Drainage Report and Supplement 82625

NOAA 24-hr D 2-Year-2020 Rainfall=3.47", 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 2 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=2.13" Flow Length=147' Tc=2.6 min CN=74/98 Runoff=1.84 cfs 5,704 cf Subcatchment E-1: Existing Drainage to Runoff Area=143,746 sf 24.72% Impervious Runoff Depth=1.86" Flow Length=408' Tc=2.8 min CN=77/98 Runoff=7.56 cfs 22,283 cf Subcatchment E-2: Existing Drainage to Subcatchment P-1: Proposed Drainage to Runoff Area=32,238 sf 36.29% Impervious Runoff Depth=1.95" Flow Length=178' Tc=2.6 min CN=74/98 Runoff=1.73 cfs 5,242 cf Subcatchment P-2: Proposed Drainage to Runoff Area=143,609 sf 24.31% Impervious Runoff Depth=1.85" Flow Length=408' Tc=2.8 min CN=77/98 Runoff=7.53 cfs 22,172 cf Total Runoff Area = 351,694 sf Runoff Volume = 55,400 cf Average Runoff Depth = 1.89" 72.51% Pervious = 255,029 sf 27.49% Impervious = 96,665 sf