251203_42 ERW_Stormwater Report

Appendix A HydroCAD Output Stormwater Management Report | October 18, 2024 – Last Revised December 3, 2025

EDA-1 (IMPERV) EDA-2 (PERV.) EDA-1 (PERV) DP2-EX DP1-EX Subcat Reach Pond Link Routing Diagram for 250903_42 ERW Waystone - Future Rainfall Prepared by Colliers Engineering & Design, Printed 11/25/2025 HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC

250903_42 ERW Waystone - Future Rainfall Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 11/25/2025 Page 2 Area Listing (selected nodes) Area (acres) CN Description (subcatchment-numbers) 2.773 0.187 0.133 3.092 74 98 98 76 >75% Grass cover, Good, HSG C (EDA-1 (PERV), EDA-2 (PERV.)) Paved parking, HSG C (EDA-1 (IMPERV)) Roofs, HSG C (EDA-1 (IMPERV)) TOTAL AREA

250903_42 ERW Waystone - Future Rainfall Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Soil Listing (selected nodes) Area (acres) Soil Group Subcatchment Numbers 0.000 0.000 3.092 0.000 0.000 3.092 HSG A HSG B HSG C HSG D Other EDA-1 (IMPERV), EDA-1 (PERV), EDA-2 (PERV.) TOTAL AREA Printed 11/25/2025 Page 3

250903_42 ERW Waystone - Future Rainfall NOAA 24-hr D 2-Year Rainfall=4.09" Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 11/25/2025 Page 4 Time span=0.00-72.00 hrs, dt=0.05 hrs, 1441 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment EDA-1 (IMPERV): Runoff Area=13,913 sf 100.00% Impervious Runoff Depth=3.85" Flow Length=275' Tc=2.8 min CN=98 Runoff=1.36 cfs 0.103 af Subcatchment EDA-1 (PERV): Runoff Area=102,351 sf 0.00% Impervious Runoff Depth=1.66" Flow Length=501' Tc=13.1 min CN=74 Runoff=3.48 cfs 0.326 af Subcatchment EDA-2 (PERV.): Runoff Area=0.423 ac 0.00% Impervious Runoff Depth=1.66" Flow Length=121' Tc=7.2 min CN=74 Runoff=0.77 cfs 0.059 af Reach DP1-EX: Inflow=3.95 cfs 0.428 af Outflow=3.95 cfs 0.428 af Reach DP2-EX: Inflow=0.77 cfs 0.059 af Outflow=0.77 cfs 0.059 af Total Runoff Area = 3.092 ac Runoff Volume = 0.487 af Average Runoff Depth = 1.89" 89.67% Pervious = 2.773 ac 10.33% Impervious = 0.319 ac

250903_42 ERW Waystone - Future Rainfall NOAA 24-hr D 2-Year Rainfall=4.09" Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 11/25/2025 Page 5 Summary for Subcatchment EDA-1 (IMPERV): Runoff = 1.36 cfs @ 12.09 hrs, Volume= Routed to Reach DP1-EX : 0.103 af, Depth= 3.85" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year Rainfall=4.09" Area (sf) 8,137 5,776 13,913 13,913 CN 98 98 98 Description Paved parking, HSG C Roofs, HSG C Weighted Average 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.1 78 0.0150 1.21 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.44" 1.0 12 0.0800 0.20 Sheet Flow, Grass: Short n= 0.150 P2= 3.44" 0.7 185 0.0830 4.64 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 2.8 275 Total Subcatchment EDA-1 (IMPERV): Hydrograph Runoff 1.36 cfs NOAA 24-hr D 2-Year Rainfall=4.09" Runoff Area=13,913 sf Runoff Volume=0.103 af Runoff Depth=3.85" Flow Length=275' Tc=2.8 min CN=98 Flow (cfs) 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)

250903_42 ERW Waystone - Future Rainfall NOAA 24-hr D 2-Year Rainfall=4.09" Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Hydrograph for Subcatchment EDA-1 (IMPERV): Time Precip. Excess (hours) (inches) (inches) 0.00 0.00 0.00 1.00 0.05 0.00 2.00 0.10 0.01 3.00 0.15 0.04 4.00 0.21 0.08 5.00 0.28 0.13 6.00 0.35 0.19 7.00 0.43 0.26 8.00 0.53 0.35 9.00 0.65 0.46 10.00 0.81 0.61 11.00 1.06 0.85 12.00 1.96 1.73 13.00 3.03 2.79 14.00 3.28 3.05 15.00 3.44 3.21 16.00 3.56 3.33 17.00 3.66 3.43 18.00 3.74 3.51 19.00 3.81 3.58 20.00 3.88 3.64 21.00 3.94 3.70 22.00 3.99 3.76 23.00 4.04 3.81 24.00 4.09 3.85 25.00 4.09 3.85 26.00 4.09 3.85 27.00 4.09 3.85 28.00 4.09 3.85 29.00 4.09 3.85 30.00 4.09 3.85 31.00 4.09 3.85 32.00 4.09 3.85 33.00 4.09 3.85 34.00 4.09 3.85 35.00 4.09 3.85 36.00 4.09 3.85 37.00 4.09 3.85 38.00 4.09 3.85 39.00 4.09 3.85 40.00 4.09 3.85 41.00 4.09 3.85 42.00 4.09 3.85 43.00 4.09 3.85 44.00 4.09 3.85 45.00 4.09 3.85 46.00 4.09 3.85 47.00 4.09 3.85 48.00 4.09 3.85 49.00 4.09 3.85 50.00 4.09 3.85 51.00 4.09 3.85 Runoff (cfs) 0.00 0.00 0.01 0.01 0.01 0.02 0.02 0.03 0.03 0.04 0.06 0.11 0.82 0.12 0.06 0.04 0.04 0.03 0.02 0.02 0.02 0.02 0.02 0.02 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Time Precip. Excess (hours) (inches) (inches) 52.00 4.09 3.85 53.00 4.09 3.85 54.00 4.09 3.85 55.00 4.09 3.85 56.00 4.09 3.85 57.00 4.09 3.85 58.00 4.09 3.85 59.00 4.09 3.85 60.00 4.09 3.85 61.00 4.09 3.85 62.00 4.09 3.85 63.00 4.09 3.85 64.00 4.09 3.85 65.00 4.09 3.85 66.00 4.09 3.85 67.00 4.09 3.85 68.00 4.09 3.85 69.00 4.09 3.85 70.00 4.09 3.85 71.00 4.09 3.85 72.00 4.09 3.85 Runoff (cfs) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Printed 11/25/2025 Page 6

NOAA 24-hr D 2-Year Rainfall=4.09" 250903_42 ERW Waystone - Future Rainfall Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 11/25/2025 Page 7 Summary for Subcatchment EDA-1 (PERV): Runoff = 3.48 cfs @ 12.22 hrs, Volume= Routed to Reach DP1-EX : 0.326 af, Depth= 1.66" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year Rainfall=4.09" Area (sf) 102,351 102,351 CN 74 Description >75% Grass cover, Good, HSG C 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.9 100 0.0140 0.15 Sheet Flow, Grass: Short n= 0.150 P2= 3.44" 2.2 401 0.0350 3.01 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 13.1 501 Total Subcatchment EDA-1 (PERV): Hydrograph Runoff 3.48 cfs NOAA 24-hr D 2-Year Rainfall=4.09" Runoff Area=102,351 sf Runoff Volume=0.326 af Runoff Depth=1.66" Flow Length=501' Tc=13.1 min CN=74 Flow (cfs) 3 2 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)

250903_42 ERW Waystone - Future Rainfall NOAA 24-hr D 2-Year Rainfall=4.09" Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Hydrograph for Subcatchment EDA-1 (PERV): Time Precip. Excess (hours) (inches) (inches) 0.00 0.00 0.00 1.00 0.05 0.00 2.00 0.10 0.00 3.00 0.15 0.00 4.00 0.21 0.00 5.00 0.28 0.00 6.00 0.35 0.00 7.00 0.43 0.00 8.00 0.53 0.00 9.00 0.65 0.00 10.00 0.81 0.00 11.00 1.06 0.03 12.00 1.96 0.33 13.00 3.03 0.93 14.00 3.28 1.09 15.00 3.44 1.20 16.00 3.56 1.28 17.00 3.66 1.35 18.00 3.74 1.41 19.00 3.81 1.46 20.00 3.88 1.51 21.00 3.94 1.55 22.00 3.99 1.59 23.00 4.04 1.63 24.00 4.09 1.66 25.00 4.09 1.66 26.00 4.09 1.66 27.00 4.09 1.66 28.00 4.09 1.66 29.00 4.09 1.66 30.00 4.09 1.66 31.00 4.09 1.66 32.00 4.09 1.66 33.00 4.09 1.66 34.00 4.09 1.66 35.00 4.09 1.66 36.00 4.09 1.66 37.00 4.09 1.66 38.00 4.09 1.66 39.00 4.09 1.66 40.00 4.09 1.66 41.00 4.09 1.66 42.00 4.09 1.66 43.00 4.09 1.66 44.00 4.09 1.66 45.00 4.09 1.66 46.00 4.09 1.66 47.00 4.09 1.66 48.00 4.09 1.66 49.00 4.09 1.66 50.00 4.09 1.66 51.00 4.09 1.66 Runoff (cfs) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.11 1.20 0.67 0.33 0.23 0.19 0.16 0.13 0.12 0.11 0.10 0.09 0.09 0.08 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Time Precip. Excess (hours) (inches) (inches) 52.00 4.09 1.66 53.00 4.09 1.66 54.00 4.09 1.66 55.00 4.09 1.66 56.00 4.09 1.66 57.00 4.09 1.66 58.00 4.09 1.66 59.00 4.09 1.66 60.00 4.09 1.66 61.00 4.09 1.66 62.00 4.09 1.66 63.00 4.09 1.66 64.00 4.09 1.66 65.00 4.09 1.66 66.00 4.09 1.66 67.00 4.09 1.66 68.00 4.09 1.66 69.00 4.09 1.66 70.00 4.09 1.66 71.00 4.09 1.66 72.00 4.09 1.66 Runoff (cfs) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Printed 11/25/2025 Page 8

NOAA 24-hr D 2-Year Rainfall=4.09" 250903_42 ERW Waystone - Future Rainfall Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 11/25/2025 Page 9 Summary for Subcatchment EDA-2 (PERV.): Runoff = 0.77 cfs @ 12.15 hrs, Volume= Routed to Reach DP2-EX : 0.059 af, Depth= 1.66" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year Rainfall=4.09" Area (ac) 0.423 0.423 CN 74 Description >75% Grass cover, Good, HSG C 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.1 100 0.0410 0.24 Sheet Flow, Grass: Short n= 0.150 P2= 3.44" 0.1 21 0.1050 5.22 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 7.2 121 Total Subcatchment EDA-2 (PERV.): Hydrograph 0.85 Runoff 0.8 0.77 cfs NOAA 24-hr D 2-Year Rainfall=4.09" Runoff Area=0.423 ac Runoff Volume=0.059 af Runoff Depth=1.66" Flow Length=121' Tc=7.2 min CN=74 0.75 0.7 0.65 0.6 Flow (cfs) 0.55 0.5 0.45 0.4 0.35 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)