251203_42 ERW_Stormwater Report

NOAA 24-hr D 10-Year Rainfall=6.37" 250903_42 ERW Waystone - Future Rainfall Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 11/25/2025 Page 18 Summary for Subcatchment EDA-1 (PERV): Runoff = 7.42 cfs @ 12.21 hrs, Volume= Routed to Reach DP1-EX : 0.685 af, Depth= 3.50" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year Rainfall=6.37" Area (sf) 102,351 102,351 CN 74 Description >75% Grass cover, Good, HSG C 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.9 100 0.0140 0.15 Sheet Flow, Grass: Short n= 0.150 P2= 3.44" 2.2 401 0.0350 3.01 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 13.1 501 Total Subcatchment EDA-1 (PERV): Hydrograph Runoff 8 7.42 cfs NOAA 24-hr D 10-Year Rainfall=6.37" Runoff Area=102,351 sf Runoff Volume=0.685 af Runoff Depth=3.50" Flow Length=501' Tc=13.1 min CN=74 7 6 Flow (cfs) 5 4 3 2 1 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 Time (hours)