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 20 Time span=0.00-72.00 hrs, dt=0.01 hrs, 7201 points Runoff by SCS TR-20 method, UH=SCS, Split Pervious/Imperv. Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=32,101 sf 45.25% Impervious Runoff Depth=7.33" Flow Length=147' Tc=2.6 min CN=74/98 Runoff=6.29 cfs 19,599 cf Subcatchment E-1: Existing Drainage to Runoff Area=143,746 sf 24.72% Impervious Runoff Depth=7.00" Flow Length=408' Tc=2.8 min CN=77/98 Runoff=27.67 cfs 83,884 cf Subcatchment E-2: Existing Drainage to Subcatchment P-1: Proposed Drainage to Runoff Area=32,238 sf 36.29% Impervious Runoff Depth=7.06" Flow Length=178' Tc=2.6 min CN=74/98 Runoff=6.19 cfs 18,973 cf Subcatchment P-2: Proposed Drainage to Runoff Area=143,609 sf 24.31% Impervious Runoff Depth=6.99" Flow Length=408' Tc=2.8 min CN=77/98 Runoff=27.62 cfs 83,679 cf Total Runoff Area = 351,694 sf Runoff Volume = 206,135 cf Average Runoff Depth = 7.03" 72.51% Pervious = 255,029 sf 27.49% Impervious = 96,665 sf

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

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 22 Subcatchment E-1: Existing Drainage to Woodland Avenue Hydrograph 7 Runoff 6.29 cfs 6 Flow (cfs) 5 4 3 2 NOAA 24-hr D 100-Year-2020 Rainfall=9.18" P2=3.47" Runoff Area=32,101 sf Runoff Volume=19,599 cf Runoff Depth=7.33" Flow Length=147' Tc=2.6 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)

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 23 Summary for Subcatchment E-2: Existing Drainage to Nicholas Avenue Runoff = 27.67 cfs @ 12.10 hrs, Volume= Routed to nonexistent node POI-2 83,884 cf, Depth= 7.00" 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) 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

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 24 Subcatchment E-2: Existing Drainage to Nicholas Avenue Hydrograph Runoff 30 27.67 cfs 28 26 24 22 Flow (cfs) 20 18 16 14 12 10 NOAA 24-hr D 100-Year-2020 Rainfall=9.18" P2=3.47" Runoff Area=143,746 sf Runoff Volume=83,884 cf Runoff Depth=7.00" Flow Length=408' Tc=2.8 min CN=77/98 8 6 4 2 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)

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 25 Summary for Subcatchment P-1: Proposed Drainage to Woodland Avenue Runoff = 6.19 cfs @ 12.10 hrs, Volume= Routed to nonexistent node P0I-1 18,973 cf, Depth= 7.06" 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) 11,698 9,040 11,500 32,238 20,540 11,698 Tc (min) 1.8 Length (feet) 23 0.1 9 0.2 41 0.2 43 0.2 36 0.1 26 2.6 178 CN 98 74 74 83 74 98 Description Impervious Surface >75% Grass cover, Good, HSG C Sand Riding Area Weighted Average 63.71% Pervious Area 36.29% Impervious Area Slope Velocity Capacity Description (ft/ft) (ft/sec) (cfs) 0.0652 0.21 Sheet Flow, B1-B2 Grass: Short n= 0.150 P2= 3.47" 0.0110 2.13 Shallow Concentrated Flow, B2-B3 Paved Kv= 20.3 fps 0.0220 3.01 Shallow Concentrated Flow, B3-B4 Paved Kv= 20.3 fps 0.0470 4.40 Shallow Concentrated Flow, B4-B5 Paved Kv= 20.3 fps 0.0280 3.40 Shallow Concentrated Flow, B5-B6 Paved Kv= 20.3 fps 0.0310 3.57 Shallow Concentrated Flow, B6-B7 Paved Kv= 20.3 fps Total

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 26 Subcatchment P-1: Proposed Drainage to Woodland Avenue Hydrograph Runoff 6.19 cfs 6 Flow (cfs) 5 4 3 2 NOAA 24-hr D 100-Year-2020 Rainfall=9.18" P2=3.47" Runoff Area=32,238 sf Runoff Volume=18,973 cf Runoff Depth=7.06" Flow Length=178' Tc=2.6 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)

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 27 Summary for Subcatchment P-2: Proposed Drainage to Nicholas Avenue Runoff = 27.62 cfs @ 12.10 hrs, Volume= Routed to nonexistent node P0I-2 83,679 cf, Depth= 6.99" 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) 34,911 69,978 22,575 16,145 143,609 108,698 34,911 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 74 96 82 77 98 Description Impervious Surface >75% Grass cover, Good, HSG C Sand Riding Area Gravel surface Weighted Average 75.69% Pervious Area 24.31% 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

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 28 Subcatchment P-2: Proposed Drainage to Nicholas Avenue Hydrograph Runoff 30 27.62 cfs 28 26 24 22 Flow (cfs) 20 18 16 14 12 10 NOAA 24-hr D 100-Year-2020 Rainfall=9.18" P2=3.47" Runoff Area=143,609 sf Runoff Volume=83,679 cf Runoff Depth=6.99" Flow Length=408' Tc=2.8 min CN=77/98 8 6 4 2 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)

NOAA 24-hr D 2-Year-2050 Rainfall=4.09", P2=4.09" 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 29 Time span=0.00-72.00 hrs, dt=0.01 hrs, 7201 points Runoff by SCS TR-20 method, UH=SCS, Split Pervious/Imperv. Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=32,101 sf 45.25% Impervious Runoff Depth=2.65" Flow Length=147' Tc=2.5 min CN=74/98 Runoff=2.31 cfs 7,101 cf Subcatchment E-1: Existing Drainage to Runoff Area=143,746 sf 24.72% Impervious Runoff Depth=2.37" Flow Length=408' Tc=2.8 min CN=77/98 Runoff=9.65 cfs 28,391 cf Subcatchment E-2: Existing Drainage to Subcatchment P-1: Proposed Drainage to Runoff Area=32,238 sf 36.29% Impervious Runoff Depth=2.46" Flow Length=178' Tc=2.5 min CN=74/98 Runoff=2.18 cfs 6,604 cf Subcatchment P-2: Proposed Drainage to Runoff Area=143,609 sf 24.31% Impervious Runoff Depth=2.36" Flow Length=408' Tc=2.8 min CN=77/98 Runoff=9.61 cfs 28,267 cf Total Runoff Area = 351,694 sf Runoff Volume = 70,363 cf Average Runoff Depth = 2.40" 72.51% Pervious = 255,029 sf 27.49% Impervious = 96,665 sf