Drainage Report and Supplement 82625

2025-08-13_Stormwater Calculations NOAA 24-hr D 100-Year-2020 Rainfall=9.18", P2=3.47" Prepared by Stonefield Engineering & Design HydroCAD® 10.20-5c s/n 10626 © 2023 HydroCAD Software Solutions LLC Printed 8/13/2025 Page 21 Summary for Subcatchment E-1: Existing Drainage to Woodland Avenue Runoff = 6.29 cfs @ 12.10 hrs, Volume= 19,599 cf, Depth= 7.33" Runoff by SCS TR-20 method, UH=SCS, Split Pervious/Imperv., Time Span= 0.00-72.00 hrs, dt= 0.01 hrs NOAA 24-hr D 100-Year-2020 Rainfall=9.18", P2=3.47" * Area (sf) 14,526 17,575 32,101 17,575 14,526 Tc (min) 1.9 Length (feet) 19 0.1 24 0.2 33 0.3 41 0.1 30 2.6 147 CN 98 74 85 74 98 Description Impervious Surface >75% Grass cover, Good, HSG C Weighted Average 54.75% Pervious Area 45.25% Impervious Area Slope Velocity Capacity Description (ft/ft) (ft/sec) (cfs) 0.0389 0.17 Sheet Flow, A1-1-A1-2 Grass: Short n= 0.150 P2= 3.47" 0.0367 3.89 Shallow Concentrated Flow, A1-2-A1-3 Paved Kv= 20.3 fps 0.0303 3.53 Shallow Concentrated Flow, A1-3-A1-4 Paved Kv= 20.3 fps 0.0244 2.51 Shallow Concentrated Flow, A1-4-A1-5 Unpaved Kv= 16.1 fps 0.0430 3.34 Shallow Concentrated Flow, A1-5-A1-6 Unpaved Kv= 16.1 fps Total