Drainage Report and Supplement 82625

NOAA 24-hr D 10-Year-2020 Rainfall=5.38", P2=3.47" Printed 8/13/2025 Prepared by Stonefield Engineering & Design 2025-08-13_Stormwater Calculations HydroCAD® 10.20-5c s/n 10626 © 2023 HydroCAD Software Solutions LLC Page 11 Time span=0.00-72.00 hrs, dt=0.01 hrs, 7201 points Runoff by SCS TR-20 method, UH=SCS, Split Pervious/Imperv. Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=32,101 sf 45.25% Impervious Runoff Depth=3.79" Flow Length=147' Tc=2.6 min CN=74/98 Runoff=3.29 cfs 10,137 cf Subcatchment E-1: Existing Drainage to Runoff Area=143,746 sf 24.72% Impervious Runoff Depth=3.49" Flow Length=408' Tc=2.8 min CN=77/98 Runoff=14.15 cfs 41,775 cf Subcatchment E-2: Existing Drainage to Subcatchment P-1: Proposed Drainage to Runoff Area=32,238 sf 36.29% Impervious Runoff Depth=3.57" Flow Length=178' Tc=2.6 min CN=74/98 Runoff=3.16 cfs 9,585 cf Subcatchment P-2: Proposed Drainage to Runoff Area=143,609 sf 24.31% Impervious Runoff Depth=3.48" Flow Length=408' Tc=2.8 min CN=77/98 Runoff=14.11 cfs 41,628 cf Total Runoff Area = 351,694 sf Runoff Volume = 103,125 cf Average Runoff Depth = 3.52" 72.51% Pervious = 255,029 sf 27.49% Impervious = 96,665 sf