251203_42 ERW_Stormwater Report

NOAA 24-hr D 25-Year Rainfall=6.44" 251202_42 ERW Waystone - Future Rainfall Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 12/3/2025 Page 17 Summary for Reach DP2-PR: Inflow Area = Inflow = Outflow = 0.170 ac, 0.00% Impervious, Inflow Depth = 3.76" for 25-Year event 0.76 cfs @ 12.11 hrs, Volume= 0.053 af 0.76 cfs @ 12.11 hrs, Volume= 0.053 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 DP2-PR: Hydrograph Inflow Outflow 0.76 cfs 0.8 0.75 0.76 cfs Inflow Area=0.170 ac 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)

NOAA 24-hr D 25-Year Rainfall=6.44" 251202_42 ERW Waystone - Future Rainfall Printed 12/3/2025 Page 18 Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Hydrograph for Reach DP2-PR: Time (hours) 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 12.00 13.00 14.00 15.00 16.00 17.00 18.00 19.00 20.00 21.00 22.00 23.00 24.00 25.00 26.00 27.00 28.00 29.00 30.00 31.00 32.00 33.00 34.00 35.00 36.00 37.00 38.00 39.00 40.00 41.00 42.00 43.00 44.00 45.00 46.00 47.00 48.00 49.00 50.00 51.00 Inflow Elevation (cfs) (feet) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.02 0.04 0.42 0.09 0.04 0.03 0.03 0.02 0.02 0.02 0.01 0.01 0.01 0.01 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 Outflow (cfs) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.02 0.04 0.42 0.09 0.04 0.03 0.03 0.02 0.02 0.02 0.01 0.01 0.01 0.01 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 (hours) 52.00 53.00 54.00 55.00 56.00 57.00 58.00 59.00 60.00 61.00 62.00 63.00 64.00 65.00 66.00 67.00 68.00 69.00 70.00 71.00 72.00 Inflow (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 Elevation (feet) Outflow (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

251202_42 ERW Waystone - Future Rainfall NOAA 24-hr D 25-Year Rainfall=6.44" Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 12/3/2025 Page 19 Summary for Pond 1P: BASIN - FAILURE Inflow Area = 2.619 ac, 32.35% Impervious, Inflow Depth = 4.76" for 25-Year event Inflow = 11.97 cfs @ 12.10 hrs, Volume= 1.040 af Outflow = 5.27 cfs @ 12.28 hrs, Volume= 0.969 af, Atten= 56%, Lag= 11.2 min Primary = 5.27 cfs @ 12.28 hrs, Volume= 0.969 af Routed to Reach DP1-PR : Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Peak Elev= 17.80' @ 12.28 hrs Surf.Area= 0.168 ac Storage= 0.332 af Plug-Flow detention time= 120.8 min calculated for 0.969 af (93% of inflow) Center-of-Mass det. time= 82.0 min ( 870.7 - 788.7 ) Volume #1A Invert 15.00' Avail.Storage 0.199 af #2A 15.75' 0.341 af 0.539 af Storage Description 51.42'W x 141.93'L x 5.00'H Field A 0.838 af Overall - 0.341 af Embedded = 0.497 af x 40.0% Voids ADS_StormTech MC-3500 d +Cap x 133 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 133 Chambers in 7 Rows Cap Storage= 14.9 cf x 2 x 7 rows = 208.6 cf Total Available Storage Storage Group A created with Chamber Wizard Device #1 Routing Primary Invert 15.89' #2 Primary 16.73' #3 Primary 18.75' Outlet Devices 14.0" W x 3.5" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads 20.0" W x 5.0" H Vert. Orifice/Grate 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 Primary OutFlow Max=5.26 cfs @ 12.28 hrs HW=17.80' (Free Discharge) 1=Orifice/Grate (Orifice Controls 2.17 cfs @ 6.39 fps) 2=Orifice/Grate (Orifice Controls 3.09 cfs @ 4.45 fps) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

251202_42 ERW Waystone - Future Rainfall NOAA 24-hr D 25-Year Rainfall=6.44" Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 12/3/2025 Page 20 Pond 1P: BASIN - FAILURE - Chamber Wizard Field A Chamber Model = ADS_StormTechMC-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 7 rows = 208.6 cf 77.0" Wide + 9.0" Spacing = 86.0" C-C Row Spacing 19 Chambers/Row x 7.17' Long +1.85' Cap Length x 2 = 139.93' Row Length +12.0" End Stone x 2 = 141.93' Base Length 7 Rows x 77.0" Wide + 9.0" Spacing x 6 + 12.0" Side Stone x 2 = 51.42' Base Width 9.0" Stone Base + 45.0" Chamber Height + 6.0" Stone Cover = 5.00' Field Height 133 Chambers x 110.0 cf + 14.9 cf Cap Volume x 2 x 7 Rows = 14,832.2 cf Chamber Storage 36,487.8 cf Field - 14,832.2 cf Chambers = 21,655.6 cf Stone x 40.0% Voids = 8,662.3 cf Stone Storage Chamber Storage + Stone Storage = 23,494.5 cf = 0.539 af Overall Storage Efficiency = 64.4% Overall System Size = 141.93' x 51.42' x 5.00' 133 Chambers 1,351.4 cy Field 802.1 cy Stone

251202_42 ERW Waystone - Future Rainfall NOAA 24-hr D 25-Year Rainfall=6.44" Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 12/3/2025 Page 21 Pond 1P: BASIN - FAILURE Hydrograph 13 Inflow Area=2.619 ac Peak Elev=17.80' Storage=0.332 af 12 11 10 9 Flow (cfs) Inflow Primary 11.97 cfs 8 7 6 5.27 cfs 5 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)

251202_42 ERW Waystone - Future Rainfall NOAA 24-hr D 25-Year Rainfall=6.44" Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Hydrograph for Pond 1P: BASIN - FAILURE Time (hours) 0.00 2.50 5.00 7.50 10.00 12.50 15.00 17.50 20.00 22.50 25.00 27.50 30.00 32.50 35.00 37.50 40.00 42.50 45.00 47.50 50.00 52.50 55.00 57.50 60.00 62.50 65.00 67.50 70.00 Inflow (cfs) 0.00 0.05 0.08 0.16 0.45 2.82 0.52 0.32 0.24 0.20 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 Storage Elevation (acre-feet) (feet) 0.000 15.00 0.005 15.07 0.019 15.28 0.041 15.61 0.091 16.03 0.307 17.60 0.139 16.37 0.102 16.11 0.095 16.06 0.092 16.04 0.081 15.96 0.074 15.91 0.072 15.90 0.071 15.90 0.071 15.89 0.071 15.89 0.071 15.89 0.071 15.89 0.071 15.89 0.071 15.89 0.071 15.89 0.071 15.89 0.071 15.89 0.071 15.89 0.071 15.89 0.071 15.89 0.071 15.89 0.071 15.89 0.071 15.89 Primary (cfs) 0.00 0.00 0.00 0.00 0.20 4.76 0.93 0.38 0.26 0.22 0.07 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 Printed 12/3/2025 Page 22

251202_42 ERW Waystone - Future Rainfall NOAA 24-hr D 25-Year Rainfall=6.44" Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Stage-Discharge for Pond 1P: BASIN - FAILURE Elevation (feet) 15.00 15.05 15.10 15.15 15.20 15.25 15.30 15.35 15.40 15.45 15.50 15.55 15.60 15.65 15.70 15.75 15.80 15.85 15.90 15.95 16.00 16.05 16.10 16.15 16.20 16.25 16.30 16.35 16.40 16.45 16.50 16.55 16.60 16.65 16.70 16.75 16.80 16.85 16.90 16.95 17.00 17.05 17.10 17.15 17.20 17.25 17.30 17.35 17.40 17.45 17.50 17.55 Primary (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 0.06 0.14 0.24 0.36 0.50 0.64 0.74 0.83 0.91 0.98 1.05 1.11 1.17 1.23 1.28 1.33 1.40 1.53 1.70 1.90 2.12 2.36 2.62 2.89 3.18 3.42 3.63 3.82 4.00 4.16 4.32 4.47 4.62 Elevation (feet) 17.60 17.65 17.70 17.75 17.80 17.85 17.90 17.95 18.00 18.05 18.10 18.15 18.20 18.25 18.30 18.35 18.40 18.45 18.50 18.55 18.60 18.65 18.70 18.75 18.80 18.85 18.90 18.95 19.00 19.05 19.10 19.15 19.20 19.25 19.30 19.35 19.40 19.45 19.50 19.55 19.60 19.65 19.70 19.75 19.80 19.85 19.90 19.95 20.00 Primary (cfs) 4.76 4.89 5.02 5.15 5.27 5.39 5.51 5.62 5.74 5.85 5.95 6.06 6.16 6.26 6.36 6.46 6.56 6.65 6.75 6.84 6.93 7.02 7.11 7.20 7.31 7.46 7.62 7.79 7.97 8.17 8.38 8.60 8.83 9.08 9.34 9.60 9.89 10.19 10.51 10.83 11.14 11.45 11.76 12.08 12.41 12.73 13.07 13.41 13.75 Printed 12/3/2025 Page 23

251202_42 ERW Waystone - Future Rainfall NOAA 24-hr D 25-Year Rainfall=6.44" Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Stage-Area-Storage for Pond 1P: BASIN - FAILURE Elevation (feet) 15.00 15.05 15.10 15.15 15.20 15.25 15.30 15.35 15.40 15.45 15.50 15.55 15.60 15.65 15.70 15.75 15.80 15.85 15.90 15.95 16.00 16.05 16.10 16.15 16.20 16.25 16.30 16.35 16.40 16.45 16.50 16.55 16.60 16.65 16.70 16.75 16.80 16.85 16.90 16.95 17.00 17.05 17.10 17.15 17.20 17.25 17.30 17.35 17.40 17.45 17.50 17.55 Storage (acre-feet) 0.000 0.003 0.007 0.010 0.013 0.017 0.020 0.023 0.027 0.030 0.034 0.037 0.040 0.044 0.047 0.050 0.058 0.065 0.072 0.079 0.086 0.094 0.101 0.108 0.115 0.122 0.129 0.136 0.143 0.151 0.158 0.165 0.172 0.179 0.186 0.193 0.199 0.206 0.213 0.220 0.227 0.234 0.241 0.247 0.254 0.261 0.267 0.274 0.281 0.287 0.294 0.300 Elevation (feet) 17.60 17.65 17.70 17.75 17.80 17.85 17.90 17.95 18.00 18.05 18.10 18.15 18.20 18.25 18.30 18.35 18.40 18.45 18.50 18.55 18.60 18.65 18.70 18.75 18.80 18.85 18.90 18.95 19.00 19.05 19.10 19.15 19.20 19.25 19.30 19.35 19.40 19.45 19.50 19.55 19.60 19.65 19.70 19.75 19.80 19.85 19.90 19.95 20.00 Storage (acre-feet) 0.307 0.313 0.320 0.326 0.332 0.339 0.345 0.351 0.357 0.363 0.369 0.375 0.381 0.387 0.393 0.399 0.405 0.410 0.416 0.421 0.427 0.432 0.438 0.443 0.448 0.453 0.458 0.463 0.467 0.472 0.476 0.480 0.484 0.488 0.492 0.495 0.499 0.502 0.506 0.509 0.513 0.516 0.519 0.523 0.526 0.529 0.533 0.536 0.539 Printed 12/3/2025 Page 24

Project No: Calculated By: Checked By: Conduit Outlet Protection Calculations Scour Hole # S2 Design Parameters: Design Storm Flow for 25 Year, Q . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vertical Dimension of Outlet Pipe, D o . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Horizontal Dimension of Outlet Pipe, W o . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tailwater Depth, TW 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Scour Hole Depth, y (1/2 D o or D o ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Apron Dimension Calculations: Minimum Bottom Width, W 1 = 2W o . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Minimum Bottom Length, L 1 = 3D o . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Minimum Top Width (max side slope of 3:1) , W 2 . . . . . . . . . . . . . . . . . . . . . . . . Minimum Top Length (max side slope of 3:1) , L 2 . . . . . . . . . . . . . . . . . . . . . . . . Rip Rap Stone Size Calculations: Unit Dicharge, q = Q/D o = · 3.51 cfs per foot Case I: y = 1/2 D o 0.0125 q 1.33 = 1.45 in Therefore, use TW Apron Thickness, TH = 2×d 50 with filter fabric . . . . . . . . . . . . . . . . . . . . . Median Stone, d 50 = · W1 = L1 = W2 = L2 = Case II: y = D o 0.0082 q 1.33 = TW Apron Thickness, TH = 2×d 50 with filter fabric . . . . . . . . . . . . . . . . . . . . . . . Median Stone, d 50 = Notes: This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. d50 = TH =

Colliers Engineering & Design is a trusted provider of multi-discipline engineering, design and consulting services providing customized solutions for public and private clients through a network of offices nationwide. For a full listing of our office locations, please visit colliersengineering.com 1 877 627 3772 Civil/Site • Traffic/Transportation • Governmental • Survey/Geospatial Infrastructure • Geotechnical/Environmental • Telecommunications • Utilities/Energy Stormwater Management Report | October 18, 2024 – Last Revised December 3, 2025