251203_42 ERW_Stormwater Report

250903_42 ERW Waystone - Future Rainfall NOAA 24-hr D 10-Year Rainfall=6.37" Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 11/25/2025 Page 15 Time span=0.00-72.00 hrs, dt=0.05 hrs, 1441 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment EDA-1 (IMPERV): Runoff Area=13,913 sf 100.00% Impervious Runoff Depth=6.13" Flow Length=275' Tc=2.8 min CN=98 Runoff=2.12 cfs 0.163 af Subcatchment EDA-1 (PERV): Runoff Area=102,351 sf 0.00% Impervious Runoff Depth=3.50" Flow Length=501' Tc=13.1 min CN=74 Runoff=7.42 cfs 0.685 af Subcatchment EDA-2 (PERV.): Runoff Area=0.423 ac 0.00% Impervious Runoff Depth=3.50" Flow Length=121' Tc=7.2 min CN=74 Runoff=1.63 cfs 0.123 af Reach DP1-EX: Inflow=8.17 cfs 0.848 af Outflow=8.17 cfs 0.848 af Reach DP2-EX: Inflow=1.63 cfs 0.123 af Outflow=1.63 cfs 0.123 af Total Runoff Area = 3.092 ac Runoff Volume = 0.972 af Average Runoff Depth = 3.77" 89.67% Pervious = 2.773 ac 10.33% Impervious = 0.319 ac