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HomeMy WebLinkAbout22SITE8 Stormwater Rep Rec101322 John U. Faulise, Jr., L.S. Demian A. Sorrentino, AICP, C.S.S. David C. McKay, P.E. Gerald J. Stefon, L.S. (1952-2021) Jacob S. Faulise, E.I.T. Boundaries LLC 179 Pachaug River Drive P.O. Box 184 Griswold, CT 06351 T 860.376.2006 | F 860.376.5899 www.boundariesllc.net STORMWATER MANAGEMENT REPORT PREPARED FOR: GATEWAY MONTVILLE, LLC 125-133 DEPOT ROAD UNCASVILLE, CONNECTICUT MAY 2022 PREPARED BY: BOUNDARIES LLC PROJECT I.D. NO. 22-3140 Page 2 Table of Contents Introduction .................................................................................................................................................. 3 Pre-Development Conditions ........................................................................................................................ 4 Post-Development Conditions ...................................................................................................................... 5 Stormwater Management System Design .................................................................................................... 8 Construction Phase Stormwater Management ............................................................................................ 9 Summary ..................................................................................................................................................... 10 Table of Appendices APPENDIX A SOILS AND WETLANDS MAPS APPENDIX B SUPPORTING STORMWATER CALCULATIONS APPENDIX C HYDRODYNAMIC SEPARATOR CUT SHEETS Table of Figures FIGURE 1 LOCATION MAP FIGURE 1 POST-DEVELOPMENT CONDITIONS WATERSHEDS Page 3 Introduction On behalf of Gateway Montville, LLC., Boundaries, LLC. has prepared the following stormwater management report for the proposed freight transportation and storage operation to be located at 125 and 133 Depot Road. The proposed operation includes the shipping and transfer of freight materials from barges, railways and trucks for short-term storage and distribution. Materials intended to be stored on- site includes solid de-icing materials, soil and stone aggregate, recyclable metals, wood, tarps, and rope, and lumber and metal construction materials. The following analysis demonstrates that the proposed stormwater management methods provide treatment of the water quality volume as recommended in the Connecticut Stormwater Quality Manual. The location of the project is shown on the Locus Map included as Figure 1. The project area is located between Depot Road and Dock Road along the bank of the Thames River. The Central Vermont Railroad passes between the two subject properties. There are no inland wetlands or watercourses located on the subject properties. The Thames River is an estuarine tidal river and has no tidal wetlands located in the vicinity of the project area per the United States Fish and Wildlife Service National Wetlands Inventory Mapper included in Appendix A. According to the Natural Resources Conservation Service (NRCS) Web Soil Survey the soils in the project area consist of Agawam fine sandy loam, 0 to 3% slopes; Udorthents-Urban Land Complex; and Urban Land. Agawam soils and Udorthents-Urban Land Complex are classified as Hydrologic Soil Group B and Urban Land is classified as Hydrologic Soil Group D. The NRCS Web Soil Survey Soils Report is provided in Appendix A. Post-development conditions watersheds were delineated using the topographic survey and the proposed grading from the site operations plans. The water quality volumes and water quality flows for each watershed were calculated using the methods detailed in the CT DEEP Stormwater Quality Manual. Supporting calculations are included in Appendix B. The project area formerly consisted of industrial buildings and a power plant located on 125 Depot Road and a coal stockpile area on 133 Depot Road. The properties are now subject to an environmental land use restriction and contain areas of impacted soils. Because the Thames River is a large, tidally influenced river, and the project area consists of less than 5% of the approximately 1,439 square mile watershed (0.0027%), the typical requirements for peak flow rate attenuation do not need to apply to this project per Section 7.6.1 and Section 7.6.3 of the CT DEEP Stormwater Quality Manual. The existing stormwater collection system discharges directly to the Thames River, therefore, the focus of this project is improvements to the existing stormwater management system that will improve the quality of the stormwater discharges from the site by capturing all stormwater runoff from the proposed operation areas and treating it prior to discharge. Per the conditions of the General Permit for the Discharge of Stormwater and Dewatering Wastewaters from Construction Activities all projects that disturb greater than 1 acre of land are required to retain the 1-inch water quality volume on-site, or in the case of redevelopment projects, one half of the water quality volume. This project is considered a redevelopment project of a site with over 40% impervious coverage and would be required to retain one half of the water quality volume on site under most circumstances. In the case of this property retention of stormwater runoff on-site is not proposed, in lieu of retention of runoff on-site, treatment systems are proposed at each outlet of the stormwater management system Page 4 and will treat greater than the water quality flow generated by the first inch of runoff. On-site retention of stormwater runoff has not been included in the development of this property for the following reasons: • The property is subject to an environmental land use restriction and is known to have impacted soils from the former industrial uses. There are also groundwater monitoring wells throughout the properties, indicating the presence of bulk petroleum storage areas in the past. Infiltration of stormwater runoff in these areas is not advisable since it could transport pollutants into site groundwater. The areas of impacted soil and groundwater monitoring wells are located throughout the site and do not leave suitable areas for infiltration of stormwater runoff. • The former coal stockpile area will be converted to a salt stockpile area. Stormwater runoff from this land use should not be infiltrated, especially given the historical use of the area as a coal stockpile. The salt stockpile will be managed in accordance with the required best management practices listed in the CT DEEP General Permit for the Discharge of Stormwater from Industrial Activities to protect downstream surface waters. • As discussed above, the project area is insignificant in the overall watershed of the Thames River. Per Sections 7.6.1 and 7.6.3 of the Stormwater Quality Manual, runoff reduction is not necessary in these circumstances. Therefore, treatment of runoff from the site is the focus of the proposed stormwater management system. Pre-Development Conditions The former industrial buildings, tanks, and silos on the property have all been demolished. 125 Depot Road consists of a mix of asphalt, concrete pads, concrete rubble and gravel areas, and the asphalt caps of areas of contaminated soils. 133 Depot Road includes the former parking lot and a grassed area in the location of the coal stockpile area. Prior to the demolition of the former buildings, the properties consisted of almost entirely impervious surfaces. After demolition the main building footprint is a mix of rubble and concrete. Remaining areas outside of the building footprint are a mix of asphalt and concrete pads. The former coal stockpile area located on 133 Depot Road is currently vegetated with grass and brush. The remaining areas are pavement for the former access driveways and parking area and concrete pads from former buildings. The current conditions of the site after the demolition and environmental cleanup are shown in the drone photo below. Drone Photograph of Site (2021) 133 Depot Road (Former Coal Stockpile) 125 Depot Road (Former Industrial Buildings) Page 5 Conditions of the site prior to the demolition are shown in the following aerial photograph. Aerial Photograph of Site (2016) Post-Development Conditions The proposed improvements include the conversion of the former coal stockpile area located on 133 Depot Road to a solid deicing material stockpile area and the construction of new railroad spurs and construction material stockpiles in the former building footprints on 125 Depot Road. Material will be delivered using the existing railroad through the property and by barge to the existing dock in the Thames River. Conveyors will be constructed throughout the site to facilitate transfer of materials from the railcars/barges to the proposed stockpile areas. The proposed salt stockpile area will be paved to minimize infiltration of runoff from the stockpiled materials and the pile will be covered with a tarp per CT DEEP requirements. All surface runoff will be collected by the proposed swales and catch basins surrounding the property that will connect to the existing discharge locations. Hydrodynamic separators will be installed at the existing discharge points to treat the collected runoff prior to discharge from the property. 133 Depot Road (Former Coal Stockpile) 125 Depot Road (Former Industrial Buildings) Page 6 The proposed stormwater management system is intended to meet the following design standards: • The conveyance system leading to, from, and through stormwater management facilities has capacity for the 10-year design storm, at a minimum, per the recommendations of the Connecticut Department of Transportation Drainage Manual, Chapter 6, Appendix A, for curb inlets/storm drainage systems and channels/ditches; and, • The water quality flow generated by the first inch of stormwater runoff (full water quality volume), at a minimum, is treated by the hydrodynamic separators prior to discharge. The post development conditions watersheds are shown on Figure 2. All watersheds on 125 Depot Road were assumed to be 100% impervious. Although the majority of the property will have a crushed stone surface per railroad requirements that will not generate as much runoff as pavement, the stormwater conveyance and treatment systems have been sized conservatively based on the assumption that all contributing areas on 125 Depot Road consist of impervious surfaces. Peak runoff rates were estimated using the Rational Method assuming the minimum Time of Concentration of five (5) minutes due to the lack of dense vegetation on the properties. Photographs of the existing discharge locations to be maintained are below. The discharge of the south watershed is not shown due to dense vegetation obscuring the photograph. The southern discharge is located at the end of Dock Road. Existing 24” CI Drainage Discharge from 133 Depot Road (West Watershed) Page 7 Existing 10” PVC Discharge to be Replaced Upslope (North Watershed) Existing 4” PVC Discharge to be Replaced Upslope (CB-E Watershed) Page 8 Existing 20” PE Discharge to be Reused (Middle Watershed) Stormwater Management System Design Pipe Sizing Stormwater runoff from the proposed development area will be collected and discharged to five (5) existing discharge locations. The existing stormwater collection system consists of catch basins and piping that collected runoff from the former building rooftops and paved circulation driveways. The existing drains were evaluated to verify that they have capacity for the 10-year storm event, at a minimum, based on the calculated Manning’s capacity of each pipe reach in accordance with the Connecticut Department of Transportation Drainage Manual. Inadequately sized existing drains are proposed to be replaced, with pipe ends located above elevation 2.3, above the high tide line. Pipe sizing calculations are included in Appendix B. Water Quality Volume and Water Quality Flow The stormwater management system is intended to provide treatment of runoff from the proposed impervious areas. Treatment of runoff from the site will be accomplished using hydrodynamic separators prior to the outlet. Water Quality Flow calculations are included in Appendix B. Cut sheets for the proposed hydrodynamic separators are included in Appendix C. The treated water quality flow as reported by the Connecticut Department of Transportation was used to select the proposed treatment systems. Hydrodynamic separator characteristics are presented in Table 1. Page 9 Table 1 Water Quality Design Criteria Discharge Location Hydrodynamic Separator Model Rated Water Quality Flow Per CT DOT Design Water Quality Flow West Watershed (HDS A) Contech CDS 5640-10-C 5.8 CFS 3.82 CFS South Watershed (HDS B) Contech Cascade CS-3 1.0 CFS 0.68 CFS CB-E Watershed Contech Cascade CS-3 1.0 CFS 0.19 CFS CB-F Watershed Contech Cascade CS-3 1.0 CFS 0.25 CFS North Watershed (HDS-1) Contech CDS 4030-8-C 3.7 CFS 2.38 CFS Middle Watershed (HDS-2) Contech CDS 5640-10-C 5.8 CFS 4.38 CFS South Watershed (HDS-3) Contech CDS 4030-8-C 3.7 CFS 2.83 CFS As presented above, the proposed stormwater management system improvements provide treatment in excess of the calculated water quality flow prior to discharge. Groundwater Recharge Volume Infiltration has not been considered as part of the stormwater management system due to the historical contamination on the property and the proposed land use being considered to have a higher potential pollutant load. Construction Phase Stormwater Management Construction phase stormwater management is intended to be provided in accordance with the Stormwater Pollution Control Plan (SWPCP) included in the Site Operations Plans. The following best management practices will be implemented to protect downstream water quality: • Downgradient sediment barriers will be installed throughout the unpaved portions of the property. • Inlet protection will be installed in all existing and proposed catch basins. • Land disturbance will be completed in phases, separated by the railroad tracks. o Phase 1 includes the construction of the new haul road and deicing material stockpile area. The disturbed area will be approximately 4.9 acres. Disturbed areas outside of the paved driveways and paved material stockpile pad will be seeded, mulched and stabilized with a straw blanket. o Phase 2 includes the construction of new railroad spurs to the east of the railroad tracks and includes the placement of fill materials in the existing rubble/debris areas. The total Page 10 disturbed area will be approximately 11.4 acres. Phase 2 will be sequenced in three portions so that the active work area is no greater than 5 acres at any time. • Intermediate sediment barriers will be installed during grading operations. • The sediment trap is sized for 134 cubic yards of storage per acre of upgradient contributing area. • Temporary seeding with perennial rye grass is intended for all stockpiles and disturbed areas that will remain unworked for greater than 21 days. Summary The proposed stormwater management system is intended to comply with the applicable requirements of CT DEEP. The proposed improvements are shown on plans titled “Site Operations Plan, Gateway Montville, LLC., 125 & 133 Depot Road, Uncasville, Connecticut” prepared by Boundaries LLC. Appendix A Wetlands and Soils Maps Gateway Montville - Depot Road Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS,USDA, USGS, AeroGRID, IGN, and the GIS User Community Wetlands Estuarine and Marine Deepwater Estuarine and Marine Wetland Freshwater Emergent Wetland Freshwater Forested/Shrub Wetland Freshwater Pond Lake Other Riverine April 5, 2022 0 0.1 0.20.05 mi 0 0.2 0.40.1 km 1:7,577 This page was produced by the NWI mapperNational Wetlands Inventory (NWI) This map is for general reference only. The US Fish and Wildlife Service is not responsible for the accuracy or currentness of the base data shown on this map. All wetlands related data should be used in accordance with the layer metadata found on the Wetlands Mapper web site. Hydrologic Soil Group—State of Connecticut Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 4/5/2022 Page 1 of 4459074045908104590880459095045910204591090459116045912304591300459074045908104590880459095045910204591090459116045912304591300742270742340742410742480742550742620742690 742270 742340 742410 742480 742550 742620 742690 41° 26' 12'' N 72° 6' 2'' W41° 26' 12'' N72° 5' 42'' W41° 25' 53'' N 72° 6' 2'' W41° 25' 53'' N 72° 5' 42'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 18N WGS84 0 100 200 400 600 Feet 0 40 80 160 240 Meters Map Scale: 1:2,940 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:12,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: State of Connecticut Survey Area Data: Version 21, Sep 7, 2021 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Mar 20, 2019—Mar 27, 2019 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Hydrologic Soil Group—State of Connecticut Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 4/5/2022 Page 2 of 4 Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 29A Agawam fine sandy loam, 0 to 3 percent slopes B 8.9 34.1% 34B Merrimac fine sandy loam, 3 to 8 percent slopes A 0.0 0.1% 306 Udorthents-Urban land complex B 0.9 3.5% 307 Urban land D 14.9 57.4% W Water 1.3 4.9% Totals for Area of Interest 26.0 100.0% Hydrologic Soil Group—State of Connecticut Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 4/5/2022 Page 3 of 4 Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Hydrologic Soil Group—State of Connecticut Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 4/5/2022 Page 4 of 4 Appendix B Supporting Stormwater Calculations Hydraulic Analysis Report Project Data Project Title: Depot Road Designer: DCM Project Date: Wednesday, April 27, 2022 Project Units: U.S. Customary Units Notes: Rational Analysis: Swale North Subarea1 Notes: Rational Method Input Parameters Runoff Coefficient: 0.95 Basin Area: 0.5200 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 3.0 cfs Rational Analysis: Swale North Subarea3 Notes: Rational Method Input Parameters Runoff Coefficient: 0.95 Basin Area: 0.2300 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 1.3 cfs Rational Analysis: Swale North Subarea2 Notes: Rational Method Input Parameters Runoff Coefficient: 0.95 Basin Area: 1.2200 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 7.1 cfs Rational Analysis: Swale North Subarea4 Notes: Rational Method Input Parameters Runoff Coefficient: 0.95 Basin Area: 0.6200 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 3.6 cfs Rational Analysis: Swale Middle Subarea1 Notes: Rational Method Input Parameters Runoff Coefficient: 0.95 Basin Area: 0.9100 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 5.3 cfs Rational Analysis: Swale Middle Subarea2 Notes: Rational Method Input Parameters Runoff Coefficient: 0.95 Basin Area: 0.9900 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 5.7 cfs Rational Analysis: Swale Middle Subarea3 Notes: Rational Method Input Parameters Runoff Coefficient: 0.95 Basin Area: 1.2900 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 7.5 cfs Rational Analysis: Swale Middle Subarea4 Notes: Rational Method Input Parameters Runoff Coefficient: 0.95 Basin Area: 1.3900 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 8.1 cfs Rational Analysis: Swale South Subarea1 Notes: Rational Method Input Parameters Runoff Coefficient: 0.95 Basin Area: 0.8600 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 5.0 cfs Rational Analysis: Swale South Subarea2 Notes: Rational Method Input Parameters Runoff Coefficient: 0.95 Basin Area: 1.2600 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 7.3 cfs Rational Analysis: Swale South Subarea3 Notes: Rational Method Input Parameters Runoff Coefficient: 0.95 Basin Area: 0.8100 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 4.7 cfs Rational Analysis: CB F Subarea Notes: Rational Method Input Parameters Runoff Coefficient: 0.95 Basin Area: 0.1800 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 1.0 cfs Rational Analysis: CB E Subarea Notes: Rational Method Input Parameters Runoff Coefficient: 0.95 Basin Area: 0.2100 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 1.2 cfs Rational Analysis: West Overall Notes: Rational Method Input Parameters Runoff Coefficient: 0.81 Basin Area: 6.3200 acres Rainfall Intensity: 5.00 in/hr Time of Concentration: 8.50 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 8.50 min Rational Method Results Flowrate: 25.8 cfs Rational Analysis: CB G Subarea Notes: Rational Method Input Parameters Runoff Coefficient: 0.95 Basin Area: 0.0800 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 0.5 cfs Rational Analysis: Bench West Subarea1 Notes: Rational Method Input Parameters Runoff Coefficient: 0.51 Basin Area: 0.5900 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 1.8 cfs Rational Analysis: Swale West Subarea3 Notes: Rational Method Input Parameters Runoff Coefficient: 0.78 Basin Area: 1.4100 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 6.7 cfs Rational Analysis: Swale West Subarea2 Notes: Rational Method Input Parameters Runoff Coefficient: 0.66 Basin Area: 1.0500 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 4.2 cfs Rational Analysis: Gutter West Subarea4 Notes: Rational Method Input Parameters Runoff Coefficient: 0.95 Basin Area: 1.8700 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 10.9 cfs Rational Analysis: Pipe Inlet Subarea Notes: Rational Method Input Parameters Runoff Coefficient: 0.95 Basin Area: 0.6900 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 4.0 cfs Rational Analysis: Basins West Subarea5 Notes: Rational Method Input Parameters Runoff Coefficient: 0.75 Basin Area: 1.4000 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 6.4 cfs Rational Analysis: Basins West Subarea4S Notes: Rational Method Input Parameters Runoff Coefficient: 0.95 Basin Area: 0.9700 acres Rainfall Intensity: 6.06 in/hr Time of Concentration: 5.00 minutes Recurrence Year: 10 year IDF Input Parameters User Supplied Data 10 year Recurrence, 5 min duration: 6.06 in/hr 10 year Recurrence, 10 min duration: 4.66 in/hr 10 year Recurrence, 15 min duration: 3.85 in/hr 10 year Recurrence, 30 min duration: 2.69 in/hr 10 year Recurrence, 60 min duration: 1.74 in/hr Time of Concentration Input Parameters Specified Time of Concentration Time of Concentration: 5.00 min Rational Method Results Flowrate: 5.6 cfs Channel Analysis: Reverse Bench Notes: Input Parameters Channel Type: Triangular Side Slope 1 (Z1): 2.0000 ft/ft Side Slope 2 (Z2): 5.0000 ft/ft Longitudinal Slope: 0.0200 ft/ft Manning's n: 0.0250 Flow 1.8000 cfs Result Parameters Depth 0.4220 ft Area of Flow 0.6233 ft^2 Wetted Perimeter 3.0954 ft Hydraulic Radius 0.2014 ft Average Velocity 2.8879 ft/s Top Width 2.9540 ft Froude Number: 1.1079 Critical Depth 0.4579 ft Critical Velocity 2.4531 ft/s Critical Slope: 0.0129 ft/ft Critical Top Width 3.93 ft Calculated Max Shear Stress 0.5267 lb/ft^2 Calculated Avg Shear Stress 0.2513 lb/ft^2 Channel Analysis: Stockpile Yard Perimeter Swales Notes: Input Parameters Channel Type: Trapezoidal Side Slope 1 (Z1): 2.0000 ft/ft Side Slope 2 (Z2): 2.0000 ft/ft Channel Width 4.00 ft Longitudinal Slope: 0.0100 ft/ft Manning's n: 0.0300 Flow 8.3000 cfs Result Parameters Depth 0.5629 ft Area of Flow 2.8852 ft^2 Wetted Perimeter 6.5173 ft Hydraulic Radius 0.4427 ft Average Velocity 2.8768 ft/s Top Width 6.2515 ft Froude Number: 0.7463 Critical Depth 0.4707 ft Critical Velocity 3.5683 ft/s Critical Slope: 0.0188 ft/ft Critical Top Width 5.88 ft Calculated Max Shear Stress 0.3512 lb/ft^2 Calculated Avg Shear Stress 0.2762 lb/ft^2 Channel Analysis: Salt Storage Perimeter Swale Notes: Input Parameters Channel Type: Trapezoidal Side Slope 1 (Z1): 2.0000 ft/ft Side Slope 2 (Z2): 2.0000 ft/ft Channel Width 5.00 ft Longitudinal Slope: 0.0100 ft/ft Manning's n: 0.0300 Flow 8.0000 cfs Result Parameters Depth 0.4908 ft Area of Flow 2.9359 ft^2 Wetted Perimeter 7.1950 ft Hydraulic Radius 0.4080 ft Average Velocity 2.7249 ft/s Top Width 6.9632 ft Froude Number: 0.7395 Critical Depth 0.4063 ft Critical Velocity 3.3879 ft/s Critical Slope: 0.0192 ft/ft Critical Top Width 6.63 ft Calculated Max Shear Stress 0.3063 lb/ft^2 Calculated Avg Shear Stress 0.2546 lb/ft^2 Appendix b Pipe Sizing Calculations Manning's Equation for Open Channel Flow Maximum pipe capacities for the trunk line drains are presented below as compared to the peak flow rates calculated using the Rational Method for the contributing watersheds. Pipes are sized with capacity for the 10-year design storm minimum in accordance with the recommendations of the CT DOT Drainage Manual for curb and gutter systems. Existing Outlet for West Side of Tracks (24-inch CI at S=0.026)Design Flow - West Overall Q=36.58 CFS Flow Rate Q10=25.8 CFS n=0.013 Roughness Coefficient A=3.14 SF Area of Pipe R=0.5 FT Hydraulic Radius = A/P S=0.026 FT/FT Pipe Slope r=1 FT Pipe Radius P=6.28 FT Pipe Perimeter HDS A to Existing 24-inch CI (24-inch HDPE at S=0.015)Design Flow - West Overall Q=27.78 CFS Flow Rate Q10=25.8 CFS n=0.013 Roughness Coefficient A=3.14 SF Area of Pipe R=0.5 FT Hydraulic Radius = A/P S=0.015 FT/FT Pipe Slope r=1 FT Pipe Radius P=6.28 FT Pipe Perimeter CB A to HDS A (18-inch HDPE at S = 0.020)Design Flow - West Subarea 5 Q=14.90 CFS Flow Rate Q10=6.4 CFS n=0.013 Roughness Coefficient A=1.77 SF Area of Pipe R=0.375 FT Hydraulic Radius = A/P S=0.02 FT/FT Pipe Slope r=0.75 FT Pipe Radius P=4.71 FT Pipe Perimeter CB B to CB A (18-inch HDPE at S = 0.005)Design Flow - West Subarea 5 Q=7.45 CFS Flow Rate Q10=6.4 CFS n=0.013 Roughness Coefficient A=1.77 SF Area of Pipe R=0.375 FT Hydraulic Radius = A/P S=0.005 FT/FT Pipe Slope r=0.75 FT Pipe Radius P=4.71 FT Pipe Perimeter 213249.1 SARnQ= Pipe Sizing Calculations Page 1 of 7 Appendix b Pipe Sizing Calculations CB C to HDS A (24-inch HDPE at S = 0.025)Design Flow - West Subarea 1-4 Q=35.87 CFS Flow Rate Q10=23.6 CFS n=0.013 Roughness Coefficient A=3.14 SF Area of Pipe R=0.5 FT Hydraulic Radius = A/P S=0.025 FT/FT Pipe Slope r=1 FT Pipe Radius P=6.28 FT Pipe Perimeter CB D to CB C (18-inch HDPE at S = 0.015)Design Flow - West Subarea 3+4S Q=12.90 CFS Flow Rate Q10=12.3 CFS n=0.013 Roughness Coefficient A=1.77 SF Area of Pipe R=0.375 FT Hydraulic Radius = A/P S=0.015 FT/FT Pipe Slope r=0.75 FT Pipe Radius P=4.71 FT Pipe Perimeter North Swale to CB C (15-inch HDPE at S = 0.063)Design Flow - West Subarea 1+2 Q=16.26 CFS Flow Rate Q10=6 CFS n=0.013 Roughness Coefficient A=1.23 SF Area of Pipe R=0.3125 FT Hydraulic Radius = A/P S=0.063 FT/FT Pipe Slope r=0.625 FT Pipe Radius P=3.93 FT Pipe Perimeter South Swale to CB C (15-inch HDPE at S = 0.020)Design Flow - West Subarea 3 Q=9.16 CFS Flow Rate Q10=6.7 CFS n=0.013 Roughness Coefficient A=1.23 SF Area of Pipe R=0.3125 FT Hydraulic Radius = A/P S=0.02 FT/FT Pipe Slope r=0.625 FT Pipe Radius P=3.93 FT Pipe Perimeter CB E to Outlet (15-inch HDPE at S = 0.005)Design Flow - CB-E Subarea Q=4.58 CFS Flow Rate Q10=1.2 CFS n=0.013 Roughness Coefficient A=1.23 SF Area of Pipe R=0.3125 FT Hydraulic Radius = A/P S=0.005 FT/FT Pipe Slope r=0.625 FT Pipe Radius P=3.93 FT Pipe Perimeter Pipe Sizing Calculations Page 2 of 7 Appendix b Pipe Sizing Calculations CB F to Outlet (15-inch HDPE at S = 0.020)Design Flow - CB-F/G Subarea Q=9.16 CFS Flow Rate Q10=1.5 CFS n=0.013 Roughness Coefficient A=1.23 SF Area of Pipe R=0.3125 FT Hydraulic Radius = A/P S=0.02 FT/FT Pipe Slope r=0.625 FT Pipe Radius P=3.93 FT Pipe Perimeter CB G to CB F (15-inch HDPE at S = 0.005)Design Flow - CB-G Subarea Q=4.58 CFS Flow Rate Q10=0.5 CFS n=0.013 Roughness Coefficient A=1.23 SF Area of Pipe R=0.3125 FT Hydraulic Radius = A/P S=0.005 FT/FT Pipe Slope r=0.625 FT Pipe Radius P=3.93 FT Pipe Perimeter Pipe Inlet to HDS B (18-inch RCP at S = 0.003)Design Flow - Pipe Inlet Subarea Q=5.77 CFS Flow Rate Q10=4 CFS n=0.013 Roughness Coefficient A=1.77 SF Area of Pipe R=0.375 FT Hydraulic Radius = A/P S=0.003 FT/FT Pipe Slope r=0.75 FT Pipe Radius P=4.71 FT Pipe Perimeter HDS B to DMH (18-inch RCP at S = 0.003)Design Flow - Pipe Inlet Subarea Q=5.77 CFS Flow Rate Q10=4 CFS n=0.013 Roughness Coefficient A=1.77 SF Area of Pipe R=0.375 FT Hydraulic Radius = A/P S=0.003 FT/FT Pipe Slope r=0.75 FT Pipe Radius P=4.71 FT Pipe Perimeter DMH to Outlet (Existing 24-inch CI at S = 0.024)Design Flow - Pipe Inlet + South Q=35.14 CFS Flow Rate Q10=21 CFS n=0.013 Roughness Coefficient A=3.14 SF Area of Pipe R=0.5 FT Hydraulic Radius = A/P S=0.024 FT/FT Pipe Slope r=1 FT Pipe Radius P=6.28 FT Pipe Perimeter Pipe Sizing Calculations Page 3 of 7 Appendix b Pipe Sizing Calculations HDS 1 to Outlet (18-inch HDPE at S = 0.021)Design Flow - North 1-4 Q=15.26 CFS Flow Rate Q10=15 CFS n=0.013 Roughness Coefficient A=1.77 SF Area of Pipe R=0.375 FT Hydraulic Radius = A/P S=0.021 FT/FT Pipe Slope r=0.75 FT Pipe Radius P=4.71 FT Pipe Perimeter CB 1 to HDS 1 (18-inch HDPE at S = 0.021)Design Flow - North 1-4 Q=15.26 CFS Flow Rate Q10=15 CFS n=0.013 Roughness Coefficient A=1.77 SF Area of Pipe R=0.375 FT Hydraulic Radius = A/P S=0.021 FT/FT Pipe Slope r=0.75 FT Pipe Radius P=4.71 FT Pipe Perimeter CB 2 to CB 1 (15-inch HDPE at S = 0.005)Design Flow - North 1 Q=4.58 CFS Flow Rate Q10=3 CFS n=0.013 Roughness Coefficient A=1.23 SF Area of Pipe R=0.3125 FT Hydraulic Radius = A/P S=0.005 FT/FT Pipe Slope r=0.625 FT Pipe Radius P=3.93 FT Pipe Perimeter CB 3 to CB 1 (15-inch HDPE at S = 0.006)Design Flow - North 3-4 Q=5.02 CFS Flow Rate Q10=4.9 CFS n=0.013 Roughness Coefficient A=1.23 SF Area of Pipe R=0.3125 FT Hydraulic Radius = A/P S=0.006 FT/FT Pipe Slope r=0.625 FT Pipe Radius P=3.93 FT Pipe Perimeter CB 4 to CB 3 (15-inch HDPE at S = 0.005)Design Flow - North4 Q=4.58 CFS Flow Rate Q10=3.6 CFS n=0.013 Roughness Coefficient A=1.23 SF Area of Pipe R=0.3125 FT Hydraulic Radius = A/P S=0.005 FT/FT Pipe Slope r=0.625 FT Pipe Radius P=3.93 FT Pipe Perimeter Pipe Sizing Calculations Page 4 of 7 Appendix b Pipe Sizing Calculations CB 5 to CB 4 (15-inch HDPE at S = 0.005)Design Flow - North4 Q=4.58 CFS Flow Rate Q10=3.6 CFS n=0.013 Roughness Coefficient A=1.23 SF Area of Pipe R=0.3125 FT Hydraulic Radius = A/P S=0.005 FT/FT Pipe Slope r=0.625 FT Pipe Radius P=3.93 FT Pipe Perimeter CB 6 to CB 5 (15-inch HDPE at S = 0.005)Design Flow - North4 Q=4.58 CFS Flow Rate Q10=3.6 CFS n=0.013 Roughness Coefficient A=1.23 SF Area of Pipe R=0.3125 FT Hydraulic Radius = A/P S=0.005 FT/FT Pipe Slope r=0.625 FT Pipe Radius P=3.93 FT Pipe Perimeter HDS 2 to DMH (24-inch HDPE at S = 0.014)Design Flow - Middle 1-4 Q=26.84 CFS Flow Rate Q10=26.6 CFS n=0.013 Roughness Coefficient A=3.14 SF Area of Pipe R=0.5 FT Hydraulic Radius = A/P S=0.014 FT/FT Pipe Slope r=1 FT Pipe Radius P=6.28 FT Pipe Perimeter CB 7 to HDS 2 (24-inch HDPE at S = 0.014)Design Flow - Middle 1-4 Q=26.84 CFS Flow Rate Q10=26.6 CFS n=0.013 Roughness Coefficient A=3.14 SF Area of Pipe R=0.5 FT Hydraulic Radius = A/P S=0.014 FT/FT Pipe Slope r=1 FT Pipe Radius P=6.28 FT Pipe Perimeter CB 8 to CB 7 (18-inch HDPE at S = 0.015)Design Flow - Middle 1-2 Q=12.90 CFS Flow Rate Q10=11 CFS n=0.013 Roughness Coefficient A=1.77 SF Area of Pipe R=0.375 FT Hydraulic Radius = A/P S=0.015 FT/FT Pipe Slope r=0.75 FT Pipe Radius P=4.71 FT Pipe Perimeter Pipe Sizing Calculations Page 5 of 7 Appendix b Pipe Sizing Calculations CB 9 to CB 8 (15-inch HDPE at S = 0.103)Design Flow - Middle 1 Q=20.79 CFS Flow Rate Q10=5.3 CFS n=0.013 Roughness Coefficient A=1.23 SF Area of Pipe R=0.3125 FT Hydraulic Radius = A/P S=0.103 FT/FT Pipe Slope r=0.625 FT Pipe Radius P=3.93 FT Pipe Perimeter CB 10 to CB 7 (15-inch HDPE at S = 0.016)Design Flow - Middle 4 Q=8.19 CFS Flow Rate Q10=8.1 CFS n=0.013 Roughness Coefficient A=1.23 SF Area of Pipe R=0.3125 FT Hydraulic Radius = A/P S=0.016 FT/FT Pipe Slope r=0.625 FT Pipe Radius P=3.93 FT Pipe Perimeter HDS 3 to Existing CB (24-inch HDPE at S = 0.006)Design Flow - South 1-3 Q=17.57 CFS Flow Rate Q10=17 CFS n=0.013 Roughness Coefficient A=3.14 SF Area of Pipe R=0.5 FT Hydraulic Radius = A/P S=0.006 FT/FT Pipe Slope r=1 FT Pipe Radius P=6.28 FT Pipe Perimeter CB 11 to HDS 3 (24-inch HDPE at S = 0.006)Design Flow - South 1-3 Q=17.57 CFS Flow Rate Q10=17 CFS n=0.013 Roughness Coefficient A=3.14 SF Area of Pipe R=0.5 FT Hydraulic Radius = A/P S=0.006 FT/FT Pipe Slope r=1 FT Pipe Radius P=6.28 FT Pipe Perimeter CB 12 to CB 11 (24-inch HDPE at S = 0.011)Design Flow - South 1-2 Q=23.79 CFS Flow Rate Q10=12.3 CFS n=0.013 Roughness Coefficient A=3.14 SF Area of Pipe R=0.5 FT Hydraulic Radius = A/P S=0.011 FT/FT Pipe Slope r=1 FT Pipe Radius P=6.28 FT Pipe Perimeter Pipe Sizing Calculations Page 6 of 7 Appendix b Pipe Sizing Calculations CB 13 to CB 12 (15-inch HDPE at S = 0.006)Design Flow - South 1 Q=5.02 CFS Flow Rate Q10=5 CFS n=0.013 Roughness Coefficient A=1.23 SF Area of Pipe R=0.3125 FT Hydraulic Radius = A/P S=0.006 FT/FT Pipe Slope r=0.625 FT Pipe Radius P=3.93 FT Pipe Perimeter Pipe Sizing Calculations Page 7 of 7 Water Quality Calculations per Appendix B, CT DEEP SWQM HDS-A - Contech CDS10 Water Quality Volume - 1" x R x A / 12 Gross Drainage Area (A)6.32 Acres Impervious Area 4.85 Acres % Impervious (I)76.74 % Volumetric Runoff Coefficient 0.74 R=0.05+(0.009 x I) Water Quality Volume 0.39 Acre-Feet Water Quality Volume 16,992 Cubic Feet Water Quality Flow Runoff Depth (Q = WQV x 12 / A)0.74 Inches CN 97.43 Tc (10 minute minimum per SWQM)10 Minutes Ia (Table 4-1 of TR-55)0.041 Inches qu (Exhibit 4-III of TR-55)650 csm/in WQF 4.75 CFS Water Quality Calculations per Appendix B, CT DEEP SWQM HDS-B - Contech Cascade CS-3 Water Quality Volume - 1" x R x A / 12 Gross Drainage Area (A)0.7 Acres Impervious Area 0.7 Acres % Impervious (I)100.00 % Volumetric Runoff Coefficient 0.95 R=0.05+(0.009 x I) Water Quality Volume 0.06 Acre-Feet Water Quality Volume 2,414 Cubic Feet Water Quality Flow Runoff Depth (Q = WQV x 12 / A)0.95 Inches CN 99.57 Tc (10 minute minimum per SWQM)10 Minutes Ia (Table 4-1 of TR-55)0.041 Inches qu (Exhibit 4-III of TR-55)650 csm/in WQF 0.68 CFS Water Quality Calculations per Appendix B, CT DEEP SWQM CB-E - Contech Cascade CS3 Water Quality Volume - 1" x R x A / 12 Gross Drainage Area (A)0.2 Acres Impervious Area 0.2 Acres % Impervious (I)100.00 % Volumetric Runoff Coefficient 0.95 R=0.05+(0.009 x I) Water Quality Volume 0.02 Acre-Feet Water Quality Volume 690 Cubic Feet Water Quality Flow Runoff Depth (Q = WQV x 12 / A)0.95 Inches CN 99.57 Tc (10 minute minimum per SWQM)10 Minutes Ia (Table 4-1 of TR-55)0.041 Inches qu (Exhibit 4-III of TR-55)650 csm/in WQF 0.19 CFS Water Quality Calculations per Appendix B, CT DEEP SWQM CB-F - Contech Cascade CS3 Water Quality Volume - 1" x R x A / 12 Gross Drainage Area (A)0.26 Acres Impervious Area 0.26 Acres % Impervious (I)100.00 % Volumetric Runoff Coefficient 0.95 R=0.05+(0.009 x I) Water Quality Volume 0.02 Acre-Feet Water Quality Volume 897 Cubic Feet Water Quality Flow Runoff Depth (Q = WQV x 12 / A)0.95 Inches CN 99.57 Tc (10 minute minimum per SWQM)10 Minutes Ia (Table 4-1 of TR-55)0.041 Inches qu (Exhibit 4-III of TR-55)650 csm/in WQF 0.25 CFS Water Quality Calculations per Appendix B, CT DEEP SWQM HDS-1 - Contech CDS8 Water Quality Volume - 1" x R x A / 12 Gross Drainage Area (A)2.47 Acres Impervious Area 2.47 Acres % Impervious (I)100 % Volumetric Runoff Coefficient 0.95 R=0.05+(0.009 x I) Water Quality Volume 0.20 Acre-Feet Water Quality Volume 8,518 Cubic Feet Water Quality Flow Runoff Depth (Q = WQV x 12 / A)0.95 Inches CN 99.57 Tc (10 minute minimum per SWQM)10 Minutes Ia (Table 4-1 of TR-55)0.041 Inches qu (Exhibit 4-III of TR-55)650 csm/in WQF 2.38 CFS Water Quality Calculations per Appendix B, CT DEEP SWQM HDS-2 - Contech CDS10 Water Quality Volume - 1" x R x A / 12 Gross Drainage Area (A)4.54 Acres Impervious Area 4.54 Acres % Impervious (I)100 % Volumetric Runoff Coefficient 0.95 R=0.05+(0.009 x I) Water Quality Volume 0.36 Acre-Feet Water Quality Volume 15,656 Cubic Feet Water Quality Flow Runoff Depth (Q = WQV x 12 / A)0.95 Inches CN 99.57 Tc (10 minute minimum per SWQM)10 Minutes Ia for CN(Table 4-1 of TR-55)0.041 Inches qu (Exhibit 4-III of TR-55)650 csm/in WQF 4.38 CFS Water Quality Calculations per Appendix B, CT DEEP SWQM HDS-3 - Contech CDS8 Water Quality Volume - 1" x R x A / 12 Gross Drainage Area (A)2.93 Acres Impervious Area 2.93 Acres % Impervious (I)100 % Volumetric Runoff Coefficient 0.95 R=0.05+(0.009 x I) Water Quality Volume 0.23 Acre-Feet Water Quality Volume 10,104 Cubic Feet Water Quality Flow Runoff Depth (Q = WQV x 12 / A)0.95 Inches CN 99.57 Tc (10 minute minimum per SWQM)10 Minutes Ia (Table 4-1 of TR-55)0.041 Inches qu (Exhibit 4-III of TR-55)650 csm/in WQF 2.83 CFS Appendix C Hydrodynamic Separator Cut Sheets (3'-0" [914])SOLIDS STORAGE SUMP INLET PIPE (MULTIPLE INLET PIPES MAY BE ACCOMMODATED) OUTLET PIPE VARIESBB 1'-814" [514]PLAN VIEW B-B NOT TO SCALE ELEVATION A-A NOT TO SCALE FIBERGLASS OR ALUMINUM INTERNAL COMPONENTS FLOW CONTRACTOR TO GROUT TO FINISHED GRADE GRADE RINGS/RISERS A A 36" [914] I.D. MANHOLE STRUCTURE TOP SLAB ACCESS (SEE FRAME AND COVER DETAIL)FLOW TOP OF CENTER CHAMBER (EXTENSIONS AVAILABLE AS REQUIRED) INLET PIPE(S) LOCATION MAY VARY WITHIN 256° PERMANENT POOL ELEVATION FRAME AND COVER (DIAMETER VARIES) NOT TO SCALE www.ContechES.com ® 800-338-1122 513-645-7000 513-645-7993 FAX 9025 Centre Pointe Dr., Suite 400, West Chester, OH 45069 CS-3 CASCADE SEPARATOR STANDARD DETAIL I:\COMMON\CAD\TREATMENT\21 CASCADE\40 STANDARD DRAWINGS\DWG\CS-3-DTL.DWG 6/18/2020 4:23 PMwww.contechES.com CASCADE SEPARATOR DESIGN NOTES THE STANDARD CS-3 CONFIGURATION IS SHOWN. ALTERNATE CONFIGURATIONS ARE AVAILABLE AND ARE LISTED BELOW. SOME CONFIGURATIONS MAY BE COMBINED TO SUIT SITE REQUIREMENTS. CONFIGURATION DESCRIPTION GRATED INLET ONLY (NO INLET PIPE) GRATED INLET WITH INLET PIPE OR PIPES CURB INLET ONLY (NO INLET PIPE) CURB INLET WITH INLET PIPE OR PIPES GENERAL NOTES 1.CONTECH TO PROVIDE ALL MATERIALS UNLESS NOTED OTHERWISE. 2.FOR SITE SPECIFIC DRAWINGS WITH DETAILED STRUCTURE DIMENSIONS AND WEIGHT, PLEASE CONTACT YOUR CONTECH ENGINEERED SOLUTIONS LLC REPRESENTATIVE. www.ContechES.com 3.CASCADE SEPARATOR WATER QUALITY STRUCTURE SHALL BE IN ACCORDANCE WITH ALL DESIGN DATA AND INFORMATION CONTAINED IN THIS DRAWING. CONTRACTOR TO CONFIRM STRUCTURE MEETS REQUIREMENTS OF PROJECT. 4.CASCADE SEPARATOR STRUCTURE SHALL MEET AASHTO HS20 LOAD RATING, ASSUMING EARTH COVER OF 0' - 2' [610], AND GROUNDWATER ELEVATION AT, OR BELOW, THE OUTLET PIPE INVERT ELEVATION. ENGINEER OF RECORD TO CONFIRM ACTUAL GROUNDWATER ELEVATION. CASTINGS SHALL MEET AASHTO M306 AND BE CAST WITH THE CONTECH LOGO. 5.CASCADE SEPARATOR STRUCTURE SHALL BE PRECAST CONCRETE CONFORMING TO ASTM C478 AND AASHTO LOAD FACTOR DESIGN METHOD. 6.ALTERNATE UNITS ARE SHOWN IN MILLIMETERS [mm ]. INSTALLATION NOTES A.ANY SUB-BASE, BACKFILL DEPTH, AND/OR ANTI-FLOTATION PROVISIONS ARE SITE-SPECIFIC DESIGN CONSIDERATIONS AND SHALL BE SPECIFIED BY ENGINEER OF RECORD. B.CONTRACTOR TO PROVIDE EQUIPMENT WITH SUFFICIENT LIFTING AND REACH CAPACITY TO LIFT AND SET THE CASCADE SEPARATOR MANHOLE STRUCTURE. C.CONTRACTOR TO INSTALL JOINT SEALANT BETWEEN ALL STRUCTURE SECTIONS AND ASSEMBLE STRUCTURE. D.CONTRACTOR TO PROVIDE, INSTALL, AND GROUT INLET AND OUTLET PIPE(S). MATCH PIPE INVERTS WITH ELEVATIONS SHOWN. ALL PIPE CENTERLINES TO MATCH PIPE OPENING CENTERLINES. E.CONTRACTOR TO TAKE APPROPRIATE MEASURES TO ASSURE UNIT IS WATER TIGHT, HOLDING WATER TO FLOWLINE INVERT MINIMUM. IT IS SUGGESTED THAT ALL JOINTS BELOW PIPE INVERTS ARE GROUTED. SITE SPECIFIC DATA REQUIREMENTS STRUCTURE ID WATER QUALITY FLOW RATE (cfs [L/s]) PEAK FLOW RATE (cfs [L/s]) RETURN PERIOD OF PEAK FLOW (yrs) RIM ELEVATION PIPE DATA:INVERT MATERIAL DIAMETER INLET PIPE 1 INLET PIPE 2 OUTLET PIPE NOTES / SPECIAL REQUIREMENTS: Figures Location Map (Uncasville Quad) Gateway Montville, LLC 125 & 133 Depot Road, Uncasville, CT GRAPHIC SCALERevisionsSHEET NO.Site Operations/Development Plan Prepared for Gateway Montville, LLC 125 & 133 Depot Road - Uncasville, ConnecticutMay 2022JOB I.D. NO.\\192.168.2.3\PROJECTS\CIVIL 3D PROJECTS\2022\22-3140 GATEWAY TERMINAL\TECH\STORMWATER\DEPOT ROAD STORMWATER.DWG 22-3140DATE:SCALE:21©2022 BOUNDARIES LLCTHIS DRAWING IS THE PROPERTY OF BOUNDARIES LLC AND HAS BEEN SPECIFICALLYPREPARED FOR THE OWNER OF THIS PROJECT, AT THIS SITE, AND IS NOT TO BEDUPLICATED OR USED IN PART OR WHOLE FOR ANY OTHER PURPOSE, PROJECT, LOCATIONOR OWNER WITHOUT THE EXPRESSED WRITTEN CONSENT OF BOUNDARIES LLC.1" = 50'"Figure 2 - Post-Development Conditions Watersheds"11NORTH SUBAREA 2AREA=1.22 AcresC=0.95Tc=5 minutesQ10=7.1 CFSNORTH SUBAREA 1AREA=0.52 AcresC=0.95Tc=5 minutesQ10=3.0 CFSNORTH SUBAREA 3AREA=0.23 AcresC=0.95Tc=5 minutesQ10=1.3 CFSNORTH SUBAREA 4AREA=0.62 AcresC=0.95Tc=5 minutesQ10=3.6 CFSMIDDLE SUBAREA 1AREA=0.91 AcresC=0.95Tc=5 minutesQ10=5.3 CFSMIDDLE SUBAREA 2AREA=0.99 AcresC=0.95Tc=5 minutesQ10=5.7 CFSMIDDLE SUBAREA 3AREA=1.29 AcresC=0.95Tc=5 minutesQ10=7.5 CFSMIDDLE SUBAREA 4AREA=1.39 AcresC=0.95Tc=5 minutesQ10=8.1 CFSSOUTH SUBAREA 1AREA=0.86 AcresC=0.95Tc=5 minutesQ10=5.0 CFSSOUTH SUBAREA 2AREA=1.26 AcresC=0.95Tc=5 minutesQ10=7.3 CFSSOUTH SUBAREA 3AREA=0.81 AcresC=0.95Tc=5 minutesQ10=4.7 CFSWEST SUBAREA 1AREA=0.59 AcresC=0.51Tc=5 minutesQ10=1.8 CFSWEST SUBAREA 2AREA=1.05 AcresC=0.66Tc=5 minutesQ10=4.2 CFSWEST SUBAREA 3AREA=1.41 AcresC=0.78Tc=5 minutesQ10=6.7 CFSWEST SUBAREA 4AREA=1.87 AcresC=0.95Tc=5 minutesQ10=10.9 CFSWEST SUBAREA 5AREA=1.40 AcresC=0.75Tc=5 minutesQ10=6.4 CFSCB E SUBAREAAREA=0.21 AcresC=0.95Tc=5 minutesQ10=1.2 CFSCB F SUBAREAAREA=0.18 AcresC=0.95Tc=5 minutesQ10=1.0 CFSCB G SUBAREAAREA=0.08 AcresC=0.95Tc=5 minutesQ10=0.5 CFSPIPE INLET SUBAREAAREA=0.69 AcresC=0.95Tc=5 minutesQ10=4.0 CFSNORTH DISCHARGEWEST DISCHARGECB-E DISCHARGEMIDDLE/CB-F DISCHARGESOUTH DISCHARGEWEST AREA OVERALLAREA=6.32 AcresC=0.81Tc=8.5 minutesQ10=25.8 CFS