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HomeMy WebLinkAbout2025-103 drainage calcs composite-645 rt 28, w. yarmouth Stormwater Management Calculations for Mixed-Use Redevelopment Project 645 Main Street West Yarmouth, Massachusetts Prepared for: Bayridge Realty, LLC 76 Tupper Road, Unit #10 Sandwich, MA 02563 November 17, 2025 BAXTER NYE ENGINEERING & SURVEYING Registered Professional Engineers, Land Surveyors & Scientists 1597 Falmouth Road ■ Centerville, MA 02632 Tel: 508-771-7502 ■ www.baxter-nye.com BAXTER NYE ENGINEERING & SURVEYING 1597 Falmouth Road, Suite 1 ■ Centerville, MA 02632 Tel: 508-771-7502 ■ www.baxter-nye.com TABLE 1: PEAK DISCHARGE AND VOLUME RELEASE STORM (YEAR) STUDY POINT PRE-DEVELOPMENT POST DEVELOPMENT PEAK DISCHARGE (cfs) VOLUME (ac-ft) PEAK DISCHARGE (cfs) VOLUME (ac-ft) 2 SP1 0.08 0.006 0.00 0.000 SP2 0.15 0.010 0.00 0.000 SP3 0.09 0.006 0.00 0.000 SP4 0.83 0.053 0.00 0.000 SP5 0.00 0.001 0.00 0.000 10 SP1 0.21 0.014 0.02 0.002 SP2 0.36 0.023 0.00 0.001 SP3 0.19 0.012 0.00 0.001 SP4 1.58 0.101 0.00 0.001 SP5 0.03 0.005 0.01 0.002 25 SP1 0.31 0.020 0.04 0.004 SP2 0.50 0.032 0.01 0.002 SP3 0.26 0.017 0.02 0.003 SP4 2.08 0.133 0.00 0.000 SP5 0.10 0.009 0.03 0.004 100 SP1 0.48 0.031 0.10 0.007 SP2 0.75 0.048 0.05 0.005 SP3 0.37 0.077 0.06 0.006 SP4 2.85 0.185 0.00 0.000 SP5 0.23 0.018 0.10 0.009 BAXTER NYEENGINEERING &SURVEYINGBayridge Realty, LLC76 Tupper Road, Unit #10Sandwich, MA 02563Proposed Mixed-UseRedevelopment Project645 Main Street (Route 28)West Yarmouth, MA 02673FOR PERMIT ONLY - NOT FOR CONSTRUCTIONSHEET TITLEDATE:CHECKED BY:JOB NO:DRAWN BY:DESCRIPTIONDATEPREPARED FOR:PROJECT TITLESHEET NOSCALE:STAMPCONSULTANTFILE:CONSULTANTSTAMPCOPYRIGHT c 2025, BY SMART ENGINEERING LLC, dba BAXTER NYE ENGINEERING & SURVEYING, ALL RIGHTS RESERVED.DA1.0Pre-DevelopmentDrainage Areas PlanO:\2025\2025-103\CIVIL\PLOT\2025-103 DA-PRE.dwg, 11/3/2025 1:16:27 PM, jlavelle, DWG To PDF.pc3, 1:1 Redevelopment Site 645 Route 28, West Yarmouth, MA Project # 2025-103 Date 11/4/25 TSS REMOVAL CALCULATION WORKSHEET New Parking Lot SWM Facility A B C D E BMP TSS Removal Rate Starting TSS Load * Amount Removed Remaining Load (BxC)(C-D) Street Sweeping 10% 1.00 0.10 0.90 Sediment Forebay 25% 0.90 0.23 0.68 Deep Sump Catch Basin 25% 0.68 0.17 0.51 Cultec Infiltration Chambers 80% 0.51 0.41 0.10 Total TSS Removed = 0.90 Baxter Nye Engineering 2025-103 TSS Removal Spreadsheet.xls 1 Area to Appleby Rd North CB 2 Area to site CB 3 Area to east 4 Area to low point 5 Area to Appleby Road South CB Routing Diagram for 2025-103 EXISTING Prepared by Baxter-Nye Engineering & Survey, Printed 12/1/2025 HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Subcat Reach Pond Link 645 Main Street, West Yarmouth, MA 2025-103 EXISTING Printed 12/1/2025Prepared by Baxter-Nye Engineering & Survey Page 2HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Rainfall Events Listing Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC 1 2-Year Type III 24-hr Default 24.00 1 3.37 2 2 10-Year Type III 24-hr Default 24.00 1 4.90 2 3 25-Year Type III 24-hr Default 24.00 1 5.86 2 4 100-Year Type III 24-hr Default 24.00 1 7.33 2 645 Main Street, West Yarmouth, MA Type III 24-hr 2-Year Rainfall=3.37"2025-103 EXISTING Printed 12/1/2025Prepared by Baxter-Nye Engineering & Survey Page 3HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1: Area to Appleby Rd North CB Runoff = 0.08 cfs @ 12.09 hrs, Volume= 0.006 af, Depth> 0.57" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 2-Year Rainfall=3.37" Area (ac) CN Description 0.052 98 Paved parking, HSG A 0.071 39 >75% Grass cover, Good, HSG A 0.123 64 Weighted Average 0.071 57.72% Pervious Area 0.052 42.28% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 2: Area to site CB Runoff = 0.15 cfs @ 12.09 hrs, Volume= 0.010 af, Depth> 0.74" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 2-Year Rainfall=3.37" Area (ac) CN Description 0.082 98 Paved parking, HSG A 0.085 39 >75% Grass cover, Good, HSG A 0.167 68 Weighted Average 0.085 50.90% Pervious Area 0.082 49.10% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 3: Area to east Runoff = 0.09 cfs @ 12.08 hrs, Volume= 0.006 af, Depth> 0.89" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 2-Year Rainfall=3.37" 645 Main Street, West Yarmouth, MA Type III 24-hr 2-Year Rainfall=3.37"2025-103 EXISTING Printed 12/1/2025Prepared by Baxter-Nye Engineering & Survey Page 4HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Area (ac) CN Description 0.042 98 Paved parking, HSG A 0.035 39 >75% Grass cover, Good, HSG A 0.077 71 Weighted Average 0.035 45.45% Pervious Area 0.042 54.55% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 4: Area to low point Runoff = 0.83 cfs @ 12.08 hrs, Volume= 0.053 af, Depth> 1.29" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 2-Year Rainfall=3.37" Area (ac) CN Description 0.294 98 Paved parking, HSG A 0.153 39 >75% Grass cover, Good, HSG A 0.036 96 Gravel surface, HSG A 0.012 30 Woods, Good, HSG A 0.495 78 Weighted Average 0.201 40.61% Pervious Area 0.294 59.39% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 5: Area to Appleby Road South CB Runoff = 0.00 cfs @ 14.72 hrs, Volume= 0.001 af, Depth> 0.06" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 2-Year Rainfall=3.37" Area (ac) CN Description 0.027 98 Paved parking, HSG A 0.076 39 >75% Grass cover, Good, HSG A 0.057 30 Woods, Good, HSG A 0.160 46 Weighted Average 0.133 83.12% Pervious Area 0.027 16.87% Impervious Area 645 Main Street, West Yarmouth, MA Type III 24-hr 2-Year Rainfall=3.37"2025-103 EXISTING Printed 12/1/2025Prepared by Baxter-Nye Engineering & Survey Page 5HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum 645 Main Street, West Yarmouth, MA Type III 24-hr 10-Year Rainfall=4.90"2025-103 EXISTING Printed 12/1/2025Prepared by Baxter-Nye Engineering & Survey Page 6HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1: Area to Appleby Rd North CB Runoff = 0.21 cfs @ 12.08 hrs, Volume= 0.014 af, Depth> 1.38" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 10-Year Rainfall=4.90" Area (ac) CN Description 0.052 98 Paved parking, HSG A 0.071 39 >75% Grass cover, Good, HSG A 0.123 64 Weighted Average 0.071 57.72% Pervious Area 0.052 42.28% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 2: Area to site CB Runoff = 0.36 cfs @ 12.08 hrs, Volume= 0.023 af, Depth> 1.66" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 10-Year Rainfall=4.90" Area (ac) CN Description 0.082 98 Paved parking, HSG A 0.085 39 >75% Grass cover, Good, HSG A 0.167 68 Weighted Average 0.085 50.90% Pervious Area 0.082 49.10% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 3: Area to east Runoff = 0.19 cfs @ 12.08 hrs, Volume= 0.012 af, Depth> 1.88" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 10-Year Rainfall=4.90" 645 Main Street, West Yarmouth, MA Type III 24-hr 10-Year Rainfall=4.90"2025-103 EXISTING Printed 12/1/2025Prepared by Baxter-Nye Engineering & Survey Page 7HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Area (ac) CN Description 0.042 98 Paved parking, HSG A 0.035 39 >75% Grass cover, Good, HSG A 0.077 71 Weighted Average 0.035 45.45% Pervious Area 0.042 54.55% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 4: Area to low point Runoff = 1.58 cfs @ 12.08 hrs, Volume= 0.101 af, Depth> 2.45" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 10-Year Rainfall=4.90" Area (ac) CN Description 0.294 98 Paved parking, HSG A 0.153 39 >75% Grass cover, Good, HSG A 0.036 96 Gravel surface, HSG A 0.012 30 Woods, Good, HSG A 0.495 78 Weighted Average 0.201 40.61% Pervious Area 0.294 59.39% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 5: Area to Appleby Road South CB Runoff = 0.03 cfs @ 12.28 hrs, Volume= 0.005 af, Depth> 0.39" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 10-Year Rainfall=4.90" Area (ac) CN Description 0.027 98 Paved parking, HSG A 0.076 39 >75% Grass cover, Good, HSG A 0.057 30 Woods, Good, HSG A 0.160 46 Weighted Average 0.133 83.12% Pervious Area 0.027 16.87% Impervious Area 645 Main Street, West Yarmouth, MA Type III 24-hr 10-Year Rainfall=4.90"2025-103 EXISTING Printed 12/1/2025Prepared by Baxter-Nye Engineering & Survey Page 8HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum 645 Main Street, West Yarmouth, MA Type III 24-hr 25-Year Rainfall=5.86"2025-103 EXISTING Printed 12/1/2025Prepared by Baxter-Nye Engineering & Survey Page 9HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1: Area to Appleby Rd North CB Runoff = 0.31 cfs @ 12.08 hrs, Volume= 0.020 af, Depth> 1.98" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 25-Year Rainfall=5.86" Area (ac) CN Description 0.052 98 Paved parking, HSG A 0.071 39 >75% Grass cover, Good, HSG A 0.123 64 Weighted Average 0.071 57.72% Pervious Area 0.052 42.28% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 2: Area to site CB Runoff = 0.50 cfs @ 12.08 hrs, Volume= 0.032 af, Depth> 2.32" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 25-Year Rainfall=5.86" Area (ac) CN Description 0.082 98 Paved parking, HSG A 0.085 39 >75% Grass cover, Good, HSG A 0.167 68 Weighted Average 0.085 50.90% Pervious Area 0.082 49.10% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 3: Area to east Runoff = 0.26 cfs @ 12.08 hrs, Volume= 0.017 af, Depth> 2.58" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 25-Year Rainfall=5.86" 645 Main Street, West Yarmouth, MA Type III 24-hr 25-Year Rainfall=5.86"2025-103 EXISTING Printed 12/1/2025Prepared by Baxter-Nye Engineering & Survey Page 10HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Area (ac) CN Description 0.042 98 Paved parking, HSG A 0.035 39 >75% Grass cover, Good, HSG A 0.077 71 Weighted Average 0.035 45.45% Pervious Area 0.042 54.55% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 4: Area to low point Runoff = 2.08 cfs @ 12.07 hrs, Volume= 0.133 af, Depth> 3.23" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 25-Year Rainfall=5.86" Area (ac) CN Description 0.294 98 Paved parking, HSG A 0.153 39 >75% Grass cover, Good, HSG A 0.036 96 Gravel surface, HSG A 0.012 30 Woods, Good, HSG A 0.495 78 Weighted Average 0.201 40.61% Pervious Area 0.294 59.39% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 5: Area to Appleby Road South CB Runoff = 0.10 cfs @ 12.11 hrs, Volume= 0.009 af, Depth> 0.71" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 25-Year Rainfall=5.86" Area (ac) CN Description 0.027 98 Paved parking, HSG A 0.076 39 >75% Grass cover, Good, HSG A 0.057 30 Woods, Good, HSG A 0.160 46 Weighted Average 0.133 83.12% Pervious Area 0.027 16.87% Impervious Area 645 Main Street, West Yarmouth, MA Type III 24-hr 25-Year Rainfall=5.86"2025-103 EXISTING Printed 12/1/2025Prepared by Baxter-Nye Engineering & Survey Page 11HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum 645 Main Street, West Yarmouth, MA Type III 24-hr 100-Year Rainfall=7.33"2025-103 EXISTING Printed 12/1/2025Prepared by Baxter-Nye Engineering & Survey Page 12HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1: Area to Appleby Rd North CB Runoff = 0.48 cfs @ 12.08 hrs, Volume= 0.031 af, Depth> 3.01" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 100-Year Rainfall=7.33" Area (ac) CN Description 0.052 98 Paved parking, HSG A 0.071 39 >75% Grass cover, Good, HSG A 0.123 64 Weighted Average 0.071 57.72% Pervious Area 0.052 42.28% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 2: Area to site CB Runoff = 0.75 cfs @ 12.08 hrs, Volume= 0.048 af, Depth> 3.42" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 100-Year Rainfall=7.33" Area (ac) CN Description 0.082 98 Paved parking, HSG A 0.085 39 >75% Grass cover, Good, HSG A 0.167 68 Weighted Average 0.085 50.90% Pervious Area 0.082 49.10% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 3: Area to east Runoff = 0.37 cfs @ 12.08 hrs, Volume= 0.024 af, Depth> 3.73" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 100-Year Rainfall=7.33" 645 Main Street, West Yarmouth, MA Type III 24-hr 100-Year Rainfall=7.33"2025-103 EXISTING Printed 12/1/2025Prepared by Baxter-Nye Engineering & Survey Page 13HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Area (ac) CN Description 0.042 98 Paved parking, HSG A 0.035 39 >75% Grass cover, Good, HSG A 0.077 71 Weighted Average 0.035 45.45% Pervious Area 0.042 54.55% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 4: Area to low point Runoff = 2.85 cfs @ 12.07 hrs, Volume= 0.185 af, Depth> 4.48" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 100-Year Rainfall=7.33" Area (ac) CN Description 0.294 98 Paved parking, HSG A 0.153 39 >75% Grass cover, Good, HSG A 0.036 96 Gravel surface, HSG A 0.012 30 Woods, Good, HSG A 0.495 78 Weighted Average 0.201 40.61% Pervious Area 0.294 59.39% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 5: Area to Appleby Road South CB Runoff = 0.23 cfs @ 12.09 hrs, Volume= 0.018 af, Depth> 1.32" Routed to nonexistent node 1P Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 100-Year Rainfall=7.33" Area (ac) CN Description 0.027 98 Paved parking, HSG A 0.076 39 >75% Grass cover, Good, HSG A 0.057 30 Woods, Good, HSG A 0.160 46 Weighted Average 0.133 83.12% Pervious Area 0.027 16.87% Impervious Area 645 Main Street, West Yarmouth, MA Type III 24-hr 100-Year Rainfall=7.33"2025-103 EXISTING Printed 12/1/2025Prepared by Baxter-Nye Engineering & Survey Page 14HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum BAXTER NYEENGINEERING &SURVEYINGBayridge Realty, LLC76 Tupper Road, Unit #10Sandwich, MA 02563Proposed Mixed-UseRedevelopment Project645 Main Street (Route 28)West Yarmouth, MA 02673FOR PERMIT ONLY - NOT FOR CONSTRUCTIONSHEET TITLEDATE:CHECKED BY:JOB NO:DRAWN BY:DESCRIPTIONDATEPREPARED FOR:PROJECT TITLESHEET NOSCALE:STAMPCONSULTANTFILE:CONSULTANTSTAMPCOPYRIGHT c 2025, BY SMART ENGINEERING LLC, dba BAXTER NYE ENGINEERING & SURVEYING, ALL RIGHTS RESERVED.DA1.1Post-DevelopmentDrainage Areas PlanO:\2025\2025-103\CIVIL\PLOT\2025-103 DA-POST.dwg, 11/3/2025 1:40:04 PM, jlavelle, DWG To PDF.pc3, 1:1 1 Area to Appleby Rd North CB 2 Area to northeast 3 Area to east 4 New Parking Lot 5 Area to Appleby Rd South CB R New Bldg Roof SP5 Study Point 5 1P Cultec 300s Routing Diagram for 2025-103 PROPOSED Prepared by Baxter-Nye Engineering & Survey, Printed 12/2/2025 HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Subcat Reach Pond Link 645 Main Street, West Yarmouth, MA 2025-103 PROPOSED Printed 12/2/2025Prepared by Baxter-Nye Engineering & Survey Page 2HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Rainfall Events Listing Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC 1 2-Year Type III 24-hr Default 24.00 1 3.37 2 2 10-Year Type III 24-hr Default 24.00 1 4.90 2 3 25-Year Type III 24-hr Default 24.00 1 5.86 2 4 100-Year Type III 24-hr Default 24.00 1 7.33 2 645 Main Street, West Yarmouth, MA Type III 24-hr 2-Year Rainfall=3.37"2025-103 PROPOSED Printed 12/2/2025Prepared by Baxter-Nye Engineering & Survey Page 3HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1: Area to Appleby Rd North CB Runoff = 0.00 cfs @ 13.76 hrs, Volume= 0.000 af, Depth> 0.08" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 2-Year Rainfall=3.37" Area (ac) CN Description 0.008 98 Paved parking, HSG A 0.053 39 >75% Grass cover, Good, HSG A 0.061 47 Weighted Average 0.053 86.89% Pervious Area 0.008 13.11% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 2: Area to northeast Runoff = 0.00 cfs @ 20.00 hrs, Volume= 0.000 af, Depth> 0.00" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 2-Year Rainfall=3.37" Area (ac) CN Description 0.083 39 >75% Grass cover, Good, HSG A 0.083 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 3: Area to east Runoff = 0.00 cfs @ 20.00 hrs, Volume= 0.000 af, Depth> 0.00" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 2-Year Rainfall=3.37" Area (ac) CN Description 0.099 39 >75% Grass cover, Good, HSG A 0.099 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum 645 Main Street, West Yarmouth, MA Type III 24-hr 2-Year Rainfall=3.37"2025-103 PROPOSED Printed 12/2/2025Prepared by Baxter-Nye Engineering & Survey Page 4HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 4: New Parking Lot Runoff = 0.53 cfs @ 12.08 hrs, Volume= 0.035 af, Depth> 0.94" Routed to Pond 1P : Cultec 300s Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 2-Year Rainfall=3.37" Area (ac) CN Description 0.252 98 Paved parking, HSG A 0.195 39 >75% Grass cover, Good, HSG A 0.447 72 Weighted Average 0.195 43.62% Pervious Area 0.252 56.38% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 5: Area to Appleby Rd South CB Runoff = 0.00 cfs @ 17.03 hrs, Volume= 0.000 af, Depth> 0.01" Routed to Reach SP5 : Study Point 5 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 2-Year Rainfall=3.37" Area (ac) CN Description 0.007 98 Paved parking, HSG A 0.081 39 >75% Grass cover, Good, HSG A 0.016 30 Woods, Good, HSG A 0.104 42 Weighted Average 0.097 93.27% Pervious Area 0.007 6.73% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment R: New Bldg Roof Runoff = 0.57 cfs @ 12.07 hrs, Volume= 0.041 af, Depth> 2.93" Routed to Pond 1P : Cultec 300s Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 2-Year Rainfall=3.37" 645 Main Street, West Yarmouth, MA Type III 24-hr 2-Year Rainfall=3.37"2025-103 PROPOSED Printed 12/2/2025Prepared by Baxter-Nye Engineering & Survey Page 5HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Area (ac) CN Description 0.168 98 Roofs, HSG A 0.168 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Reach SP5: Study Point 5 Inflow Area = 0.719 ac, 59.39% Impervious, Inflow Depth > 0.00" for 2-Year event Inflow = 0.00 cfs @ 17.03 hrs, Volume= 0.000 af Outflow = 0.00 cfs @ 17.03 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Summary for Pond 1P: Cultec 300s Inflow Area = 0.615 ac, 68.29% Impervious, Inflow Depth > 1.49" for 2-Year event Inflow = 1.09 cfs @ 12.08 hrs, Volume= 0.076 af Outflow = 0.23 cfs @ 12.52 hrs, Volume= 0.076 af, Atten= 79%, Lag= 26.3 min Discarded = 0.23 cfs @ 12.52 hrs, Volume= 0.076 af Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af Routed to Reach SP5 : Study Point 5 Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs / 3 Peak Elev= 6.10' @ 12.52 hrs Surf.Area= 1,000 sf Storage= 882 cf Plug-Flow detention time= 26.3 min calculated for 0.076 af (100% of inflow) Center-of-Mass det. time= 26.1 min ( 801.4 - 775.3 ) Volume Invert Avail.Storage Storage Description #1A 4.70' 741 cf 20.50'W x 39.02'L x 3.50'H Field A 2,799 cf Overall - 946 cf Embedded = 1,853 cf x 40.0% Voids #2A 5.20' 946 cf Cultec R-300HD x 20 Inside #1 Effective Size= 45.6"W x 30.0"H => 6.53 sf x 7.08'L = 46.2 cf Overall Size= 51.0"W x 30.0"H x 7.54'L with 0.46' Overlap 20 Chambers in 4 Rows Cap Storage= 2.7 cf x 2 x 4 rows = 21.2 cf #3 5.00' 1,263 cf Custom Stage Data (Conic) Listed below (Recalc) #4 8.75' 1,374 cf Custom Stage Data (Conic) Listed below (Recalc) 4,325 cf Total Available Storage Storage Group A created with Chamber Wizard 645 Main Street, West Yarmouth, MA Type III 24-hr 2-Year Rainfall=3.37"2025-103 PROPOSED Printed 12/2/2025Prepared by Baxter-Nye Engineering & Survey Page 6HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Elevation Surf.Area Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (cubic-feet) (cubic-feet) (sq-ft) 5.00 93 0 0 93 7.00 320 390 390 340 8.00 674 486 876 703 8.50 878 387 1,263 912 Elevation Surf.Area Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (cubic-feet) (cubic-feet) (sq-ft) 8.75 4 0 0 4 9.00 1,538 135 135 1,538 9.50 3,556 1,239 1,374 3,558 Device Routing Invert Outlet Devices #1 Discarded 4.70'8.270 in/hr Exfiltration over Wetted area from 4.60' - 8.20' Excluded Wetted area = 0 sf #2 Discarded 5.99'8.410 in/hr Exfiltration over Surface area from 5.99' - 8.74' Excluded Surface area = 988 sf #3 Primary 9.40'10.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s) 0.5' Crest Height Discarded OutFlow Max=0.23 cfs @ 12.52 hrs HW=6.10' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.23 cfs) 2=Exfiltration (Exfiltration Controls 0.00 cfs) Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=4.70' (Free Discharge) 3=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs) 645 Main Street, West Yarmouth, MA Type III 24-hr 10-Year Rainfall=4.90"2025-103 PROPOSED Printed 12/2/2025Prepared by Baxter-Nye Engineering & Survey Page 7HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1: Area to Appleby Rd North CB Runoff = 0.02 cfs @ 12.13 hrs, Volume= 0.002 af, Depth> 0.43" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 10-Year Rainfall=4.90" Area (ac) CN Description 0.008 98 Paved parking, HSG A 0.053 39 >75% Grass cover, Good, HSG A 0.061 47 Weighted Average 0.053 86.89% Pervious Area 0.008 13.11% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 2: Area to northeast Runoff = 0.00 cfs @ 12.48 hrs, Volume= 0.001 af, Depth> 0.14" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 10-Year Rainfall=4.90" Area (ac) CN Description 0.083 39 >75% Grass cover, Good, HSG A 0.083 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 3: Area to east Runoff = 0.00 cfs @ 12.48 hrs, Volume= 0.001 af, Depth> 0.14" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 10-Year Rainfall=4.90" Area (ac) CN Description 0.099 39 >75% Grass cover, Good, HSG A 0.099 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum 645 Main Street, West Yarmouth, MA Type III 24-hr 10-Year Rainfall=4.90"2025-103 PROPOSED Printed 12/2/2025Prepared by Baxter-Nye Engineering & Survey Page 8HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 4: New Parking Lot Runoff = 1.14 cfs @ 12.08 hrs, Volume= 0.073 af, Depth> 1.96" Routed to Pond 1P : Cultec 300s Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 10-Year Rainfall=4.90" Area (ac) CN Description 0.252 98 Paved parking, HSG A 0.195 39 >75% Grass cover, Good, HSG A 0.447 72 Weighted Average 0.195 43.62% Pervious Area 0.252 56.38% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 5: Area to Appleby Rd South CB Runoff = 0.01 cfs @ 12.38 hrs, Volume= 0.002 af, Depth> 0.23" Routed to Reach SP5 : Study Point 5 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 10-Year Rainfall=4.90" Area (ac) CN Description 0.007 98 Paved parking, HSG A 0.081 39 >75% Grass cover, Good, HSG A 0.016 30 Woods, Good, HSG A 0.104 42 Weighted Average 0.097 93.27% Pervious Area 0.007 6.73% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment R: New Bldg Roof Runoff = 0.83 cfs @ 12.07 hrs, Volume= 0.061 af, Depth> 4.33" Routed to Pond 1P : Cultec 300s Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 10-Year Rainfall=4.90" 645 Main Street, West Yarmouth, MA Type III 24-hr 10-Year Rainfall=4.90"2025-103 PROPOSED Printed 12/2/2025Prepared by Baxter-Nye Engineering & Survey Page 9HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Area (ac) CN Description 0.168 98 Roofs, HSG A 0.168 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Reach SP5: Study Point 5 Inflow Area = 0.719 ac, 59.39% Impervious, Inflow Depth > 0.03" for 10-Year event Inflow = 0.01 cfs @ 12.38 hrs, Volume= 0.002 af Outflow = 0.01 cfs @ 12.38 hrs, Volume= 0.002 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Summary for Pond 1P: Cultec 300s Inflow Area = 0.615 ac, 68.29% Impervious, Inflow Depth > 2.60" for 10-Year event Inflow = 1.97 cfs @ 12.07 hrs, Volume= 0.133 af Outflow = 0.35 cfs @ 12.54 hrs, Volume= 0.133 af, Atten= 82%, Lag= 27.8 min Discarded = 0.35 cfs @ 12.54 hrs, Volume= 0.133 af Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af Routed to Reach SP5 : Study Point 5 Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs / 3 Peak Elev= 7.35' @ 12.54 hrs Surf.Area= 1,228 sf Storage= 1,918 cf Plug-Flow detention time= 51.3 min calculated for 0.133 af (100% of inflow) Center-of-Mass det. time= 51.0 min ( 823.1 - 772.1 ) Volume Invert Avail.Storage Storage Description #1A 4.70' 741 cf 20.50'W x 39.02'L x 3.50'H Field A 2,799 cf Overall - 946 cf Embedded = 1,853 cf x 40.0% Voids #2A 5.20' 946 cf Cultec R-300HD x 20 Inside #1 Effective Size= 45.6"W x 30.0"H => 6.53 sf x 7.08'L = 46.2 cf Overall Size= 51.0"W x 30.0"H x 7.54'L with 0.46' Overlap 20 Chambers in 4 Rows Cap Storage= 2.7 cf x 2 x 4 rows = 21.2 cf #3 5.00' 1,263 cf Custom Stage Data (Conic) Listed below (Recalc) #4 8.75' 1,374 cf Custom Stage Data (Conic) Listed below (Recalc) 4,325 cf Total Available Storage Storage Group A created with Chamber Wizard 645 Main Street, West Yarmouth, MA Type III 24-hr 10-Year Rainfall=4.90"2025-103 PROPOSED Printed 12/2/2025Prepared by Baxter-Nye Engineering & Survey Page 10HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Elevation Surf.Area Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (cubic-feet) (cubic-feet) (sq-ft) 5.00 93 0 0 93 7.00 320 390 390 340 8.00 674 486 876 703 8.50 878 387 1,263 912 Elevation Surf.Area Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (cubic-feet) (cubic-feet) (sq-ft) 8.75 4 0 0 4 9.00 1,538 135 135 1,538 9.50 3,556 1,239 1,374 3,558 Device Routing Invert Outlet Devices #1 Discarded 4.70'8.270 in/hr Exfiltration over Wetted area from 4.60' - 8.20' Excluded Wetted area = 0 sf #2 Discarded 5.99'8.410 in/hr Exfiltration over Surface area from 5.99' - 8.74' Excluded Surface area = 988 sf #3 Primary 9.40'10.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s) 0.5' Crest Height Discarded OutFlow Max=0.35 cfs @ 12.54 hrs HW=7.35' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.30 cfs) 2=Exfiltration (Exfiltration Controls 0.05 cfs) Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=4.70' (Free Discharge) 3=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs) 645 Main Street, West Yarmouth, MA Type III 24-hr 25-Year Rainfall=5.86"2025-103 PROPOSED Printed 12/2/2025Prepared by Baxter-Nye Engineering & Survey Page 11HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1: Area to Appleby Rd North CB Runoff = 0.04 cfs @ 12.10 hrs, Volume= 0.004 af, Depth> 0.77" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 25-Year Rainfall=5.86" Area (ac) CN Description 0.008 98 Paved parking, HSG A 0.053 39 >75% Grass cover, Good, HSG A 0.061 47 Weighted Average 0.053 86.89% Pervious Area 0.008 13.11% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 2: Area to northeast Runoff = 0.01 cfs @ 12.34 hrs, Volume= 0.002 af, Depth> 0.34" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 25-Year Rainfall=5.86" Area (ac) CN Description 0.083 39 >75% Grass cover, Good, HSG A 0.083 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 3: Area to east Runoff = 0.02 cfs @ 12.34 hrs, Volume= 0.003 af, Depth> 0.34" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 25-Year Rainfall=5.86" Area (ac) CN Description 0.099 39 >75% Grass cover, Good, HSG A 0.099 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum 645 Main Street, West Yarmouth, MA Type III 24-hr 25-Year Rainfall=5.86"2025-103 PROPOSED Printed 12/2/2025Prepared by Baxter-Nye Engineering & Survey Page 12HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 4: New Parking Lot Runoff = 1.56 cfs @ 12.08 hrs, Volume= 0.100 af, Depth> 2.67" Routed to Pond 1P : Cultec 300s Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 25-Year Rainfall=5.86" Area (ac) CN Description 0.252 98 Paved parking, HSG A 0.195 39 >75% Grass cover, Good, HSG A 0.447 72 Weighted Average 0.195 43.62% Pervious Area 0.252 56.38% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 5: Area to Appleby Rd South CB Runoff = 0.03 cfs @ 12.14 hrs, Volume= 0.004 af, Depth> 0.48" Routed to Reach SP5 : Study Point 5 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 25-Year Rainfall=5.86" Area (ac) CN Description 0.007 98 Paved parking, HSG A 0.081 39 >75% Grass cover, Good, HSG A 0.016 30 Woods, Good, HSG A 0.104 42 Weighted Average 0.097 93.27% Pervious Area 0.007 6.73% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment R: New Bldg Roof Runoff = 1.00 cfs @ 12.07 hrs, Volume= 0.073 af, Depth> 5.20" Routed to Pond 1P : Cultec 300s Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 25-Year Rainfall=5.86" 645 Main Street, West Yarmouth, MA Type III 24-hr 25-Year Rainfall=5.86"2025-103 PROPOSED Printed 12/2/2025Prepared by Baxter-Nye Engineering & Survey Page 13HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Area (ac) CN Description 0.168 98 Roofs, HSG A 0.168 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Reach SP5: Study Point 5 Inflow Area = 0.719 ac, 59.39% Impervious, Inflow Depth > 0.07" for 25-Year event Inflow = 0.03 cfs @ 12.14 hrs, Volume= 0.004 af Outflow = 0.03 cfs @ 12.14 hrs, Volume= 0.004 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Summary for Pond 1P: Cultec 300s Inflow Area = 0.615 ac, 68.29% Impervious, Inflow Depth > 3.36" for 25-Year event Inflow = 2.56 cfs @ 12.07 hrs, Volume= 0.172 af Outflow = 0.47 cfs @ 12.53 hrs, Volume= 0.172 af, Atten= 82%, Lag= 27.1 min Discarded = 0.47 cfs @ 12.53 hrs, Volume= 0.172 af Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af Routed to Reach SP5 : Study Point 5 Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs / 3 Peak Elev= 8.08' @ 12.53 hrs Surf.Area= 1,505 sf Storage= 2,582 cf Plug-Flow detention time= 58.6 min calculated for 0.172 af (100% of inflow) Center-of-Mass det. time= 58.4 min ( 828.2 - 769.8 ) Volume Invert Avail.Storage Storage Description #1A 4.70' 741 cf 20.50'W x 39.02'L x 3.50'H Field A 2,799 cf Overall - 946 cf Embedded = 1,853 cf x 40.0% Voids #2A 5.20' 946 cf Cultec R-300HD x 20 Inside #1 Effective Size= 45.6"W x 30.0"H => 6.53 sf x 7.08'L = 46.2 cf Overall Size= 51.0"W x 30.0"H x 7.54'L with 0.46' Overlap 20 Chambers in 4 Rows Cap Storage= 2.7 cf x 2 x 4 rows = 21.2 cf #3 5.00' 1,263 cf Custom Stage Data (Conic) Listed below (Recalc) #4 8.75' 1,374 cf Custom Stage Data (Conic) Listed below (Recalc) 4,325 cf Total Available Storage Storage Group A created with Chamber Wizard 645 Main Street, West Yarmouth, MA Type III 24-hr 25-Year Rainfall=5.86"2025-103 PROPOSED Printed 12/2/2025Prepared by Baxter-Nye Engineering & Survey Page 14HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Elevation Surf.Area Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (cubic-feet) (cubic-feet) (sq-ft) 5.00 93 0 0 93 7.00 320 390 390 340 8.00 674 486 876 703 8.50 878 387 1,263 912 Elevation Surf.Area Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (cubic-feet) (cubic-feet) (sq-ft) 8.75 4 0 0 4 9.00 1,538 135 135 1,538 9.50 3,556 1,239 1,374 3,558 Device Routing Invert Outlet Devices #1 Discarded 4.70'8.270 in/hr Exfiltration over Wetted area from 4.60' - 8.20' Excluded Wetted area = 0 sf #2 Discarded 5.99'8.410 in/hr Exfiltration over Surface area from 5.99' - 8.74' Excluded Surface area = 988 sf #3 Primary 9.40'10.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s) 0.5' Crest Height Discarded OutFlow Max=0.47 cfs @ 12.53 hrs HW=8.08' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.37 cfs) 2=Exfiltration (Exfiltration Controls 0.10 cfs) Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=4.70' (Free Discharge) 3=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs) 645 Main Street, West Yarmouth, MA Type III 24-hr 100-Year Rainfall=7.33"2025-103 PROPOSED Printed 12/2/2025Prepared by Baxter-Nye Engineering & Survey Page 15HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1: Area to Appleby Rd North CB Runoff = 0.10 cfs @ 12.09 hrs, Volume= 0.007 af, Depth> 1.41" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 100-Year Rainfall=7.33" Area (ac) CN Description 0.008 98 Paved parking, HSG A 0.053 39 >75% Grass cover, Good, HSG A 0.061 47 Weighted Average 0.053 86.89% Pervious Area 0.008 13.11% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 2: Area to northeast Runoff = 0.05 cfs @ 12.12 hrs, Volume= 0.005 af, Depth> 0.77" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 100-Year Rainfall=7.33" Area (ac) CN Description 0.083 39 >75% Grass cover, Good, HSG A 0.083 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 3: Area to east Runoff = 0.06 cfs @ 12.12 hrs, Volume= 0.006 af, Depth> 0.77" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 100-Year Rainfall=7.33" Area (ac) CN Description 0.099 39 >75% Grass cover, Good, HSG A 0.099 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum 645 Main Street, West Yarmouth, MA Type III 24-hr 100-Year Rainfall=7.33"2025-103 PROPOSED Printed 12/2/2025Prepared by Baxter-Nye Engineering & Survey Page 16HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 4: New Parking Lot Runoff = 2.24 cfs @ 12.07 hrs, Volume= 0.143 af, Depth> 3.84" Routed to Pond 1P : Cultec 300s Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 100-Year Rainfall=7.33" Area (ac) CN Description 0.252 98 Paved parking, HSG A 0.195 39 >75% Grass cover, Good, HSG A 0.447 72 Weighted Average 0.195 43.62% Pervious Area 0.252 56.38% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment 5: Area to Appleby Rd South CB Runoff = 0.10 cfs @ 12.10 hrs, Volume= 0.009 af, Depth> 1.00" Routed to Reach SP5 : Study Point 5 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 100-Year Rainfall=7.33" Area (ac) CN Description 0.007 98 Paved parking, HSG A 0.081 39 >75% Grass cover, Good, HSG A 0.016 30 Woods, Good, HSG A 0.104 42 Weighted Average 0.097 93.27% Pervious Area 0.007 6.73% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Subcatchment R: New Bldg Roof Runoff = 1.25 cfs @ 12.07 hrs, Volume= 0.091 af, Depth> 6.53" Routed to Pond 1P : Cultec 300s Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type III 24-hr 100-Year Rainfall=7.33" 645 Main Street, West Yarmouth, MA Type III 24-hr 100-Year Rainfall=7.33"2025-103 PROPOSED Printed 12/2/2025Prepared by Baxter-Nye Engineering & Survey Page 17HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Area (ac) CN Description 0.168 98 Roofs, HSG A 0.168 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Minimum Summary for Reach SP5: Study Point 5 Inflow Area = 0.719 ac, 59.39% Impervious, Inflow Depth > 0.14" for 100-Year event Inflow = 0.10 cfs @ 12.10 hrs, Volume= 0.009 af Outflow = 0.10 cfs @ 12.10 hrs, Volume= 0.009 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Summary for Pond 1P: Cultec 300s Inflow Area = 0.615 ac, 68.29% Impervious, Inflow Depth > 4.57" for 100-Year event Inflow = 3.49 cfs @ 12.07 hrs, Volume= 0.234 af Outflow = 0.52 cfs @ 12.19 hrs, Volume= 0.234 af, Atten= 85%, Lag= 7.0 min Discarded = 0.52 cfs @ 12.19 hrs, Volume= 0.234 af Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af Routed to Reach SP5 : Study Point 5 Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.01 hrs / 3 Peak Elev= 9.33' @ 12.57 hrs Surf.Area= 4,474 sf Storage= 3,800 cf Plug-Flow detention time= 71.7 min calculated for 0.234 af (100% of inflow) Center-of-Mass det. time= 71.4 min ( 837.9 - 766.5 ) Volume Invert Avail.Storage Storage Description #1A 4.70' 741 cf 20.50'W x 39.02'L x 3.50'H Field A 2,799 cf Overall - 946 cf Embedded = 1,853 cf x 40.0% Voids #2A 5.20' 946 cf Cultec R-300HD x 20 Inside #1 Effective Size= 45.6"W x 30.0"H => 6.53 sf x 7.08'L = 46.2 cf Overall Size= 51.0"W x 30.0"H x 7.54'L with 0.46' Overlap 20 Chambers in 4 Rows Cap Storage= 2.7 cf x 2 x 4 rows = 21.2 cf #3 5.00' 1,263 cf Custom Stage Data (Conic) Listed below (Recalc) #4 8.75' 1,374 cf Custom Stage Data (Conic) Listed below (Recalc) 4,325 cf Total Available Storage Storage Group A created with Chamber Wizard 645 Main Street, West Yarmouth, MA Type III 24-hr 100-Year Rainfall=7.33"2025-103 PROPOSED Printed 12/2/2025Prepared by Baxter-Nye Engineering & Survey Page 18HydroCAD® 10.20-6a s/n 04803 © 2024 HydroCAD Software Solutions LLC Elevation Surf.Area Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (cubic-feet) (cubic-feet) (sq-ft) 5.00 93 0 0 93 7.00 320 390 390 340 8.00 674 486 876 703 8.50 878 387 1,263 912 Elevation Surf.Area Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (cubic-feet) (cubic-feet) (sq-ft) 8.75 4 0 0 4 9.00 1,538 135 135 1,538 9.50 3,556 1,239 1,374 3,558 Device Routing Invert Outlet Devices #1 Discarded 4.70'8.270 in/hr Exfiltration over Wetted area from 4.60' - 8.20' Excluded Wetted area = 0 sf #2 Discarded 5.99'8.410 in/hr Exfiltration over Surface area from 5.99' - 8.74' Excluded Surface area = 988 sf #3 Primary 9.40'10.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s) 0.5' Crest Height Discarded OutFlow Max=0.52 cfs @ 12.19 hrs HW=8.91' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.38 cfs) 2=Exfiltration (Exfiltration Controls 0.13 cfs) Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=4.70' (Free Discharge) 3=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs)