JMA02P003 262 270 Main Street Development Stormwater Management Report

1S 2S Existing Impervious Existing Pervious 3L Total Site Flows Subcat Reach Pond Link Routing Diagram for Existing Flows Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net, Printed 5/26/2026 HydroCAD® 10.20-8a Sampler s/n S05110 © 2025 HydroCAD Software Solutions LLC

Existing Flows Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 5/26/2026 HydroCAD® 10.20-8a Sampler s/n S05110 © 2025 HydroCAD Software Solutions LLC This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and educational use ONLY. For actual design or modeling applications you MUST use a full version of HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete technical support,training materials, and additional features which are essential for actual design work. Rainfall Events Listing Event# Event Storm Type Curve Mode Duration B/B Depth AMC Name (hours) (inches) 1 2-Year-Current NOAA10 24-hr D Default 24.00 1 3.43 2 2 10-Year-Current NOAA10 24-hr D Default 24.00 1 5.33 2 3 100-Year-Current NOAA10 24-hr D Default 24.00 1 9.18 2 4 2-Year-Future NOAA10 24-hr D Default 24.00 1 4.04 2 5 10-Year-Future NOAA10 24-hr D Default 24.00 1 6.31 2 6 100-Year-Future NOAA10 24-hr D Default 24.00 1 11.52 2

Existing Flows Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 5/26/2026 HydroCAD® 10.20-8a Sampler s/n S05110 © 2025 HydroCAD Software Solutions LLC This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and educational use ONLY. For actual design or modeling applications you MUST use a full version of HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete technical support,training materials, and additional features which are essential for actual design work. Area Listing (all nodes) Area CN Description (sq-ft) (subcatchment-numbers) 302 74 >75% Grass cover, Good, HSG C (2S) 18,867 98 Paved parking, HSG C (1S) 11,049 98 Roofs, HSG C (1S) 30,218 98 TOTAL AREA

Existing Flows Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 5/26/2026 HydroCAD® 10.20-8a Sampler s/n S05110 © 2025 HydroCAD Software Solutions LLC This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and educational use ONLY. For actual design or modeling applications you MUST use a full version of HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete technical support,training materials, and additional features which are essential for actual design work. Soil Listing (all nodes) Area Soil Subcatchment (sq-ft) Group Numbers 0 HSG A 0 HSG B 30,218 HSG C 1S, 2S 0 HSG D 0 Other 30,218 TOTAL AREA

Existing Flows Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 5/26/2026 HydroCAD® 10.20-8a Sampler s/n S05110 © 2025 HydroCAD Software Solutions LLC This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and educational use ONLY. For actual design or modeling applications you MUST use a full version of HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete technical support,training materials, and additional features which are essential for actual design work. Ground Covers (all nodes) HSG-A HSG-B HSG-C HSG-D Other Total Ground Subcatch (sq-ft) (sq-ft) (sq-ft) (sq-ft) (sq-ft) (sq-ft) Cover Numbers 0 0 302 0 0 302 >75% Grass cover, Good 0 0 18,867 0 0 18,867 Paved parking 0 0 11,049 0 0 11,049 Roofs 0 0 30,218 0 0 30,218 TOTAL AREA

Existing Flows NOAA10 24-hr D 2-Year-Current Rainfall=3.43" Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 5/26/2026 HydroCAD® 10.20-8a Sampler s/n S05110 © 2025 HydroCAD Software Solutions LLC This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and educational use ONLY. For actual design or modeling applications you MUST use a full version of HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete technical support,training materials, and additional features which are essential for actual design work. 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 1S: Existing Impervious Runoff Area=29,916 sf 100.00% Impervious Runoff Depth=3.20" Flow Length=166' Tc=0.9 min CN=98 Runoff=2.67 cfs 7,969 cf Subcatchment 2S: Existing Pervious Runoff Area=302 sf 0.00% Impervious Runoff Depth=1.19" Tc=1.0 min CN=74 Runoff=0.01 cfs 30 cf Link 3L: Total Site Flows Inflow=2.68 cfs 7,999 cf Primary=2.68 cfs 7,999 cf Total Runoff Area = 30,218 sf Runoff Volume = 7,999 cf Average Runoff Depth = 3.18" 1.00% Pervious = 302 sf 99.00% Impervious = 29,916 sf

Existing Flows NOAA10 24-hr D 2-Year-Current Rainfall=3.43" Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 5/26/2026 HydroCAD® 10.20-8a Sampler s/n S05110 © 2025 HydroCAD Software Solutions LLC This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and educational use ONLY. For actual design or modeling applications you MUST use a full version of HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete technical support,training materials, and additional features which are essential for actual design work. Summary for Subcatchment 1S: Existing Impervious Runoff = 2.67 cfs @ 12.06 hrs, Volume= 7,969 cf, Depth= 3.20" Routed to Link 3L : Total Site Flows Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA10 24-hr D 2-Year-Current Rainfall=3.43" Area (sf) CN Description 11,049 98 Roofs, HSG C 18,867 98 Paved parking, HSG C 29,916 98 Weighted Average 29,916 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.7 100 0.0750 2.42 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.43" 0.2 66 0.0530 4.67 Shallow Concentrated Flow, Paved Kv= 20.3 fps 0.9 166 Total

Existing Flows NOAA10 24-hr D 2-Year-Current Rainfall=3.43" Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 5/26/2026 HydroCAD® 10.20-8a Sampler s/n S05110 © 2025 HydroCAD Software Solutions LLC This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and educational use ONLY. For actual design or modeling applications you MUST use a full version of HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete technical support,training materials, and additional features which are essential for actual design work. Subcatchment 1S: Existing Impervious Hydrograph Runoff 2.67 cfs NOAA10 24-hr D 2-Year-Current Rainfall=3.43" Runoff Area=29,916 sf 2 Runoff Volume=7,969 cf Runoff Depth=3.20" Flow (cfs) Flow Length=166' Tc=0.9 min CN=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)

Existing Flows NOAA10 24-hr D 2-Year-Current Rainfall=3.43" Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 5/26/2026 HydroCAD® 10.20-8a Sampler s/n S05110 © 2025 HydroCAD Software Solutions LLC This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and educational use ONLY. For actual design or modeling applications you MUST use a full version of HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete technical support,training materials, and additional features which are essential for actual design work. Hydrograph for Subcatchment 1S: Existing Impervious Time Precip. Excess Runoff Time Precip. Excess Runoff (hours) (inches) (inches) (cfs) (hours) (inches) (inches) (cfs) 0.00 0.00 0.00 0.00 47.00 3.43 3.20 0.00 1.00 0.04 0.00 0.00 48.00 3.43 3.20 0.00 2.00 0.10 0.01 0.01 49.00 3.43 3.20 0.00 3.00 0.16 0.04 0.03 50.00 3.43 3.20 0.00 4.00 0.22 0.09 0.04 51.00 3.43 3.20 0.00 5.00 0.30 0.14 0.04 52.00 3.43 3.20 0.00 6.00 0.38 0.21 0.05 53.00 3.43 3.20 0.00 7.00 0.47 0.29 0.06 54.00 3.43 3.20 0.00 8.00 0.57 0.38 0.06 55.00 3.43 3.20 0.00 9.00 0.68 0.48 0.08 56.00 3.43 3.20 0.00 10.00 0.82 0.62 0.10 57.00 3.43 3.20 0.00 11.00 1.02 0.81 0.17 58.00 3.43 3.20 0.00 12.00 1.62 1.40 1.67 59.00 3.43 3.20 0.00 13.00 2.41 2.19 0.18 60.00 3.43 3.20 0.00 14.00 2.61 2.38 0.11 61.00 3.43 3.20 0.00 15.00 2.75 2.52 0.09 62.00 3.43 3.20 0.00 16.00 2.86 2.63 0.07 63.00 3.43 3.20 0.00 17.00 2.96 2.73 0.06 64.00 3.43 3.20 0.00 18.00 3.05 2.82 0.06 65.00 3.43 3.20 0.00 19.00 3.13 2.90 0.05 66.00

2.96 2.73 0.06 64.00 3.43 3.20 0.00 18.00 3.05 2.82 0.06 65.00 3.43 3.20 0.00 19.00 3.13 2.90 0.05 66.00 3.43 3.20 0.00 20.00 3.21 2.97 0.05 67.00 3.43 3.20 0.00 21.00 3.27 3.04 0.04 68.00 3.43 3.20 0.00 22.00 3.33 3.10 0.04 69.00 3.43 3.20 0.00 23.00 3.39 3.15 0.03 70.00 3.43 3.20 0.00 24.00 3.43 3.20 0.02 71.00 3.43 3.20 0.00 25.00 3.43 3.20 0.00 72.00 3.43 3.20 0.00 26.00 3.43 3.20 0.00 27.00 3.43 3.20 0.00 28.00 3.43 3.20 0.00 29.00 3.43 3.20 0.00 30.00 3.43 3.20 0.00 31.00 3.43 3.20 0.00 32.00 3.43 3.20 0.00 33.00 3.43 3.20 0.00 34.00 3.43 3.20 0.00 35.00 3.43 3.20 0.00 36.00 3.43 3.20 0.00 37.00 3.43 3.20 0.00 38.00 3.43 3.20 0.00 39.00 3.43 3.20 0.00 40.00 3.43 3.20 0.00 41.00 3.43 3.20 0.00 42.00 3.43 3.20 0.00 43.00 3.43 3.20 0.00 44.00 3.43 3.20 0.00 45.00 3.43 3.20 0.00 46.00 3.43 3.20 0.00