Drainage Report

basin 4 with exfiltration Proposed basin 4 R4 with exfiltration NOAA 24-hr D 2-Year Rainfall=3.44" Prepared by Anderson Consulting Services Printed 10/23/2023 HydroCAD® 10.20-3f s/n 06666 © 2023 HydroCAD Software Solutions LLC Page 8 Summary for Subcatchment 16S: Basin 4 Porous pvmt [47] Hint: Peak is 202% of capacity of segment #3 Runoff = 4.96 cfs @ 12.15 hrs, Volume= 0.432 af, Depth= 2.64" Routed to Pond 17P : Porous pavement system 4 Runoff by SCS TR-20 method, UH=SCS, Split Pervious/Imperv., Time Span= 0.00-72.00 hrs, dt= 0.03 hrs NOAA 24-hr D 2-Year Rainfall=3.44" Area (sf) CN Description * 61,324 98 roof and parking 24,384 74 >75% Grass cover, Good, HSG C 85,708 91 Weighted Average Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.4 100 0.0520 0.26 Sheet Flow, grass Grass: Short n= 0.150 P2= 3.44" 0.6 100 0.0300 2.60 Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps 1.0 309 0.0261 5.35 2.45 Pipe Channel, 15.0" Round w/ 9.0" inside fill Area= 0.5 sf Perim= 2.9' r= 0.16' n= 0.013 Corrugated PE, smooth interior 8.1 509 Total Subcatchment 16S: Basin 4 Porous pvmt Hydrograph Runoff 4.96 cfs

Runoff 4.96 cfs 5 NOAA 24-hr D 2-Year Rainfall=3.44" 4 Runoff Area=85,708 sf Runoff Volume=0.432 af Flow (cfs) 3 Runoff Depth=2.64" Flow Length=509' 2 Tc=8.1 min CN=74/98 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)