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23-4121 storm calcs - Proposed Type II 24-hr 25-Year Rainfall=3.84" Prepared by Carmina Wood Design Printed 5/14/2026 HydroCAD® 10.20-8a s/n 05019 © 2025 HydroCAD Software Solutions LLC Page 29 Summary for Pond 1P: Detention Pond Inflow Area = 253,441 sf, 50.75% Impervious, Inflow Depth = 2.67" for 25-Year event Inflow = 15.59 cfs @ 12.15 hrs, Volume= 56,458 cf Outflow = 3.10 cfs @ 12.70 hrs, Volume= 56,458 cf, Atten= 80%, Lag= 33.0 min Primary = 3.10 cfs @ 12.70 hrs, Volume= 56,458 cf Routing by Stor-Ind method, Time Span= 0.50-70.02 hrs, dt= 0.04 hrs Peak Elev= 673.70' @ 12.70 hrs Surf.Area= 10,997 sf Storage= 21,268 cf Plug-Flow detention time= 60.6 min calculated for 56,426 cf (100% of inflow) Center-of-Mass det. time= 60.6 min ( 877.2 - 816.6 ) Volume Invert Avail.Storage Storage Description #1 669.00' 38,878 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 669.00 0 0 0 670.00 3,130 1,565 1,565 671.00 4,065 3,598 5,163 672.00 5,060 4,563 9,725 673.00 6,110 5,585 15,310 674.00 13,125 9,618 24,928 675.00 14,775 13,950 38,878 Device Routing Invert Outlet Devices #1 Device 3 669.00' 8.0" Round Culvert L= 17.0' CPP, mitered to conform to fill, Ke= 0.700 Inlet / Outlet Invert= 669.00' / 668.92' S= 0.0047 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.35 sf #2 Device 3 674.80' 24.0" x 24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Primary 668.92' 8.0" Round Culvert L= 25.0' CPP, mitered to conform to fill, Ke= 0.700 Inlet / Outlet Invert= 668.92' / 668.80' S= 0.0048 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.35 sf Primary OutFlow Max=3.10 cfs @ 12.70 hrs HW=673.70' (Free Discharge) 3=Culvert (Passes 3.10 cfs of 3.13 cfs potential flow) 1=Culvert (Inlet Controls 3.10 cfs @ 8.87 fps) 2=Orifice/Grate ( Controls 0.00 cfs) Page 551 of 849