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HomeMy WebLinkAbout2200 W Main Street Drainage Report 03312023 TABLE OF CONTENTS Stormwater Drainage Technical Report Page 1.0 PREFACE ...................................................................................................1 2.0 EXISTING CONDITIONS .......................................................................1 3.0 PROPOSED CONDITIONS .....................................................................2 FIGURES Figure 1 – Site Location Figure 2 – USDA Soils Mapping Figure 3 – Existing Hydrologic Condition Figure 4 – Proposed Hydrologic Condition Appendix A: 2, 10, 100 YR Existing Condition Modeling Appendix B: 2, 10, 100 YR Proposed Condition Modeling 2200 W Main Street March 2023 Hamilton County, Indiana 1 1.0. PREFACE MJ Gibson Land Surveying has completed a development plan to support the construction of a single family residence and associated utilities on an approximately 5 acre parcel located north and adjacent of West Main Street between Towne and Ditch Road as shown on Figure 1 in Hamilton County, Indiana. A dry basin detention amenity is proposed between the proposed residence and W. Main Street as shown on the plot plan. The purpose of this reporting is to demonstrate the adequacy of the size of the detention system, and that all runoff from the improvements are responsibly designed. A summary of existing conditions are discussed in Section 2.0, while a discussion of the proposed conditions are discussed in Section 3.0. 2.0. EXISTING CONDITIONS As shown on Figure 1, the site consists of mostly turf grass. An existing residence, driveway, and outbuilding account for a total of 0.16 acres of impervious surface. The site is relatively flat with the drainage break between north and south being uncertain. For the purposes of this analysis, the largest conceivable area draining south is assumed as a conservative measure. According to the USDA Web Soil Survey (Figure 2), the site consists mostly of Brookston Silty Clay Loam and Crosby Silt Loam, designated as HSG of B/D and C/D type soils, respectively. In the current condition, these soils are relatively poorly drained soils, most accurately assigned a Hydrologic Soil Grouping (HSG) of ‘D’. FEMA does not associate the area with any Special Flood Hazard Zones, and no known ‘hot spots’ are associated with the SITE. Figure 3 provides the overall considered delineation draining to the south. As shown, 3.204 acres may drain to the subject outlet. An unabridged detail of all existing runoff parameters is provided in Appendix ‘A’ for the 2, 10, and 100 year design events. The 24-hour NRCS Type 2 rainfall distribution and 24-hour rainfall depths for the events from the Manual are used. As detailed in the Appendix, The TOC of the existing watershed computes to 25 minutes. Table 1 summarizes the overall computed peak rates for the existing site: Table 1: Existing Peak Runoff DA ID 2 YR 10 YR 100 YR EX1 3.04 5.95 13.15 2200 W Main Street March 2023 Hamilton County, Indiana 2 3.0. PROPOSED SYSTEM DESIGN As shown on the Plot Plan the project proposes an 18,000 square foot house with a service driveway, a pool, and pergola structures; all of which have been accounted for as impervious surface. The total impervious surface will increase to 0.738 acres. As provided on Figure 4, the proposed contributing drainage watershed is the same as the existing condition as perimeter grading is not proposed with the project. Only the roof of the proposed residence (PR1) will be served by the proposed subsurface drain, while the remainder of the drainage area (PR2) will overland flow to the proposed dry basin. The time of concentration is assumed to be unchanged due to the development regarding the overall flow path to the proposed dry basin. An unabridged detail of all proposed runoff parameters is provided in Appendix ‘B’ for the 2, 10, and 100 year design events. Table 2 summarizes the overall computed peak rates for the existing site. The overall time of concentration will occur on undisturbed areas of the site and will be the same as the existing condition. Table 2: Proposed Peak Runoff 2 YR Peak (cfs) 10 YR Peak (cfs) 100 YR Peak (cfs) 100 YR Stage (ft) Dry Pond 0.46 0.55 0.72 901.4 As shown above, the discharge rate reduction is evident. As to the sizing of the dry basin, the 100 year event stage in the dry pond will leave approximately 0.9 feet of freeboard below the overflow weir elevation of 902.30. Therefore, given the conservatively large drainage area assumed to reach the proposed dry pond, it does appear it is of adequate size. Figure 1 2200 W Main Street - PT NW 1/4 S 28-T18N-R3E eria Main an Prert an HMITON COUNTY, INDIN SITE OCTION Prepared by: Figure 2 USD SOI MPPING TERRY EE MINOR SUBDIVISION S20-T17N-R1E USD WEB SOI SURVEY HENDRICKS COUNTY, INDIN Prepared by: Figure 3 EXISTING CONDITION HYDROOGY TERRY EE MINOR SUBDIVISION S20-T17N-R1E HENDRICKS COUNTY, INDIN N Figure 4 PROPOSED CONDITION HYDROLOGY TERRY LEE MINOR SUBDIVISION S20-T17N-R1E HENDRICKS COUNTY, INDIANA N APPENDIX ‘A’ EXISTING CONDITION MODELING 31S EX1 Routing Diagram for 2200 W Hamilton County Prepared by MJ Gibson, Printed 3/31/2023 HydroCAD® 10.00-22 s/n 10388 © 2018 HydroCAD Software Solutions LLC Subcat Reach Pond Link Existing Condition Discharge 2200 W Hamilton County Printed 3/31/2023Prepared by MJ Gibson Page 2HydroCAD® 10.00-22 s/n 10388 © 2018 HydroCAD Software Solutions LLC Area Listing (selected nodes) Area (acres) CN Description (subcatchment-numbers) 3.047 80 >75% Grass cover, Good, HSG D (31S) 0.157 98 Unconnected pavement, HSG D (31S) 3.204 81 TOTAL AREA Existing Condition Discharge 2200 W Hamilton County Printed 3/31/2023Prepared by MJ Gibson Page 3HydroCAD® 10.00-22 s/n 10388 © 2018 HydroCAD Software Solutions LLC Soil Listing (selected nodes) Area (acres) Soil Group Subcatchment Numbers 0.000 HSG A 0.000 HSG B 0.000 HSG C 3.204 HSG D 31S 0.000 Other 3.204 TOTAL AREA Existing Condition Discharge 2200 W Hamilton County Printed 3/31/2023Prepared by MJ Gibson Page 4HydroCAD® 10.00-22 s/n 10388 © 2018 HydroCAD Software Solutions LLC Ground Covers (selected nodes) HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers 0.000 0.000 0.000 3.047 0.000 3.047 >75% Grass cover, Good 31S 0.000 0.000 0.000 0.157 0.000 0.157 Unconnected pavement 31S 0.000 0.000 0.000 3.204 0.000 3.204 TOTAL AREA Existing Condition Discharge Type II 24-hr 2 YR Rainfall=2.66"2200 W Hamilton County Printed 3/31/2023Prepared by MJ Gibson Page 5HydroCAD® 10.00-22 s/n 10388 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 31S: EX1 Runoff = 3.04 cfs @ 12.19 hrs, Volume= 0.267 af, Depth= 1.00" 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 2 YR Rainfall=2.66" Area (ac) CN Adj Description 3.047 80 >75% Grass cover, Good, HSG D 0.157 98 Unconnected pavement, HSG D 3.204 81 80 Weighted Average, UI Adjusted 3.047 95.10% Pervious Area 0.157 4.90% Impervious Area 0.157 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 19.5 100 0.0045 0.09 Sheet Flow, Sheet Grass: Short n= 0.150 P2= 2.66" 5.2 340 0.0045 1.08 Shallow Concentrated Flow, Shallow Unpaved Kv= 16.1 fps 24.7 440 Total Subcatchment 31S: EX1 Runoff Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420Flow (cfs)3 2 1 0 Type II 24-hr 2 YR Rainfall=2.66" Runoff Area=3.204 ac Runoff Volume=0.267 af Runoff Depth=1.00" Flow Length=440' Slope=0.0045 '/' Tc=24.7 min UI Adjusted CN=80 3.04 cfs Existing Condition Discharge Type II 24-hr 10 YR Rainfall=3.83"2200 W Hamilton County Printed 3/31/2023Prepared by MJ Gibson Page 6HydroCAD® 10.00-22 s/n 10388 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 31S: EX1 Runoff = 5.95 cfs @ 12.18 hrs, Volume= 0.508 af, Depth= 1.90" 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 10 YR Rainfall=3.83" Area (ac) CN Adj Description 3.047 80 >75% Grass cover, Good, HSG D 0.157 98 Unconnected pavement, HSG D 3.204 81 80 Weighted Average, UI Adjusted 3.047 95.10% Pervious Area 0.157 4.90% Impervious Area 0.157 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 19.5 100 0.0045 0.09 Sheet Flow, Sheet Grass: Short n= 0.150 P2= 2.66" 5.2 340 0.0045 1.08 Shallow Concentrated Flow, Shallow Unpaved Kv= 16.1 fps 24.7 440 Total Subcatchment 31S: EX1 Runoff Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420Flow (cfs)6 5 4 3 2 1 0 Type II 24-hr 10 YR Rainfall=3.83" Runoff Area=3.204 ac Runoff Volume=0.508 af Runoff Depth=1.90" Flow Length=440' Slope=0.0045 '/' Tc=24.7 min UI Adjusted CN=80 5.95 cfs Existing Condition Discharge Type II 24-hr 100 YR Rainfall=6.46"2200 W Hamilton County Printed 3/31/2023Prepared by MJ Gibson Page 7HydroCAD® 10.00-22 s/n 10388 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 31S: EX1 Runoff = 13.15 cfs @ 12.18 hrs, Volume= 1.121 af, Depth= 4.20" 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 Rainfall=6.46" Area (ac) CN Adj Description 3.047 80 >75% Grass cover, Good, HSG D 0.157 98 Unconnected pavement, HSG D 3.204 81 80 Weighted Average, UI Adjusted 3.047 95.10% Pervious Area 0.157 4.90% Impervious Area 0.157 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 19.5 100 0.0045 0.09 Sheet Flow, Sheet Grass: Short n= 0.150 P2= 2.66" 5.2 340 0.0045 1.08 Shallow Concentrated Flow, Shallow Unpaved Kv= 16.1 fps 24.7 440 Total Subcatchment 31S: EX1 Runoff Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420Flow (cfs)14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Type II 24-hr 100 YR Rainfall=6.46" Runoff Area=3.204 ac Runoff Volume=1.121 af Runoff Depth=4.20" Flow Length=440' Slope=0.0045 '/' Tc=24.7 min UI Adjusted CN=80 13.15 cfs APPENDIX ‘B’ PROPOSED CONDITION MODELING 67S PR COMBINED 68P Dry Basin Routing Diagram for 2200 W Hamilton County Prepared by MJ Gibson, Printed 3/31/2023 HydroCAD® 10.00-22 s/n 10388 © 2018 HydroCAD Software Solutions LLC Subcat Reach Pond Link Proposed Detention Dynamics 2200 W Hamilton County Printed 3/31/2023Prepared by MJ Gibson Page 2HydroCAD® 10.00-22 s/n 10388 © 2018 HydroCAD Software Solutions LLC Area Listing (selected nodes) Area (acres) CN Description (subcatchment-numbers) 2.231 80 >75% Grass cover, Good, HSG D (67S) 0.973 98 Unconnected pavement, HSG D (67S) Proposed Detention Dynamics Type II 24-hr 2 YR Rainfall=2.66"2200 W Hamilton County Printed 3/31/2023Prepared by MJ Gibson Page 3HydroCAD® 10.00-22 s/n 10388 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 67S: PR COMBINED Runoff = 4.09 cfs @ 12.18 hrs, Volume= 0.349 af, Depth= 1.31" 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 2 YR Rainfall=2.66" Area (ac) CN Description 2.231 80 >75% Grass cover, Good, HSG D 0.973 98 Unconnected pavement, HSG D 3.204 85 Weighted Average 2.231 69.63% Pervious Area 0.973 30.37% Impervious Area 0.973 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 19.5 100 0.0045 0.09 Sheet Flow, Sheet Grass: Short n= 0.150 P2= 2.66" 5.2 340 0.0045 1.08 Shallow Concentrated Flow, Shallow Unpaved Kv= 16.1 fps 24.7 440 Total Subcatchment 67S: PR COMBINED Runoff Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420Flow (cfs)4 3 2 1 0 Type II 24-hr 2 YR Rainfall=2.66" Runoff Area=3.204 ac Runoff Volume=0.349 af Runoff Depth=1.31" Flow Length=440' Slope=0.0045 '/' Tc=24.7 min CN=85 4.09 cfs Proposed Detention Dynamics Type II 24-hr 2 YR Rainfall=2.66"2200 W Hamilton County Printed 3/31/2023Prepared by MJ Gibson Page 4HydroCAD® 10.00-22 s/n 10388 © 2018 HydroCAD Software Solutions LLC Summary for Pond 68P: Dry Basin Inflow Area = 3.204 ac, 30.37% Impervious, Inflow Depth = 1.31" for 2 YR event Inflow = 4.09 cfs @ 12.18 hrs, Volume= 0.349 af Outflow = 0.46 cfs @ 13.22 hrs, Volume= 0.349 af, Atten= 89%, Lag= 61.9 min Primary = 0.46 cfs @ 13.22 hrs, Volume= 0.349 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs Peak Elev= 899.65' @ 13.22 hrs Surf.Area= 10,820 sf Storage= 7,111 cf Plug-Flow detention time= 168.0 min calculated for 0.349 af (100% of inflow) Center-of-Mass det. time= 168.0 min ( 1,016.8 - 848.8 ) Volume Invert Avail.Storage Storage Description #1 898.35' 52,901 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 898.35 120 0 0 900.00 13,700 11,401 11,401 902.00 18,137 31,837 43,238 902.50 20,512 9,662 52,901 Device Routing Invert Outlet Devices #1 Primary 898.35'6.0" Round Culvert L= 57.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 898.35' / 898.00' S= 0.0061 '/' Cc= 0.900 n= 0.021, Flow Area= 0.20 sf Primary OutFlow Max=0.46 cfs @ 13.22 hrs HW=899.65' (Free Discharge) 1=Culvert (Barrel Controls 0.46 cfs @ 2.33 fps) Proposed Detention Dynamics Type II 24-hr 2 YR Rainfall=2.66"2200 W Hamilton County Printed 3/31/2023Prepared by MJ Gibson Page 5HydroCAD® 10.00-22 s/n 10388 © 2018 HydroCAD Software Solutions LLC Pond 68P: Dry Basin Inflow Primary Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420Flow (cfs)4 3 2 1 0 Inflow Area=3.204 ac Peak Elev=899.65' Storage=7,111 cf 6.0" Round Culvert n=0.021 L=57.0' S=0.0061 '/' 4.09 cfs 0.46 cfs Proposed Detention Dynamics Type II 24-hr 10 YR Rainfall=3.83"2200 W Hamilton County Printed 3/31/2023Prepared by MJ Gibson Page 6HydroCAD® 10.00-22 s/n 10388 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 67S: PR COMBINED Runoff = 7.25 cfs @ 12.18 hrs, Volume= 0.616 af, Depth= 2.31" 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 10 YR Rainfall=3.83" Area (ac) CN Description 2.231 80 >75% Grass cover, Good, HSG D 0.973 98 Unconnected pavement, HSG D 3.204 85 Weighted Average 2.231 69.63% Pervious Area 0.973 30.37% Impervious Area 0.973 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 19.5 100 0.0045 0.09 Sheet Flow, Sheet Grass: Short n= 0.150 P2= 2.66" 5.2 340 0.0045 1.08 Shallow Concentrated Flow, Shallow Unpaved Kv= 16.1 fps 24.7 440 Total Subcatchment 67S: PR COMBINED Runoff Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420Flow (cfs)8 7 6 5 4 3 2 1 0 Type II 24-hr 10 YR Rainfall=3.83" Runoff Area=3.204 ac Runoff Volume=0.616 af Runoff Depth=2.31" Flow Length=440' Slope=0.0045 '/' Tc=24.7 min CN=85 7.25 cfs Proposed Detention Dynamics Type II 24-hr 10 YR Rainfall=3.83"2200 W Hamilton County Printed 3/31/2023Prepared by MJ Gibson Page 7HydroCAD® 10.00-22 s/n 10388 © 2018 HydroCAD Software Solutions LLC Summary for Pond 68P: Dry Basin Inflow Area = 3.204 ac, 30.37% Impervious, Inflow Depth = 2.31" for 10 YR event Inflow = 7.25 cfs @ 12.18 hrs, Volume= 0.616 af Outflow = 0.55 cfs @ 13.67 hrs, Volume= 0.616 af, Atten= 92%, Lag= 89.3 min Primary = 0.55 cfs @ 13.67 hrs, Volume= 0.616 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs Peak Elev= 900.19' @ 13.67 hrs Surf.Area= 14,132 sf Storage= 14,112 cf Plug-Flow detention time= 282.7 min calculated for 0.616 af (100% of inflow) Center-of-Mass det. time= 282.8 min ( 1,115.4 - 832.6 ) Volume Invert Avail.Storage Storage Description #1 898.35' 52,901 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 898.35 120 0 0 900.00 13,700 11,401 11,401 902.00 18,137 31,837 43,238 902.50 20,512 9,662 52,901 Device Routing Invert Outlet Devices #1 Primary 898.35'6.0" Round Culvert L= 57.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 898.35' / 898.00' S= 0.0061 '/' Cc= 0.900 n= 0.021, Flow Area= 0.20 sf Primary OutFlow Max=0.55 cfs @ 13.67 hrs HW=900.19' (Free Discharge) 1=Culvert (Barrel Controls 0.55 cfs @ 2.83 fps) Proposed Detention Dynamics Type II 24-hr 10 YR Rainfall=3.83"2200 W Hamilton County Printed 3/31/2023Prepared by MJ Gibson Page 8HydroCAD® 10.00-22 s/n 10388 © 2018 HydroCAD Software Solutions LLC Pond 68P: Dry Basin Inflow Primary Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420Flow (cfs)8 7 6 5 4 3 2 1 0 Inflow Area=3.204 ac Peak Elev=900.19' Storage=14,112 cf 6.0" Round Culvert n=0.021 L=57.0' S=0.0061 '/' 7.25 cfs 0.55 cfs Proposed Detention Dynamics Type II 24-hr 100 YR Rainfall=6.46"2200 W Hamilton County Printed 3/31/2023Prepared by MJ Gibson Page 9HydroCAD® 10.00-22 s/n 10388 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 67S: PR COMBINED Runoff = 14.67 cfs @ 12.16 hrs, Volume= 1.265 af, Depth= 4.74" 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 Rainfall=6.46" Area (ac) CN Description 2.231 80 >75% Grass cover, Good, HSG D 0.973 98 Unconnected pavement, HSG D 3.204 85 Weighted Average 2.231 69.63% Pervious Area 0.973 30.37% Impervious Area 0.973 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 19.5 100 0.0045 0.09 Sheet Flow, Sheet Grass: Short n= 0.150 P2= 2.66" 5.2 340 0.0045 1.08 Shallow Concentrated Flow, Shallow Unpaved Kv= 16.1 fps 24.7 440 Total Subcatchment 67S: PR COMBINED Runoff Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420Flow (cfs)16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Type II 24-hr 100 YR Rainfall=6.46" Runoff Area=3.204 ac Runoff Volume=1.265 af Runoff Depth=4.74" Flow Length=440' Slope=0.0045 '/' Tc=24.7 min CN=85 14.67 cfs Proposed Detention Dynamics Type II 24-hr 100 YR Rainfall=6.46"2200 W Hamilton County Printed 3/31/2023Prepared by MJ Gibson Page 10HydroCAD® 10.00-22 s/n 10388 © 2018 HydroCAD Software Solutions LLC Summary for Pond 68P: Dry Basin Inflow Area = 3.204 ac, 30.37% Impervious, Inflow Depth = 4.74" for 100 YR event Inflow = 14.67 cfs @ 12.16 hrs, Volume= 1.265 af Outflow = 0.72 cfs @ 14.43 hrs, Volume= 1.265 af, Atten= 95%, Lag= 136.1 min Primary = 0.72 cfs @ 14.43 hrs, Volume= 1.265 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-60.00 hrs, dt= 0.01 hrs Peak Elev= 901.39' @ 14.43 hrs Surf.Area= 16,787 sf Storage= 32,616 cf Plug-Flow detention time= 504.1 min calculated for 1.265 af (100% of inflow) Center-of-Mass det. time= 504.0 min ( 1,316.1 - 812.1 ) Volume Invert Avail.Storage Storage Description #1 898.35' 52,901 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 898.35 120 0 0 900.00 13,700 11,401 11,401 902.00 18,137 31,837 43,238 902.50 20,512 9,662 52,901 Device Routing Invert Outlet Devices #1 Primary 898.35'6.0" Round Culvert L= 57.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 898.35' / 898.00' S= 0.0061 '/' Cc= 0.900 n= 0.021, Flow Area= 0.20 sf Primary OutFlow Max=0.72 cfs @ 14.43 hrs HW=901.39' (Free Discharge) 1=Culvert (Barrel Controls 0.72 cfs @ 3.69 fps) Proposed Detention Dynamics Type II 24-hr 100 YR Rainfall=6.46"2200 W Hamilton County Printed 3/31/2023Prepared by MJ Gibson Page 11HydroCAD® 10.00-22 s/n 10388 © 2018 HydroCAD Software Solutions LLC Pond 68P: Dry Basin Inflow Primary Hydrograph Time (hours) 605856545250484644424038363432302826242220181614121086420Flow (cfs)16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=3.204 ac Peak Elev=901.39' Storage=32,616 cf 6.0" Round Culvert n=0.021 L=57.0' S=0.0061 '/' 14.67 cfs 0.72 cfs