251203_42 ERW_Stormwater Report

251202_42 ERW Waystone - Future Rainfall NOAA 24-hr D 2-Year Rainfall=4.09" Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 12/3/2025 Page 4 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 PR 1A-P: Runoff Area=13,167 sf 0.00% Impervious Runoff Depth=1.96" Flow Length=203' Tc=5.9 min CN=78 Runoff=0.68 cfs 0.049 af Subcatchment PR 1B-I: Runoff Area=36,906 sf 100.00% Impervious Runoff Depth=3.85" Flow Length=136' Tc=1.5 min CN=98 Runoff=3.62 cfs 0.272 af Subcatchment PR 1B-P: Runoff Area=77,195 sf 0.00% Impervious Runoff Depth=2.04" Flow Length=195' Tc=7.7 min CN=79 Runoff=3.92 cfs 0.301 af Subcatchment PR 2-P: Runoff Area=7,405 sf 0.00% Impervious Runoff Depth=1.81" Flow Length=84' Slope=0.0833 '/' Tc=4.6 min CN=76 Runoff=0.37 cfs 0.026 af Reach 10R: Inflow=6.68 cfs 0.573 af Outflow=6.68 cfs 0.573 af Reach DP1-PR: Inflow=1.75 cfs 0.278 af Outflow=1.75 cfs 0.278 af Reach DP2-PR: Inflow=0.37 cfs 0.026 af Outflow=0.37 cfs 0.026 af Pond BASIN: Peak Elev=16.73' Storage=0.189 af Inflow=6.68 cfs 0.573 af Discarded=0.31 cfs 0.345 af Primary=1.36 cfs 0.228 af Outflow=1.68 cfs 0.573 af Total Runoff Area = 3.092 ac Runoff Volume = 0.648 af Average Runoff Depth = 2.51" 72.60% Pervious = 2.244 ac 27.40% Impervious = 0.847 ac