2026 05 Storm Water Management Report rcd 5 6 2026

2026-04 Proposed & Existing CoNOAA 24-hr D 100-Year-Projected Rainfall=11.52", P2=4.09" 2026-04 Proposed & Existing CoNOAA 24-hr D 100-Year-Projected Rainfall=11.52", P2=4.09" Prepared by Dynamic Engineering Printed 5/5/2026 Prepared by Dynamic Engineering Printed 5/5/2026 HydroCAD® 10.20-7a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 85 HydroCAD® 10.20-7a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 86 Summary for Subcatchment 14S: PDA #3 - Pervious Summary for Pond 1P: UG BASIN Runoff = 0.69 cfs @ 12.16 hrs, Volume= 0.057 af, Depth= 8.98" Inflow Area = 0.142 ac,100.00% Impervious, Inflow Depth = 11.28" for 100-Year-Projected event Routed to Link 6L : POI #3 Inflow = 1.72 cfs @ 12.10 hrs, Volume= 0.133 af Outflow = 1.35 cfs @ 12.11 hrs, Volume= 0.133 af, Atten= 21%, Lag= 0.6 min Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.001 hrs Primary = 1.35 cfs @ 12.11 hrs, Volume= 0.133 af NOAA 24-hr D 100-Year-Projected Rainfall=11.52", P2=4.09" Routed to Link 4L : POI #1 Area (ac) CN Description Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.001 hrs 0.076 80 >75% Grass cover, Good, HSG D

r-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.001 hrs 0.076 80 >75% Grass cover, Good, HSG D Peak Elev= 621.43' @ 12.11 hrs Surf.Area= 0.004 ac Storage= 0.019 af 0.076 100.00% Pervious Area Plug-Flow detention time= 10.9 min calculated for 0.133 af (100% of inflow) Tc Length Slope Velocity Capacity Description Center-of-Mass det. time= 10.9 min ( 744.1 - 733.1 ) (min) (feet) (ft/ft) (ft/sec) (cfs) Volume Invert Avail.Storage Storage Description 8.2 83 0.0400 0.17 Sheet Flow, A-B Grass: Dense n= 0.240 P2= 4.09" #1 617.75' 0.020 af 48.0" Round Pipe Storage Using McCuen-Spiess flow length L= 70.0' 0.3 62 0.0540 3.49 Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps Device Routing Invert Outlet Devices 8.5 145 Total #1 Primary 617.75' 15.0" Round RCP_Round 15" L= 15.0' RCP, rounded edge headwall, Ke= 0.100 Inlet / Outlet Invert= 617.75' / 617.55' S= 0.0133 '/' Cc=

Inlet / Outlet Invert= 617.75' / 617.55' S= 0.0133 '/' Cc= 0.900 Subcatchment 14S: PDA #3 - Pervious n= 0.012 Concrete pipe, finished, Flow Area= 1.23 sf Hydrograph #2 Device 1 617.75' 3.0" Vert. Orifice C= 0.600 Limited to weir flow at low heads #3 Device 1 620.25' 6.0" Vert. Orifice C= 0.600 Limited to weir flow at low heads Runoff #4 Device 1 621.45' 4.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s) 0.75 0.69 cfs 0.7 NOAA 24-hr D Primary OutFlow Max=1.35 cfs @ 12.11 hrs HW=621.42' (Free Discharge) 0.65 100-Year-Projected Rainfall=11.52" 1=RCP_Round 15" (Passes 1.35 cfs of 13.49 cfs potential flow) 0.6 P2=4.09" 2=Orifice (Orifice Controls 0.45 cfs @ 9.07 fps) 0.55 Runoff Area=0.076 ac 3=Orifice (Orifice Controls 0.91 cfs @ 4.63 fps) 0.5 Runoff Volume=0.057 af 4=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs) 0.45

Runoff Volume=0.057 af 4=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs) 0.45 Runoff Depth=8.98" Flow (cfs) 0.4 Flow Length=145' 0.35 Tc=8.5 min CN=80 0.3 0.25 0.2 0.15 0.1 0.05 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)