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60 Damon Road Stormwater Amendment Letter4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com BerkshireDesignGroup August 26, 2021 Doug McDonald Northampton DPW 210 Main Street Northampton, MA 01060 RE: 60 Damon Road – Marijuana Manufacturing Facility Stormwater Management Amendment Doug, The purpose of this letter is to address proposed amendments to the previously approved stormwater management system at 60 Damon Road in Northampton. A previous project at this site submitted a Stormwater Drainage Report to the City of Northampton in July 2012. The project was for the ‘Connecticut River Greenway: Lane Business Park & Northampton Community Boathouse’. The proposed stormwater management system consisted of four separate treatment trains, each with their own discharge that eventually flowed to the Connecticut River. One train consisted of a rain garden, two trains consisted of proprietary Stormwater Treatment Chambers (SWTCs) discharging to level lip spreaders, and the last train consisted of deep sump catch basins flowing into an infiltration trench. After many rounds of reviews and comments, the City approved the final proposed stormwater system in the Fall of 2012. Existing Conditions (October 2012) Prior to any construction, as of October 2012, runoff from the entire site sheet flowed overland to various swales and ultimately discharged into the Connecticut River. ‘Figure 1: Existing Conditions Subcatchment Plan’ from October 9, 2012, shows two drainage areas. The majority of the site was modeled as one drainage area, E- 1, from which runoff flowed directly to the control point (Connecticut River). A small portion of the site, just east of center, was modeled as another drainage area, E-2, that flowed through a swale to the control point. Conditions Post-Phase I (2018) Following the approval and issuance of relevant permits, the project was only partially constructed. In 2018, the boathouse and surrounding parking and paved drives were built, along with the relevant components of the stormwater management system. These components included the rain garden treatment train and a portion of one SWTC treatment train. ‘Figure 2: Proposed Conditions Subcatchment Plan’ shows the drainage areas that were approved in October 2012. The rain garden treatment train captures and treats stormwater runoff from the boathouse itself and the surrounding pavement area. The entirety of the designed train was constructed and is currently in use. This is drainage area P-3 in Figure 2. The partially constructed SWTC train was designed to treat runoff from two parking areas as well as roof runoff from a new building. Out of the designed areas, only one parking area was constructed and routed to the SWTC and level lip spreader. This treatment train is for drainage area P-2 in Figure 2. Neither the infiltration trench treatment train nor the other SWTC train were constructed. The areas that these trains were designed to treat remain unchanged from the original existing conditions. In Figure 2, the infiltration trench treats runoff from area P-4 and the other SWTC treats runoff from P-5. August 26, 2021 60 Damon Road – Marijuana Manufacturing Facility Stormwater Management Amendment Page 2 of 4 4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com Proposed Phase II Amendments (Modifications) The new project proposes to finish constructing the remainder of the previously approved project, including the stormwater treatment trains, with some adjustments. ‘Figure 3: Modified Design Subcatchment Plan’ shows the modified drainage areas. Drainage Area P-2 The new project proposes changes to the building and parking in drainage area P-2 that will be conveyed to the partially constructed SWTC (North SWTC) treatment train. ‘Table 2: North SWTC, P-2’ shows a breakdown between the original design areas and the modified design areas. Table 2: North SWTC, P-2 Original Design Area (sf)Modified Design Area (sf) Grass 6,713 Grass 1,730 Roof 10,053 Roof 13,751 Pavement 25,682 Pavement 18,179 Treated Impervious Area 35,735 Treated Impervious Area 31,930 Total Area 42,448 Total Area 33,660 As is evident, under the modified design the North SWTC treats 8,788 square-feet less than the original design. While the roof area routed to the North SWTC increases in the modified design, the pavement area decreases by a larger amount. In total, the impervious area conveyed to the North SWTC is reduced by 3,805 square-feet. Therefore, the original and approved SWTC treatment train will adequately handle the modified design. Drainage Area P-4 In drainage area P-4, the new project proposes to modify the original building area and completely fore-go the parking lot in the original design. This is the largest adjustment to the original design from the new project. ‘Table 3: Infiltration Trench, P-4’ shows a breakdown between the original design areas and the modified design areas. Table 3: Infiltration Trench, P-4 Original Design Area (sf)Modified Design Area (sf) Grass 5,504 Grass 0 Roof 9,801 Roof 4,700 Pavement 14,877 Pavement 0 Treated Impervious Area 24,678 Treated Impervious Area 4,700 Total Area 30,182 Total Area 4,700 Under the modified design the infiltration trench receives significantly less runoff than the original design (25,482 square-feet). The reason the area is reduced so much is from the removal of the parking lot from the original design. The modified roof area is also over 3,000 square-feet less than the original design. The discrepancy in area is incorporated into area P-1 in the modified design, which is essentially existing conditions. Therefore, the original and approved infiltration trench will more than adequately handle the modified design. August 26, 2021 60 Damon Road – Marijuana Manufacturing Facility Stormwater Management Amendment Page 3 of 4 4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com Drainage Area P-5 The new project proposes slight changes to the building and road layout in drainage area P-5. The original design proposed a small building, a parking lot, and road access for the rest of the site in this area. The modified design replaces the building and parking lot with one larger building and adjusts the layout of the road access to accommodate these changes. As part of these adjustments, the catch-basins that capture and convey the stormwater runoff within this area have been relocated to continue to capture all runoff. ‘Table 4: South SWTC, P-5’ shows a breakdown between the original design areas and the modified areas. Table 4: South SWTC, P-5 Original Design Area (sf)Modified Design Area (sf) Grass 19,429 Grass 14,306 Roof 9,801 Roof 23,661 Pavement 35,023 Pavement 27,642 Treated Impervious Area 44,824 Treated Impervious Area 51,303 Total Area 64,253 Total Area 65,609 As is evident, both the total area and the amount of impervious area conveyed to the South SWTC increases in the modified design. The pavement area, however, decreases from the original to the modified design. The original design called for the South SWTC to be a Stormceptor 450i made by Contech. The modified design area was inputted into Contech’s Stormceptor sizing program, which calculated that the 450i (original design SWTC) will achieve 80% TSS removal. See attached ‘Brief Stormceptor Sizing Report Modified P-5’. Therefore, the original and approved SWTC will adequately handle the modified design. Drainage Area P-1 All the proposed changes to drainage areas P-2, P-4, and P-5 affect P-1. ‘Table 5: P-1’ shows these effects on P- 1. The area added to P-1 mostly consists of grass surfaces, with the exception of the existing gravel parking area around the building in P-4 that will remain. Table 5: P-1 Original Design Area (sf)Modified Design Area (sf) Grass 93,913 Grass 121,933 Woods 648,260 Woods 648,260 Gravel 11,979 Gravel 16,460 Roof 9,670 Roof 9,670 Pavement 49,045 Pavement 49,045 Total Area 812,867 Total Area 845,368 Peak Runoff ‘Table 6: Peak Runoff Comparison’ shows the peak flow and total volume of runoff to the control point (Connecticut River) for the existing, original proposed, and modified proposed conditions. August 26, 2021 60 Damon Road – Marijuana Manufacturing Facility Stormwater Management Amendment Page 4 of 4 4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com Table 6: Peak Runoff Comparison 2-YR Storm (3.0")10-YR Storm (4.5")100-YR Storm (6.5")Point of Analysis Connecticut River Peak Flow (cfs) Total Volume (ac- ft) Peak Flow (cfs) Total Volume (ac- ft) Peak Flow (cfs) Total Volume (ac- ft) Existing-CP 9.42 1.233 26.63 3.019 54.46 5.934 Proposed-CP (Oct. 2012)8.72 1.214 26.87 2.655 53.18 5.744 Proposed-CP (Aug. 2021)8.59 1.262 26.31 2.981 54.11 5.801 Conclusion The original and approved stormwater management system will be able to adequately treat and handle the proposed modifications to the original design. Please do not hesitate to contact me at (413) 582-7000 or liam@berkshiredesign.com if you have any questions about the information contained in this letter. Sincerely, Berkshire Design Group, Inc. Liam McCann, EIT E-1 Existing Site E-2 Existing Site- Portion to NE Swale P-1 Proposed Site P-2 Proposed Site P-3 Proposed Site P-4 Proposed Site P-5 Proposed Site E-CP Connecticut River ES Existing Swale 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 Smith Boathouse - Modified Design 2021.08.25 Prepared by Berkshire Design Group, Printed 8/26/2021 HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Subcat Reach Pond Link Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared 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 Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared 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) 1.492 79 <50% Grass cover, Poor, HSG B (E-1, E-2) 3.926 61 >75% Grass cover, Good, HSG B (E-1, P-1, P-2, P-3, P-5) 1.274 74 >75% Grass cover, Good, HSG C (E-1, P-1) 0.378 96 Gravel (P-1) 1.664 96 Gravel Area (E-1) 5.091 98 Paved parking & roofs (E-1, P-1, P-2, P-3, P-4, P-5) 2.045 98 Paved parking, HSG B (E-1, P-1) 21.642 55 Woods, Good, HSG B (E-1, E-2, P-1) 4.500 70 Woods, Good, HSG C (E-1, P-1) 5.521 65 Woods/grass comb., Fair, HSG B (E-1, E-2, P-1) 47.532 68 TOTAL AREA Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared 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 34.626 HSG B E-1, E-2, P-1, P-2, P-3, P-5 5.773 HSG C E-1, P-1 0.000 HSG D 7.133 Other E-1, P-1, P-2, P-3, P-4, P-5 47.532 TOTAL AREA Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared 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 1.492 0.000 0.000 0.000 1.492 <50% Grass cover, Poor E-1, E-2 0.000 3.926 1.274 0.000 0.000 5.199 >75% Grass cover, Good E-1, 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 0.000 0.000 0.000 1.664 1.664 Gravel Area E-1 0.000 2.045 0.000 0.000 0.000 2.045 Paved parking E-1, P-1 0.000 0.000 0.000 0.000 5.091 5.091 Paved parking & roofs E-1, P-1, P-2, P-3, P-4, P-5 0.000 21.642 4.500 0.000 0.000 26.142 Woods, Good E-1, E-2, P-1 0.000 5.521 0.000 0.000 0.000 5.521 Woods/grass comb., Fair E-1, E-2, P-1 0.000 34.626 5.773 0.000 7.133 47.532 TOTAL AREA Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared 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=1,013,902 sf 11.37% Impervious Runoff Depth>0.62"Subcatchment E-1: Existing Site Flow Length=1,101' Tc=21.0 min CN=68 Runoff=9.26 cfs 1.208 af Runoff Area=21,035 sf 0.00% Impervious Runoff Depth>0.63"Subcatchment E-2: Existing Site- Portion to Tc=6.0 min CN=68 Runoff=0.29 cfs 0.025 af Runoff Area=845,368 sf 6.95% Impervious Runoff Depth>0.43"Subcatchment P-1: Proposed Site Flow Length=841' Tc=17.4 min CN=63 Runoff=4.64 cfs 0.696 af Runoff Area=33,660 sf 94.86% Impervious Runoff Depth>2.55"Subcatchment P-2: Proposed Site Tc=6.0 min CN=96 Runoff=2.11 cfs 0.164 af Runoff Area=86,240 sf 56.77% Impervious Runoff Depth>1.38"Subcatchment P-3: Proposed Site Tc=6.0 min CN=82 Runoff=3.12 cfs 0.227 af Runoff Area=4,700 sf 100.00% Impervious Runoff Depth>2.77"Subcatchment P-4: Proposed Site Tc=6.0 min CN=98 Runoff=0.31 cfs 0.025 af Runoff Area=65,608 sf 78.20% Impervious Runoff Depth>1.98"Subcatchment P-5: Proposed Site Tc=6.0 min CN=90 Runoff=3.40 cfs 0.249 af Inflow=9.42 cfs 1.233 afReach E-CP: Connecticut River Outflow=9.42 cfs 1.233 af Avg. Flow Depth=0.25' Max Vel=2.12 fps Inflow=1.70 cfs 0.162 afReach ES: Existing Swale n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs Outflow=1.70 cfs 0.161 af Avg. Flow Depth=0.09' Max Vel=1.21 fps Inflow=0.29 cfs 0.025 afReach ES.: Existing Swale n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs Outflow=0.27 cfs 0.025 af Inflow=8.59 cfs 1.262 afReach P-CP: Connecticut River Outflow=8.59 cfs 1.262 af Peak Elev=142.98' Storage=1,083 cf Inflow=0.31 cfs 0.025 afPond IT: Infiltration Trench Outflow=0.00 cfs 0.000 af Peak Elev=147.11' Storage=145 cf Inflow=2.11 cfs 0.164 afPond LLS1: Level Spreader 1 Outflow=2.11 cfs 0.161 af Peak Elev=145.15' Storage=199 cf Inflow=3.40 cfs 0.249 afPond LLS2: Level Spreader 2 Outflow=3.42 cfs 0.244 af Peak Elev=141.75' Storage=3,121 cf Inflow=3.12 cfs 0.227 afPond RG: Rain Garden Outflow=2.04 cfs 0.165 af Peak Elev=137.21' Storage=486 cf Inflow=2.04 cfs 0.165 afPond WL: New Low Wetland Area Outflow=1.70 cfs 0.162 af Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 7HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Total Runoff Area = 47.532 ac Runoff Volume = 2.594 af Average Runoff Depth = 0.65" 84.99% Pervious = 40.396 ac 15.01% Impervious = 7.136 ac Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 8HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment E-1: Existing Site Runoff = 9.26 cfs @ 12.35 hrs, Volume= 1.208 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 98,000 70 Woods, Good, HSG C 14,000 61 >75% Grass cover, Good, HSG B 25,000 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 1,013,902 68 Weighted Average 898,666 88.63% Pervious Area 115,236 11.37% 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"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 9HydroCAD® 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=1,013,902 sf Runoff Volume=1.208 af Runoff Depth>0.62" Flow Length=1,101' Tc=21.0 min CN=68 9.26 cfs Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 10HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment E-2: Existing Site- Portion to NE Swale Runoff = 0.29 cfs @ 12.11 hrs, Volume= 0.025 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 8,829 65 Woods/grass comb., Fair, HSG B 4,300 55 Woods, Good, HSG B 7,906 79 <50% Grass cover, Poor, HSG B 21,035 68 Weighted Average 21,035 100.00% 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)0.32 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=21,035 sf Runoff Volume=0.025 af Runoff Depth>0.63" Tc=6.0 min CN=68 0.29 cfs Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 11HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-1: Proposed Site Runoff = 4.64 cfs @ 12.35 hrs, Volume= 0.696 af, Depth> 0.43" 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 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 103,698 61 >75% Grass cover, Good, HSG B 14,985 74 >75% Grass cover, Good, HSG C 49,045 98 Paved parking, HSG B 3,250 74 >75% Grass cover, Good, HSG C 845,368 63 Weighted Average 786,653 93.05% Pervious Area 58,715 6.95% 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"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 12HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Subcatchment P-1: Proposed Site Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)5 4 3 2 1 0 Type III 24-hr 2 YRS Rainfall=3.00" Runoff Area=845,368 sf Runoff Volume=0.696 af Runoff Depth>0.43" Flow Length=841' Tc=17.4 min CN=63 4.64 cfs Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 13HydroCAD® 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= 0.164 af, Depth> 2.55" 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 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) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Type III 24-hr 2 YRS Rainfall=3.00" Runoff Area=33,660 sf Runoff Volume=0.164 af Runoff Depth>2.55" Tc=6.0 min CN=96 2.11 cfs Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 14HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-3: Proposed Site Runoff = 3.12 cfs @ 12.10 hrs, Volume= 0.227 af, Depth> 1.38" 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 48,961 98 Paved parking & roofs 37,279 61 >75% Grass cover, Good, HSG B 86,240 82 Weighted Average 37,279 43.23% Pervious Area 48,961 56.77% 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) 2423222120191817161514131211109876543210Flow (cfs)3 2 1 0 Type III 24-hr 2 YRS Rainfall=3.00" Runoff Area=86,240 sf Runoff Volume=0.227 af Runoff Depth>1.38" Tc=6.0 min CN=82 3.12 cfs Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 15HydroCAD® 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= 0.025 af, Depth> 2.77" 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 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) 2423222120191817161514131211109876543210Flow (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=0.025 af Runoff Depth>2.77" Tc=6.0 min CN=98 0.31 cfs Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 16HydroCAD® 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= 0.249 af, Depth> 1.98" 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 51,303 98 Paved parking & roofs 14,305 61 >75% Grass cover, Good, HSG B 65,608 90 Weighted Average 14,305 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) 2423222120191817161514131211109876543210Flow (cfs)3 2 1 0 Type III 24-hr 2 YRS Rainfall=3.00" Runoff Area=65,608 sf Runoff Volume=0.249 af Runoff Depth>1.98" Tc=6.0 min CN=90 3.40 cfs Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 17HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach E-CP: Connecticut River Inflow Area = 23.759 ac, 11.13% Impervious, Inflow Depth > 0.62" for 2 YRS event Inflow = 9.42 cfs @ 12.35 hrs, Volume= 1.233 af Outflow = 9.42 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=23.759 ac 9.42 cfs9.42 cfs Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 18HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach ES: Existing Swale Inflow Area = 1.980 ac, 56.77% Impervious, Inflow Depth > 0.98" for 2 YRS event Inflow = 1.70 cfs @ 12.30 hrs, Volume= 0.162 af Outflow = 1.70 cfs @ 12.32 hrs, Volume= 0.161 af, Atten= 0%, Lag= 1.2 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 2.12 fps, Min. Travel Time= 0.6 min Avg. Velocity = 0.91 fps, Avg. Travel Time= 1.5 min Peak Storage= 64 cf @ 12.31 hrs Average Depth at Peak Storage= 0.25' , Surface Width= 4.49' 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=1.980 ac Avg. Flow Depth=0.25' Max Vel=2.12 fps n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs 1.70 cfs1.70 cfs Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 19HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach ES.: Existing Swale Inflow Area = 0.483 ac, 0.00% Impervious, Inflow Depth > 0.63" for 2 YRS event Inflow = 0.29 cfs @ 12.11 hrs, Volume= 0.025 af Outflow = 0.27 cfs @ 12.15 hrs, Volume= 0.025 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= 1.21 fps, Min. Travel Time= 1.1 min Avg. Velocity = 0.46 fps, Avg. Travel Time= 2.8 min Peak Storage= 18 cf @ 12.12 hrs Average Depth at Peak Storage= 0.09' , Surface Width= 2.94' 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)0.32 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=0.483 ac Avg. Flow Depth=0.09' Max Vel=1.21 fps n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs 0.29 cfs 0.27 cfs Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 20HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach P-CP: Connecticut River Inflow Area = 23.774 ac, 18.89% Impervious, Inflow Depth > 0.64" for 2 YRS event Inflow = 8.59 cfs @ 12.30 hrs, Volume= 1.262 af Outflow = 8.59 cfs @ 12.30 hrs, Volume= 1.262 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 P-CP: Connecticut River Inflow Outflow Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)9 8 7 6 5 4 3 2 1 0 Inflow Area=23.774 ac 8.59 cfs8.59 cfs Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 21HydroCAD® 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 > 2.77" for 2 YRS event Inflow = 0.31 cfs @ 12.09 hrs, Volume= 0.025 af Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 100%, Lag= 0.0 min Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 142.98' @ 24.00 hrs Surf.Area= 1,370 sf Storage= 1,083 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 @ 0.00 hrs HW=141.00' (Free Discharge) 1=Orifice/Grate ( Controls 0.00 cfs) Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 22HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond IT: Infiltration Trench Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (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=142.98' Storage=1,083 cf 0.31 cfs 0.00 cfs Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 23HydroCAD® 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 > 2.55" for 2 YRS event Inflow = 2.11 cfs @ 12.09 hrs, Volume= 0.164 af Outflow = 2.11 cfs @ 12.09 hrs, Volume= 0.161 af, Atten= 0%, Lag= 0.0 min Primary = 2.11 cfs @ 12.09 hrs, Volume= 0.161 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 147.11' @ 12.09 hrs Surf.Area= 230 sf Storage= 145 cf Plug-Flow detention time= 21.3 min calculated for 0.161 af (98% of inflow) Center-of-Mass det. time= 9.1 min ( 784.6 - 775.5 ) 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"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 24HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond LLS1: Level Spreader 1 Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Inflow Area=0.773 ac Peak Elev=147.11' Storage=145 cf 2.11 cfs2.11 cfs Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 25HydroCAD® 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 > 1.98" for 2 YRS event Inflow = 3.40 cfs @ 12.09 hrs, Volume= 0.249 af Outflow = 3.42 cfs @ 12.09 hrs, Volume= 0.244 af, Atten= 0%, Lag= 0.0 min Primary = 3.42 cfs @ 12.09 hrs, Volume= 0.244 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 145.15' @ 12.09 hrs Surf.Area= 292 sf Storage= 199 cf Plug-Flow detention time= 16.6 min calculated for 0.244 af (98% of inflow) Center-of-Mass det. time= 5.9 min ( 814.8 - 808.9 ) 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"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 26HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond LLS2: Level Spreader 2 Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (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"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 27HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond RG: Rain Garden Inflow Area = 1.980 ac, 56.77% Impervious, Inflow Depth > 1.38" for 2 YRS event Inflow = 3.12 cfs @ 12.10 hrs, Volume= 0.227 af Outflow = 2.04 cfs @ 12.22 hrs, Volume= 0.165 af, Atten= 35%, Lag= 7.3 min Primary = 2.04 cfs @ 12.22 hrs, Volume= 0.165 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 141.75' @ 12.22 hrs Surf.Area= 4,438 sf Storage= 3,121 cf Plug-Flow detention time= 148.7 min calculated for 0.165 af (73% of inflow) Center-of-Mass det. time= 54.7 min ( 893.6 - 838.8 ) 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=1.94 cfs @ 12.22 hrs HW=141.75' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 1.94 cfs @ 0.79 fps) Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 28HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond RG: Rain Garden Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)3 2 1 0 Inflow Area=1.980 ac Peak Elev=141.75' Storage=3,121 cf 3.12 cfs 2.04 cfs Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 29HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond WL: New Low Wetland Area Inflow Area = 1.980 ac, 56.77% Impervious, Inflow Depth > 1.00" for 2 YRS event Inflow = 2.04 cfs @ 12.22 hrs, Volume= 0.165 af Outflow = 1.70 cfs @ 12.30 hrs, Volume= 0.162 af, Atten= 17%, Lag= 4.9 min Primary = 1.70 cfs @ 12.30 hrs, Volume= 0.162 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 137.21' @ 12.30 hrs Surf.Area= 2,369 sf Storage= 486 cf Plug-Flow detention time= 19.0 min calculated for 0.161 af (98% of inflow) Center-of-Mass det. time= 7.2 min ( 900.8 - 893.6 ) 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=1.70 cfs @ 12.30 hrs HW=137.21' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 1.70 cfs @ 1.03 fps) Type III 24-hr 2 YRS Rainfall=3.00"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 30HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond WL: New Low Wetland Area Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Inflow Area=1.980 ac Peak Elev=137.21' Storage=486 cf 2.04 cfs 1.70 cfs Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 31HydroCAD® 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=1,013,902 sf 11.37% Impervious Runoff Depth>1.52"Subcatchment E-1: Existing Site Flow Length=1,101' Tc=21.0 min CN=68 Runoff=26.21 cfs 2.957 af Runoff Area=21,035 sf 0.00% Impervious Runoff Depth>1.53"Subcatchment E-2: Existing Site- Portion to Tc=6.0 min CN=68 Runoff=0.82 cfs 0.062 af Runoff Area=845,368 sf 6.95% Impervious Runoff Depth>1.20"Subcatchment P-1: Proposed Site Flow Length=841' Tc=17.4 min CN=63 Runoff=17.43 cfs 1.935 af Runoff Area=33,660 sf 94.86% Impervious Runoff Depth>4.03"Subcatchment P-2: Proposed Site Tc=6.0 min CN=96 Runoff=3.25 cfs 0.260 af Runoff Area=86,240 sf 56.77% Impervious Runoff Depth>2.63"Subcatchment P-3: Proposed Site Tc=6.0 min CN=82 Runoff=5.99 cfs 0.435 af Runoff Area=4,700 sf 100.00% Impervious Runoff Depth>4.26"Subcatchment P-4: Proposed Site Tc=6.0 min CN=98 Runoff=0.46 cfs 0.038 af Runoff Area=65,608 sf 78.20% Impervious Runoff Depth>3.39"Subcatchment P-5: Proposed Site Tc=6.0 min CN=90 Runoff=5.69 cfs 0.426 af Inflow=26.63 cfs 3.019 afReach E-CP: Connecticut River Outflow=26.63 cfs 3.019 af Avg. Flow Depth=0.44' Max Vel=2.89 fps Inflow=5.35 cfs 0.368 afReach ES: Existing Swale n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs Outflow=5.25 cfs 0.368 af Avg. Flow Depth=0.17' Max Vel=1.70 fps Inflow=0.82 cfs 0.062 afReach ES.: Existing Swale n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs Outflow=0.78 cfs 0.062 af Inflow=26.31 cfs 2.981 afReach P-CP: Connecticut River Outflow=26.31 cfs 2.981 af Peak Elev=144.05' Storage=1,669 cf Inflow=0.46 cfs 0.038 afPond IT: Infiltration Trench Outflow=0.00 cfs 0.000 af Peak Elev=147.14' Storage=145 cf Inflow=3.25 cfs 0.260 afPond LLS1: Level Spreader 1 Outflow=3.26 cfs 0.256 af Peak Elev=145.21' Storage=199 cf Inflow=5.69 cfs 0.426 afPond LLS2: Level Spreader 2 Outflow=5.73 cfs 0.421 af Peak Elev=141.85' Storage=3,560 cf Inflow=5.99 cfs 0.435 afPond RG: Rain Garden Outflow=5.65 cfs 0.372 af Peak Elev=137.40' Storage=972 cf Inflow=5.65 cfs 0.372 afPond WL: New Low Wetland Area Outflow=5.35 cfs 0.368 af Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 32HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Total Runoff Area = 47.532 ac Runoff Volume = 6.112 af Average Runoff Depth = 1.54" 84.99% Pervious = 40.396 ac 15.01% Impervious = 7.136 ac Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 33HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment E-1: Existing Site Runoff = 26.21 cfs @ 12.31 hrs, Volume= 2.957 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 98,000 70 Woods, Good, HSG C 14,000 61 >75% Grass cover, Good, HSG B 25,000 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 1,013,902 68 Weighted Average 898,666 88.63% Pervious Area 115,236 11.37% 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"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 34HydroCAD® 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=1,013,902 sf Runoff Volume=2.957 af Runoff Depth>1.52" Flow Length=1,101' Tc=21.0 min CN=68 26.21 cfs Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 35HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment E-2: Existing Site- Portion to NE Swale Runoff = 0.82 cfs @ 12.10 hrs, Volume= 0.062 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 8,829 65 Woods/grass comb., Fair, HSG B 4,300 55 Woods, Good, HSG B 7,906 79 <50% Grass cover, Poor, HSG B 21,035 68 Weighted Average 21,035 100.00% 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)0.9 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=21,035 sf Runoff Volume=0.062 af Runoff Depth>1.53" Tc=6.0 min CN=68 0.82 cfs Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 36HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-1: Proposed Site Runoff = 17.43 cfs @ 12.27 hrs, Volume= 1.935 af, Depth> 1.20" 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 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 103,698 61 >75% Grass cover, Good, HSG B 14,985 74 >75% Grass cover, Good, HSG C 49,045 98 Paved parking, HSG B 3,250 74 >75% Grass cover, Good, HSG C 845,368 63 Weighted Average 786,653 93.05% Pervious Area 58,715 6.95% 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"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 37HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Subcatchment P-1: Proposed Site Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (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=845,368 sf Runoff Volume=1.935 af Runoff Depth>1.20" Flow Length=841' Tc=17.4 min CN=63 17.43 cfs Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 38HydroCAD® 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= 0.260 af, Depth> 4.03" 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 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) 2423222120191817161514131211109876543210Flow (cfs)3 2 1 0 Type III 24-hr 10 YRS Rainfall=4.50" Runoff Area=33,660 sf Runoff Volume=0.260 af Runoff Depth>4.03" Tc=6.0 min CN=96 3.25 cfs Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 39HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-3: Proposed Site Runoff = 5.99 cfs @ 12.09 hrs, Volume= 0.435 af, Depth> 2.63" 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 10 YRS Rainfall=4.50" Area (sf) CN Description 48,961 98 Paved parking & roofs 37,279 61 >75% Grass cover, Good, HSG B 86,240 82 Weighted Average 37,279 43.23% Pervious Area 48,961 56.77% 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) 2423222120191817161514131211109876543210Flow (cfs)6 5 4 3 2 1 0 Type III 24-hr 10 YRS Rainfall=4.50" Runoff Area=86,240 sf Runoff Volume=0.435 af Runoff Depth>2.63" Tc=6.0 min CN=82 5.99 cfs Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 40HydroCAD® 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= 0.038 af, Depth> 4.26" 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 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) 2423222120191817161514131211109876543210Flow (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=0.038 af Runoff Depth>4.26" Tc=6.0 min CN=98 0.46 cfs Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 41HydroCAD® 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= 0.426 af, Depth> 3.39" 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 51,303 98 Paved parking & roofs 14,305 61 >75% Grass cover, Good, HSG B 65,608 90 Weighted Average 14,305 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) 2423222120191817161514131211109876543210Flow (cfs)6 5 4 3 2 1 0 Type III 24-hr 10 YRS Rainfall=4.50" Runoff Area=65,608 sf Runoff Volume=0.426 af Runoff Depth>3.39" Tc=6.0 min CN=90 5.69 cfs Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 42HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach E-CP: Connecticut River Inflow Area = 23.759 ac, 11.13% Impervious, Inflow Depth > 1.52" for 10 YRS event Inflow = 26.63 cfs @ 12.31 hrs, Volume= 3.019 af Outflow = 26.63 cfs @ 12.31 hrs, Volume= 3.019 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=23.759 ac 26.63 cfs26.63 cfs Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 43HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach ES: Existing Swale Inflow Area = 1.980 ac, 56.77% Impervious, Inflow Depth > 2.23" for 10 YRS event Inflow = 5.35 cfs @ 12.16 hrs, Volume= 0.368 af Outflow = 5.25 cfs @ 12.17 hrs, Volume= 0.368 af, Atten= 2%, Lag= 0.8 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 2.89 fps, Min. Travel Time= 0.5 min Avg. Velocity = 1.12 fps, Avg. Travel Time= 1.2 min Peak Storage= 146 cf @ 12.16 hrs Average Depth at Peak Storage= 0.44' , Surface Width= 6.39' 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)5 4 3 2 1 0 Inflow Area=1.980 ac Avg. Flow Depth=0.44' Max Vel=2.89 fps n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs 5.35 cfs5.25 cfs Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 44HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach ES.: Existing Swale Inflow Area = 0.483 ac, 0.00% Impervious, Inflow Depth > 1.53" for 10 YRS event Inflow = 0.82 cfs @ 12.10 hrs, Volume= 0.062 af Outflow = 0.78 cfs @ 12.12 hrs, Volume= 0.062 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= 1.70 fps, Min. Travel Time= 0.8 min Avg. Velocity = 0.60 fps, Avg. Travel Time= 2.2 min Peak Storage= 38 cf @ 12.11 hrs Average Depth at Peak Storage= 0.17' , Surface Width= 3.68' 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)0.9 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=0.483 ac Avg. Flow Depth=0.17' Max Vel=1.70 fps n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs 0.82 cfs 0.78 cfs Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 45HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach P-CP: Connecticut River Inflow Area = 23.774 ac, 18.89% Impervious, Inflow Depth > 1.50" for 10 YRS event Inflow = 26.31 cfs @ 12.21 hrs, Volume= 2.981 af Outflow = 26.31 cfs @ 12.21 hrs, Volume= 2.981 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 P-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 26.31 cfs26.31 cfs Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 46HydroCAD® 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 > 4.26" for 10 YRS event Inflow = 0.46 cfs @ 12.09 hrs, Volume= 0.038 af Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 100%, Lag= 0.0 min Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 144.05' @ 24.00 hrs Surf.Area= 1,370 sf Storage= 1,669 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 @ 0.00 hrs HW=141.00' (Free Discharge) 1=Orifice/Grate ( Controls 0.00 cfs) Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 47HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond IT: Infiltration Trench Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (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=144.05' Storage=1,669 cf 0.46 cfs 0.00 cfs Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 48HydroCAD® 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 > 4.03" for 10 YRS event Inflow = 3.25 cfs @ 12.09 hrs, Volume= 0.260 af Outflow = 3.26 cfs @ 12.09 hrs, Volume= 0.256 af, Atten= 0%, Lag= 0.0 min Primary = 3.26 cfs @ 12.09 hrs, Volume= 0.256 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 147.14' @ 12.09 hrs Surf.Area= 230 sf Storage= 145 cf Plug-Flow detention time= 14.9 min calculated for 0.256 af (99% of inflow) Center-of-Mass det. time= 6.8 min ( 771.3 - 764.5 ) 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=3.17 cfs @ 12.09 hrs HW=147.14' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 3.17 cfs @ 1.01 fps) Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 49HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond LLS1: Level Spreader 1 Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)3 2 1 0 Inflow Area=0.773 ac Peak Elev=147.14' Storage=145 cf 3.25 cfs3.26 cfs Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 50HydroCAD® 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 > 3.39" for 10 YRS event Inflow = 5.69 cfs @ 12.09 hrs, Volume= 0.426 af Outflow = 5.73 cfs @ 12.09 hrs, Volume= 0.421 af, Atten= 0%, Lag= 0.1 min Primary = 5.73 cfs @ 12.09 hrs, Volume= 0.421 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 145.21' @ 12.09 hrs Surf.Area= 292 sf Storage= 199 cf Plug-Flow detention time= 10.8 min calculated for 0.421 af (99% of inflow) Center-of-Mass det. time= 4.4 min ( 798.3 - 793.9 ) 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=5.58 cfs @ 12.09 hrs HW=145.21' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 5.58 cfs @ 1.23 fps) Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 51HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond LLS2: Level Spreader 2 Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)6 5 4 3 2 1 0 Inflow Area=1.506 ac Peak Elev=145.21' Storage=199 cf 5.69 cfs5.73 cfs Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 52HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond RG: Rain Garden Inflow Area = 1.980 ac, 56.77% Impervious, Inflow Depth > 2.63" for 10 YRS event Inflow = 5.99 cfs @ 12.09 hrs, Volume= 0.435 af Outflow = 5.65 cfs @ 12.12 hrs, Volume= 0.372 af, Atten= 6%, Lag= 1.7 min Primary = 5.65 cfs @ 12.12 hrs, Volume= 0.372 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 141.85' @ 12.12 hrs Surf.Area= 4,513 sf Storage= 3,560 cf Plug-Flow detention time= 93.1 min calculated for 0.372 af (86% of inflow) Center-of-Mass det. time= 30.7 min ( 850.9 - 820.2 ) 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=5.48 cfs @ 12.12 hrs HW=141.85' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 5.48 cfs @ 1.12 fps) Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 53HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond RG: Rain Garden Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)6 5 4 3 2 1 0 Inflow Area=1.980 ac Peak Elev=141.85' Storage=3,560 cf 5.99 cfs 5.65 cfs Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 54HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond WL: New Low Wetland Area Inflow Area = 1.980 ac, 56.77% Impervious, Inflow Depth > 2.26" for 10 YRS event Inflow = 5.65 cfs @ 12.12 hrs, Volume= 0.372 af Outflow = 5.35 cfs @ 12.16 hrs, Volume= 0.368 af, Atten= 5%, Lag= 2.2 min Primary = 5.35 cfs @ 12.16 hrs, Volume= 0.368 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 137.40' @ 12.16 hrs Surf.Area= 2,904 sf Storage= 972 cf Plug-Flow detention time= 10.4 min calculated for 0.367 af (99% of inflow) Center-of-Mass det. time= 4.4 min ( 855.3 - 850.9 ) 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=5.27 cfs @ 12.16 hrs HW=137.40' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 5.27 cfs @ 1.52 fps) Type III 24-hr 10 YRS Rainfall=4.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 55HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond WL: New Low Wetland Area Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)6 5 4 3 2 1 0 Inflow Area=1.980 ac Peak Elev=137.40' Storage=972 cf 5.65 cfs 5.35 cfs Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 56HydroCAD® 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=1,013,902 sf 11.37% Impervious Runoff Depth>3.00"Subcatchment E-1: Existing Site Flow Length=1,101' Tc=21.0 min CN=68 Runoff=53.64 cfs 5.813 af Runoff Area=21,035 sf 0.00% Impervious Runoff Depth>3.01"Subcatchment E-2: Existing Site- Portion to Tc=6.0 min CN=68 Runoff=1.66 cfs 0.121 af Runoff Area=845,368 sf 6.95% Impervious Runoff Depth>2.52"Subcatchment P-1: Proposed Site Flow Length=841' Tc=17.4 min CN=63 Runoff=39.82 cfs 4.080 af Runoff Area=33,660 sf 94.86% Impervious Runoff Depth>6.02"Subcatchment P-2: Proposed Site Tc=6.0 min CN=96 Runoff=4.76 cfs 0.388 af Runoff Area=86,240 sf 56.77% Impervious Runoff Depth>4.45"Subcatchment P-3: Proposed Site Tc=6.0 min CN=82 Runoff=9.98 cfs 0.734 af Runoff Area=4,700 sf 100.00% Impervious Runoff Depth>6.26"Subcatchment P-4: Proposed Site Tc=6.0 min CN=98 Runoff=0.67 cfs 0.056 af Runoff Area=65,608 sf 78.20% Impervious Runoff Depth>5.33"Subcatchment P-5: Proposed Site Tc=6.0 min CN=90 Runoff=8.72 cfs 0.669 af Inflow=54.46 cfs 5.934 afReach E-CP: Connecticut River Outflow=54.46 cfs 5.934 af Avg. Flow Depth=0.56' Max Vel=3.33 fps Inflow=9.05 cfs 0.667 afReach ES: Existing Swale n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs Outflow=8.93 cfs 0.666 af Avg. Flow Depth=0.25' Max Vel=2.10 fps Inflow=1.66 cfs 0.121 afReach ES.: Existing Swale n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs Outflow=1.61 cfs 0.121 af Inflow=54.11 cfs 5.801 afReach P-CP: Connecticut River Outflow=54.11 cfs 5.801 af Peak Elev=147.50' Storage=2,192 cf Inflow=0.67 cfs 0.056 afPond IT: Infiltration Trench Outflow=0.03 cfs 0.006 af Peak Elev=147.19' Storage=145 cf Inflow=4.76 cfs 0.388 afPond LLS1: Level Spreader 1 Outflow=4.77 cfs 0.384 af Peak Elev=145.28' Storage=199 cf Inflow=8.72 cfs 0.669 afPond LLS2: Level Spreader 2 Outflow=8.75 cfs 0.664 af Peak Elev=141.93' Storage=3,934 cf Inflow=9.98 cfs 0.734 afPond RG: Rain Garden Outflow=9.59 cfs 0.671 af Peak Elev=137.54' Storage=1,422 cf Inflow=9.59 cfs 0.671 afPond WL: New Low Wetland Area Outflow=9.05 cfs 0.667 af Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 57HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Total Runoff Area = 47.532 ac Runoff Volume = 11.860 af Average Runoff Depth = 2.99" 84.99% Pervious = 40.396 ac 15.01% Impervious = 7.136 ac Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 58HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment E-1: Existing Site Runoff = 53.64 cfs @ 12.30 hrs, Volume= 5.813 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 98,000 70 Woods, Good, HSG C 14,000 61 >75% Grass cover, Good, HSG B 25,000 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 1,013,902 68 Weighted Average 898,666 88.63% Pervious Area 115,236 11.37% 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"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 59HydroCAD® 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=1,013,902 sf Runoff Volume=5.813 af Runoff Depth>3.00" Flow Length=1,101' Tc=21.0 min CN=68 53.64 cfs Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 60HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment E-2: Existing Site- Portion to NE Swale Runoff = 1.66 cfs @ 12.10 hrs, Volume= 0.121 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 8,829 65 Woods/grass comb., Fair, HSG B 4,300 55 Woods, Good, HSG B 7,906 79 <50% Grass cover, Poor, HSG B 21,035 68 Weighted Average 21,035 100.00% 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=21,035 sf Runoff Volume=0.121 af Runoff Depth>3.01" Tc=6.0 min CN=68 1.66 cfs Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 61HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-1: Proposed Site Runoff = 39.82 cfs @ 12.25 hrs, Volume= 4.080 af, Depth> 2.52" 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 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 103,698 61 >75% Grass cover, Good, HSG B 14,985 74 >75% Grass cover, Good, HSG C 49,045 98 Paved parking, HSG B 3,250 74 >75% Grass cover, Good, HSG C 845,368 63 Weighted Average 786,653 93.05% Pervious Area 58,715 6.95% 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"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 62HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Subcatchment P-1: Proposed Site Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (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=845,368 sf Runoff Volume=4.080 af Runoff Depth>2.52" Flow Length=841' Tc=17.4 min CN=63 39.82 cfs Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 63HydroCAD® 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= 0.388 af, Depth> 6.02" 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 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) 2423222120191817161514131211109876543210Flow (cfs)5 4 3 2 1 0 Type III 24-hr 100 YRS Rainfall=6.50" Runoff Area=33,660 sf Runoff Volume=0.388 af Runoff Depth>6.02" Tc=6.0 min CN=96 4.76 cfs Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 64HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-3: Proposed Site Runoff = 9.98 cfs @ 12.09 hrs, Volume= 0.734 af, Depth> 4.45" 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 48,961 98 Paved parking & roofs 37,279 61 >75% Grass cover, Good, HSG B 86,240 82 Weighted Average 37,279 43.23% Pervious Area 48,961 56.77% 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) 2423222120191817161514131211109876543210Flow (cfs)11 10 9 8 7 6 5 4 3 2 1 0 Type III 24-hr 100 YRS Rainfall=6.50" Runoff Area=86,240 sf Runoff Volume=0.734 af Runoff Depth>4.45" Tc=6.0 min CN=82 9.98 cfs Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 65HydroCAD® 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= 0.056 af, Depth> 6.26" 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 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) 2423222120191817161514131211109876543210Flow (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=0.056 af Runoff Depth>6.26" Tc=6.0 min CN=98 0.67 cfs Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 66HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment P-5: Proposed Site Runoff = 8.72 cfs @ 12.09 hrs, Volume= 0.669 af, Depth> 5.33" 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 51,303 98 Paved parking & roofs 14,305 61 >75% Grass cover, Good, HSG B 65,608 90 Weighted Average 14,305 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) 2423222120191817161514131211109876543210Flow (cfs)9 8 7 6 5 4 3 2 1 0 Type III 24-hr 100 YRS Rainfall=6.50" Runoff Area=65,608 sf Runoff Volume=0.669 af Runoff Depth>5.33" Tc=6.0 min CN=90 8.72 cfs Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 67HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach E-CP: Connecticut River Inflow Area = 23.759 ac, 11.13% Impervious, Inflow Depth > 3.00" for 100 YRS event Inflow = 54.46 cfs @ 12.30 hrs, Volume= 5.934 af Outflow = 54.46 cfs @ 12.30 hrs, Volume= 5.934 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=23.759 ac 54.46 cfs54.46 cfs Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 68HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach ES: Existing Swale Inflow Area = 1.980 ac, 56.77% Impervious, Inflow Depth > 4.04" for 100 YRS event Inflow = 9.05 cfs @ 12.15 hrs, Volume= 0.667 af Outflow = 8.93 cfs @ 12.16 hrs, Volume= 0.666 af, Atten= 1%, Lag= 0.6 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 3.33 fps, Min. Travel Time= 0.4 min Avg. Velocity = 1.31 fps, Avg. Travel Time= 1.0 min Peak Storage= 215 cf @ 12.16 hrs Average Depth at Peak Storage= 0.56' , Surface Width= 7.64' 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)10 9 8 7 6 5 4 3 2 1 0 Inflow Area=1.980 ac Avg. Flow Depth=0.56' Max Vel=3.33 fps n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs 9.05 cfs8.93 cfs Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 69HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach ES.: Existing Swale Inflow Area = 0.483 ac, 0.00% Impervious, Inflow Depth > 3.01" for 100 YRS event Inflow = 1.66 cfs @ 12.10 hrs, Volume= 0.121 af Outflow = 1.61 cfs @ 12.11 hrs, Volume= 0.121 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= 2.10 fps, Min. Travel Time= 0.6 min Avg. Velocity = 0.71 fps, Avg. Travel Time= 1.8 min Peak Storage= 63 cf @ 12.10 hrs Average Depth at Peak Storage= 0.25' , Surface Width= 4.45' 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=0.483 ac Avg. Flow Depth=0.25' Max Vel=2.10 fps n=0.100 L=79.0' S=0.2025 '/' Capacity=32.33 cfs 1.66 cfs 1.61 cfs Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 70HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Reach P-CP: Connecticut River Inflow Area = 23.774 ac, 18.89% Impervious, Inflow Depth > 2.93" for 100 YRS event Inflow = 54.11 cfs @ 12.21 hrs, Volume= 5.801 af Outflow = 54.11 cfs @ 12.21 hrs, Volume= 5.801 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 P-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 54.11 cfs54.11 cfs Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 71HydroCAD® 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 > 6.26" for 100 YRS event Inflow = 0.67 cfs @ 12.09 hrs, Volume= 0.056 af Outflow = 0.03 cfs @ 16.60 hrs, Volume= 0.006 af, Atten= 96%, Lag= 270.8 min Primary = 0.03 cfs @ 16.60 hrs, Volume= 0.006 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 147.50' @ 16.60 hrs Surf.Area= 1,370 sf Storage= 2,192 cf Plug-Flow detention time= 818.2 min calculated for 0.006 af (11% of inflow) Center-of-Mass det. time= 440.4 min ( 1,184.0 - 743.6 ) 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=0.01 cfs @ 16.60 hrs HW=147.50' (Free Discharge) 1=Orifice/Grate (Weir Controls 0.01 cfs @ 0.20 fps) Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 72HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond IT: Infiltration Trench Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (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 0.03 cfs Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 73HydroCAD® 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 > 6.02" for 100 YRS event Inflow = 4.76 cfs @ 12.09 hrs, Volume= 0.388 af Outflow = 4.77 cfs @ 12.09 hrs, Volume= 0.384 af, Atten= 0%, Lag= 0.0 min Primary = 4.77 cfs @ 12.09 hrs, Volume= 0.384 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 147.19' @ 12.09 hrs Surf.Area= 230 sf Storage= 145 cf Plug-Flow detention time= 10.5 min calculated for 0.384 af (99% of inflow) Center-of-Mass det. time= 5.0 min ( 761.1 - 756.1 ) 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"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 74HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond LLS1: Level Spreader 1 Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)5 4 3 2 1 0 Inflow Area=0.773 ac Peak Elev=147.19' Storage=145 cf 4.76 cfs4.77 cfs Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 75HydroCAD® 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 > 5.33" for 100 YRS event Inflow = 8.72 cfs @ 12.09 hrs, Volume= 0.669 af Outflow = 8.75 cfs @ 12.09 hrs, Volume= 0.664 af, Atten= 0%, Lag= 0.0 min Primary = 8.75 cfs @ 12.09 hrs, Volume= 0.664 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 145.28' @ 12.09 hrs Surf.Area= 292 sf Storage= 199 cf Plug-Flow detention time= 7.6 min calculated for 0.664 af (99% of inflow) Center-of-Mass det. time= 3.3 min ( 785.1 - 781.7 ) 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=8.52 cfs @ 12.09 hrs HW=145.27' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 8.52 cfs @ 1.41 fps) Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 76HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond LLS2: Level Spreader 2 Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)9 8 7 6 5 4 3 2 1 0 Inflow Area=1.506 ac Peak Elev=145.28' Storage=199 cf 8.72 cfs8.75 cfs Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 77HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond RG: Rain Garden Inflow Area = 1.980 ac, 56.77% Impervious, Inflow Depth > 4.45" for 100 YRS event Inflow = 9.98 cfs @ 12.09 hrs, Volume= 0.734 af Outflow = 9.59 cfs @ 12.11 hrs, Volume= 0.671 af, Atten= 4%, Lag= 1.4 min Primary = 9.59 cfs @ 12.11 hrs, Volume= 0.671 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 141.93' @ 12.11 hrs Surf.Area= 4,575 sf Storage= 3,934 cf Plug-Flow detention time= 66.5 min calculated for 0.671 af (91% of inflow) Center-of-Mass det. time= 23.8 min ( 829.2 - 805.3 ) 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=9.33 cfs @ 12.11 hrs HW=141.93' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 9.33 cfs @ 1.35 fps) Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 78HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond RG: Rain Garden Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=1.980 ac Peak Elev=141.93' Storage=3,934 cf 9.98 cfs 9.59 cfs Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 79HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Summary for Pond WL: New Low Wetland Area Inflow Area = 1.980 ac, 56.77% Impervious, Inflow Depth > 4.07" for 100 YRS event Inflow = 9.59 cfs @ 12.11 hrs, Volume= 0.671 af Outflow = 9.05 cfs @ 12.15 hrs, Volume= 0.667 af, Atten= 6%, Lag= 2.2 min Primary = 9.05 cfs @ 12.15 hrs, Volume= 0.667 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 137.54' @ 12.15 hrs Surf.Area= 3,324 sf Storage= 1,422 cf Plug-Flow detention time= 7.5 min calculated for 0.667 af (99% of inflow) Center-of-Mass det. time= 3.7 min ( 832.8 - 829.2 ) 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=9.05 cfs @ 12.15 hrs HW=137.54' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 9.05 cfs @ 1.83 fps) Type III 24-hr 100 YRS Rainfall=6.50"Smith Boathouse - Modified Design 2021.08.25 Printed 8/26/2021Prepared by Berkshire Design Group Page 80HydroCAD® 10.10-5a s/n 11721 © 2020 HydroCAD Software Solutions LLC Pond WL: New Low Wetland Area Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)10 9 8 7 6 5 4 3 2 1 0 Inflow Area=1.980 ac Peak Elev=137.54' Storage=1,422 cf 9.59 cfs 9.05 cfs Project Information & Location Project Name 60 Damon Road Project Number 39195 City Northampton State/ Province Massachusetts Country United States of America Date 8/24/2021 Designer Information EOR Information (optional) Name Liam McCann Name Company Berkshire Design Group Company Phone #978-877-8808 Phone # Email liam@berkshiredesign.com Email Brief Stormceptor Sizing Report - Modified P-5 Site Name Modified P-5 Target TSS Removal (%)80 TSS Removal (%) Provided 80 Recommended Stormceptor Model STC 450i Stormceptor Sizing Summary Stormceptor Model % TSS Removal Provided STC 450i 80 STC 900 87 STC 1200 87 STC 1800 87 STC 2400 90 STC 3600 91 STC 4800 93 STC 6000 93 STC 7200 94 STC 11000 96 STC 13000 96 STC 16000 97 The recommended Stormceptor Model achieves the water quality objectives based on the selected inputs, historical rainfall records and selected particle size distribution. Stormwater Treatment Recommendation The recommended Stormceptor Model(s) which achieve or exceed the user defined water quality objective for each site within the project are listed in the below Sizing Summary table. Stormceptor Brief Sizing Report ±Page 1 of 2 Notes ‡Stormceptor performance estimates are based on simulations using PCSWMM for Stormceptor, which uses the EPA Rainfall and Runoff modules. ‡Design estimates listed are only representative of specific project requirements based on total suspended solids (TSS) removal defined by the selected PSD, and based on stable site conditions only, after construction is completed. ‡For submerged applications or sites specific to spill control, please contact your local Stormceptor representative for further design assistance. Drainage Area Total Area (acres)1.51 Imperviousness %42.1 Water Quality Objective TSS Removal (%)80.0 Runoff Volume Capture (%) Oil Spill Capture Volume (Gal) Peak Conveyed Flow Rate (CFS) Water Quality Flow Rate (CFS) Rainfall Station Name KNIGHTVILLE DAM State/Province Massachusetts Station ID #3985 Years of Records 14 Latitude 42°10'12"N Longitude 72°31'12"W Up Stream Storage Storage (ac-ft)Discharge (cfs) 0.000 0.000 Particle Size Distribution (PSD) The selected PSD defines TSS removal Fine Distribution Particle Diameter (microns) Distribution % Specific Gravity 20.0 20.0 1.30 60.0 20.0 1.80 150.0 20.0 2.20 400.0 20.0 2.65 2000.0 20.0 2.65 Up Stream Flow Diversion Max. Flow to Stormceptor (cfs) Sizing Details For Stormceptor Specifications and Drawings Please Visit: https://www.conteches.com/technical-guides/search?filter=1WBC0O5EYX Stormceptor Brief Sizing Report ±Page 2 of 2