopes, eroded C 5.2 33.2% Totals for Area of Interest 15.6 100.0% Hydrologic Soil Group—Hamilton County, Indiana Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/13/2025 Page 3 of 4 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. Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Hydrologic Soil Group—Hamilton County, Indiana Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/13/2025 Page 4 of 4 Buckingham Gramercy – Areas A, B, & C June 23, 2025 Appendix B: Existing Conditions GRAMERCY- E & F EXISTING DRAINAGE AREA MAP CARMEL, IN 0'150'75' SCALE: 1" = 150' NORTH PROJECT: BY: DATE: Hydrologic Group % A 0.0% B 0.0% C 100.0% D 0.0% Total 100.0% Soil Group Weighted Runoff Coefficient C Actual Soil Group Next Less Infiltrating Soil Group Undeveloped Wooded Good Cover 0.20 70 77 Fully Developed Open Space Good Condition (>75% Cover)0.30 74 80 Fully Developed Impervious Paved 0.85 98 98 Undeveloped Wooded Thin Stand 0.20 77 83 Fully Developed Impervious Rooftop 0.90 98 98 Water Pond or Lake -1.00 100 100 Weighted CN Weighted CN Wooded - Good Cover Open Space - Good Condition (>75% Cover)Impervious - Paved Wooded - Thin Stand Impervious - Rooftop Water - Pond or Lake Total Actual Soil Group Next Less Infiltrating Soil Group Existing Drainage E &F Basin 0.00 6.68 0.44 0.00 0.10 0.00 7.23 0.34 76 81 Soil Group Weighted CN Basin Area (ac) Weighted C Areas E &F Cover Type Condition Gramercy - Areas E & F CWF 18-Jun-25 Site Soil Project: By: Date: Entity: 2-YR 24-HR RAINFALL DEPTH (in.)=2.64 Length Slope Manning's Tc1 Length Slope Condition Vavg Tc2 Length Manning's Width Side Slope Depth Area Perimeter Radius Slope Vavg Tc3 TcTOTAL * (ft)(ft/ft)"n"(min)(ft)(ft/ft)TR-55 Fig. 3-1 (ft/s)(min)(ft)"n"(ft)(ft/ft)(ft)(ft^2)(ft)(ft)(ft/ft)(ft/s)(min)(min) EXISTING DRAINAGE AREA E & F 100 850.3 847.7 0.0261 Short Grass, Prairie 0.150 9.7 905.3148 847.68 837.17 0.0116 Unpaved 1.74 8.7 V-bottom 689 0.15 25 0.33 4 50 51.248809 0.98 833.0 828.89 0.0059 0.75 15.29 33.7 ADD 152 LF of pipe (assume 2.5 FPS)34.7 Elev1 Channel Type Gramercy - Areas E & F AMS 6/18/2025 City of Carmel DRAINAGE AREA TIME OF CONCENTRATION CALCULATIONS BASIN SHEET FLOW SHALLOW CONCENTRATED FLOW OPEN CHANNEL FLOW TOTAL Elev2 Tc = (0.007(nL)^0.8)/(P2^0.5)(s^0.4)Tc = L / 60*V V = (1.49/n)*R^(2/3)*s^(1/2) Tc = L / 60*V Elev1 Elev2 Land Cover Elev1 Elev2 9S Existing Area E & F 15L Outlet Routing Diagram for Proposed Areas E and F Prepared by Kimley-Horn & Associates, Printed 6/18/2025 HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Subcat Reach Pond Link 170291005- Existing Gramercy E & F Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 2HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Rainfall Events Listing Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC 1 002 Yr-24 Hr Type II 24-hr Default 24.00 1 2.66 2 2 010 Yr-24 Hr Type II 24-hr Default 24.00 1 3.83 2 3 100 Yr-24 Hr Type II 24-hr Default 24.00 1 6.46 2 170291005- Existing Gramercy E & F Type II 24-hr 002 Yr-24 Hr Rainfall=2.66"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 3HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Summary for Link 15L: Outlet Inflow Area =7.230 ac, 0.00% Impervious, Inflow Depth = 1.06" for 002 Yr-24 Hr event Inflow =5.82 cfs @ 12.30 hrs, Volume=0.637 af Primary =5.82 cfs @ 12.30 hrs, Volume=0.637 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs Link 15L: Outlet Inflow Primary Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420 Flow (cfs) 6 5 4 3 2 1 0 Inflow Area=7.230 ac 5.82 cfs5.82 cfs 170291005- Existing Gramercy E & F Type II 24-hr 010 Yr-24 Hr Rainfall=3.83"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 4HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Summary for Link 15L: Outlet Inflow Area =7.230 ac, 0.00% Impervious, Inflow Depth = 1.98" for 010 Yr-24 Hr event Inflow =11.24 cfs @ 12.30 hrs, Volume=1.193 af Primary =11.24 cfs @ 12.30 hrs, Volume=1.193 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs Link 15L: Outlet Inflow Primary Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420 Flow (cfs) 12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=7.230 ac 11.24 cfs11.24 cfs 170291005- Existing Gramercy E & F Type II 24-hr 100 Yr-24 Hr Rainfall=6.46"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 5HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Summary for Link 15L: Outlet Inflow Area =7.230 ac, 0.00% Impervious, Inflow Depth = 4.31" for 100 Yr-24 Hr event Inflow =24.52 cfs @ 12.30 hrs, Volume=2.594 af Primary =24.52 cfs @ 12.30 hrs, Volume=2.594 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs Link 15L: Outlet Inflow Primary Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420 Flow (cfs) 26 24 22 20 18 16 14 12 10 8 6 4 2 0 Inflow Area=7.230 ac 24.52 cfs24.52 cfs Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Wednesday, Jun 18 2025 Existing Downstream Swale Depth User-defined Invert Elev (ft) = 825.44 Slope (%) = 1.00 N-Value = 0.026 Calculations Compute by: Known Q Known Q (cfs) = 43.74 (Sta, El, n)-(Sta, El, n)... ( 23.12, 829.55)-(29.03, 828.91, 0.026)-(40.77, 825.44, 0.026)-(42.83, 825.71, 0.026)-(58.42, 831.32, 0.026) Highlighted Depth (ft) = 1.52 Q (cfs) = 43.74 Area (sqft) = 8.93 Velocity (ft/s) = 4.90 Wetted Perim (ft) = 11.13 Crit Depth, Yc (ft) = 1.49 Top Width (ft) = 10.68 EGL (ft) = 1.89 10 15 20 25 30 35 40 45 50 55 60 65 Elev (ft) Depth (ft)Section 824.00 -1.44 825.00 -0.44 826.00 0.56 827.00 1.56 828.00 2.56 829.00 3.56 830.00 4.56 831.00 5.56 832.00 6.56 Sta (ft) 100-Year Discharge from: Area ABC (detained) - 27 cfs Area E & F (undetained)- 11.24 cfs Existing West Pond - 5.5 cfs Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Wednesday, Jun 18 2025 Downstream Culvert- Existing Conditions Rectangular Bottom Width (ft) = 8.70 Total Depth (ft) = 2.30 Invert Elev (ft) = 827.50 Slope (%) = 0.60 N-Value = 0.013 Calculations Compute by: Known Q Known Q (cfs) = 43.74 Highlighted Depth (ft) = 0.76 Q (cfs) = 43.74 Area (sqft) = 6.61 Velocity (ft/s) = 6.62 Wetted Perim (ft) = 10.22 Crit Depth, Yc (ft) = 0.93 Top Width (ft) = 8.70 EGL (ft) = 1.44 0 1 2 3 4 5 6 7 8 9 10 11 Elev (ft) Depth (ft)Section 827.00 -0.50 827.50 0.00 828.00 0.50 828.50 1.00 829.00 1.50 829.50 2.00 830.00 2.50 Reach (ft) 100-Year Discharge from: Area ABC (detained) - 27 cfs Area E & F (undetained)- 11.24 cfs Existing West Pond - 5.5 cfs Buckingham Gramercy – Areas A, B, & C June 23, 2025 Appendix C: Proposed Conditions GRAMERCY- E & F PROPOSED DRAINAGE AREA MAP CARMEL, IN 0'150'75' SCALE: 1" = 150' NORTH PROJECT: BY: DATE: Hydrologic Group % A 0.0% B 0.0% C 100.0% D 0.0% Total 100.0% Soil Group Weighted Runoff Coefficient C Actual Soil Group Next Less Infiltrating Soil Group Undeveloped Wooded Good Cover 0.20 70 77 Fully Developed Open Space Good Condition (>75% Cover)0.30 74 80 Fully Developed Impervious Paved 0.85 98 98 Undeveloped Wooded Thin Stand 0.20 77 83 Fully Developed Impervious Rooftop 0.90 98 98 Water Pond or Lake -1.00 100 100 Weighted CN Weighted CN Wooded - Good Cover Open Space - Good Condition (>75% Cover)Impervious - Paved Wooded - Thin Stand Impervious - Rooftop Water - Pond or Lake Total Actual Soil Group Next Less Infiltrating Soil Group Existing Drainage E &F Basin 0.00 6.68 0.44 0.00 0.10 0.00 7.23 0.34 76 81 Proposed Drainage F Basin 0.00 1.50 1.66 0.00 1.36 0.00 4.52 0.68 90 92 Proposed Drainage E Basin 0.00 0.62 1.18 0.00 0.91 0.00 2.71 0.74 93 94 Soil Group Weighted CN Basin Area (ac) Weighted C Areas E &F Cover Type Condition Gramercy - Areas E & F CWF 18-Jun-25 Site Soil 3S Proposed Area E 18S Proposed Area F 11P Area F Underground 16P Dry Pond Routing Diagram for Proposed Areas E and F Prepared by Kimley-Horn & Associates, Printed 6/18/2025 HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Subcat Reach Pond Link 170291005- Gramercy E & F Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 2HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Rainfall Events Listing Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC 1 002 Yr-24 Hr Type II 24-hr Default 24.00 1 2.66 2 2 010 Yr-24 Hr Type II 24-hr Default 24.00 1 3.83 2 3 100 Yr-24 Hr Type II 24-hr Default 24.00 1 6.46 2 170291005- Gramercy E & F Type II 24-hr 002 Yr-24 Hr Rainfall=2.66"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 3HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Proposed Area E Runoff =7.70 cfs @ 12.03 hrs, Volume=0.457 af, Depth= 2.02" Routed to Pond 16P : Dry Pond Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs Type II 24-hr 002 Yr-24 Hr Rainfall=2.66" Area (ac) CN Description *2.710 94 Matches value from spreadseet 2.710 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 11.3 Direct Entry, From Storm Calcs Subcatchment 3S: Proposed Area E Runoff Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420 Flow (cfs) 8 7 6 5 4 3 2 1 0 Type II 24-hr 002 Yr-24 Hr Rainfall=2.66" Runoff Area=2.710 ac Runoff Volume=0.457 af Runoff Depth=2.02" Tc=11.3 min CN=94 7.70 cfs 170291005- Gramercy E & F Type II 24-hr 002 Yr-24 Hr Rainfall=2.66"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 4HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment 18S: Proposed Area F Runoff =10.73 cfs @ 12.06 hrs, Volume=0.694 af, Depth= 1.84" Routed to Pond 11P : Area F Underground Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs Type II 24-hr 002 Yr-24 Hr Rainfall=2.66" Area (ac) CN Description *4.520 92 Matches value from spreadsheet 4.520 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 14.6 Direct Entry, From Storm Calcs Subcatchment 18S: Proposed Area F Runoff Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420 Flow (cfs) 12 11 10 9 8 7 6 5 4 3 2 1 0 Type II 24-hr 002 Yr-24 Hr Rainfall=2.66" Runoff Area=4.520 ac Runoff Volume=0.694 af Runoff Depth=1.84" Tc=14.6 min CN=92 10.73 cfs 170291005- Gramercy E & F Type II 24-hr 002 Yr-24 Hr Rainfall=2.66"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 5HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Summary for Pond 11P: Area F Underground Inflow Area =4.520 ac, 0.00% Impervious, Inflow Depth = 1.84" for 002 Yr-24 Hr event Inflow =10.73 cfs @ 12.06 hrs, Volume=0.694 af Outflow =5.67 cfs @ 12.17 hrs, Volume=0.693 af, Atten= 47%, Lag= 6.8 min Primary =5.67 cfs @ 12.17 hrs, Volume=0.693 af Routed to Pond 16P : Dry Pond Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs Peak Elev= 832.52' @ 12.21 hrs Surf.Area= 0.169 ac Storage= 0.169 af Plug-Flow detention time= 41.6 min calculated for 0.693 af (100% of inflow) Center-of-Mass det. time= 40.9 min ( 850.4 - 809.5 ) Volume Invert Avail.Storage Storage Description #1A 830.96'0.272 af 92.08'W x 79.97'L x 6.75'H Field A 1.141 af Overall - 0.462 af Embedded = 0.679 af x 40.0% Voids #2A 831.71'0.462 af ADS_StormTech MC-7200 +Cap x 110 Inside #1 Effective Size= 91.2"W x 60.0"H => 26.68 sf x 6.59'L = 175.9 cf Overall Size= 100.0"W x 60.0"H x 6.95'L with 0.36' Overlap 110 Chambers in 10 Rows Cap Storage= 39.5 cf x 2 x 10 rows = 790.0 cf 0.734 af Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Primary 830.96'24.0" Round Culvert L= 680.0' RCP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 830.96' / 829.60' S= 0.0020 '/' Cc= 0.900 n= 0.013, Flow Area= 3.14 sf Primary OutFlow Max=5.60 cfs @ 12.17 hrs HW=832.51' TW=831.28' (Dynamic Tailwater) 1=Culvert (Outlet Controls 5.60 cfs @ 2.96 fps) 170291005- Gramercy E & F Type II 24-hr 002 Yr-24 Hr Rainfall=2.66"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 6HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Pond 11P: Area F Underground Inflow Primary Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420 Flow (cfs) 12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=4.520 ac Peak Elev=832.52' Storage=0.169 af 24.0" Round Culvert n=0.013 L=680.0' S=0.0020 '/' 10.73 cfs 5.67 cfs 170291005- Gramercy E & F Type II 24-hr 002 Yr-24 Hr Rainfall=2.66"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 7HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Summary for Pond 16P: Dry Pond Inflow Area =7.230 ac, 0.00% Impervious, Inflow Depth = 1.91" for 002 Yr-24 Hr event Inflow =11.91 cfs @ 12.05 hrs, Volume=1.150 af Outflow =4.83 cfs @ 12.43 hrs, Volume=1.150 af, Atten= 59%, Lag= 23.0 min Primary =4.83 cfs @ 12.43 hrs, Volume=1.150 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs Peak Elev= 831.55' @ 12.43 hrs Surf.Area= 6,238 sf Storage= 9,517 cf Plug-Flow detention time= 15.5 min calculated for 1.150 af (100% of inflow) Center-of-Mass det. time= 15.5 min ( 843.9 - 828.4 ) Volume Invert Avail.Storage Storage Description #1 828.33'58,491 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 828.33 0 0 0 830.00 2,896 2,418 2,418 836.00 15,795 56,073 58,491 Device Routing Invert Outlet Devices #1 Primary 828.33'30.0" Round Culvert L= 50.0' RCP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 828.33' / 827.33' S= 0.0200 '/' Cc= 0.900 n= 0.013, Flow Area= 4.91 sf #2 Device 1 828.33'10.5" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 833.65'4.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s) Primary OutFlow Max=4.83 cfs @ 12.43 hrs HW=831.55' (Free Discharge) 1=Culvert (Passes 4.83 cfs of 33.21 cfs potential flow) 2=Orifice/Grate (Orifice Controls 4.83 cfs @ 8.04 fps) 3=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs) 170291005- Gramercy E & F Type II 24-hr 002 Yr-24 Hr Rainfall=2.66"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 8HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Pond 16P: Dry Pond Inflow Primary Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420 Flow (cfs) 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=7.230 ac Peak Elev=831.55' Storage=9,517 cf 11.91 cfs 4.83 cfs 170291005- Gramercy E & F Type II 24-hr 010 Yr-24 Hr Rainfall=3.83"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 9HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Proposed Area E Runoff =11.71 cfs @ 12.02 hrs, Volume=0.713 af, Depth= 3.16" Routed to Pond 16P : Dry Pond Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs Type II 24-hr 010 Yr-24 Hr Rainfall=3.83" Area (ac) CN Description *2.710 94 Matches value from spreadseet 2.710 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 11.3 Direct Entry, From Storm Calcs Subcatchment 3S: Proposed Area E Runoff Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420 Flow (cfs) 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Type II 24-hr 010 Yr-24 Hr Rainfall=3.83" Runoff Area=2.710 ac Runoff Volume=0.713 af Runoff Depth=3.16" Tc=11.3 min CN=94 11.71 cfs 170291005- Gramercy E & F Type II 24-hr 010 Yr-24 Hr Rainfall=3.83"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 10HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment 18S: Proposed Area F Runoff =16.83 cfs @ 12.06 hrs, Volume=1.113 af, Depth= 2.95" Routed to Pond 11P : Area F Underground Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs Type II 24-hr 010 Yr-24 Hr Rainfall=3.83" Area (ac) CN Description *4.520 92 Matches value from spreadsheet 4.520 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 14.6 Direct Entry, From Storm Calcs Subcatchment 18S: Proposed Area F Runoff Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420 Flow (cfs) 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Type II 24-hr 010 Yr-24 Hr Rainfall=3.83" Runoff Area=4.520 ac Runoff Volume=1.113 af Runoff Depth=2.95" Tc=14.6 min CN=92 16.83 cfs 170291005- Gramercy E & F Type II 24-hr 010 Yr-24 Hr Rainfall=3.83"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 11HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Summary for Pond 11P: Area F Underground Inflow Area =4.520 ac, 0.00% Impervious, Inflow Depth = 2.95" for 010 Yr-24 Hr event Inflow =16.83 cfs @ 12.06 hrs, Volume=1.113 af Outflow =8.20 cfs @ 12.16 hrs, Volume=1.112 af, Atten= 51%, Lag= 6.0 min Primary =8.20 cfs @ 12.16 hrs, Volume=1.112 af Routed to Pond 16P : Dry Pond Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs Peak Elev= 833.25' @ 12.23 hrs Surf.Area= 0.169 ac Storage= 0.272 af Plug-Flow detention time= 40.5 min calculated for 1.112 af (100% of inflow) Center-of-Mass det. time= 40.4 min ( 836.6 - 796.2 ) Volume Invert Avail.Storage Storage Description #1A 830.96'0.272 af 92.08'W x 79.97'L x 6.75'H Field A 1.141 af Overall - 0.462 af Embedded = 0.679 af x 40.0% Voids #2A 831.71'0.462 af ADS_StormTech MC-7200 +Cap x 110 Inside #1 Effective Size= 91.2"W x 60.0"H => 26.68 sf x 6.59'L = 175.9 cf Overall Size= 100.0"W x 60.0"H x 6.95'L with 0.36' Overlap 110 Chambers in 10 Rows Cap Storage= 39.5 cf x 2 x 10 rows = 790.0 cf 0.734 af Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Primary 830.96'24.0" Round Culvert L= 680.0' RCP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 830.96' / 829.60' S= 0.0020 '/' Cc= 0.900 n= 0.013, Flow Area= 3.14 sf Primary OutFlow Max=8.04 cfs @ 12.16 hrs HW=833.17' TW=832.14' (Dynamic Tailwater) 1=Culvert (Outlet Controls 8.04 cfs @ 2.88 fps) 170291005- Gramercy E & F Type II 24-hr 010 Yr-24 Hr Rainfall=3.83"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 12HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Pond 11P: Area F Underground Inflow Primary Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420 Flow (cfs) 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=4.520 ac Peak Elev=833.25' Storage=0.272 af 24.0" Round Culvert n=0.013 L=680.0' S=0.0020 '/' 16.83 cfs 8.20 cfs 170291005- Gramercy E & F Type II 24-hr 010 Yr-24 Hr Rainfall=3.83"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 13HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Summary for Pond 16P: Dry Pond Inflow Area =7.230 ac, 0.00% Impervious, Inflow Depth = 3.03" for 010 Yr-24 Hr event Inflow =18.05 cfs @ 12.05 hrs, Volume=1.825 af Outflow =5.69 cfs @ 12.50 hrs, Volume=1.825 af, Atten= 68%, Lag= 27.0 min Primary =5.69 cfs @ 12.50 hrs, Volume=1.825 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs Peak Elev= 832.63' @ 12.50 hrs Surf.Area= 8,552 sf Storage= 17,479 cf Plug-Flow detention time= 23.9 min calculated for 1.825 af (100% of inflow) Center-of-Mass det. time= 23.9 min ( 839.5 - 815.6 ) Volume Invert Avail.Storage Storage Description #1 828.33'58,491 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 828.33 0 0 0 830.00 2,896 2,418 2,418 836.00 15,795 56,073 58,491 Device Routing Invert Outlet Devices #1 Primary 828.33'30.0" Round Culvert L= 50.0' RCP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 828.33' / 827.33' S= 0.0200 '/' Cc= 0.900 n= 0.013, Flow Area= 4.91 sf #2 Device 1 828.33'10.5" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 833.65'4.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s) Primary OutFlow Max=5.69 cfs @ 12.50 hrs HW=832.63' (Free Discharge) 1=Culvert (Passes 5.69 cfs of 41.28 cfs potential flow) 2=Orifice/Grate (Orifice Controls 5.69 cfs @ 9.46 fps) 3=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs) 170291005- Gramercy E & F Type II 24-hr 010 Yr-24 Hr Rainfall=3.83"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 14HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Pond 16P: Dry Pond Inflow Primary Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420 Flow (cfs) 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=7.230 ac Peak Elev=832.63' Storage=17,479 cf 18.05 cfs 5.69 cfs 170291005- Gramercy E & F Type II 24-hr 100 Yr-24 Hr Rainfall=6.46"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 15HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Proposed Area E Runoff =20.59 cfs @ 12.02 hrs, Volume=1.299 af, Depth= 5.75" Routed to Pond 16P : Dry Pond Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs Type II 24-hr 100 Yr-24 Hr Rainfall=6.46" Area (ac) CN Description *2.710 94 Matches value from spreadseet 2.710 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 11.3 Direct Entry, From Storm Calcs Subcatchment 3S: Proposed Area E Runoff Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420 Flow (cfs) 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Type II 24-hr 100 Yr-24 Hr Rainfall=6.46" Runoff Area=2.710 ac Runoff Volume=1.299 af Runoff Depth=5.75" Tc=11.3 min CN=94 20.59 cfs 170291005- Gramercy E & F Type II 24-hr 100 Yr-24 Hr Rainfall=6.46"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 16HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment 18S: Proposed Area F Runoff =30.38 cfs @ 12.06 hrs, Volume=2.080 af, Depth= 5.52" Routed to Pond 11P : Area F Underground Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs Type II 24-hr 100 Yr-24 Hr Rainfall=6.46" Area (ac) CN Description *4.520 92 Matches value from spreadsheet 4.520 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 14.6 Direct Entry, From Storm Calcs Subcatchment 18S: Proposed Area F Runoff Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420 Flow (cfs) 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 Type II 24-hr 100 Yr-24 Hr Rainfall=6.46" Runoff Area=4.520 ac Runoff Volume=2.080 af Runoff Depth=5.52" Tc=14.6 min CN=92 30.38 cfs 170291005- Gramercy E & F Type II 24-hr 100 Yr-24 Hr Rainfall=6.46"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 17HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Summary for Pond 11P: Area F Underground Inflow Area =4.520 ac, 0.00% Impervious, Inflow Depth = 5.52" for 100 Yr-24 Hr event Inflow =30.38 cfs @ 12.06 hrs, Volume=2.080 af Outflow =10.68 cfs @ 12.21 hrs, Volume=2.079 af, Atten= 65%, Lag= 9.4 min Primary =10.68 cfs @ 12.21 hrs, Volume=2.079 af Routed to Pond 16P : Dry Pond Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs Peak Elev= 835.62' @ 12.28 hrs Surf.Area= 0.169 ac Storage= 0.571 af Plug-Flow detention time= 46.1 min calculated for 2.079 af (100% of inflow) Center-of-Mass det. time= 45.8 min ( 825.3 - 779.5 ) Volume Invert Avail.Storage Storage Description #1A 830.96'0.272 af 92.08'W x 79.97'L x 6.75'H Field A 1.141 af Overall - 0.462 af Embedded = 0.679 af x 40.0% Voids #2A 831.71'0.462 af ADS_StormTech MC-7200 +Cap x 110 Inside #1 Effective Size= 91.2"W x 60.0"H => 26.68 sf x 6.59'L = 175.9 cf Overall Size= 100.0"W x 60.0"H x 6.95'L with 0.36' Overlap 110 Chambers in 10 Rows Cap Storage= 39.5 cf x 2 x 10 rows = 790.0 cf 0.734 af Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Primary 830.96'24.0" Round Culvert L= 680.0' RCP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 830.96' / 829.60' S= 0.0020 '/' Cc= 0.900 n= 0.013, Flow Area= 3.14 sf Primary OutFlow Max=10.58 cfs @ 12.21 hrs HW=835.52' TW=833.77' (Dynamic Tailwater) 1=Culvert (Outlet Controls 10.58 cfs @ 3.37 fps) 170291005- Gramercy E & F Type II 24-hr 100 Yr-24 Hr Rainfall=6.46"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 18HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Pond 11P: Area F Underground Inflow Primary Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420 Flow (cfs) 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 Inflow Area=4.520 ac Peak Elev=835.62' Storage=0.571 af 24.0" Round Culvert n=0.013 L=680.0' S=0.0020 '/' 30.38 cfs 10.68 cfs 170291005- Gramercy E & F Type II 24-hr 100 Yr-24 Hr Rainfall=6.46"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 19HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Summary for Pond 16P: Dry Pond Inflow Area =7.230 ac, 0.00% Impervious, Inflow Depth = 5.61" for 100 Yr-24 Hr event Inflow =29.62 cfs @ 12.02 hrs, Volume=3.378 af Outflow =10.61 cfs @ 12.49 hrs, Volume=3.378 af, Atten= 64%, Lag= 28.6 min Primary =10.61 cfs @ 12.49 hrs, Volume=3.378 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs Peak Elev= 834.11' @ 12.49 hrs Surf.Area= 11,721 sf Storage= 32,421 cf Plug-Flow detention time= 35.3 min calculated for 3.378 af (100% of inflow) Center-of-Mass det. time= 35.3 min ( 838.5 - 803.2 ) Volume Invert Avail.Storage Storage Description #1 828.33'58,491 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 828.33 0 0 0 830.00 2,896 2,418 2,418 836.00 15,795 56,073 58,491 Device Routing Invert Outlet Devices #1 Primary 828.33'30.0" Round Culvert L= 50.0' RCP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 828.33' / 827.33' S= 0.0200 '/' Cc= 0.900 n= 0.013, Flow Area= 4.91 sf #2 Device 1 828.33'10.5" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 833.65'4.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s) Primary OutFlow Max=10.61 cfs @ 12.49 hrs HW=834.11' (Free Discharge) 1=Culvert (Passes 10.61 cfs of 50.28 cfs potential flow) 2=Orifice/Grate (Orifice Controls 6.69 cfs @ 11.12 fps) 3=Sharp-Crested Rectangular Weir (Weir Controls 3.92 cfs @ 2.21 fps) 170291005- Gramercy E & F Type II 24-hr 100 Yr-24 Hr Rainfall=6.46"Proposed Areas E and F Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 20HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Pond 16P: Dry Pond Inflow Primary Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420 Flow (cfs) 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 Inflow Area=7.230 ac Peak Elev=834.11' Storage=32,421 cf 29.62 cfs 10.61 cfs Weir Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Wednesday, Jun 18 2025 Spillway Calculation Trapezoidal Weir Crest = Sharp Bottom Length (ft) = 30.00 Total Depth (ft) = 1.00 Side Slope (z:1) = 3.00 Calculations Weir Coeff. Cw = 3.10 Compute by: Known Q Known Q (cfs) = 44.29 Highlighted Depth (ft) = 0.60 Q (cfs) = 44.29 Area (sqft) = 19.08 Velocity (ft/s) = 2.32 Top Width (ft) = 33.60 0 5 10 15 20 25 30 35 40 45 50 Depth (ft) Depth (ft)Spillway Calculation -0.50 -0.50 0.00 0.00 0.50 0.50 1.00 1.00 1.50 1.50 2.00 2.00 Length (ft)Weir W.S. TOTAL INFLOW WITH OFFSITE RUNOFF= 29.93 CFS OVERALL RELEASE RATE FROM EXISTING WET POND BYPASS = 5.5 CFS TOTAL PEAK INFLOW DISCHARGE= 29.93 + 5.5= 35.43 CFS EMERGENCY OVERFLOW= PEAK FLOW X 1.25 EMERGENCY OVERFLOW = 36.24 x 1.25= 44.29 CFS Buckingham Gramercy – Areas A, B, & C June 23, 2025 Appendix D: Proposed Storm Sewer Design GRAMERCY- E & F STORM BASINS MAP CARMEL, IN 0'200'100' SCALE: 1" = 200' NORTH 200-6 TABLE 201-2: Rainfall Intensities for Various Return Periods and Storm Durations Rainfall Intensity (Inches/Hour) Return Period (Years) Duration 2 5 10 25 50 100 5 Min. 4.63 5.43 6.12 7.17 8.09 9.12 10 Min. 3.95 4.63 5.22 6.12 6.90 7.78 15 Min. 3.44 4.03 4.55 5.33 6.01 6.77 20 Min. 3.04 3.56 4.02 4.71 5.31 5.99 30 Min. 2.46 2.88 3.25 3.81 4.29 4.84 40 Min. 2.05 2.41 2.71 3.18 3.59 4.05 50 Min. 1.76 2.06 2.33 2.73 3.07 3.47 1 Hr. 1.54 1.80 2.03 2.38 2.68 3.03 1.5 Hrs. 1.07 1.23 1.42 1.63 1.91 2.24 2 Hrs. 0.83 0.95 1.11 1.37 1.60 1.87 3 Hrs. 0.59 0.72 0.84 1.04 1.22 1.42 4 Hrs. 0.47 0.58 0.68 0.84 0.99 1.15 5 Hrs. 0.40 0.49 0.58 0.71 0.83 0.97 6 Hrs. 0.35 0.43 0.50 0.62 0.72 0.85 7 Hrs. 0.31 0.38 0.44 0.55 0.64 0.75 8 Hrs. 0.28 0.34 0.40 0.49 0.57 0.67 9 Hrs. 0.25 0.31 0.36 0.45 0.52 0.61 10 Hrs. 0.23 0.28 0.33 0.41 0.48 0.56 12 Hrs. 0.20 0.24 0.29 0.35 0.41 0.48 14 Hrs. 0.17 0.22 0.25 0.31 0.36 0.42 16 Hrs. 0.16 0.19 0.23 0.28 0.32 0.38 18 Hrs. 0.14 0.17 0.20 0.25 0.29 0.34 20 Hrs. 0.13 0.16 0.19 0.23 0.27 0.31 24 Hrs. 0.11 0.14 0.16 0.20 0.23 0.27 Source: Purdue,A.M., et. al., "Statistical Characteristics of Short Time Incremental Rainfall", Aug., 1992. (Values in this table are based on IDF equation and coefficients provided for Indianapolis, IN.) TABLE 201-3: Rainfall Depths for Various Return Periods 170291005 Buckingham Gramercy DATE:6/17/2025 10 Structure ID Inlet Area C 10-YR Peak Discharge (cfs) Grate Max Ponding Depth H (ft) Max Allowable Ponding Depth H (ft) Entrance Grate Area A (sf) Entrance Perimeter P (ft) Entrance Loss Coefficient C 50% Grate Capacity (cfs) D107 0.41 0.52 1.31 R-3287-SB10 0.29 0.50 0.75 2.75 0.61 2.55 D106 0.41 0.53 1.33 R-3501-TR 0.33 0.50 0.70 2.30 0.61 2.38 D105 0.39 0.52 1.25 R-3501-TR 0.32 0.50 0.70 2.30 0.61 2.38 D104 0.42 0.65 1.68 R-3501-TR 0.39 0.50 0.70 2.30 0.61 2.38 D103 0.27 0.57 0.94 R-3501-TR 0.26 0.50 0.70 2.30 0.61 2.38 D140 0.32 0.67 1.31 R-3501-TR 0.33 0.50 0.70 2.30 0.61 2.38 D211 0.33 0.56 1.12 R-3287-SB10 0.26 0.50 0.75 2.75 0.61 2.55 D115 0.10 0.58 0.36 R-3287-15 0.10 0.50 1.80 3.75 0.61 4.38 D114 0.27 0.77 1.26 R-3287-15 0.23 0.50 1.80 3.75 0.61 4.38 D113 0.26 0.76 1.23 R-3287-15 0.23 0.50 1.80 3.75 0.61 4.38 D112 0.33 0.70 1.41 R-3287-SB10 0.31 0.50 0.75 2.75 0.61 2.55 D120 0.32 0.68 1.33 R-3472 0.24 0.50 0.65 3.65 0.61 2.21 D121 0.11 0.67 0.46 R-3287-SB10 0.15 0.50 0.75 2.75 0.61 2.55 D123 0.14 0.79 0.67 R-3472 0.15 0.50 0.65 3.65 0.61 2.21 D132 0.26 0.44 0.70 R-4342 0.18 0.50 1.00 3.00 0.61 3.40 D131 0.36 0.39 0.86 R-4342 0.21 0.50 1.00 3.00 0.61 3.40 D210 0.21 0.58 0.73 R-3287-SB10 0.20 0.50 0.75 2.75 0.61 2.55 D208 0.14 0.81 0.69 R-3287-SB10 0.19 0.50 0.75 2.75 0.61 2.55 D207 0.25 0.69 1.06 R-3287-SB10 0.25 0.50 0.75 2.75 0.61 2.55 D206 0.19 0.78 0.93 R-3287-SB10 0.23 0.50 0.75 2.75 0.61 2.55 D205 0.23 0.73 1.02 R-3287-SB10 0.25 0.50 0.75 2.75 0.61 2.55 D204 0.19 0.72 0.83 R-3287-SB10 0.22 0.50 0.75 2.75 0.61 2.55 D214 0.13 0.71 0.55 R-3287-SB10 0.17 0.50 0.75 2.75 0.61 2.55 D215 0.27 0.69 1.15 R-3287-SB10 0.27 0.50 0.75 2.75 0.61 2.55 D216 0.20 0.73 0.89 R-3287-SB10 0.23 0.50 0.75 2.75 0.61 2.55 D217 0.31 0.70 1.32 R-3287-SB10 0.29 0.50 0.75 2.75 0.61 2.55 D218 0.26 0.54 0.85 R-3287-SB10 0.22 0.50 0.75 2.75 0.61 2.55 Notes 260 ex2 328 329 1)Runoff = CIA 2)10-YR Design Storm =6.12 in/hr 3)Grate Capacity Lesser of Q=3.3*P*H3/2 & Q=0.6*A*(2*32.2*H)1/2 4)Inlet Capacity Open Area* (sf) Entrance Perimeter* (ft) 50% Open Area (sf) 50% Entrance Perimeter* (ft) Neenah R-4215-C 3.30 11.30 1.65 5.65 Neenah R-4342 2.00 6.00 1.00 3.00 Neenah R-3455-C 2.60 10.00 1.30 5.00 Neenah R-3287-15 3.60 7.50 1.80 3.75 Neenah R-3501-N 1.60 4.30 0.80 2.15 Neenah R-3501-TR 1.40 4.60 0.70 2.30 Neenah R-3010 1.00 4.60 0.50 2.30 Neenah R-3287-10V 2.10 5.50 1.05 2.75 Neenah R-3287-SB10 1.50 5.50 0.75 2.75 Roll Curb Casting Neenah R-3501-TR 1.40 4.60 0.70 2.30 Roll Curb Casting Neenah R-3516 4.00 6.20 2.00 3.10 Roll Curb Casting Neenah R-3516-1 2.00 4.30 1.00 2.15 Neenah R-3472 1.30 7.30 0.65 3.65 ADS 12" Standard 0.42 3.65 0.21 1.83 *Open Area & Entrance Perimeter values obtained from manufacturer ADS Nyoplast Rectangular Castings Curb Inlet ONSITE INLET CAPACITY CALCULATIONS Beehive Casting Curb Inlet Curb Inlet Curb Inlet Curb Inlet Curb Inlet Curb Inlet Beehive Casting Buckingham Gramercy – Areas A, B, & C June 23, 2025 Appendix E: Stormwater Quality Design GRAMERCY- E & F PROPOSED DRAINAGE AREA MAP CARMEL, IN 0'150'75' SCALE: 1" = 150' NORTH Description:Gramercy - Areas E & F BMP Location:Area E BMP Reviewing Entity: Job #: Date:06/16/25 CNwq= PARAMETERS P =1 (in.) Pervious Area 0.62 Impervious Area 2.09 Area 2.71 I =77%(%) Rv =0.74409594 Qa=0.74 (in.) CALCULATED CNwq Area E CNwq =97 1000 [10+5P+10Qa-10(Qa2+1.25Qa(P))1/2] PROPOSED STORMWATER SYSTEM WATER QUALITY CURVE NUMBER Job Information Carmel 170291005 14S WQV- AREA E Routing Diagram for 170291005_Area E Water Quality Prepared by Kimley-Horn & Associates, Printed 6/18/2025 HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Subcat Reach Pond Link 170291005- Gramercy E & F 170291005_Area E Water Quality Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 2HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Rainfall Events Listing Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC 1 WQV Type II 24-hr Default 24.00 1 1.00 2 170291005- Gramercy E & F Type II 24-hr WQV Rainfall=1.00"170291005_Area E Water Quality Printed 6/18/2025Prepared by Kimley-Horn & Associates Page 3HydroCAD® 10.20-5c s/n 02344 © 2023 HydroCAD Software Solutions LLC Summary for Subcatchment 14S: WQV- AREA E Runoff =2.70 cfs @ 12.03 hrs, Volume=0.160 af, Depth= 0.71" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-60.00 hrs, dt= 0.05 hrs Type II 24-hr WQV Rainfall=1.00" Area (ac) CN Description *2.190 98 Matches Excel Spreadsheet *0.523 94 Kinzer Avenue- Matches Excel Spreadsheet 2.713 97 Weighted Average 0.523 19.28% Pervious Area 2.190 80.72% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 11.3 Direct Entry, Matches value from storm calcs Subcatchment 14S: WQV- AREA E Runoff Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420 Flow (cfs) 3 2 1 0 Type II 24-hr WQV Rainfall=1.00" Runoff Area=2.713 ac Runoff Volume=0.160 af Runoff Depth=0.71" Tc=11.3 min CN=97 2.70 cfs City of Indianapolis Stormwater Quality Unit (SQU) Selection Guide Pg. 2 02/11/2020 Version 17.0 Manufactured SQU SQU System Model Max Treatment Flow (cfs) Max 10-yr On-Line Flow Rate (cfs) Cleanout Depth (Inches) 4-ft 1.12 2.95 9 6-ft 2.52 6.63 12 8-ft 4.49 11.81 15 10-ft 7.00 18.40 18 Hydro International Downstream Defender1 12 ft 10.08 26.51 21 3-ft 0.85 1.84 9 4-ft 1.5 3.24 9 5-ft 2.35 5.08 9 6-ft 3.38 7.30 9 7-ft 4.60 9.94 9 Hydro International First Defense High Capacity1 8-ft 6.00 12.96 9 HS-3 0.50 1.00 6 HS-4 0.88 1.76 6 HS-5 1.37 2.74 6 HS-6 1.98 3.96 6 HS-7 2.69 5.38 6 HS-8 3.52 7.04 6 HS-9 4.45 8.9 6 HS-10 5.49 10.98 6 HS-11 6.65 13.3 6 HydroStorm by Hydroworks, LLC1 HS-12 7.91 15.82 6 XC-2 0.57 1.16 6 XC-3 1.13 2.30 6 XC-4 1.86 3.79 6 XC-5 2.78 5.66 6 XC-6 3.88 7.90 6 XC-7 5.17 10.52 6 XC-8 6.64 13.51 6 XC-9 8.29 16.87 6 XC-10 10.13 20.62 6 XC-11 12.15 24.73 6 XC-12 14.35 29.20 6 AquaShield Aqua-Swirl Xcelerator1 XC-13 15.53 31.60 6 CS-4 1.80 4.03 9 CS-5 2.81 6.29 9 CS-6 4.05 9.07 9 CS-8 7.20 16.1 9 CS-10 11.3 25.3 9 Contech Cascade Separator CS-12 16.2 36.3 9 Pod E BMP Qwq = 3.30 cfs Plan View SCALE 1:40 Elevation View SCALE 1:40 Projected View SCALE 1:70 2733 Kanasita Drive, Suite 111, Chattanooga, TN 37343 Phone (888) 344-9044 Fax (423) 826-2112 www.aquashieldinc.com Structure #: Drawn By: Scale: Date: OFlores Rvwed Rvw. Date U.S. Patent No. 6524473 and other Patent Pending Aqua-SwirlŠ XCelerator Standard Detail As Shown 2/25/2021 el. Varies Inlet/Outlet Invert el. Varies el. Varies Grade (Rim) el. Varies XC-5 CCW XC-5 STD Aqua-SwirlŠ Polymer Coated Steel (PCS) Stormwater Treatment System 12 in [305 mm] Manhole Frame & Cover Detail For Non-Traffic Areas Only NTS 48 in [1219 mm] Min. Gravel Backfill Concrete Wrap Compressible Expansion Joint Material to a minimum 1/2-inch [13 mm] thickness around top of riser to allow transfer of inadvertent loading from manhole cover to concrete slab. Riser Soil Cover Frame 1/2 in [13 mm] 1/2 in [13 mm] Place small amount of concrete [3,000 psi [20 MPa] (min)] to support and level manhole frame. DO NOT allow manhole frame to rest upon riser. Backfill (90% Proctor Density) 8 in [203 mm] 4 1/2 in [114 mm] Unless other traffic barriers are present, bollards shall be placed around access riser(s) in non-traffic areas to prevent inadvertent loading by maintenance vehicles. Manhole Frame & Cover Detail For Traffic Loading Areas NTS Cover Frame 48 in [1219 mm] Min. Backfill (90% Proctor Density) 3,000 psi [20 MPa] (min) Concrete #4 [13 mm] Rebar @ 6 in [152 mm] Each Way 30 in [762 mm] Riser 1/2 in [13 mm] 4 1/2 in [114 mm] 14 in [356 mm] 1/2 in [13 mm] Thick Expansion Joint Material If traffic loading (HS-25) is required or anticipated, a 4-foot [1.22 m] diameter, 14-inch [356 mm] thick reinforced concrete pad must be placed over the Stormwater Treatment System Riser to support and level the manhole frame, as shown. The top of riser pipe must be wrapped with compressible expansion joint material to a minimum 1/2-inch [13 mm] thickness to allow transfer of wheel loads from manhole cover to concrete slab. Manhole cover shall bear on concrete slab and not on riser pipe. The concrete slab shall have a minimum strength of 3,000 psi [20 MPa] and be reinforced with #4 [13 mm] reinforcing steel as shown. Minimum cover over reinforcing steel shall be 1-inch [25 mm]. Top of manhole cover and concrete slab shall be level with finish grade. Please see accompanied Aqua-SwirlŠ specification notes. See Site Plan for actual System orientation. Approximate dry (pick) weight: 2200 lbs [1000 kg]. Backfill shall extend at least 18 inches [457 mm] outward from Swirl Concentrator and for the full height of the Swirl Concentrator (including riser) extending laterally to undisturbed soils. (See MH Detail Below) 1 1 As an alternative, 42 in [1067 mm] diameter, HS-20/25 rated precast concrete rings may be substituted. 14 in [356 mm] thickness must be maintained. XC-5 inlet/outlet pipe size ranges up to 30 in [762 mm]. XC-5 chamber height may vary up to 116 in [2946 mm], depending on inlet/outlet pipe size. Orientation may vary from a minimum of 90ƒ to a maximum of 180ƒ. Clockwise or counterclockwise orientation as needed. 2 3 3 2 78 in [1981 mm] 78 in [1981 mm] P30 in [P762 mm] 2 Octagonal Base Plate P66 in [P1680 mm] 116 in [2946 mm] Varies Varies 5 [127 mm] MH Frame P30 in [P762 mm] Band Coupler by Manufacturer. (as needed)Riser Manhole Frame and Cover by Manufacturer. (See Details) Rim elevations to match finish grade. 68 in [1727 mm] Pipe coupling by Contractor. 12 in [305 mm] long Stub-out by Manufacturer. Pipe coupling by Contractor. 12 in [305 mm] long Stub-out by Manufacturer. 4 4 P66 in [P1676 mm] Optional inlet orientations available (See note 4) P30 in [P762 mm] 180ƒ Lifting Lugs Lifting Lugs Backfill Bedding Undisturbed soil 18 in [457 mm] 6 in [152 mm] Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Wednesday, Jun 18 2025 East Diversion Structure Circular Diameter (ft) = 1.50 Invert Elev (ft) = 829.07 Slope (%) = 0.17 N-Value = 0.013 Calculations Compute by: Known Q Known Q (cfs) = 2.70 Highlighted Depth (ft) = 0.86 Q (cfs) = 2.700 Area (sqft) = 1.05 Velocity (ft/s) = 2.57 Wetted Perim (ft) = 2.58 Crit Depth, Yc (ft) = 0.63 Top Width (ft) = 1.48 EGL (ft) = 0.96 0 1 2 3 Elev (ft)Section 828.50 829.00 829.50 830.00 830.50 831.00 Reach (ft) Treatment Flow for East BMP Weir Height BU C K I N G H A M A T GR A M E R C Y AR E A S E & F E 1 2 6 T H S T & K E Y S T O N E PK W Y © NO T A P P R O V E D F O R CO N S T R U C T I O N BU C K I N G H A M A T GR A M E R C Y AR E A S E & F E 1 2 6 T H S T & K E Y S T O N E PK W Y © NO T A P P R O V E D F O R CO N S T R U C T I O N C7.2 CO N S T R U C T I O N DE T A I L S Buckingham Gramercy – Areas A, B, & C June 23, 2025 Appendix F: Previous Report Excerpts GRAMERCY SECTION 2, 3 & 4 DRAINAGE REPORT PREPARED FOR: MOHAWK WB, LLC Contact Person: Ed Flemming 9757 Westpoint Drive Suite 600 Indianapolis, Indiana 46256 Contact Phone Number: (317) 564-7301 PREPARED BY: Stoeppelwerth & Associates, Inc. Contact Person: Christian C. Esposito 7965 East 106th Street Fishers, Indiana 46038 Contact Phone Number: (317) 570-4713 Contact Email Address: cesposito@stoeppelwerth.com DATE PREPARED March 19, 2019 DATE REVISED May 10, 2019 ENGINEERING CERTIFICATION GRAMERCY, SECTION 2/3/4 DRAINAGE REPORT AND ANALYSIS David J. Stoeppelwerth, P. E. Indiana Registration No. 19358 I, David J. Stoeppelwerth, certify that this drainage report and supporting calculations are in compliance with the requirements set forth by the Hamilton County Drainage Board and/or Hamilton County Surveyor in the Hamilton County, Indiana Stormwater Management Ordinance. 5/10/2019 3 of 79 DRAINAGE REPORT GRAMERCY, SECTION 2/3/4 JOB # 65840BKM TABLE OF CONTENTS DRAINAGE NARRATIVE APPENDIX A - PRE-DEVELOPED CALCULATIONS APPENDIX B - PROPOSED SITE CONDITONS CALCULATIONS APPENDIX C - STORM SEWER DESIGN CALCULATIONS APPENDIX D - INLET CAPACITY & GUTTER SPREAD CALCULATIONS APPENDIX E - WATER QUALITY CALCULATIONS APPENDIX F - EMERGENCY SPILLWAY CALCULATIONS APPENDIX G - BASIN MAPS 5/10/2019 4 of 79 DRAINAGE NARRATIVE GRAMERCY, SECTION 2/3/4 MOHAWK WB, LLC. CREATED BY: CHRISTIAN C. ESPOSITO INTRODUCTION MoHawk WB, LLC is proposing the development of a residential subdivision in Hamilton County to be known as Gramercy. The site is located on the south side of 126th Street and east of East Auman Drive. The site is more specifically located in a part of the North Half of Section 31, Township 18 North, Range 4 East Clay Township, Hamilton County. PROPOSED SITE CONDITIONS In order to determine the pre-developed allowable release rates, the entire site has been delineated into their respective sub-basins. After speaking with the reviewer and at the direction of the City of Carmel we will be utilizing only the watershed basin that drains to what will be our post- developed outlet location. Also, at the direction of the City of Carmel, we will be responsible for detaining all of the offsite that enters our pond. This is due to the fact that in its pre-developed state the offsite drains to our site and is detained in the existing onsite ponds. In this line of thinking, this firm will include the offsite acreage to the onsite basin to get the total area and, using the unit allowable, come up with the post-developed allowable release rates. This acreage was then applied to the 0.1 cfs per acre and the 0.3 cfs per acre unit allowable. Pre-developed modeling for the outlet has also been completed to show the conditions of the outlet in the pre-developed site. Below is a list of the release rates produced by the onsite as well as the offsite basins. Table 1: Pre-Developed Site Conditions Model – Release rates to Pre-Developed outlet. 2-Year 10-Year 100-Year 2.709 cfs 8.483 cfs 29.951 cfs Table 2: Proposed Site Conditions – Onsite Release Rates (Unit Allowable) Storm Event 10-Year 100-Year Unit Allowable Release Rate 0.1 cfs/acre 0.3 cfs/acre Existing Onsite Acreage 20.32 = acres 20.32 = acres Calculation 0.1 cfs/acre x acres 0.3 cfs/acre x acres Onsite Allowable Release Rates 2.032 cfs 6.096 cfs Proposed Onsite Release Rates 2.032 cfs 6.096 cfs There will be one pond that will handle all of the runoff for the entire sire. This pond will be installed on the south side of the site and completely constructed with Section 1. This pond and the addition of in-line water quality units will handle all of the water quality for the site before the runoff enters the creek. 5/10/2019 5 of 79 Table 3: Proposed Site Conditions – Overall Release Rates with offsite being detained in the stormwater pond. Storm Event 2-Year 10-Year 100-Year Proposed Overall Release Rates 1.316 cfs 1.737 cfs 5.455 cfs The proposed peak discharges are based on TR-55 methodology. A detention analysis was performed using the 2, 10 and 100-year storm events and their corresponding 24-hour rainfall depths. The NRCS Type II rainfall distribution was used to generate the hydrographs. STORM SEWER DESIGN The use of Manning’s equation was used for determination of storm drain pipe sizes for non- submerged conditions. The storm drain system is capable of passing the 10-year storm event with free water surface elevations below the crown of pipe. To be conservative we have used a general front and rear yard c-factors for the entire site; 0.58 for the front yard and 0.46 for the rear yard. Also, we have used a general time of concentration of 5 minutes for each onsite basin. In doing this we have added a safety feature to each basin to ensure that each pipe would have added capacity in the 10-year event. The offsite basin time of concentrations were calculated using the Rational method. There is one small area off offsite hat has been added to the modeling from the existing golf club to the east of the site and a portion of the apartments to the west. These areas have been taken into account as additional area in the StormCAD modeling, as well as being detained in the storm water pond.. Minimum storm drain flowing velocity for full pipe flow shall be 2.5 fps and maximum storm drain flowing velocity for full pipe flow is 10 fps. The inlet grate castings are designed such that the 10-year storm event shall be sufficiently conveyed into the storm sewer system at 50% efficiency. The inlets are spaced to allow one lane of traffic to remain open during the 10-year storm event. WATER QUALITY Water quality for the site will be handled via in-line water quality units and a wet detention pond. There will be one pond serving the entire site’s water quality at the most downstream end of the site. REFERENCES Design and data methods are based on the following references: 1. Hamilton County Stormwater Technical Standards Manual 2. HERPICC Stormwater Drainage Manual 3. USDA – Urban Hydrology for Small Watersheds 4. USDA – Soil Conservation Service 5/10/2019 6 of 79