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2021-10-21 60 Damon Rd Stormwater - Response to DPW Comments4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com BerkshireDesignGroup October 21, 2021 Doug McDonald Northampton DPW 210 Main Street Northampton, MA 01060 RE: 60 Damon Road – Marijuana Manufacturing Facility Response to Stormwater Permit Comments Doug, The intent of this letter is to provide our response to your comments you sent us on 10/15/2021. Our responses are shown in the red font below your comments. 1.The drainage calculations for proposed conditions include 16,111 sf less area than the existing condition area. The discrepancy may be in subwatershed area P-3. The total pre and post areas should be equal in the drainage calculations. Attached are two separate HydroCAD reports; one for the pre-development hydrology, and the other for the post-development hydrology. As is evident in those reports, the total area of the site remains 23.774 acres in both conditions. Below is an updated table comparing the peak discharge between pre- and post-development site conditions. Peak Discharge Comparison 2-YR Storm (3.0")10-YR Storm (4.5")100-YR Storm (6.5")Site Conditions at CP (Connecticut River)Peak Flow (cfs) Total Volume (ac-ft) Peak Flow (cfs) Total Volume (ac-ft) Peak Flow (cfs) Total Volume (ac-ft) Pre-Development (2012)9.42 1.233 26.63 3.019 54.46 5.934 Post-Development (2021)9.09 1.152 26.25 2.742 53.90 5.370 2. Subcatchment area P-3 (City property) in the drainage calculations has been modeled with 8,615 sf less impervious area. The future plans have not changed for this area so the model should not change in this area. The attached HydroCAD report for the proposed site has an updated subcatchment area P-3 with the original footprint of the boathouse; increasing the modeled impervious area by 8,615 sf. The most up-to-date survey of the project site in area P-3 (post Phase-I construction), as well as the updated site plan of this project, has a slight effect on the boundary of this area. The high-point of the constructed parking lot on the west side of this area has shifted to the center of the lot, which removes a portion of said parking lot from area P-3. The updated site plan of the project no longer has the parking lots in areas P-2 and P-3 connecting at their northern end, which also effects the boundary of P-3. Therefore, area P-3 is marginally smaller than in the original analysis. October 21, 2021 60 Damon Road – Marijuana Manufacturing Facility Response to Stormwater Permit Comments Page 2 of 3 4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com 3. The proposed plans and drainage calculations include an "existing gravel area" west and north of the existing building. This area is currently paved. If this area is to be left unchanged, the drainage calculations and plans should specify this as paved. The attached revised Stormwater Permit Plan Set has updated the surface conditions of the parking area in question to “existing pavement area”. The HydroCAD model for the proposed site has been updated to reflect these changes. 4. The Restoration Notes on Sheet S2 do not include areas of pavement or the mitigation areas specified in the NOI plans. The proposed plans should include a demolition and restoration plan(s) that include all structures and areas of gravel and pavement that will be removed and restored. The areas of gravel outside of the "limit of work" that will be mitigated as shown in the NOI plans should be included in this plan since the proposed drainage calculations include this change. Erosion and sediment control will be required in the mitigation areas. The attached revised Stormwater Permit Plan Set has updated Restoration Notes on Sheet S2 that include pavement areas specified in the NOI plans, as well as Sheet R1 which calls out the mitigation areas specified in the NOI plans. Sheet E1 shows the buildings and walls that are to remain and that are to be removed. Sheet S1 shows which existing pavement and gravel areas will remain, while the notes on Sheet S2 call for all other pavement and gravel to be removed. Sheet S1.1 includes erosion and sediment control notes and details for each phase of the project. 5. The plans should include a phasing plan. The work to expand the existing building should coincide with construction of the infiltration basin and demolition and restoration work around the building. The attached revised Stormwater Permit Plan Set includes a phasing plan on Sheet S1.1. 6. A Stormwater O&M plan should be submitted for the proposed stormwater systems. A Stormwater Management Operation, Inspection and Maintenance Agreement will need to be finalized prior to building permits. There is a Stormwater O&M Plan attached to this letter. A draft of the Stormwater Management Operation, Inspection and Maintenance Agreement has been attached, as well. 7. An NOI and SWPPP for the EPA Stormwater Construction General Permit will also be required for this project. An NOI and SWPP for the EPA Stormwater Construction General Permit is being put together by the owner and the contractor, starting with work for Phase I. Both documents will be submitted prior to starting work. October 21, 2021 60 Damon Road – Marijuana Manufacturing Facility Response to Stormwater Permit Comments Page 3 of 3 4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com Please do not hesitate to contact Liam at (413) 582-7000 or liam@berkshiredesign.com if you have any additional questions or require any more materials. Sincerely, Berkshire Design Group, Inc. Chris Chamberland, PE Attached Documents: Stormwater Permit Amendment Plan Set - 60 Damon Road (Revised 10/20/2021) HydroCAD Reports for Pre- and Post-Development (Revised 10/20/2021) O&M Plan (Revised 10/20/2021) Draft O&M Agreement and Drainage Easement 60 Damon Road – Marijuana Manufacturing Facility October 12, 2021 Northampton, Massachusetts Revised October 20, 2021 The Berkshire Design Group, Inc.Appendix HydroCAD Reports E-1 Existing Site E-2 Existing Site- Portion to NE Swale E-CP Connecticut River ES. Existing Swale Routing Diagram for 60 Damon Road - EXIST Prepared by Berkshire Design Group, Printed 10/20/2021 HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Subcat Reach Pond Link 60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 2HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Rainfall Events Listing (selected events) Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC 1 2 YRS Type III 24-hr Default 24.00 1 3.00 2 2 10 YRS Type III 24-hr Default 24.00 1 4.50 2 3 100 YRS Type III 24-hr Default 24.00 1 6.50 2 60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 3HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (acres) CN Description (subcatchment-numbers) 1.487 79 <50% Grass cover, Poor, HSG B (E-1, E-2) 0.333 61 >75% Grass cover, Good, HSG B (E-1) 0.867 74 >75% Grass cover, Good, HSG C (E-1) 1.664 96 Gravel Area (E-1) 1.726 98 Paved parking & roofs (E-1) 0.920 98 Paved parking, HSG B (E-1) 10.823 55 Woods, Good, HSG B (E-1, E-2) 2.261 70 Woods, Good, HSG C (E-1) 3.692 65 Woods/grass comb., Fair, HSG B (E-1, E-2) 23.774 68 TOTAL AREA 60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 4HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Soil Listing (all nodes) Area (acres) Soil Group Subcatchment Numbers 0.000 HSG A 17.255 HSG B E-1, E-2 3.128 HSG C E-1 0.000 HSG D 3.390 Other E-1 23.774 TOTAL AREA 60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 5HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Ground Covers (all nodes) HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers 0.000 1.487 0.000 0.000 0.000 1.487 <50% Grass cover, Poor E-1, E-2 0.000 0.333 0.867 0.000 0.000 1.200 >75% Grass cover, Good E-1 0.000 0.000 0.000 0.000 1.664 1.664 Gravel Area E-1 0.000 0.920 0.000 0.000 0.000 0.920 Paved parking E-1 0.000 0.000 0.000 0.000 1.726 1.726 Paved parking & roofs E-1 0.000 10.823 2.261 0.000 0.000 13.084 Woods, Good E-1, E-2 0.000 3.692 0.000 0.000 0.000 3.692 Woods/grass comb., Fair E-1, E-2 0.000 17.255 3.128 0.000 3.390 23.774 TOTAL AREA Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 6HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=1,015,442 sf 11.35% Impervious Runoff Depth>0.62"Subcatchment E-1: Existing Site Flow Length=1,101' Tc=21.0 min CN=68 Runoff=9.28 cfs 1.209 af Runoff Area=20,135 sf 0.00% Impervious Runoff Depth>0.63"Subcatchment E-2: Existing Site- Portion to Tc=6.0 min CN=68 Runoff=0.28 cfs 0.024 af Inflow=9.43 cfs 1.233 afReach E-CP: Connecticut River Outflow=9.43 cfs 1.233 af Avg. Flow Depth=0.09' Max Vel=1.20 fps Inflow=0.28 cfs 0.024 afReach ES.: Existing Swale n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs Outflow=0.26 cfs 0.024 af Total Runoff Area = 23.774 ac Runoff Volume = 1.233 af Average Runoff Depth = 0.62" 88.87% Pervious = 21.128 ac 11.13% Impervious = 2.645 ac Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 7HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment E-1: Existing Site Runoff = 9.28 cfs @ 12.35 hrs, Volume= 1.209 af, Depth> 0.62" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2 YRS Rainfall=3.00" Area (sf) CN Description 75,181 98 Paved parking & roofs * 72,493 96 Gravel Area 152,762 65 Woods/grass comb., Fair, HSG B 467,077 55 Woods, Good, HSG B 98,510 70 Woods, Good, HSG C 14,510 61 >75% Grass cover, Good, HSG B 25,520 74 >75% Grass cover, Good, HSG C 57,094 79 <50% Grass cover, Poor, HSG B 40,055 98 Paved parking, HSG B 12,240 74 >75% Grass cover, Good, HSG C 1,015,442 68 Weighted Average 900,206 88.65% Pervious Area 115,236 11.35% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.7 100 0.0100 1.01 Sheet Flow, Sheet flow over gravel Smooth surfaces n= 0.011 P2= 3.00" 2.5 260 0.0120 1.76 Shallow Concentrated Flow, Flow Over Gravel Unpaved Kv= 16.1 fps 11.0 430 0.0170 0.65 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 1.8 131 0.0600 1.22 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 4.0 180 0.0230 0.76 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 21.0 1,101 Total Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 8HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Subcatchment E-1: Existing Site Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)10 9 8 7 6 5 4 3 2 1 0 Type III 24-hr 2 YRS Rainfall=3.00" Runoff Area=1,015,442 sf Runoff Volume=1.209 af Runoff Depth>0.62" Flow Length=1,101' Tc=21.0 min CN=68 9.28 cfs Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 9HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment E-2: Existing Site- Portion to NE Swale Runoff = 0.28 cfs @ 12.11 hrs, Volume= 0.024 af, Depth> 0.63" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2 YRS Rainfall=3.00" Area (sf) CN Description 8,062 65 Woods/grass comb., Fair, HSG B 4,372 55 Woods, Good, HSG B 7,701 79 <50% Grass cover, Poor, HSG B 20,135 68 Weighted Average 20,135 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment E-2: Existing Site- Portion to NE Swale Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type III 24-hr 2 YRS Rainfall=3.00" Runoff Area=20,135 sf Runoff Volume=0.024 af Runoff Depth>0.63" Tc=6.0 min CN=68 0.28 cfs Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 10HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach E-CP: Connecticut River Inflow Area = 23.774 ac, 11.13% Impervious, Inflow Depth > 0.62" for 2 YRS event Inflow = 9.43 cfs @ 12.35 hrs, Volume= 1.233 af Outflow = 9.43 cfs @ 12.35 hrs, Volume= 1.233 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach E-CP: Connecticut River Inflow Outflow Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)10 9 8 7 6 5 4 3 2 1 0 Inflow Area=23.774 ac 9.43 cfs9.43 cfs Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 11HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach ES.: Existing Swale Inflow Area = 0.462 ac, 0.00% Impervious, Inflow Depth > 0.63" for 2 YRS event Inflow = 0.28 cfs @ 12.11 hrs, Volume= 0.024 af Outflow = 0.26 cfs @ 12.15 hrs, Volume= 0.024 af, Atten= 5%, Lag= 2.3 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 1.20 fps, Min. Travel Time= 1.1 min Avg. Velocity = 0.46 fps, Avg. Travel Time= 2.9 min Peak Storage= 18 cf @ 12.12 hrs Average Depth at Peak Storage= 0.09' , Surface Width= 2.92' Bank-Full Depth= 1.00' Flow Area= 7.0 sf, Capacity= 32.33 cfs 2.00' x 1.00' deep channel, n= 0.100 Earth, dense brush, high stage Side Slope Z-value= 5.0 '/' Top Width= 12.00' Length= 79.0' Slope= 0.2025 '/' Inlet Invert= 137.00', Outlet Invert= 121.00' ‡ Reach ES.: Existing Swale Inflow Outflow Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Inflow Area=0.462 ac Avg. Flow Depth=0.09' Max Vel=1.20 fps n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs 0.28 cfs 0.26 cfs Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 12HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=1,015,442 sf 11.35% Impervious Runoff Depth>1.52"Subcatchment E-1: Existing Site Flow Length=1,101' Tc=21.0 min CN=68 Runoff=26.25 cfs 2.962 af Runoff Area=20,135 sf 0.00% Impervious Runoff Depth>1.53"Subcatchment E-2: Existing Site- Portion to Tc=6.0 min CN=68 Runoff=0.78 cfs 0.059 af Inflow=26.65 cfs 3.020 afReach E-CP: Connecticut River Outflow=26.65 cfs 3.020 af Avg. Flow Depth=0.16' Max Vel=1.68 fps Inflow=0.78 cfs 0.059 afReach ES.: Existing Swale n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs Outflow=0.75 cfs 0.059 af Total Runoff Area = 23.774 ac Runoff Volume = 3.021 af Average Runoff Depth = 1.52" 88.87% Pervious = 21.128 ac 11.13% Impervious = 2.645 ac Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 13HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment E-1: Existing Site Runoff = 26.25 cfs @ 12.31 hrs, Volume= 2.962 af, Depth> 1.52" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10 YRS Rainfall=4.50" Area (sf) CN Description 75,181 98 Paved parking & roofs * 72,493 96 Gravel Area 152,762 65 Woods/grass comb., Fair, HSG B 467,077 55 Woods, Good, HSG B 98,510 70 Woods, Good, HSG C 14,510 61 >75% Grass cover, Good, HSG B 25,520 74 >75% Grass cover, Good, HSG C 57,094 79 <50% Grass cover, Poor, HSG B 40,055 98 Paved parking, HSG B 12,240 74 >75% Grass cover, Good, HSG C 1,015,442 68 Weighted Average 900,206 88.65% Pervious Area 115,236 11.35% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.7 100 0.0100 1.01 Sheet Flow, Sheet flow over gravel Smooth surfaces n= 0.011 P2= 3.00" 2.5 260 0.0120 1.76 Shallow Concentrated Flow, Flow Over Gravel Unpaved Kv= 16.1 fps 11.0 430 0.0170 0.65 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 1.8 131 0.0600 1.22 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 4.0 180 0.0230 0.76 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 21.0 1,101 Total Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 14HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Subcatchment E-1: Existing Site Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 Type III 24-hr 10 YRS Rainfall=4.50" Runoff Area=1,015,442 sf Runoff Volume=2.962 af Runoff Depth>1.52" Flow Length=1,101' Tc=21.0 min CN=68 26.25 cfs Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 15HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment E-2: Existing Site- Portion to NE Swale Runoff = 0.78 cfs @ 12.10 hrs, Volume= 0.059 af, Depth> 1.53" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10 YRS Rainfall=4.50" Area (sf) CN Description 8,062 65 Woods/grass comb., Fair, HSG B 4,372 55 Woods, Good, HSG B 7,701 79 <50% Grass cover, Poor, HSG B 20,135 68 Weighted Average 20,135 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment E-2: Existing Site- Portion to NE Swale Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type III 24-hr 10 YRS Rainfall=4.50" Runoff Area=20,135 sf Runoff Volume=0.059 af Runoff Depth>1.53" Tc=6.0 min CN=68 0.78 cfs Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 16HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach E-CP: Connecticut River Inflow Area = 23.774 ac, 11.13% Impervious, Inflow Depth > 1.52" for 10 YRS event Inflow = 26.65 cfs @ 12.31 hrs, Volume= 3.020 af Outflow = 26.65 cfs @ 12.31 hrs, Volume= 3.020 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach E-CP: Connecticut River Inflow Outflow Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 Inflow Area=23.774 ac 26.65 cfs26.65 cfs Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 17HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach ES.: Existing Swale Inflow Area = 0.462 ac, 0.00% Impervious, Inflow Depth > 1.53" for 10 YRS event Inflow = 0.78 cfs @ 12.10 hrs, Volume= 0.059 af Outflow = 0.75 cfs @ 12.12 hrs, Volume= 0.059 af, Atten= 4%, Lag= 1.3 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 1.68 fps, Min. Travel Time= 0.8 min Avg. Velocity = 0.59 fps, Avg. Travel Time= 2.2 min Peak Storage= 37 cf @ 12.11 hrs Average Depth at Peak Storage= 0.16' , Surface Width= 3.64' Bank-Full Depth= 1.00' Flow Area= 7.0 sf, Capacity= 32.33 cfs 2.00' x 1.00' deep channel, n= 0.100 Earth, dense brush, high stage Side Slope Z-value= 5.0 '/' Top Width= 12.00' Length= 79.0' Slope= 0.2025 '/' Inlet Invert= 137.00', Outlet Invert= 121.00' ‡ Reach ES.: Existing Swale Inflow Outflow Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Inflow Area=0.462 ac Avg. Flow Depth=0.16' Max Vel=1.68 fps n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs 0.78 cfs 0.75 cfs Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 18HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=1,015,442 sf 11.35% Impervious Runoff Depth>3.00"Subcatchment E-1: Existing Site Flow Length=1,101' Tc=21.0 min CN=68 Runoff=53.73 cfs 5.822 af Runoff Area=20,135 sf 0.00% Impervious Runoff Depth>3.01"Subcatchment E-2: Existing Site- Portion to Tc=6.0 min CN=68 Runoff=1.59 cfs 0.116 af Inflow=54.51 cfs 5.938 afReach E-CP: Connecticut River Outflow=54.51 cfs 5.938 af Avg. Flow Depth=0.24' Max Vel=2.07 fps Inflow=1.59 cfs 0.116 afReach ES.: Existing Swale n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs Outflow=1.54 cfs 0.116 af Total Runoff Area = 23.774 ac Runoff Volume = 5.938 af Average Runoff Depth = 3.00" 88.87% Pervious = 21.128 ac 11.13% Impervious = 2.645 ac Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 19HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment E-1: Existing Site Runoff = 53.73 cfs @ 12.30 hrs, Volume= 5.822 af, Depth> 3.00" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100 YRS Rainfall=6.50" Area (sf) CN Description 75,181 98 Paved parking & roofs * 72,493 96 Gravel Area 152,762 65 Woods/grass comb., Fair, HSG B 467,077 55 Woods, Good, HSG B 98,510 70 Woods, Good, HSG C 14,510 61 >75% Grass cover, Good, HSG B 25,520 74 >75% Grass cover, Good, HSG C 57,094 79 <50% Grass cover, Poor, HSG B 40,055 98 Paved parking, HSG B 12,240 74 >75% Grass cover, Good, HSG C 1,015,442 68 Weighted Average 900,206 88.65% Pervious Area 115,236 11.35% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.7 100 0.0100 1.01 Sheet Flow, Sheet flow over gravel Smooth surfaces n= 0.011 P2= 3.00" 2.5 260 0.0120 1.76 Shallow Concentrated Flow, Flow Over Gravel Unpaved Kv= 16.1 fps 11.0 430 0.0170 0.65 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 1.8 131 0.0600 1.22 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 4.0 180 0.0230 0.76 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 21.0 1,101 Total Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 20HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Subcatchment E-1: Existing Site Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)60 55 50 45 40 35 30 25 20 15 10 5 0 Type III 24-hr 100 YRS Rainfall=6.50" Runoff Area=1,015,442 sf Runoff Volume=5.822 af Runoff Depth>3.00" Flow Length=1,101' Tc=21.0 min CN=68 53.73 cfs Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 21HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment E-2: Existing Site- Portion to NE Swale Runoff = 1.59 cfs @ 12.10 hrs, Volume= 0.116 af, Depth> 3.01" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100 YRS Rainfall=6.50" Area (sf) CN Description 8,062 65 Woods/grass comb., Fair, HSG B 4,372 55 Woods, Good, HSG B 7,701 79 <50% Grass cover, Poor, HSG B 20,135 68 Weighted Average 20,135 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment E-2: Existing Site- Portion to NE Swale Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 100 YRS Rainfall=6.50" Runoff Area=20,135 sf Runoff Volume=0.116 af Runoff Depth>3.01" Tc=6.0 min CN=68 1.59 cfs Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 22HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach E-CP: Connecticut River Inflow Area = 23.774 ac, 11.13% Impervious, Inflow Depth > 3.00" for 100 YRS event Inflow = 54.51 cfs @ 12.30 hrs, Volume= 5.938 af Outflow = 54.51 cfs @ 12.30 hrs, Volume= 5.938 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Reach E-CP: Connecticut River Inflow Outflow Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)60 55 50 45 40 35 30 25 20 15 10 5 0 Inflow Area=23.774 ac 54.51 cfs54.51 cfs Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - EXIST Printed 10/20/2021Prepared by Berkshire Design Group Page 23HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach ES.: Existing Swale Inflow Area = 0.462 ac, 0.00% Impervious, Inflow Depth > 3.01" for 100 YRS event Inflow = 1.59 cfs @ 12.10 hrs, Volume= 0.116 af Outflow = 1.54 cfs @ 12.11 hrs, Volume= 0.116 af, Atten= 3%, Lag= 1.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 2.07 fps, Min. Travel Time= 0.6 min Avg. Velocity = 0.70 fps, Avg. Travel Time= 1.9 min Peak Storage= 61 cf @ 12.10 hrs Average Depth at Peak Storage= 0.24' , Surface Width= 4.40' Bank-Full Depth= 1.00' Flow Area= 7.0 sf, Capacity= 32.33 cfs 2.00' x 1.00' deep channel, n= 0.100 Earth, dense brush, high stage Side Slope Z-value= 5.0 '/' Top Width= 12.00' Length= 79.0' Slope= 0.2025 '/' Inlet Invert= 137.00', Outlet Invert= 121.00' ‡ Reach ES.: Existing Swale Inflow Outflow Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=0.462 ac Avg. Flow Depth=0.24' Max Vel=2.07 fps n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs 1.59 cfs1.54 cfs P-1 Proposed Site P-2 Proposed Site P-3 Proposed Site P-4 Proposed Site P-5 Proposed Site ES Existing Swale P-CP Connecticut River IT Infiltration Trench LLS1 Level Spreader 1 LLS2 Level Spreader 2 RG Rain Garden WL New Low Wetland Area Routing Diagram for 60 Damon Road - PROP Prepared by Berkshire Design Group, Printed 10/20/2021 HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Subcat Reach Pond Link 60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 2HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Rainfall Events Listing (selected events) Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC 1 2 YRS Type III 24-hr Default 24.00 1 3.00 2 2 10 YRS Type III 24-hr Default 24.00 1 4.50 2 3 100 YRS Type III 24-hr Default 24.00 1 6.50 2 60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 3HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (acres) CN Description (subcatchment-numbers) 3.490 61 >75% Grass cover, Good, HSG B (P-1, P-2, P-3, P-5) 0.419 74 >75% Grass cover, Good, HSG C (P-1) 0.378 96 Gravel (P-1) 3.365 98 Paved parking & roofs (P-1, P-2, P-3, P-4, P-5) 1.241 98 Paved parking, HSG B (P-1) 10.821 55 Woods, Good, HSG B (P-1) 2.250 70 Woods, Good, HSG C (P-1) 1.811 65 Woods/grass comb., Fair, HSG B (P-1) 23.774 67 TOTAL AREA 60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 4HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Soil Listing (all nodes) Area (acres) Soil Group Subcatchment Numbers 0.000 HSG A 17.362 HSG B P-1, P-2, P-3, P-5 2.669 HSG C P-1 0.000 HSG D 3.743 Other P-1, P-2, P-3, P-4, P-5 23.774 TOTAL AREA 60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 5HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Ground Covers (all nodes) HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers 0.000 3.490 0.419 0.000 0.000 3.908 >75% Grass cover, Good P-1, P-2, P-3, P-5 0.000 0.000 0.000 0.000 0.378 0.378 Gravel P-1 0.000 1.241 0.000 0.000 0.000 1.241 Paved parking P-1 0.000 0.000 0.000 0.000 3.365 3.365 Paved parking & roofs P-1, P-2, P-3, P-4, P-5 0.000 10.821 2.250 0.000 0.000 13.071 Woods, Good P-1 0.000 1.811 0.000 0.000 0.000 1.811 Woods/grass comb., Fair P-1 0.000 17.362 2.669 0.000 3.743 23.774 TOTAL AREA Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 6HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=862,118 sf 7.39% Impervious Runoff Depth>0.38"Subcatchment P-1: Proposed Site Flow Length=841' Tc=17.4 min CN=63 Runoff=4.73 cfs 0.621 af Runoff Area=33,660 sf 94.86% Impervious Runoff Depth>2.41"Subcatchment P-2: Proposed Site Tc=6.0 min CN=96 Runoff=2.11 cfs 0.155 af Runoff Area=69,490 sf 70.46% Impervious Runoff Depth>1.62"Subcatchment P-3: Proposed Site Tc=6.0 min CN=87 Runoff=3.19 cfs 0.216 af Runoff Area=4,700 sf 100.00% Impervious Runoff Depth>2.59"Subcatchment P-4: Proposed Site Tc=6.0 min CN=98 Runoff=0.31 cfs 0.023 af Runoff Area=65,609 sf 78.20% Impervious Runoff Depth>1.86"Subcatchment P-5: Proposed Site Tc=6.0 min CN=90 Runoff=3.40 cfs 0.234 af Avg. Flow Depth=0.29' Max Vel=2.26 fps Inflow=2.25 cfs 0.150 afReach ES: Existing Swale n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs Outflow=2.13 cfs 0.150 af Inflow=9.09 cfs 1.152 afReach P-CP: Connecticut River Outflow=9.09 cfs 1.152 af Peak Elev=142.85' Storage=1,014 cf Inflow=0.31 cfs 0.023 afPond IT: Infiltration Trench Outflow=0.00 cfs 0.000 af Peak Elev=147.11' Storage=145 cf Inflow=2.11 cfs 0.155 afPond LLS1: Level Spreader 1 Outflow=2.10 cfs 0.152 af Peak Elev=145.15' Storage=199 cf Inflow=3.40 cfs 0.234 afPond LLS2: Level Spreader 2 Outflow=3.42 cfs 0.229 af Peak Elev=141.77' Storage=3,204 cf Inflow=3.19 cfs 0.216 afPond RG: Rain Garden Outflow=2.64 cfs 0.154 af Peak Elev=137.25' Storage=569 cf Inflow=2.64 cfs 0.154 afPond WL: New Low Wetland Area Outflow=2.25 cfs 0.150 af Total Runoff Area = 23.774 ac Runoff Volume = 1.249 af Average Runoff Depth = 0.63" 80.63% Pervious = 19.168 ac 19.37% Impervious = 4.605 ac Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 7HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-1: Proposed Site Runoff = 4.73 cfs @ 12.35 hrs, Volume= 0.621 af, Depth> 0.38" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2 YRS Rainfall=3.00" Area (sf) CN Description 9,670 98 Paved parking & roofs * 16,460 96 Gravel 78,887 65 Woods/grass comb., Fair, HSG B 471,363 55 Woods, Good, HSG B 98,010 70 Woods, Good, HSG C 115,448 61 >75% Grass cover, Good, HSG B 14,985 74 >75% Grass cover, Good, HSG C 54,045 98 Paved parking, HSG B 3,250 74 >75% Grass cover, Good, HSG C 862,118 63 Weighted Average 798,403 92.61% Pervious Area 63,715 7.39% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.6 100 0.0400 3.00 Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps 11.0 430 0.0170 0.65 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 1.8 131 0.0600 1.22 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 4.0 180 0.0230 0.76 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 17.4 841 Total Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 8HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Subcatchment P-1: Proposed Site Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)5 4 3 2 1 0 Type III 24-hr 2 YRS Rainfall=3.00" Runoff Area=862,118 sf Runoff Volume=0.621 af Runoff Depth>0.38" Flow Length=841' Tc=17.4 min CN=63 4.73 cfs Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 9HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-2: Proposed Site Runoff = 2.11 cfs @ 12.09 hrs, Volume= 0.155 af, Depth> 2.41" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2 YRS Rainfall=3.00" Area (sf) CN Description 31,930 98 Paved parking & roofs 1,730 61 >75% Grass cover, Good, HSG B 33,660 96 Weighted Average 1,730 5.14% Pervious Area 31,930 94.86% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment P-2: Proposed Site Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)2 1 0 Type III 24-hr 2 YRS Rainfall=3.00" Runoff Area=33,660 sf Runoff Volume=0.155 af Runoff Depth>2.41" Tc=6.0 min CN=96 2.11 cfs Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 10HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-3: Proposed Site Runoff = 3.19 cfs @ 12.09 hrs, Volume= 0.216 af, Depth> 1.62" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2 YRS Rainfall=3.00" Area (sf) CN Description 48,961 98 Paved parking & roofs 20,529 61 >75% Grass cover, Good, HSG B 69,490 87 Weighted Average 20,529 29.54% Pervious Area 48,961 70.46% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment P-3: Proposed Site Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)3 2 1 0 Type III 24-hr 2 YRS Rainfall=3.00" Runoff Area=69,490 sf Runoff Volume=0.216 af Runoff Depth>1.62" Tc=6.0 min CN=87 3.19 cfs Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 11HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-4: Proposed Site Runoff = 0.31 cfs @ 12.09 hrs, Volume= 0.023 af, Depth> 2.59" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2 YRS Rainfall=3.00" Area (sf) CN Description 4,700 98 Paved parking & roofs 4,700 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment P-4: Proposed Site Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type III 24-hr 2 YRS Rainfall=3.00" Runoff Area=4,700 sf Runoff Volume=0.023 af Runoff Depth>2.59" Tc=6.0 min CN=98 0.31 cfs Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 12HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-5: Proposed Site Runoff = 3.40 cfs @ 12.09 hrs, Volume= 0.234 af, Depth> 1.86" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2 YRS Rainfall=3.00" Area (sf) CN Description 51,303 98 Paved parking & roofs 14,306 61 >75% Grass cover, Good, HSG B 65,609 90 Weighted Average 14,306 21.80% Pervious Area 51,303 78.20% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment P-5: Proposed Site Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)3 2 1 0 Type III 24-hr 2 YRS Rainfall=3.00" Runoff Area=65,609 sf Runoff Volume=0.234 af Runoff Depth>1.86" Tc=6.0 min CN=90 3.40 cfs Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 13HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach ES: Existing Swale Inflow Area = 1.595 ac, 70.46% Impervious, Inflow Depth > 1.13" for 2 YRS event Inflow = 2.25 cfs @ 12.22 hrs, Volume= 0.150 af Outflow = 2.13 cfs @ 12.25 hrs, Volume= 0.150 af, Atten= 5%, Lag= 1.8 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Max. Velocity= 2.26 fps, Min. Travel Time= 0.6 min Avg. Velocity = 1.00 fps, Avg. Travel Time= 1.3 min Peak Storage= 80 cf @ 12.22 hrs Average Depth at Peak Storage= 0.29' , Surface Width= 4.93' Bank-Full Depth= 1.00' Flow Area= 7.0 sf, Capacity= 32.33 cfs 2.00' x 1.00' deep channel, n= 0.100 Earth, dense brush, high stage Side Slope Z-value= 5.0 '/' Top Width= 12.00' Length= 79.0' Slope= 0.2025 '/' Inlet Invert= 137.00', Outlet Invert= 121.00' ‡ Reach ES: Existing Swale Inflow Outflow Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)2 1 0 Inflow Area=1.595 ac Avg. Flow Depth=0.29' Max Vel=2.26 fps n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs 2.25 cfs 2.13 cfs Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 14HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach P-CP: Connecticut River Inflow Area = 23.774 ac, 19.37% Impervious, Inflow Depth > 0.58" for 2 YRS event Inflow = 9.09 cfs @ 12.26 hrs, Volume= 1.152 af Outflow = 9.09 cfs @ 12.26 hrs, Volume= 1.152 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Reach P-CP: Connecticut River Inflow Outflow Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)10 9 8 7 6 5 4 3 2 1 0 Inflow Area=23.774 ac 9.09 cfs9.09 cfs Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 15HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond IT: Infiltration Trench Inflow Area = 0.108 ac,100.00% Impervious, Inflow Depth > 2.59" for 2 YRS event Inflow = 0.31 cfs @ 12.09 hrs, Volume= 0.023 af Outflow = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af, Atten= 100%, Lag= 0.0 min Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 142.85' @ 20.00 hrs Surf.Area= 1,370 sf Storage= 1,014 cf Plug-Flow detention time= (not calculated: initial storage exceeds outflow) Center-of-Mass det. time= (not calculated: no outflow) Volume Invert Avail.Storage Storage Description #1 141.00' 2,192 cf Custom Stage Data (Prismatic) Listed below (Recalc) 5,480 cf Overall x 40.0% Voids Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 141.00 1,370 0 0 145.00 1,370 5,480 5,480 Device Routing Invert Outlet Devices #1 Primary 147.50'24.0" x 24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=141.00' (Free Discharge) 1=Orifice/Grate ( Controls 0.00 cfs) Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 16HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond IT: Infiltration Trench Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Inflow Area=0.108 ac Peak Elev=142.85' Storage=1,014 cf 0.31 cfs 0.00 cfs Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 17HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond LLS1: Level Spreader 1 Inflow Area = 0.773 ac, 94.86% Impervious, Inflow Depth > 2.41" for 2 YRS event Inflow = 2.11 cfs @ 12.09 hrs, Volume= 0.155 af Outflow = 2.10 cfs @ 12.09 hrs, Volume= 0.152 af, Atten= 0%, Lag= 0.0 min Primary = 2.10 cfs @ 12.09 hrs, Volume= 0.152 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 147.11' @ 12.09 hrs Surf.Area= 230 sf Storage= 145 cf Plug-Flow detention time= 17.3 min calculated for 0.152 af (98% of inflow) Center-of-Mass det. time= 8.1 min ( 757.9 - 749.8 ) Volume Invert Avail.Storage Storage Description #1 146.00' 145 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 146.00 60 0 0 147.00 230 145 145 Device Routing Invert Outlet Devices #1 Primary 147.00'22.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Primary OutFlow Max=2.05 cfs @ 12.09 hrs HW=147.11' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 2.05 cfs @ 0.88 fps) Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 18HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond LLS1: Level Spreader 1 Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)2 1 0 Inflow Area=0.773 ac Peak Elev=147.11' Storage=145 cf 2.11 cfs2.10 cfs Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 19HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond LLS2: Level Spreader 2 Inflow Area = 1.506 ac, 78.20% Impervious, Inflow Depth > 1.86" for 2 YRS event Inflow = 3.40 cfs @ 12.09 hrs, Volume= 0.234 af Outflow = 3.42 cfs @ 12.09 hrs, Volume= 0.229 af, Atten= 0%, Lag= 0.0 min Primary = 3.42 cfs @ 12.09 hrs, Volume= 0.229 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 145.15' @ 12.09 hrs Surf.Area= 292 sf Storage= 199 cf Plug-Flow detention time= 13.2 min calculated for 0.229 af (98% of inflow) Center-of-Mass det. time= 5.6 min ( 782.3 - 776.7 ) Volume Invert Avail.Storage Storage Description #1 144.00' 199 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 144.00 105 0 0 145.00 292 199 199 Device Routing Invert Outlet Devices #1 Primary 145.00'22.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Primary OutFlow Max=3.34 cfs @ 12.09 hrs HW=145.15' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 3.34 cfs @ 1.03 fps) Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 20HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond LLS2: Level Spreader 2 Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)3 2 1 0 Inflow Area=1.506 ac Peak Elev=145.15' Storage=199 cf 3.40 cfs3.42 cfs Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 21HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond RG: Rain Garden Inflow Area = 1.595 ac, 70.46% Impervious, Inflow Depth > 1.62" for 2 YRS event Inflow = 3.19 cfs @ 12.09 hrs, Volume= 0.216 af Outflow = 2.64 cfs @ 12.16 hrs, Volume= 0.154 af, Atten= 17%, Lag= 4.3 min Primary = 2.64 cfs @ 12.16 hrs, Volume= 0.154 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 141.77' @ 12.16 hrs Surf.Area= 4,453 sf Storage= 3,204 cf Plug-Flow detention time= 108.9 min calculated for 0.153 af (71% of inflow) Center-of-Mass det. time= 44.6 min ( 831.4 - 786.9 ) Volume Invert Avail.Storage Storage Description #1 141.00' 4,248 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 141.00 3,869 0 0 142.00 4,627 4,248 4,248 Device Routing Invert Outlet Devices #1 Primary 141.65'25.0' long x 2.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 Primary OutFlow Max=2.52 cfs @ 12.16 hrs HW=141.77' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 2.52 cfs @ 0.87 fps) Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 22HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond RG: Rain Garden Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)3 2 1 0 Inflow Area=1.595 ac Peak Elev=141.77' Storage=3,204 cf 3.19 cfs 2.64 cfs Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 23HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond WL: New Low Wetland Area Inflow Area = 1.595 ac, 70.46% Impervious, Inflow Depth > 1.16" for 2 YRS event Inflow = 2.64 cfs @ 12.16 hrs, Volume= 0.154 af Outflow = 2.25 cfs @ 12.22 hrs, Volume= 0.150 af, Atten= 15%, Lag= 3.6 min Primary = 2.25 cfs @ 12.22 hrs, Volume= 0.150 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 137.25' @ 12.22 hrs Surf.Area= 2,469 sf Storage= 569 cf Plug-Flow detention time= 14.7 min calculated for 0.150 af (98% of inflow) Center-of-Mass det. time= 5.9 min ( 837.3 - 831.4 ) Volume Invert Avail.Storage Storage Description #1 136.95' 3,241 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 136.95 10 0 0 137.00 1,745 44 44 138.00 4,650 3,198 3,241 Device Routing Invert Outlet Devices #1 Primary 137.05'10.0' long x 2.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 Primary OutFlow Max=2.13 cfs @ 12.22 hrs HW=137.24' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 2.13 cfs @ 1.11 fps) Type III 24-hr 2 YRS Rainfall=3.00"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 24HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond WL: New Low Wetland Area Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)2 1 0 Inflow Area=1.595 ac Peak Elev=137.25' Storage=569 cf 2.64 cfs 2.25 cfs Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 25HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=862,118 sf 7.39% Impervious Runoff Depth>1.08"Subcatchment P-1: Proposed Site Flow Length=841' Tc=17.4 min CN=63 Runoff=17.78 cfs 1.783 af Runoff Area=33,660 sf 94.86% Impervious Runoff Depth>3.79"Subcatchment P-2: Proposed Site Tc=6.0 min CN=96 Runoff=3.25 cfs 0.244 af Runoff Area=69,490 sf 70.46% Impervious Runoff Depth>2.92"Subcatchment P-3: Proposed Site Tc=6.0 min CN=87 Runoff=5.60 cfs 0.388 af Runoff Area=4,700 sf 100.00% Impervious Runoff Depth>3.96"Subcatchment P-4: Proposed Site Tc=6.0 min CN=98 Runoff=0.46 cfs 0.036 af Runoff Area=65,609 sf 78.20% Impervious Runoff Depth>3.21"Subcatchment P-5: Proposed Site Tc=6.0 min CN=90 Runoff=5.69 cfs 0.402 af Avg. Flow Depth=0.43' Max Vel=2.84 fps Inflow=4.99 cfs 0.321 afReach ES: Existing Swale n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs Outflow=4.91 cfs 0.321 af Inflow=26.25 cfs 2.742 afReach P-CP: Connecticut River Outflow=26.25 cfs 2.742 af Peak Elev=143.83' Storage=1,552 cf Inflow=0.46 cfs 0.036 afPond IT: Infiltration Trench Outflow=0.00 cfs 0.000 af Peak Elev=147.14' Storage=145 cf Inflow=3.25 cfs 0.244 afPond LLS1: Level Spreader 1 Outflow=3.24 cfs 0.241 af Peak Elev=145.21' Storage=199 cf Inflow=5.69 cfs 0.402 afPond LLS2: Level Spreader 2 Outflow=5.71 cfs 0.398 af Peak Elev=141.84' Storage=3,520 cf Inflow=5.60 cfs 0.388 afPond RG: Rain Garden Outflow=5.28 cfs 0.325 af Peak Elev=137.38' Storage=928 cf Inflow=5.28 cfs 0.325 afPond WL: New Low Wetland Area Outflow=4.99 cfs 0.321 af Total Runoff Area = 23.774 ac Runoff Volume = 2.853 af Average Runoff Depth = 1.44" 80.63% Pervious = 19.168 ac 19.37% Impervious = 4.605 ac Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 26HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-1: Proposed Site Runoff = 17.78 cfs @ 12.27 hrs, Volume= 1.783 af, Depth> 1.08" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10 YRS Rainfall=4.50" Area (sf) CN Description 9,670 98 Paved parking & roofs * 16,460 96 Gravel 78,887 65 Woods/grass comb., Fair, HSG B 471,363 55 Woods, Good, HSG B 98,010 70 Woods, Good, HSG C 115,448 61 >75% Grass cover, Good, HSG B 14,985 74 >75% Grass cover, Good, HSG C 54,045 98 Paved parking, HSG B 3,250 74 >75% Grass cover, Good, HSG C 862,118 63 Weighted Average 798,403 92.61% Pervious Area 63,715 7.39% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.6 100 0.0400 3.00 Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps 11.0 430 0.0170 0.65 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 1.8 131 0.0600 1.22 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 4.0 180 0.0230 0.76 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 17.4 841 Total Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 27HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Subcatchment P-1: Proposed Site Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Type III 24-hr 10 YRS Rainfall=4.50" Runoff Area=862,118 sf Runoff Volume=1.783 af Runoff Depth>1.08" Flow Length=841' Tc=17.4 min CN=63 17.78 cfs Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 28HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-2: Proposed Site Runoff = 3.25 cfs @ 12.09 hrs, Volume= 0.244 af, Depth> 3.79" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10 YRS Rainfall=4.50" Area (sf) CN Description 31,930 98 Paved parking & roofs 1,730 61 >75% Grass cover, Good, HSG B 33,660 96 Weighted Average 1,730 5.14% Pervious Area 31,930 94.86% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment P-2: Proposed Site Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)3 2 1 0 Type III 24-hr 10 YRS Rainfall=4.50" Runoff Area=33,660 sf Runoff Volume=0.244 af Runoff Depth>3.79" Tc=6.0 min CN=96 3.25 cfs Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 29HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-3: Proposed Site Runoff = 5.60 cfs @ 12.09 hrs, Volume= 0.388 af, Depth> 2.92" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10 YRS Rainfall=4.50" Area (sf) CN Description 48,961 98 Paved parking & roofs 20,529 61 >75% Grass cover, Good, HSG B 69,490 87 Weighted Average 20,529 29.54% Pervious Area 48,961 70.46% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment P-3: Proposed Site Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)6 5 4 3 2 1 0 Type III 24-hr 10 YRS Rainfall=4.50" Runoff Area=69,490 sf Runoff Volume=0.388 af Runoff Depth>2.92" Tc=6.0 min CN=87 5.60 cfs Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 30HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-4: Proposed Site Runoff = 0.46 cfs @ 12.09 hrs, Volume= 0.036 af, Depth> 3.96" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10 YRS Rainfall=4.50" Area (sf) CN Description 4,700 98 Paved parking & roofs 4,700 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment P-4: Proposed Site Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)0.5 0.48 0.46 0.44 0.42 0.4 0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type III 24-hr 10 YRS Rainfall=4.50" Runoff Area=4,700 sf Runoff Volume=0.036 af Runoff Depth>3.96" Tc=6.0 min CN=98 0.46 cfs Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 31HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-5: Proposed Site Runoff = 5.69 cfs @ 12.09 hrs, Volume= 0.402 af, Depth> 3.21" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10 YRS Rainfall=4.50" Area (sf) CN Description 51,303 98 Paved parking & roofs 14,306 61 >75% Grass cover, Good, HSG B 65,609 90 Weighted Average 14,306 21.80% Pervious Area 51,303 78.20% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment P-5: Proposed Site Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)6 5 4 3 2 1 0 Type III 24-hr 10 YRS Rainfall=4.50" Runoff Area=65,609 sf Runoff Volume=0.402 af Runoff Depth>3.21" Tc=6.0 min CN=90 5.69 cfs Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 32HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach ES: Existing Swale Inflow Area = 1.595 ac, 70.46% Impervious, Inflow Depth > 2.41" for 10 YRS event Inflow = 4.99 cfs @ 12.16 hrs, Volume= 0.321 af Outflow = 4.91 cfs @ 12.17 hrs, Volume= 0.321 af, Atten= 2%, Lag= 0.8 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Max. Velocity= 2.84 fps, Min. Travel Time= 0.5 min Avg. Velocity = 1.22 fps, Avg. Travel Time= 1.1 min Peak Storage= 139 cf @ 12.16 hrs Average Depth at Peak Storage= 0.43' , Surface Width= 6.25' Bank-Full Depth= 1.00' Flow Area= 7.0 sf, Capacity= 32.33 cfs 2.00' x 1.00' deep channel, n= 0.100 Earth, dense brush, high stage Side Slope Z-value= 5.0 '/' Top Width= 12.00' Length= 79.0' Slope= 0.2025 '/' Inlet Invert= 137.00', Outlet Invert= 121.00' ‡ Reach ES: Existing Swale Inflow Outflow Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)5 4 3 2 1 0 Inflow Area=1.595 ac Avg. Flow Depth=0.43' Max Vel=2.84 fps n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs 4.99 cfs4.91 cfs Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 33HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach P-CP: Connecticut River Inflow Area = 23.774 ac, 19.37% Impervious, Inflow Depth > 1.38" for 10 YRS event Inflow = 26.25 cfs @ 12.22 hrs, Volume= 2.742 af Outflow = 26.25 cfs @ 12.22 hrs, Volume= 2.742 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Reach P-CP: Connecticut River Inflow Outflow Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 Inflow Area=23.774 ac 26.25 cfs26.25 cfs Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 34HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond IT: Infiltration Trench Inflow Area = 0.108 ac,100.00% Impervious, Inflow Depth > 3.96" for 10 YRS event Inflow = 0.46 cfs @ 12.09 hrs, Volume= 0.036 af Outflow = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af, Atten= 100%, Lag= 0.0 min Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 143.83' @ 20.00 hrs Surf.Area= 1,370 sf Storage= 1,552 cf Plug-Flow detention time= (not calculated: initial storage exceeds outflow) Center-of-Mass det. time= (not calculated: no outflow) Volume Invert Avail.Storage Storage Description #1 141.00' 2,192 cf Custom Stage Data (Prismatic) Listed below (Recalc) 5,480 cf Overall x 40.0% Voids Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 141.00 1,370 0 0 145.00 1,370 5,480 5,480 Device Routing Invert Outlet Devices #1 Primary 147.50'24.0" x 24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=141.00' (Free Discharge) 1=Orifice/Grate ( Controls 0.00 cfs) Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 35HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond IT: Infiltration Trench Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)0.5 0.48 0.46 0.44 0.42 0.4 0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Inflow Area=0.108 ac Peak Elev=143.83' Storage=1,552 cf 0.46 cfs 0.00 cfs Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 36HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond LLS1: Level Spreader 1 Inflow Area = 0.773 ac, 94.86% Impervious, Inflow Depth > 3.79" for 10 YRS event Inflow = 3.25 cfs @ 12.09 hrs, Volume= 0.244 af Outflow = 3.24 cfs @ 12.09 hrs, Volume= 0.241 af, Atten= 0%, Lag= 0.0 min Primary = 3.24 cfs @ 12.09 hrs, Volume= 0.241 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 147.14' @ 12.09 hrs Surf.Area= 230 sf Storage= 145 cf Plug-Flow detention time= 11.6 min calculated for 0.240 af (98% of inflow) Center-of-Mass det. time= 5.5 min ( 748.5 - 743.0 ) Volume Invert Avail.Storage Storage Description #1 146.00' 145 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 146.00 60 0 0 147.00 230 145 145 Device Routing Invert Outlet Devices #1 Primary 147.00'22.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Primary OutFlow Max=3.16 cfs @ 12.09 hrs HW=147.14' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 3.16 cfs @ 1.01 fps) Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 37HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond LLS1: Level Spreader 1 Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)3 2 1 0 Inflow Area=0.773 ac Peak Elev=147.14' Storage=145 cf 3.25 cfs3.24 cfs Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 38HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond LLS2: Level Spreader 2 Inflow Area = 1.506 ac, 78.20% Impervious, Inflow Depth > 3.21" for 10 YRS event Inflow = 5.69 cfs @ 12.09 hrs, Volume= 0.402 af Outflow = 5.71 cfs @ 12.09 hrs, Volume= 0.398 af, Atten= 0%, Lag= 0.0 min Primary = 5.71 cfs @ 12.09 hrs, Volume= 0.398 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 145.21' @ 12.09 hrs Surf.Area= 292 sf Storage= 199 cf Plug-Flow detention time= 9.1 min calculated for 0.398 af (99% of inflow) Center-of-Mass det. time= 4.2 min ( 768.0 - 763.8 ) Volume Invert Avail.Storage Storage Description #1 144.00' 199 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 144.00 105 0 0 145.00 292 199 199 Device Routing Invert Outlet Devices #1 Primary 145.00'22.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Primary OutFlow Max=5.57 cfs @ 12.09 hrs HW=145.21' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 5.57 cfs @ 1.22 fps) Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 39HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond LLS2: Level Spreader 2 Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)6 5 4 3 2 1 0 Inflow Area=1.506 ac Peak Elev=145.21' Storage=199 cf 5.69 cfs5.71 cfs Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 40HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond RG: Rain Garden Inflow Area = 1.595 ac, 70.46% Impervious, Inflow Depth > 2.92" for 10 YRS event Inflow = 5.60 cfs @ 12.09 hrs, Volume= 0.388 af Outflow = 5.28 cfs @ 12.12 hrs, Volume= 0.325 af, Atten= 6%, Lag= 1.7 min Primary = 5.28 cfs @ 12.12 hrs, Volume= 0.325 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 141.84' @ 12.12 hrs Surf.Area= 4,506 sf Storage= 3,520 cf Plug-Flow detention time= 76.8 min calculated for 0.324 af (84% of inflow) Center-of-Mass det. time= 31.7 min ( 804.9 - 773.1 ) Volume Invert Avail.Storage Storage Description #1 141.00' 4,248 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 141.00 3,869 0 0 142.00 4,627 4,248 4,248 Device Routing Invert Outlet Devices #1 Primary 141.65'25.0' long x 2.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 Primary OutFlow Max=5.12 cfs @ 12.12 hrs HW=141.84' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 5.12 cfs @ 1.10 fps) Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 41HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond RG: Rain Garden Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)6 5 4 3 2 1 0 Inflow Area=1.595 ac Peak Elev=141.84' Storage=3,520 cf 5.60 cfs 5.28 cfs Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 42HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond WL: New Low Wetland Area Inflow Area = 1.595 ac, 70.46% Impervious, Inflow Depth > 2.44" for 10 YRS event Inflow = 5.28 cfs @ 12.12 hrs, Volume= 0.325 af Outflow = 4.99 cfs @ 12.16 hrs, Volume= 0.321 af, Atten= 5%, Lag= 2.2 min Primary = 4.99 cfs @ 12.16 hrs, Volume= 0.321 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 137.38' @ 12.16 hrs Surf.Area= 2,860 sf Storage= 928 cf Plug-Flow detention time= 8.8 min calculated for 0.320 af (98% of inflow) Center-of-Mass det. time= 4.0 min ( 808.9 - 804.9 ) Volume Invert Avail.Storage Storage Description #1 136.95' 3,241 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 136.95 10 0 0 137.00 1,745 44 44 138.00 4,650 3,198 3,241 Device Routing Invert Outlet Devices #1 Primary 137.05'10.0' long x 2.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 Primary OutFlow Max=4.94 cfs @ 12.16 hrs HW=137.38' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 4.94 cfs @ 1.49 fps) Type III 24-hr 10 YRS Rainfall=4.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 43HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond WL: New Low Wetland Area Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)5 4 3 2 1 0 Inflow Area=1.595 ac Peak Elev=137.38' Storage=928 cf 5.28 cfs 4.99 cfs Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 44HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=862,118 sf 7.39% Impervious Runoff Depth>2.32"Subcatchment P-1: Proposed Site Flow Length=841' Tc=17.4 min CN=63 Runoff=40.61 cfs 3.821 af Runoff Area=33,660 sf 94.86% Impervious Runoff Depth>5.63"Subcatchment P-2: Proposed Site Tc=6.0 min CN=96 Runoff=4.76 cfs 0.363 af Runoff Area=69,490 sf 70.46% Impervious Runoff Depth>4.72"Subcatchment P-3: Proposed Site Tc=6.0 min CN=87 Runoff=8.83 cfs 0.628 af Runoff Area=4,700 sf 100.00% Impervious Runoff Depth>5.78"Subcatchment P-4: Proposed Site Tc=6.0 min CN=98 Runoff=0.67 cfs 0.052 af Runoff Area=65,609 sf 78.20% Impervious Runoff Depth>5.04"Subcatchment P-5: Proposed Site Tc=6.0 min CN=90 Runoff=8.73 cfs 0.633 af Avg. Flow Depth=0.53' Max Vel=3.22 fps Inflow=7.99 cfs 0.560 afReach ES: Existing Swale n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs Outflow=7.89 cfs 0.560 af Inflow=53.90 cfs 5.370 afReach P-CP: Connecticut River Outflow=53.90 cfs 5.370 af Peak Elev=147.50' Storage=2,192 cf Inflow=0.67 cfs 0.052 afPond IT: Infiltration Trench Outflow=0.02 cfs 0.002 af Peak Elev=147.19' Storage=145 cf Inflow=4.76 cfs 0.363 afPond LLS1: Level Spreader 1 Outflow=4.78 cfs 0.359 af Peak Elev=145.28' Storage=199 cf Inflow=8.73 cfs 0.633 afPond LLS2: Level Spreader 2 Outflow=8.73 cfs 0.628 af Peak Elev=141.91' Storage=3,834 cf Inflow=8.83 cfs 0.628 afPond RG: Rain Garden Outflow=8.47 cfs 0.565 af Peak Elev=137.50' Storage=1,293 cf Inflow=8.47 cfs 0.565 afPond WL: New Low Wetland Area Outflow=7.99 cfs 0.560 af Total Runoff Area = 23.774 ac Runoff Volume = 5.496 af Average Runoff Depth = 2.77" 80.63% Pervious = 19.168 ac 19.37% Impervious = 4.605 ac Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 45HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-1: Proposed Site Runoff = 40.61 cfs @ 12.25 hrs, Volume= 3.821 af, Depth> 2.32" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100 YRS Rainfall=6.50" Area (sf) CN Description 9,670 98 Paved parking & roofs * 16,460 96 Gravel 78,887 65 Woods/grass comb., Fair, HSG B 471,363 55 Woods, Good, HSG B 98,010 70 Woods, Good, HSG C 115,448 61 >75% Grass cover, Good, HSG B 14,985 74 >75% Grass cover, Good, HSG C 54,045 98 Paved parking, HSG B 3,250 74 >75% Grass cover, Good, HSG C 862,118 63 Weighted Average 798,403 92.61% Pervious Area 63,715 7.39% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.6 100 0.0400 3.00 Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps 11.0 430 0.0170 0.65 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 1.8 131 0.0600 1.22 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 4.0 180 0.0230 0.76 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 17.4 841 Total Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 46HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Subcatchment P-1: Proposed Site Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 Type III 24-hr 100 YRS Rainfall=6.50" Runoff Area=862,118 sf Runoff Volume=3.821 af Runoff Depth>2.32" Flow Length=841' Tc=17.4 min CN=63 40.61 cfs Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 47HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-2: Proposed Site Runoff = 4.76 cfs @ 12.09 hrs, Volume= 0.363 af, Depth> 5.63" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100 YRS Rainfall=6.50" Area (sf) CN Description 31,930 98 Paved parking & roofs 1,730 61 >75% Grass cover, Good, HSG B 33,660 96 Weighted Average 1,730 5.14% Pervious Area 31,930 94.86% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment P-2: Proposed Site Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)5 4 3 2 1 0 Type III 24-hr 100 YRS Rainfall=6.50" Runoff Area=33,660 sf Runoff Volume=0.363 af Runoff Depth>5.63" Tc=6.0 min CN=96 4.76 cfs Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 48HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-3: Proposed Site Runoff = 8.83 cfs @ 12.09 hrs, Volume= 0.628 af, Depth> 4.72" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100 YRS Rainfall=6.50" Area (sf) CN Description 48,961 98 Paved parking & roofs 20,529 61 >75% Grass cover, Good, HSG B 69,490 87 Weighted Average 20,529 29.54% Pervious Area 48,961 70.46% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment P-3: Proposed Site Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)9 8 7 6 5 4 3 2 1 0 Type III 24-hr 100 YRS Rainfall=6.50" Runoff Area=69,490 sf Runoff Volume=0.628 af Runoff Depth>4.72" Tc=6.0 min CN=87 8.83 cfs Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 49HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-4: Proposed Site Runoff = 0.67 cfs @ 12.09 hrs, Volume= 0.052 af, Depth> 5.78" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100 YRS Rainfall=6.50" Area (sf) CN Description 4,700 98 Paved parking & roofs 4,700 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment P-4: Proposed Site Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type III 24-hr 100 YRS Rainfall=6.50" Runoff Area=4,700 sf Runoff Volume=0.052 af Runoff Depth>5.78" Tc=6.0 min CN=98 0.67 cfs Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 50HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-5: Proposed Site Runoff = 8.73 cfs @ 12.09 hrs, Volume= 0.633 af, Depth> 5.04" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100 YRS Rainfall=6.50" Area (sf) CN Description 51,303 98 Paved parking & roofs 14,306 61 >75% Grass cover, Good, HSG B 65,609 90 Weighted Average 14,306 21.80% Pervious Area 51,303 78.20% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment P-5: Proposed Site Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)9 8 7 6 5 4 3 2 1 0 Type III 24-hr 100 YRS Rainfall=6.50" Runoff Area=65,609 sf Runoff Volume=0.633 af Runoff Depth>5.04" Tc=6.0 min CN=90 8.73 cfs Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 51HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach ES: Existing Swale Inflow Area = 1.595 ac, 70.46% Impervious, Inflow Depth > 4.21" for 100 YRS event Inflow = 7.99 cfs @ 12.15 hrs, Volume= 0.560 af Outflow = 7.89 cfs @ 12.16 hrs, Volume= 0.560 af, Atten= 1%, Lag= 0.7 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Max. Velocity= 3.22 fps, Min. Travel Time= 0.4 min Avg. Velocity = 1.41 fps, Avg. Travel Time= 0.9 min Peak Storage= 196 cf @ 12.15 hrs Average Depth at Peak Storage= 0.53' , Surface Width= 7.33' Bank-Full Depth= 1.00' Flow Area= 7.0 sf, Capacity= 32.33 cfs 2.00' x 1.00' deep channel, n= 0.100 Earth, dense brush, high stage Side Slope Z-value= 5.0 '/' Top Width= 12.00' Length= 79.0' Slope= 0.2025 '/' Inlet Invert= 137.00', Outlet Invert= 121.00' ‡ Reach ES: Existing Swale Inflow Outflow Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)8 7 6 5 4 3 2 1 0 Inflow Area=1.595 ac Avg. Flow Depth=0.53' Max Vel=3.22 fps n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs 7.99 cfs7.89 cfs Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 52HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach P-CP: Connecticut River Inflow Area = 23.774 ac, 19.37% Impervious, Inflow Depth > 2.71" for 100 YRS event Inflow = 53.90 cfs @ 12.21 hrs, Volume= 5.370 af Outflow = 53.90 cfs @ 12.21 hrs, Volume= 5.370 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Reach P-CP: Connecticut River Inflow Outflow Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)60 55 50 45 40 35 30 25 20 15 10 5 0 Inflow Area=23.774 ac 53.90 cfs53.90 cfs Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 53HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond IT: Infiltration Trench Inflow Area = 0.108 ac,100.00% Impervious, Inflow Depth > 5.78" for 100 YRS event Inflow = 0.67 cfs @ 12.09 hrs, Volume= 0.052 af Outflow = 0.02 cfs @ 18.10 hrs, Volume= 0.002 af, Atten= 97%, Lag= 360.8 min Primary = 0.02 cfs @ 18.10 hrs, Volume= 0.002 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 147.50' @ 18.10 hrs Surf.Area= 1,370 sf Storage= 2,192 cf Plug-Flow detention time= 779.8 min calculated for 0.002 af (3% of inflow) Center-of-Mass det. time= 407.2 min ( 1,141.0 - 733.8 ) Volume Invert Avail.Storage Storage Description #1 141.00' 2,192 cf Custom Stage Data (Prismatic) Listed below (Recalc) 5,480 cf Overall x 40.0% Voids Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 141.00 1,370 0 0 145.00 1,370 5,480 5,480 Device Routing Invert Outlet Devices #1 Primary 147.50'24.0" x 24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.00 cfs @ 18.10 hrs HW=147.50' (Free Discharge) 1=Orifice/Grate (Weir Controls 0.00 cfs @ 0.19 fps) Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 54HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond IT: Infiltration Trench Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Inflow Area=0.108 ac Peak Elev=147.50' Storage=2,192 cf 0.67 cfs 0.02 cfs Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 55HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond LLS1: Level Spreader 1 Inflow Area = 0.773 ac, 94.86% Impervious, Inflow Depth > 5.63" for 100 YRS event Inflow = 4.76 cfs @ 12.09 hrs, Volume= 0.363 af Outflow = 4.78 cfs @ 12.09 hrs, Volume= 0.359 af, Atten= 0%, Lag= 0.0 min Primary = 4.78 cfs @ 12.09 hrs, Volume= 0.359 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 147.19' @ 12.09 hrs Surf.Area= 230 sf Storage= 145 cf Plug-Flow detention time= 8.2 min calculated for 0.359 af (99% of inflow) Center-of-Mass det. time= 3.9 min ( 742.5 - 738.6 ) Volume Invert Avail.Storage Storage Description #1 146.00' 145 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 146.00 60 0 0 147.00 230 145 145 Device Routing Invert Outlet Devices #1 Primary 147.00'22.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Primary OutFlow Max=4.64 cfs @ 12.09 hrs HW=147.18' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 4.64 cfs @ 1.15 fps) Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 56HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond LLS1: Level Spreader 1 Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)5 4 3 2 1 0 Inflow Area=0.773 ac Peak Elev=147.19' Storage=145 cf 4.76 cfs4.78 cfs Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 57HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond LLS2: Level Spreader 2 Inflow Area = 1.506 ac, 78.20% Impervious, Inflow Depth > 5.04" for 100 YRS event Inflow = 8.73 cfs @ 12.09 hrs, Volume= 0.633 af Outflow = 8.73 cfs @ 12.09 hrs, Volume= 0.628 af, Atten= 0%, Lag= 0.0 min Primary = 8.73 cfs @ 12.09 hrs, Volume= 0.628 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 145.28' @ 12.09 hrs Surf.Area= 292 sf Storage= 199 cf Plug-Flow detention time= 6.2 min calculated for 0.628 af (99% of inflow) Center-of-Mass det. time= 3.0 min ( 757.2 - 754.2 ) Volume Invert Avail.Storage Storage Description #1 144.00' 199 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 144.00 105 0 0 145.00 292 199 199 Device Routing Invert Outlet Devices #1 Primary 145.00'22.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Primary OutFlow Max=8.50 cfs @ 12.09 hrs HW=145.27' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 8.50 cfs @ 1.41 fps) Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 58HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond LLS2: Level Spreader 2 Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)9 8 7 6 5 4 3 2 1 0 Inflow Area=1.506 ac Peak Elev=145.28' Storage=199 cf 8.73 cfs8.73 cfs Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 59HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond RG: Rain Garden Inflow Area = 1.595 ac, 70.46% Impervious, Inflow Depth > 4.72" for 100 YRS event Inflow = 8.83 cfs @ 12.09 hrs, Volume= 0.628 af Outflow = 8.47 cfs @ 12.11 hrs, Volume= 0.565 af, Atten= 4%, Lag= 1.5 min Primary = 8.47 cfs @ 12.11 hrs, Volume= 0.565 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 141.91' @ 12.11 hrs Surf.Area= 4,559 sf Storage= 3,834 cf Plug-Flow detention time= 59.8 min calculated for 0.563 af (90% of inflow) Center-of-Mass det. time= 27.0 min ( 788.7 - 761.7 ) Volume Invert Avail.Storage Storage Description #1 141.00' 4,248 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 141.00 3,869 0 0 142.00 4,627 4,248 4,248 Device Routing Invert Outlet Devices #1 Primary 141.65'25.0' long x 2.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 Primary OutFlow Max=8.25 cfs @ 12.11 hrs HW=141.91' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 8.25 cfs @ 1.29 fps) Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 60HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond RG: Rain Garden Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)9 8 7 6 5 4 3 2 1 0 Inflow Area=1.595 ac Peak Elev=141.91' Storage=3,834 cf 8.83 cfs 8.47 cfs Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 61HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond WL: New Low Wetland Area Inflow Area = 1.595 ac, 70.46% Impervious, Inflow Depth > 4.25" for 100 YRS event Inflow = 8.47 cfs @ 12.11 hrs, Volume= 0.565 af Outflow = 7.99 cfs @ 12.15 hrs, Volume= 0.560 af, Atten= 6%, Lag= 2.1 min Primary = 7.99 cfs @ 12.15 hrs, Volume= 0.560 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 137.50' @ 12.15 hrs Surf.Area= 3,210 sf Storage= 1,293 cf Plug-Flow detention time= 6.8 min calculated for 0.558 af (99% of inflow) Center-of-Mass det. time= 3.7 min ( 792.4 - 788.7 ) Volume Invert Avail.Storage Storage Description #1 136.95' 3,241 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 136.95 10 0 0 137.00 1,745 44 44 138.00 4,650 3,198 3,241 Device Routing Invert Outlet Devices #1 Primary 137.05'10.0' long x 2.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 Primary OutFlow Max=7.98 cfs @ 12.15 hrs HW=137.50' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 7.98 cfs @ 1.76 fps) Type III 24-hr 100 YRS Rainfall=6.50"60 Damon Road - PROP Printed 10/20/2021Prepared by Berkshire Design Group Page 62HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond WL: New Low Wetland Area Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)9 8 7 6 5 4 3 2 1 0 Inflow Area=1.595 ac Peak Elev=137.50' Storage=1,293 cf 8.47 cfs 7.99 cfs 60 Damon Road – Marijuana Manufacturing Facility October 13, 2021 Northampton, Massachusetts Revised October 20, 2021 The Berkshire Design Group, Inc.Appendix Operation & Maintenance Plan and Form 60 Damon Road – Marijuana Manufacturing Facility October 13, 2021 Northampton, Massachusetts Revised October 20, 2021 1 Proposed Stormwater Management Plan System Operation & Maintenance This Operation & Maintenance Plan is an amendment to an existing Plan for ‘CT River Greenway & Lane Business Park’ dated July 27, 2012, and revised September 18, 2013. The system components, inspection, and maintenance schedule are the same as the original Plan. Ownership and responsibility for operation and maintenance remain the City of Northampton until an agreement is made between the City and the owners of 60 Damon Road. During Construction The Contractor shall be responsible for inspection and maintenance during construction. At all times, siltation fabric fencing, stakes and hay bales sufficient to construct a sedimentation control barrier a minimum of 50 feet long will be stockpiled on the site in order to repair established barriers which may have been damaged or breached. An inspection of all erosion control and stormwater management systems shall be conducted by the Contractor at least once a week and during all rain storms until the completion of construction. In case of any noted breach or failure, the Contractor shall immediately make appropriate repairs to any erosion control system and notify the engineer of any problems involving stormwater management systems. A rain storm shall be defined as all or one of the following: Any storm in which rain is predicted to last for twelve consecutive hours or more. Any storm for which a flash flood watch or warning is issued. Any single storm predicted to have a cumulative rainfall of greater than one-half inch. Any storm not meeting the previous three thresholds but which would mark a third consecutive day of measurable rainfall. The Contractor shall also inspect the erosion control and stormwater management systems at times of significant increase in surface water runoff due to rapid thawing when the risk of failure of erosion control measures is significant. In such instances as remedial action is necessary, the Contractor shall repair any and all significant deficiencies in erosion control systems within two days. The Northampton Department of Public Works shall be notified of any significant failure of stormwater management systems and erosion and sediment control measures and shall be notified of any release of pollutants to a water body (stream, brook, pond, etc.). The Contractor shall remove the sediment from behind the fence of the sedimentation control barrier when the accumulated sediment has reached one-half of the original installed height of the barrier. 60 Damon Road – Marijuana Manufacturing Facility October 13, 2021 Northampton, Massachusetts Revised October 20, 2021 2 This project requires a NPDES General Permit for Stormwater Discharges from Constriction Activities. Contractor and Owner are responsible for finalizing a Stormwater Pollution Prevention Plan (SWPPP) and filing for the NDPES permit prior to the start of construction. All clearing, grading, drainage, construction, and development shall be conducted in strict accordance with the SWPPP. Post-Construction Stormwater Management System Owner: Green Delta Holdings LLC 60 Damon Road Northampton, MA 01060 Party Responsible for Operation & Maintenance: Green Delta Holdings LLC 60 Damon Road Northampton, MA 01060 Inspection & Maintenance Schedule: 1)Street Sweeping Street and parking area sweeping shall take place a minimum of 2 times per year. 2)Hooded Catch Basin and/or Drain Manhole with Sump Oil and water separators should be inspected at least four times per year and cleaned annually or more often if required. Oil and sediments should be removed and disposed of in accordance with local, state and federal guidelines and regulations. In the case of an oil or bulk pollutant release, the system must be cleaned immediately following the spill and the proper authorities notified. 3)Stormwater Treatment Chambers The Stormwater Treatment Chamber, of which there are 2 StormCeptor (Model # STC450) water quality structures or equal treatment chambers, shall be inspected and maintained according the manufacturer’s specifications. Rinker, the manufacturer of Stormceptor recommends that maintenance be completed on the structures at least once per year, but advises that the units be checked once every three months during the first year to determine the rate of sediment and oil accumulation and to establish an appropriate maintenance schedule. The rate at which the system collects pollutants will depend on site activities. Maintenance or cleaning shall be performed when the stored volume reaches 15% (6 inch sediment depth) of the Stormceptor capacity, when oil (hydrocarbon) has 60 Damon Road – Marijuana Manufacturing Facility October 13, 2021 Northampton, Massachusetts Revised October 20, 2021 3 accumulated to 1 inch or greater depth, or immediately in the event of a fuel or oil spill according the manufacturer’s specifications. All material removed from the Stormceptor shall be disposed in accordance with applicable local, state, and federal guidelines and regulations. For more detail of how the StormCeptor should be maintained see the StormCeptor's Owner Manual. 4)Infiltration Trench Infiltration trenches require regular removal of accumulated sediment to maintain an optimal rate of infiltration. The Pretreatment BMP (Deep Sump Hooded Catch Basin) should be routinely inspected and cleaned as described in this document to prevent sediment from entering the infiltration system. Inspect the infiltration trench after the first several rainfall events, after all major storms, and on regularly scheduled dates every six months. After large storms the trench should be inspected for ponding water through the observation well. If ponding is occurring this may indicate that the trench requires rehabilitation. To rehabilitate a trench all accumulated sediment must be stripped from the bottom, the bottom of the trench must be scarified and tilled to induce infiltration, and all of the stone aggregate and filter fabric or media must be removed and replaced. The grass on top of the trench should be mowed seasonally to maintain a level of no higher than 4 inches. The maintenance log (attached) for the project, including inspections, repairs, replacement and disposal shall be maintained for a period of three (3) years and be made available to MassDEP and the Northampton Conservation Commission upon request. INSPECTION AND MAINTANENCE REPORT FORM The Berkshire Design Group, Inc.Page 1/2 IIINNNSSSPPPEEECCCTTTIIIOOONNN AAANNNDDD MMMAAAIIINNNTTTEEENNNAAANNNCCCEEE RRREEEPPPOOORRRTTT FFFOOORRRMMM For Stormwater Infrastructure 60 Damon Road - Northampton, MA Inspection Schedule: FORM TO BE COMPLETED PER SCHEDULE PRESENTED IN OPERATION & MAINTENANCE PLAN Inspector: Date:Time: Inspector’s Qualifications: Days Since Last Rainfall: Amount of Last Rainfall (inches): Catch Basins CB # or Location Is Surface Runoff Being Directed to Catch Basins Properly Are Sediment Traps Installed at Catch Basin Inlets Are Catch Basin Outlet Hoods Installed and Working Properly Depth of Sediment in Basin Sump Are Any Correction Measures Required INSPECTION AND MAINTANENCE REPORT FORM The Berkshire Design Group, Inc.Page 2/2 Maintenance Required: To Be Performed By:On or Before: Stormwater Treatment Chambers SWTC #Is Stormwater Being Retained and Discharged Properly Depth of Sediment in Sump Are Any Correction Measures Required 1 Maintenance Required: To Be Performed By:On or Before: Infiltration Trench Structure Is Structure Working Properly Are Any Correction Measures Required Is the Basin Drawn Down 72 Hours After Storm Infiltration Trench Maintenance Required: To Be Performed By:On or Before: OOTTHHEERR CCOONNTTRROOLLSS List Other Miscellaneous Controls and Observations Item Describe Failure/Inadequate Control Describe Recommended Remedy Maintenance Required: To Be Performed By:On or Before: 60 Damon Road – Marijuana Manufacturing Facility October 20, 2021 Northampton, Massachusetts The Berkshire Design Group, Inc.Appendix Operation & Maintenance Agreement And Drainage Easment O&M Agreement_rev 2012 Page 1 of 3 STORMWATER MANAGEMENT OPERATION, MAINTENANCE, AND INSPECTION AGREEMENT City of Northampton, MA Department of Public Works (413) 587-1570 THIS AGREEMENT, made and entered into this ___ day of October________, 2021, by and between (Insert Full Name of Owner) Green Delta Holdings LLC hereinafter called the "Landowner", and the City of Northampton, hereinafter called the "City". WITNESSETH, that WHEREAS, the Landowner is the owner of certain real property at (Street Address) 60 Damon Road__________________________________________ as described as (City of Northampton Assessors Map/Parcel/Lot Number) ______18-009______________________________________ as recorded by deed in the land records of Hampshire County, Massachusetts, Deed Book __________ Page __________, hereinafter called the "Property". WHEREAS, the Landowner is proceeding to build on and develop the property; and WHEREAS, the Site Plan/Subdivision Plan known as 60 Damon Road – Marijuana Manufacturing Facility, (Name of Plan/Development) hereinafter called the "Plan", which is expressly made a part hereof, as approved or to be approved by the City, which provides for the conveyance, treatment, and/or detention of stormwater within the confines of the Property; and WHEREAS, the City and the Landowner, its successors and assigns, including any association, agree that the health, safety, and welfare of the residents of the City of Northampton, Massachusetts, require that on-site stormwater management facilities be constructed and maintained on the Property; and WHEREAS, the City requires that on-site stormwater management facilities as shown on the Plan be constructed and adequately maintained by the Landowner, its successors and assigns, including any homeowners association. NOW, THEREFORE, in consideration of the foregoing premises, in accordance with the Northampton Stormwater Management Ordinance (Chapter 281 of the City’s Code of Ordinance), the mutual covenants contained herein, and the following terms and conditions, the parties hereto agree as follows: 1. The on-site stormwater management facilities shall be constructed by the Landowner, its successors and assigns, in accordance with the plans and specifications identified in the Plans and documents reviewed and approved by the Northampton Department of Public Works (DPW). 2. The Landowner, its successors and assigns, including any association, shall adequately maintain the stormwater management facilities according to the maintenance schedule described in Attachment A. This includes all pipes and channels built to convey stormwater to the facility, as well as all structures, improvements, and vegetation provided to control the quantity and quality of the stormwater. Adequate maintenance is herein defined as good working condition so that these facilities are performing their design functions and so that water quality standards are met in all seasons and throughout the life of the stormwater system. 3. The Landowner, its successors and assigns, shall inspect the stormwater management facility; and shall submit an annual report documenting the inspection and maintenance of the stormwater management system as certified by a Registered Professional Engineer or other qualified stormwater professional as approved by the DPW and submitted to the Northampton Department O&M Agreement_rev 2012 Page 2 of 3 of Public Works by October 1st each year. The purpose of the inspection is to assure safe and proper functioning of the facilities. The inspection shall cover the entire facilities, stormwater systems, berms, outlet structure, pond areas, access roads, etc. Deficiencies and a plan to correct deficiencies shall be noted in the inspection report. 4. The Landowner, its successors and assigns, hereby grant permission to the City, its authorized agents and employees, to enter upon the Property and to inspect the stormwater management facilities whenever the City deems necessary. The purpose of inspection is to follow-up on reported deficiencies, inspect the stormwater management facilities when annual reports have not been submitted and/or to respond to citizen complaints. The City shall provide the Landowner, its successors and assigns, copies of the inspection findings and a directive to commence with the repairs if necessary. 5. In the event the Landowner, its successors and assigns, fails to maintain the stormwater management facilities in good working condition acceptable to the City, and if after notice by the City Engineer to correct a violation requiring maintenance work, satisfactory corrections are not made by the Landowner, its successors and assigns within thirty days, the City may enter upon the Property and perform all necessary work to place the facility in proper working condition and assess the costs of such work and any penalties to the Landowner, its successors and assigns. This provision shall not be construed to allow the City to erect any structure of permanent nature on the land of the Landowner outside of the easement for the stormwater management facilities. It is expressly understood and agreed that the City is under no obligation to routinely maintain or repair said facilities, and in no event shall this Agreement be construed to impose any such obligation on the City. 6. In the event the City pursuant to this Agreement, performs work of any nature, or expends any funds in performance of said work for labor, use of equipment, supplies, materials, and the like, the Landowner, its successors and assigns, shall reimburse the City upon demand, within thirty (30) days of receipt thereof for all actual costs incurred by the City hereunder. 7. A portion of City property discharges storm water into the storm system covered under this agreement as described and shown and recorded in the Deed (BK:11332 PG:206). Aside from the permissions granted and described in the easement, this Agreement imposes no liability of any kind whatsoever on the City; and further the Landowner agrees to hold the City harmless from any liability in the event the stormwater management facilities fail to operate properly. 8. The Landowner, its successors and assigns, including any homeowners association, shall provide stormwater management easements as necessary for all areas used for off-site stormwater control, preservation of stormwater runoff conveyance, infiltration, and detention areas and facilities, including flood routes for the 100-year storm event, and access for facility maintenance and inspection. A list of easements with the purpose and location of each shall be specified in Attachment B. The Landowner, its successors and assigns shall record all easements in the land records of the Hampshire County Registry of Deeds, Commonwealth of Massachusetts. 9. The Landowner, its successors and assigns, shall notify the DPW of any changes in ownership, assignment of financial responsibility, reconstruction of the approved stormwater management facilities and/or amendments to the maintenance schedule described in Attachment A. The maintenance schedule described in Attachment A may be amended to achieve the purpose of the Northampton Stormwater Management Ordinance by mutual agreement of the DPW and the Landowner, its successors and assigns. Amendments shall be in writing and signed by the DPW and all responsible parties. 10. This Agreement shall be recorded by the property owners or at the property owners expense among the land records of Hampshire County, Commonwealth of Massachusetts, and shall constitute a covenant running with the land, and shall be binding on the Landowner, its administrators, executors, assigns, heirs and any other successors in interests, including any homeowners association. O&M Agreement_rev 2012 Page 3 of 3 WITNESS the following signatures and seals: Green Delta Holdings, LLC Company/Corporation/Partnership Name (Seal) By:_____________________________________________ Ilya Tunitskiy (Type Name) ______________________________________________ (Type Title) COMMONWEALTH OF MASSACHUSETTS County of Hampshire On this _____ day of ________________, 2021, before me, the undersigned notary public, personally appeared _________________________, proved to me through satisfactory evidence of identification, which was a Driver’s License, to be the person whose name is signed on the proceeding document, and acknowledged to me that he signed it voluntarily for its stated purpose. _______________________________________ NOTARY PUBLIC My Commission Expires: ____________ CITY OF NORTHAMPTON By:________________________________________ David J. Narkewicz, Mayor COMMONWEALTH OF MASSACHUSETTS County of Hampshire On this _____ day of ________________, 2021, before me, the undersigned notary public, personally appeared _________________________, proved to me through satisfactory evidence of identification, which was a Driver’s License, to be the person whose name is signed on the proceeding document, and acknowledged to me that he signed it voluntarily for its stated purpose. _______________________________________ NOTARY PUBLIC My Commission Expires: ____________