Drainage Report and Supplement 82625

NOAA 24-hr D 10-Year-2020 Rainfall=5.38", 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 14 Summary for Subcatchment E-2: Existing Drainage to Nicholas Avenue Runoff = 14.15 cfs @ 12.11 hrs, Volume= Routed to nonexistent node POI-2 41,775 cf, Depth= 3.49" 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 10-Year-2020 Rainfall=5.38", P2=3.47" * * * Area (sf) 35,530 58,832 4,420 27,460 17,504 143,746 108,216 35,530 Tc (min) 0.0 Length (feet) 4 0.0 3 0.2 29 0.3 45 1.1 107 0.7 77 0.1 27 0.1 24 0.1 17 0.0 16 0.0 7 0.2 52 2.8 408 CN 98 74 70 74 96 82 77 98 Description Impervious Surface >75% Grass cover, Good, HSG C Woods, Good, HSG C Sand Riding Area Gravel surface Weighted Average 75.28% Pervious Area 24.72% Impervious Area Slope Velocity Capacity Description (ft/ft) (ft/sec) (cfs) 0.2410 2.04 Sheet Flow, D1-D2 Smooth surfaces n= 0.011 P2= 3.47" 0.2930 10.99 Shallow Concentrated Flow, D2-D3 Paved Kv= 20.3 fps 0.0340 2.97 Shallow Concentrated Flow, D3-D4 Unpaved Kv= 16.1 fps 0.0220 2.39 Shallow Concentrated Flow, D4-D5 Unpaved Kv= 16.1 fps 0.0100 1.61 Shallow Concentrated Flow, D5-D6 Unpaved Kv= 16.1 fps 0.0130 1.84 Shallow Concentrated Flow, D6-D7 Unpaved Kv= 16.1 fps 0.0370 3.10 Shallow Concentrated Flow, D7-D8 Unpaved Kv= 16.1 fps 0.0420 3.30 Shallow Concentrated Flow, D8-D9 Unpaved Kv= 16.1 fps 0.1170 5.51 Shallow Concentrated Flow, D9-D10 Unpaved Kv= 16.1 fps 0.1220 5.62 Shallow Concentrated Flow, D10-D11 Unpaved Kv= 16.1 fps 0.2860 8.61 Shallow Concentrated Flow, D11-D12 Unpaved Kv= 16.1 fps 0.0580 3.88 Shallow Concentrated Flow, D12-D13 Unpaved Kv= 16.1 fps Total