250701_42 ERW_Stormwater Report

250624_42 ERW Waymaker Printed 7/1/2025 Page 6 Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Ground Covers (selected nodes) HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers 0.000 0.000 1.453 0.000 0.000 1.453 0.000 0.000 0.621 0.000 0.000 0.621 0.000 0.000 0.355 0.000 0.000 0.355 0.000 0.000 0.492 0.000 0.000 0.492 0.000 0.000 2.922 0.000 0.000 2.922 >75% Grass cover, Good PR 1A-P , PR 1B-P Gravel roads PR 1A-P , PR 1B-P Paved parking PR 1B-I Roofs PR 1B-I TOTAL AREA

NOAA 24-hr D 2-Year Rainfall=3.44" 250624_42 ERW Waymaker Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 7/1/2025 Page 7 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 PR 1A-P: Runoff Area=13,167 sf 0.00% Impervious Runoff Depth=1.45" Flow Length=203' Tc=5.9 min CN=78 Runoff=0.50 cfs 0.037 af Subcatchment PR 1B-I: Runoff Area=36,906 sf 100.00% Impervious Runoff Depth=3.21" Flow Length=136' Tc=1.5 min CN=98 Runoff=3.04 cfs 0.226 af Subcatchment PR 1B-P: Runoff Area=77,195 sf 0.00% Impervious Runoff Depth=1.52" Flow Length=180' Tc=7.5 min CN=79 Runoff=2.95 cfs 0.224 af Reach 10R: Inflow=5.32 cfs 0.451 af Outflow=5.32 cfs 0.451 af Reach DP1-PR: Inflow=1.22 cfs 0.132 af Outflow=1.22 cfs 0.132 af Pond BASIN: Peak Elev=16.66' Storage=0.115 af Inflow=5.32 cfs 0.451 af Discarded=0.60 cfs 0.355 af Primary=1.05 cfs 0.096 af Outflow=1.65 cfs 0.451 af Total Runoff Area = 2.922 ac Runoff Volume = 0.487 af Average Runoff Depth = 2.00" 71.00% Pervious = 2.074 ac 29.00% Impervious = 0.847 ac

NOAA 24-hr D 2-Year Rainfall=3.44" 250624_42 ERW Waymaker Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 7/1/2025 Page 8 Summary for Subcatchment PR 1A-P: [49] Hint: Tc<2dt may require smaller dt Runoff = 0.50 cfs @ 12.13 hrs, Volume= Routed to Reach DP1-PR : 0.037 af, Depth= 1.45" 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=3.44" Area (sf) 9,975 3,192 13,167 13,167 CN 74 89 78 Description >75% Grass cover, Good, HSG C Gravel roads, HSG C Weighted Average 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.6 100 0.0725 0.30 Sheet Flow, Grass: Short n= 0.150 P2= 3.44" 0.3 103 0.1090 5.32 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 5.9 203 Total Subcatchment PR 1A-P: Hydrograph 0.55 Runoff 0.50 cfs 0.5 0.45 0.4 Flow (cfs) 0.35 0.3 0.25 0.2 0.15 NOAA 24-hr D 2-Year Rainfall=3.44" Runoff Area=13,167 sf Runoff Volume=0.037 af Runoff Depth=1.45" Flow Length=203' Tc=5.9 min CN=78 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)

NOAA 24-hr D 2-Year Rainfall=3.44" 250624_42 ERW Waymaker Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 7/1/2025 Page 9 Summary for Subcatchment PR 1B-I: [49] Hint: Tc<2dt may require smaller dt Runoff = 3.04 cfs @ 12.07 hrs, Volume= Routed to Reach 10R : 0.226 af, Depth= 3.21" 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=3.44" Area (sf) 21,449 15,457 36,906 36,906 CN 98 98 98 Description Roofs, HSG C Paved parking, HSG C Weighted Average 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.2 100 0.0200 1.43 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.44" 0.3 36 0.0139 2.39 Shallow Concentrated Flow, Paved Kv= 20.3 fps 1.5 136 Total Subcatchment PR 1B-I: Hydrograph Runoff 3.04 cfs Flow (cfs) 3 2 1 0 0 NOAA 24-hr D 2-Year Rainfall=3.44" Runoff Area=36,906 sf Runoff Volume=0.226 af Runoff Depth=3.21" Flow Length=136' Tc=1.5 min CN=98 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 Rainfall=3.44" 250624_42 ERW Waymaker Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 7/1/2025 Page 10 Summary for Subcatchment PR 1B-P: Runoff = 2.95 cfs @ 12.15 hrs, Volume= Routed to Reach 10R : 0.224 af, Depth= 1.52" 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=3.44" Area (sf) 53,321 23,874 77,195 77,195 CN 74 89 79 Description >75% Grass cover, Good, HSG C Gravel roads, HSG C Weighted Average 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.2 100 0.0400 0.23 Sheet Flow, Grass: Short n= 0.150 P2= 3.44" 0.3 80 0.0812 4.59 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 7.5 180 Total Subcatchment PR 1B-P: Hydrograph Runoff 2.95 cfs 3 Flow (cfs) 2 1 0 0 NOAA 24-hr D 2-Year Rainfall=3.44" Runoff Area=77,195 sf Runoff Volume=0.224 af Runoff Depth=1.52" Flow Length=180' Tc=7.5 min CN=79 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 Rainfall=3.44" 250624_42 ERW Waymaker Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 7/1/2025 Page 11 Summary for Reach 10R: [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 2.619 ac, 32.35% Impervious, Inflow Depth = 2.07" for 2-Year event Inflow = 5.32 cfs @ 12.09 hrs, Volume= 0.451 af Outflow = 5.32 cfs @ 12.09 hrs, Volume= 0.451 af, Atten= 0%, Lag= 0.0 min Routed to Pond BASIN : Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Reach 10R: Hydrograph 5.32 cfs 5.32 cfs Inflow Outflow Inflow Area=2.619 ac 5 Flow (cfs) 4 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)

NOAA 24-hr D 2-Year Rainfall=3.44" 250624_42 ERW Waymaker Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 7/1/2025 Page 12 Summary for Reach DP1-PR: [40] Hint: Not Described (Outflow=Inflow) Inflow Area = Inflow = Outflow = 2.922 ac, 29.00% Impervious, Inflow Depth = 0.54" for 2-Year event 1.22 cfs @ 12.15 hrs, Volume= 0.132 af 1.22 cfs @ 12.15 hrs, Volume= 0.132 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Reach DP1-PR: Hydrograph 1.22 cfs 1.22 cfs Inflow Outflow Inflow Area=2.922 ac 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)

NOAA 24-hr D 2-Year Rainfall=3.44" 250624_42 ERW Waymaker Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 7/1/2025 Page 13 Summary for Pond BASIN: Inflow Area = 2.619 ac, 32.35% Impervious, Inflow Depth = 2.07" for 2-Year event Inflow = 5.32 cfs @ 12.09 hrs, Volume= 0.451 af Outflow = 1.65 cfs @ 12.36 hrs, Volume= 0.451 af, Atten= 69%, Lag= 16.4 min Discarded = 0.60 cfs @ 12.37 hrs, Volume= 0.355 af Primary = 1.05 cfs @ 12.36 hrs, Volume= 0.096 af Routed to Reach DP1-PR : Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Peak Elev= 16.66' @ 12.37 hrs Surf.Area= 0.108 ac Storage= 0.115 af Plug-Flow detention time= 39.5 min calculated for 0.450 af (100% of inflow) Center-of-Mass det. time= 39.5 min ( 842.9 - 803.4 ) Volume #1A Invert 15.00' Avail.Storage 0.129 af #2A 15.75' 0.216 af 0.345 af Storage Description 44.25'W x 106.08'L x 5.00'H Field A 0.539 af Overall - 0.216 af Embedded = 0.323 af x 40.0% Voids ADS_StormTech MC-3500 d +Cap x 84 Inside #1 Effective Size= 70.4"W x 45.0"H => 15.33 sf x 7.17'L = 110.0 cf Overall Size= 77.0"W x 45.0"H x 7.50'L with 0.33' Overlap 84 Chambers in 6 Rows Cap Storage= 14.9 cf x 2 x 6 rows = 178.8 cf Total Available Storage Storage Group A created with Chamber Wizard Device #1 Routing Primary Invert 15.96' #2 Primary 16.55' #3 Primary 18.90' #4 Discarded 15.00' Outlet Devices 3.5" Vert. Orifice/Grate X 4.00 C= 0.600 Limited to weir flow at low heads 5.0" Vert. Orifice/Grate X 3.00 C= 0.600 Limited to weir flow at low heads 1.0' long x 0.5' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 3.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 13.00' Discarded OutFlow Max=0.60 cfs @ 12.37 hrs HW=16.66' (Free Discharge) 4=Exfiltration ( Controls 0.60 cfs) Primary OutFlow Max=1.05 cfs @ 12.36 hrs HW=16.66' (Free Discharge) 1=Orifice/Grate (Orifice Controls 0.96 cfs @ 3.58 fps) 2=Orifice/Grate (Orifice Controls 0.09 cfs @ 1.12 fps) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

250624_42 ERW Waymaker NOAA 24-hr D 2-Year Rainfall=3.44" Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 7/1/2025 Page 14 Pond BASIN: - Chamber Wizard Field A Chamber Model = ADS_StormTech MC-3500 d +Cap (ADS StormTech® MC-3500 d rev 03/14 with Cap volume) Effective Size= 70.4"W x 45.0"H => 15.33 sf x 7.17'L = 110.0 cf Overall Size= 77.0"W x 45.0"H x 7.50'L with 0.33' Overlap Cap Storage= 14.9 cf x 2 x 6 rows = 178.8 cf 77.0" Wide + 9.0" Spacing = 86.0" C-C Row Spacing 14 Chambers/Row x 7.17' Long +1.85' Cap Length x 2 = 104.08' Row Length +12.0" End Stone x 2 = 106.08' Base Length 6 Rows x 77.0" Wide + 9.0" Spacing x 5 + 12.0" Side Stone x 2 = 44.25' Base Width 9.0" Stone Base + 45.0" Chamber Height + 6.0" Stone Cover = 5.00' Field Height 84 Chambers x 110.0 cf + 14.9 cf Cap Volume x 2 x 6 Rows = 9,414.8 cf Chamber Storage 23,470.2 cf Field - 9,414.8 cf Chambers = 14,055.4 cf Stone x 40.0% Voids = 5,622.2 cf Stone Storage Chamber Storage + Stone Storage = 15,036.9 cf = 0.345 af Overall Storage Efficiency = 64.1% Overall System Size = 106.08' x 44.25' x 5.00' 84 Chambers 869.3 cy Field 520.6 cy Stone

NOAA 24-hr D 2-Year Rainfall=3.44" 250624_42 ERW Waymaker Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 7/1/2025 Page 15 Pond BASIN: Hydrograph 5.32 cfs 5 Inflow Area=2.619 ac Peak Elev=16.66' Storage=0.115 af Flow (cfs) 4 3 1.65 cfs 2 1 0 1.05 cfs 0.60 cfs 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) Inflow Outflow Discarded Primary