The URL can be used to link to this page

180614 - Stormwater Report_2018-10-18 - BOUND Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page i TABLE OF CONTENTS SECTION PAGE NO. 1. INTRODUCTION....................................................................................................................................... 1-1 2. SITE DESCRIPTION ............................................................................................................................... 2-1 2.1 Predevelopment Conditions ............................................................................................................... 2-1 2.2 Resource Areas ...................................................................................................................................... 2-1 2.2.1 Floodplain ............................................................................................................................................... 2-1 2.2.2 Natural Heritage and Endangered Species Program ................................................................. 2-1 2.2.3 Aquifer Protection District .................................................................................................................... 2-2 2.3 Soils ........................................................................................................................................................... 2-2 2.4 Post Development Conditions............................................................................................................ 2-2 3. STORMWATER MANAGEMENT SYSTEM ................................................................................... 3-1 3.1 Drainage Calculations ......................................................................................................................... 3-1 3.1.1 Design Points .......................................................................................................................................... 3-2 3.1.2 Pre-Development Hydrology .............................................................................................................. 3-2 3.1.3 Post-Development Hydrology ............................................................................................................ 3-2 3.1.4 Peak Discharge Rates ........................................................................................................................... 3-3 3.2 Hydraulic Analysis ................................................................................................................................. 3-3 3.3 MassDEP Stormwater Management Standards ............................................................................ 3-3 3.4 Stormwater Best Management Practices ......................................................................................... 3-6 3.4.1 Deep Sump Catch Basins ................................................................................................................... 3-6 3.4.2 Proprietary Sedimentation Devices ................................................................................................... 3-6 3.4.3 Bioretention Areas ................................................................................................................................. 3-7 3.4.4 Extended Dry Detention Basins with Sediment Forebays ........................................................... 3-7 3.5 Protection of Stormwater Best Management Practices during Construction ......................... 3-7 3.6 Inspection and Maintenance of Stormwater Best Management Practices ............................. 3-7 3.7 Illicit Discharge Compliance Statement .......................................................................................... 3-7 3.8 Northampton DPW Inspection Schedule Checklist ...................................................................... 3-8 3.9 Low-Impact Development Alternatives Analysis Narrative ........................................................ 3-8 4. CONCLUSION ........................................................................................................................................... 4-1 List of Tables Table Page No. Table 2.4: Hydrologic Soil Group Classification ...................................................................................................... 2-2 Table 3.1: Design Rainfall Data .................................................................................................................................... 3-1 Table 3.1.4 Pre- and Post-Development Peak Discharge Rates ........................................................................... 3-3 Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page ii List of Figures Figure Figure 1: Site Locus – USGS Map Figure 2: FEMA Flood Map Figure 3: NHESP and Zone II Map Figure 4: Pre-Development Watershed Plan Figure 5: Post-Development Watershed Plan Figure 6: Inlet Area Plan Appendices APPENDIX A: CHECKLIST FOR STORMWATER REPORT APPENDIX B: SOILS INFORMATION APPENDIX C: PRE- AND POST- DEVELOPMENT HYDROLOGIC ANALYSIS (2, 10 & 100 YEAR STORM EVENTS) APPENDIX D: HYDRAULIC ANALYSIS APPENDIX E: MASSDEP CALCULATIONS APPENDIX F: CONSTRUCTION PERIOD EROSION CONTROL PLAN APPENDIX G: LONG-TERM OPERATION AND MAINTENANCE PLAN APPENDIX H: ILLICIT DISCHARGE COMPLIANCE STATEMENT APPENDIX I: NORTHAMPTON DPW INSPECTION SCHEDULE APPENDIX J: LOW IMPACT DEVELOPMENT ALTERNATIVES ANALYSIS NARRATIVE Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 1-1 1. INTRODUCTION The applicant, Platinum Self Storage, is proposing to construct a self-storage facility located on a currently vacant parcel identified as lot 15-32-E in East Longmeadow, Massachusetts. Currently, there are no stormwater best management practices located on the project site. Generally, stormwater runoff from the property is tributary toward existing wetland areas north of the site and low points located off the property to the east. The proposed project involves the following: 1. Construction of 2 buildings to house storage units; 2. Construction of associated site improvements including an office building and access drives; 3. Installation of underground utilities to the office building including, water service, sanitary sewer, electric and communication services; 4. Construction of a stormwater management system including deep-sump hooded catch basins, underground infrastructure, proprietary sedimentation devices, bioretention areas and extended dry detention basins with sediment forebays. This report has been prepared to document the compliance of the proposed stormwater management system. The stormwater system has been designed to meet the standards set forth in the City of Northampton Stormwater Management Ordinance as well as the Massachusetts Department of Environmental Protection Stormwater Management Handbook. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 2-1 2. SITE DESCRIPTION 2.1 Predevelopment Conditions The property to be redeveloped is located west of Easthampton Road and listed as Parcel 44-031- 001 in the Northampton Assessor’s Office. Figure 1 – USGS Map illustrates the location of the project. The property is bounded to the East by Easthampton Road, to the south by Sunnyside Early Childhood Center, to the west by pine grove golf course and vacant land and to the north by vacant land. The Locus parcel is zoned Office Industrial. The total parcel area is approximately 8.13 acres in size. In general, the topography of the site can be described as moderately sloped. Terrain is lowest along the parcel frontage with elevations ranging from 107 to 114 feet. From the parcel frontage, terrain climbs at an average grade of 9% to a ridgeline and knoll near the parcel center. Elevations along the ridgeline range from 148 to 151 feet. From the ridgeline/knoll terrain drops down toward the western property line at an average grade of 7%. Elevations along the western property line range from 137 feet to 140. The existing on-site areas have been analyzed as discharging to two separate design points. The area east of the ridgeline discharges to the existing drainage infrastructure along Easthampton Road. The area west of the ridgeline drains to downgradient areas west of the property. See section 3.1.2 for a detailed description of the pre-development hydrology. 2.2 Resource Areas There are no bordering or isolated vegetation wetland areas delineated on or adjacent to the site. 2.2.1 Floodplain R. Levesque Associates, Inc. performed due diligence research on the property in regards to FEMA flood zone mapping. As demonstrated by the most recent FEMA Flood Insurance Rate Maps, the property is not located within any flood hazard areas a defined by the most recent FEMA Flood Insurance Rate Maps, see Figure 2 – FEMA FIRM Map. 2.2.2 Natural Heritage and Endangered Species Program R. Levesque Associates, Inc. performed due diligence research on the property in regards to Natural Heritage and Endangered Species Program (NHESP) areas. The property is not located within any areas delineated by NHESP as estimated or priority habitats of endangered species, see Figure 3 – NHESP & Zone II Map. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 2-2 2.2.3 Aquifer Protection District R. Levesque Associates, Inc. performed due diligence research on the property in regards to the Aquifer Protection District. The property is not located within an area delineated as a Zone II Wellhead Protection Area, see Figure 3 – NHESP & Zone II Map. 2.3 Soils R. Levesque Associates, Inc. researched the soils located on site with information available from the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS). Based on a review of the USDA Soil Survey of Hampshire County, Massachusetts, the site is comprised of the following soil types: Table 2.4: Hydrologic Soil Group Classification Soil Description Map Unit Symbol Hydrologic Soil Group Belgrade silt loam 225B C Hinckley loamy sand 253B A A series of test pits were conducted by Filipe J. Cravo, P.E. SE#12839 to evaluate the ability of the site to support the stormwater drainage system components. A total of nine test holes were dug on the property in the vicinity of the proposed bioretention areas and detention basins. The test pits showed evidence of seasonal high groundwater at depths ranging from 36-inches to 66- inches. See Appendix B for the United States Department of Agriculture Natural Resources Conservation Service Soil Resource Report (NRCS) and Soil Evaluation log sheets. In general, the soil evaluations confirmed the NRCS mapping. All of the test pits uncovered a firm sandy loam layer which would prevent any infiltration best management practice to be properly installed. 2.4 Post Development Conditions The proposed site improvements include a number of stormwater management features to properly meet the requirements set forth by the City of Northampton Stormwater Management Ordinance as well as the Massachusetts Department of Environmental Protection Stormwater Management Handbook. The proposed stormwater features include:  Deep Sump Hooded Catch Basins;  Proprietary Sedimentation Devices;  Bioretention Areas  Extended Dry Detention Basins with Sediment Forebays; Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 2-3 The developer is proposing to construct a new self-storage facility on the subject property. The proposed self-storage facility includes the construction of 2 new buildings to house the storage units, an office building, associated site improvements including paved access drives, and a stormwater management system. Utilities to provide services for the new buildings will be brought on site via Easthampton Road. The storage facilities will receive electric and communication services while the office building will require water, sanitary sewer, electric and communication services. The majority of the proposed stormwater management system will collect runoff from the building roofs and the paved surfaces via deep sump catch basin structures strategically located at various low points throughout the site. The inlet structures will be connected to a network of underground infrastructure which will convey the runoff towards proprietary sedimentation devices for additional water quality treatment (required for detention basin treatment train only) prior to discharge to bioretention areas or detention basin located throughout the site. Bioretention areas and basins were designed such that the runoff can be infiltrated to provide groundwater recharge to the maximum extent practicable as well as provide peak rate attenuation. The proposed site improvements will maintain the general drainage patterns of the site by discharging runoff to the same design points in post-development as pre-development conditions. Each component of the proposed stormwater management systems has been designed to meet the standards set forth by the City of Northampton Stormwater Management Ordinance as well as the Massachusetts Department of Environmental Protection Stormwater Management Handbook. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 3-1 3. STORMWATER MANAGEMENT SYSTEM R. Levesque Associates, Inc. has prepared the following drainage system calculations for the proposed project site. These calculations were performed to document compliance with the guidelines set forth by Chapter 281 – Stormwater Management Ordinance of the Code of Ordinances of the City of Northampton, Massachusetts as well as the Massachusetts Department of Environmental Protection Stormwater Management Handbook (MassDEP Handbook). A detailed hydrologic analysis of the system was completed in order to evaluate the performance of the stormwater management system components, see Appendix C – Pre- and Post-Development Hydrologic Analysis. The proposed stormwater management system will collect runoff from on-site impervious areas and utilize stormwater best management practices to provide water quality treatment, groundwater recharge, and peak discharge rate attenuation. 3.1 Drainage Calculations R. Levesque Associates, Inc. utilized the HydroCAD software program, Version 10.0, developed by HydroCAD Software Solutions LLC, in order to create and analyze the site hydrology. The HydroCAD software is based upon the Soil Conservation Service (SCS) “Technical Release 20 – Urban Hydrology for Small Watersheds” and “Technical Release 55 – Urban Hydrology for small Watersheds” which are generally accepted industry standard methodologies. The analysis was conducted in order to establish the peak discharge rates and estimated run-off volume from the project site. This was accomplished to properly evaluate pre- and post-development conditions during various storm events. Contributing drainage areas were identified and soils, surface cover, watershed slope, and flow paths were evaluated to develop the necessary HydroCAD model input parameters. Drainage calculations were performed for the Pre- and Post-Development conditions for the 24- hour, 2, 10, and 100-year Type III storm events. The total rainfall for each of the storm events was based upon data provided by the United States Department of Commerce Technical Paper No. 40 – Rainfall Frequency Atlas of the United States. The total rainfall values used in the hydrologic modeling for each event are shown in the following table: Table 3.1: Design Rainfall Data 2-year, 24-hour storm 10-year, 24-hour storm 100-year, 24-hour storm 3.00 inches 4.50 inches 6.40 inches Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 3-2 3.1.1 Design Points In order to compare the difference between pre- and post-development peak flows, existing and proposed watersheds were delineated. Three subcatchments draining to two Design Points (DP) were established with flow paths representing the longest time of concentration of run-off in each tributary watershed. For this analysis, the design points were determined as follows:  DP-1: This design point represents runoff from the property which is tributary to the existing drainage infrastructure in Easthampton Road;  DP-2: This design point represents the runoff from the property which is directed off-site towards the westerly property line. 3.1.2 Pre-Development Hydrology The project area under existing conditions was broken down into three (3) sub-catchments discharging to the two design points as described above. The sub-catchments were delineated based on the existing topography of the parcel and surrounding areas. The existing watershed areas are shown on the attached Figure 4 entitled “Pre-Development Watershed Plan”. Peak discharge rates for the design point are depicted in Table 3.1.4 below. 3.1.3 Post-Development Hydrology The project area under proposed conditions was broken down into seven (7) sub-catchments discharging to the same design points as the existing conditions. The proposed watershed areas are shown on the attached Figure 5 entitled “Post-Development Watershed Plan”. Peak discharge rates for the design point are depicted in Table 3.1.4 below. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 3-3 3.1.4 Peak Discharge Rates The table below summarizes the Pre and Post-Development peak discharge rates for each Design Point: Table 3.1.4 Pre- and Post-Development Peak Discharge Rates 2-year storm (cfs) 10-year storm (cfs) 100-year storm (cfs) Pre- Post- Pre- Post- Pre- Post- Design Point 1 1.64 1.63 5.95 5.55 13.16 12.89 Design Point 2 1.06 0.52 2.78 2.22 5.34 4.72 As depicted in the table, the post-development peak discharge rates do not increase over pre- development peak discharge rates for each of the storm events presented. This is accomplished by providing onsite attenuation with the proposed bioretention areas and detention basins. 3.2 Hydraulic Analysis R. Levesque Associates, Inc. utilized the Hydraflow Storm Sewer Extension for AutoCAD Civil 3D 2012 software program, Version 9, developed by Autodesk, Inc., in order to analyze the hydraulic capacity of the proposed underground infrastructure. The analysis was conducted in order to verify that the proposed conveyance piping has sufficient capacity to convey up to and including the 24-hour, 100-year storm event. The data from the analysis was used to properly size the conveyance piping such that there is no or minimal surcharge of stormwater above the rim elevations within the paved areas. As part of the input parameters required for the hydraulic analysis, the tributary inlet areas were delineated based on topography, any additional connected discharges, characteristic land use coverages and flow paths, see Figure 6 – Inlet Area Plan. A minimum Time of Concentration (Tc) of (6) minutes was used in the calculations. Please refer to Appendix D for the hydraulic analysis of the proposed stormwater management system. 3.3 MassDEP Stormwater Management Standards R. Levesque Associates, Inc. has designed the proposed stormwater management system to be in compliance with the MassDEP Stormwater Management Standards. Chapter 1, Volume 3 of the MassDEP Handbook outlines specific calculations, and other information, that must be submitted with each report to document compliance. The following summary highlights elements of the proposed project and how they apply to each standard. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 3-4  Standard #1 - No new stormwater conveyances (e.g., outfalls) may discharge untreated stormwater directly to or cause erosion in wetlands or waters of the Commonwealth. The proposed stormwater management system has been designed to provide best management practices to the guidelines of the MassDEP Handbook. Therefore, no new untreated stormwater is discharged.  Standard #2 – Stormwater management systems shall be designed so that post- development peak discharge rates do not exceed pre-development peak discharge rates. This Standard may be waived for discharges to land subject to coastal storm flowage as defined in 310 CMR 10.04. The proposed stormwater management system has been designed such that the post- development peak discharge rates are less than the pre-development discharge rates for the 2-year, 10-year, and 100-year 24-hour storms. See Appendix C for the Hydrologic Analysis.  Standard #3 - Loss of annual recharge to groundwater shall be eliminated or minimized through the use of environmentally sensitive site design, low impact development techniques, stormwater BMPs, and good operation and maintenance. At a minimum, the annual recharge from the post-development site shall approximate the annual recharge from pre-development conditions based on soil type. This Standard is met when the stormwater management system is designed to infiltrate the required volume as determined in accordance with the Massachusetts Stormwater Handbook. The proposed bioretention areas and detention basin have been designed to infiltrate the required recharge volume to the maximum extent practicable based on soil conditions.  Standard #4 – Stormwater management systems shall be designed to remove 80% of the average annual post-construction load of TSS. It is presumed that this standard is met when: a. Suitable practices for source control and pollution prevention are identified in a long term pollution prevention plan, and thereafter are implemented and maintained; b. Structural stormwater BMPs practices are sized to capture the required water quality volume determined in accordance with the Massachusetts Stormwater Handbook; and c. Pretreatment is provided in accordance with the Massachusetts Stormwater Handbook The stormwater management system has been designed to provide the required total suspended solids pre-treatment prior to discharge to the bioretention and detention basins. See Appendix E for the Total Suspended Solids Calculations. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 3-5  Standard #5 - For land uses with higher potential pollutant loads, source control and pollution prevention shall be implemented in accordance with the Massachusetts Stormwater Handbook to eliminate or reduce the discharge of stormwater runoff from such land uses to the maximum extent practicable. If through source control and/or pollution prevention all land uses with higher potential pollutant loads cannot be completely protected from exposure to rain, snow, snow melt, and stormwater runoff, the proponent shall use the specific structural stormwater BMPs determined by MassDEP to be suitable for such uses as provided in the Massachusetts Stormwater Handbook. Stormwater discharges from land uses with higher potential pollutant loads shall also comply with the requirements of the Massachusetts Clean Waters Act, M.G.L. c. 21, §§ 26-53 and the regulations promulgated thereunder at 314 CMR 3.00, 314 CMR 4.00 and 314 CMR 5.00. This standard is not applicable.  Standard #6 – Stormwater discharges within the Zone II or Interim Wellhead Protection Area of a public water supply, and stormwater discharges near or to any other critical area, require the use of the specific source control and pollution prevention measures and the specific structural stormwater BMPs determined by MassDEP to be suitable for managing discharges to such areas, as provided in the Massachusetts Stormwater Handbook. A discharge is near a critical area if there is a strong likelihood of a significant impact occurring to said area, taking into account site-specific factors. Stormwater discharges to Outstanding Resource Waters and Special Resource Waters shall be removed and set back from the receiving water or wetland and receive the highest and best practical method of treatment. A “storm water discharge” as defined in 314 CMR 3.04(2)(a)1 or (b) to an Outstanding Resource Water or Special Resource Water shall comply with 314 CMR 3.00 and 314 CMR 4.00. Stormwater discharges to a Zone I or Zone A are prohibited unless essential to the operation of a public water supply. This standard is not applicable.  Standard #7 – A redevelopment project is required to meet the following Stormwater Management Standards only to the maximum extent practicable: Standard 2, Standard 3, and the pretreatment and structural BMPs requirements of Standards 4, 5, and 6. Existing stormwater discharges shall comply with Standard 1 only to the maximum extent practicable. A redevelopment project shall also comply with all other requirements of the Stormwater Management Standards and improve existing conditions. This standard is not applicable.  Standard #8 – A plan to control construction-related impacts including erosion, sedimentation and other pollutant sources during construction and land disturbance Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 3-6 activities (construction period erosion, sedimentation, and pollution prevention) shall be developed and implemented. A Construction Period Erosion Control Plan has been provided in Appendix F.  Standard #9 – A long-term operation and maintenance plan shall be developed and implemented to ensure that stormwater management systems function as designed. A Long-term Operation & Maintenance Plan has been provided in Appendix G.  Standard #10 - All illicit discharges to the stormwater management system are prohibited. An illicit discharge statement will be provided prior to discharge of stormwater to post- construction BMPs. See Appendix H for a copy of the Illicit Discharge Statement. 3.4 Stormwater Best Management Practices The proposed stormwater management system was designed utilizing stormwater best management practices (BMP) as set forth by the MassDEP Handbook. The BMPs utilized as part of the stormwater management system include deep-sump hooded catch basins, proprietary sedimentation devices, a surface infiltration basin with sediment forebay, and a bio-retention area. All of the BMPs were designed to meet the requirements of the MassDEP Handbook and will provide water quality treatment, groundwater recharge, and peak rate attenuation in order to mitigate the impacts of the proposed site improvements. See Appendix E – MassDEP Calculations for the calculations required to document compliance. The following section provides a description of the best management practices (BMPs) being utilized on site. 3.4.1 Deep Sump Catch Basins Deep-sump catch basins equipped with an oil/gas hoods are being utilized as structural pretreatment devices within the proposed stormwater management system. The catch basins will be constructed with a 4’-0” deep sumps to act as a settling chamber and allow for adequate storage of collected sediments. Catch basins are typically first in the line of water quality treatment. 3.4.2 Proprietary Sedimentation Devices Proprietary sedimentation devices are being utilized on site for the pretreatment of stormwater runoff, in addition to a catch basin, prior to conveyance to basins and bioretention areas. The stormwater management system is utilizing the proprietary treatment device in order to ensure that the required water quality treatment is being performed prior to discharge to own gradient infrastructures. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 3-7 3.4.3 Bioretention Areas Bio-retention areas are being utilized on site as part of the stormwater management system treatment train process to enhance water runoff quality, provide groundwater recharge, and attenuate peak-discharge rates. Bio-retention areas utilize soils, plants, and microbes to treat stormwater before discharge and infiltrate stormwater to provide groundwater recharge. The proposed bio-retention areas associated with this project will provide aesthetically pleasing vegetation within the site. 3.4.4 Extended Dry Detention Basins with Sediment Forebays Extended dry detention basins accompanied by sediment forebays are well suited to meet the water quality and water quantity requirements from watershed areas such as those associated with this project. The extended dry detention basins with associated sediment forebays mitigate the impact of the proposed site improvements by attenuating the peak discharge rates and retaining a stormwater volume over a period of time. The proposed extended dry detention basins have been designed to attenuate up to and including the 100-year storm event. The tributary watersheds consist of the proposed access drives, parking lot, and surrounding landscaped areas. 3.5 Protection of Stormwater Best Management Practices during Construction Protection of the stormwater best management practices during construction will ensure the proper functioning of the stormwater management system and provide protection to the undisturbed areas until the site has been stabilized. Certain specific erosion and sedimentation controls and good practices to be performed by the site contractor have been documented in a Construction Period Erosion Control Plan. See Appendix F – Construction Period Erosion Control Plan. 3.6 Inspection and Maintenance of Stormwater Best Management Practices Frequent maintenance of the stormwater best management practices is essential to ensuring that the stormwater management system will function properly long-term. The MassDEP provides guidelines for the regular inspection and maintenance of the proposed stormwater best management practices. A Long-Term Stormwater Operation and Maintenance Plan has been prepared which dictates the inspection frequency and maintenance operations for each BMP. See Appendix G – Long-Term Operation and Maintenance Plan. 3.7 Illicit Discharge Compliance Statement RLA has prepared an Illicit Discharge Compliance Statement to document compliance with the Massachusetts Department of Environmental Protection Stormwater Management Handbook, see Appendix H. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 3-8 3.8 Northampton DPW Inspection Schedule Checklist RLA has prepared a checklist for the proposed project in order to identify specific milestones where the Department of Public Works shall make an inspection, see Appendix I. 3.9 Low-Impact Development Alternatives Analysis Narrative RLA has prepared a Low-Impact Development Alternatives Analysis Narrative as part of the Stormwater Drainage Report, see Appendix J. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 4-1 4. CONCLUSION The proposed stormwater management system has been designed to mitigate the impacts of the proposed site improvements by providing a control for runoff water quality and water quantity. Implementation of stormwater best management practices such as deep-sump hooded catch basins, proprietary sedimentation devices, bioretention areas and extended dry detention basins with sediment forebays allow for a stormwater drainage design that is in conformance with the criteria set forth in the City of Northampton Stormwater Management Ordinance as well as the Massachusetts Department of Environmental Protection Stormwater Management Handbook. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Figure 1: Site Locus – USGS Map R L A SCALE: DATE: JOB NO: ph: 413.568.0985 fax: 413.568.0986 rlaland.com 6FKRRO6WUHHWĈ32%R[Ĉ:HVWILHOG0$ R LEVESQUE ASSOCIATES, INC A Land Planning Services Company 180614 9/14/18 AS NOTED Platinum Self Storage 2100 Main St. Suite 106 Irvine, CA 92614 Proposed Self Storage Facility Easthampton Road Northampton, Massachusetts SITE FIG-1 SITE LOCUS USGS MAP Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Figure 2: FEMA Flood Map SITE R L A SCALE: DATE: JOB NO: ph: 413.568.0985 fax: 413.568.0986 rlaland.com 6FKRRO6WUHHWĈ32%R[Ĉ:HVWILHOG0$ R LEVESQUE ASSOCIATES, INC A Land Planning Services Company 180614 9/14/18 AS NOTED Platinum Self Storage 2100 Main St. Suite 106 Irvine, CA 92614 Proposed Self Storage Facility Easthampton Road Northampton, Massachusetts FIG-2 FEMA FLOOD MAP Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Figure 3: NHESP and Zone II Map SITE R L A SCALE: DATE: JOB NO: ph: 413.568.0985 fax: 413.568.0986 rlaland.com 6FKRRO6WUHHWĈ32%R[Ĉ:HVWILHOG0$ R LEVESQUE ASSOCIATES, INC A Land Planning Services Company 180614 9/14/18 AS NOTED Platinum Self Storage 2100 Main St. Suite 106 Irvine, CA 92614 Proposed Self Storage Facility Easthampton Road Northampton, Massachusetts FIG-3 NHESP & Zone II Map ZONE II BOUNDARY NHESP BOUNDARY Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Figure 4: Pre-Development Watershed Plan SCALE: DATE: JOB NO.:ph: 413.568.0985 fax: 413.568.0986 rlaland.com6FKRRO6WUHHWĈ32%R[Ĉ:HVWILHOG0$R LEVESQUE ASSOCIATES, INCA Land Planning Services CompanyPre-DevelopmentWatershed PlanProposed Storage FacilityEasthampton RoadNorthampton, MassachusettsPlatinum Self Storage2100 Main Street, Suite 106Irvine, California180614 10/18/18 As Noted FIG-4 Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Figure 5: Post-Development Watershed Plan SCALE: DATE: JOB NO.:ph: 413.568.0985 fax: 413.568.0986 rlaland.com6FKRRO6WUHHWĈ32%R[Ĉ:HVWILHOG0$R LEVESQUE ASSOCIATES, INCA Land Planning Services CompanyPost-DevelopmentWatershed PlanProposed Self-Storage FacilityEasthampton RoadNorthampton, MassachusettsPlatinum Self Storage2100 Main Street, Suite 106Irvine, California180614 10/18/18 As Noted FIG-5 Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Figure 6: Inlet Area Plan SCALE: DATE: JOB NO.:ph: 413.568.0985 fax: 413.568.0986 rlaland.com6FKRRO6WUHHWĈ32%R[Ĉ:HVWILHOG0$R LEVESQUE ASSOCIATES, INCA Land Planning Services CompanyInlet Area PlanProposed Self-Storage FacilityEasthampton RoadNorthampton, MassachusettsPlatinum Self Storage2100 Main Street, Suite 106Irvine, California180614 10/18/18 As Noted FIG-6 Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Appendix A: Checklist for Stormwater Report 180614 - MassDEP Stormwater Checklist.doc • 04/01/08 Stormwater Report Checklist • Page 1 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report A. Introduction Important: When filling out forms on the computer, use only the tab key to move your cursor - do not use the return key. A Stormwater Report must be submitted with the Notice of Intent permit application to document compliance with the Stormwater Management Standards. The following checklist is NOT a substitute for the Stormwater Report (which should provide more substantive and detailed information) but is offered here as a tool to help the applicant organize their Stormwater Management documentation for their Report and for the reviewer to assess this information in a consistent format. As noted in the Checklist, the Stormwater Report must contain the engineering computations and supporting information set forth in Volume 3 of the Massachusetts Stormwater Handbook. The Stormwater Report must be prepared and certified by a Registered Professional Engineer (RPE) licensed in the Commonwealth. The Stormwater Report must include:  The Stormwater Checklist completed and stamped by a Registered Professional Engineer (see page 2) that certifies that the Stormwater Report contains all required submittals.1 This Checklist is to be used as the cover for the completed Stormwater Report.  Applicant/Project Name  Project Address  Name of Firm and Registered Professional Engineer that prepared the Report  Long-Term Pollution Prevention Plan required by Standards 4-6  Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan required by Standard 82  Operation and Maintenance Plan required by Standard 9 In addition to all plans and supporting information, the Stormwater Report must include a brief narrative describing stormwater management practices, including environmentally sensitive site design and LID techniques, along with a diagram depicting runoff through the proposed BMP treatment train. Plans are required to show existing and proposed conditions, identify all wetland resource areas, NRCS soil types, critical areas, Land Uses with Higher Potential Pollutant Loads (LUHPPL), and any areas on the site where infiltration rate is greater than 2.4 inches per hour. The Plans shall identify the drainage areas for both existing and proposed conditions at a scale that enables verification of supporting calculations. As noted in the Checklist, the Stormwater Management Report shall document compliance with each of the Stormwater Management Standards as provided in the Massachusetts Stormwater Handbook. The soils evaluation and calculations shall be done using the methodologies set forth in Volume 3 of the Massachusetts Stormwater Handbook. To ensure that the Stormwater Report is complete, applicants are required to fill in the Stormwater Report Checklist by checking the box to indicate that the specified information has been included in the Stormwater Report. If any of the information specified in the checklist has not been submitted, the applicant must provide an explanation. The completed Stormwater Report Checklist and Certification must be submitted with the Stormwater Report. 1 The Stormwater Report may also include the Illicit Discharge Compliance Statement required by Standard 10. If not included in the Stormwater Report, the Illicit Discharge Compliance Statement must be submitted prior to the discharge of stormwater runoff to the post-construction best management practices. 2 For some complex projects, it may not be possible to include the Construction Period Erosion and Sedimentation Control Plan in the Stormwater Report. In that event, the issuing authority has the discretion to issue an Order of Conditions that approves the project and includes a condition requiring the proponent to submit the Construction Period Erosion and Sedimentation Control Plan before commencing any land disturbance activity on the site. 180614 - MassDEP Stormwater Checklist.doc • 04/01/08 Stormwater Report Checklist • Page 3 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) LID Measures: Stormwater Standards require LID measures to be considered. Document what environmentally sensitive design and LID Techniques were considered during the planning and design of the project: No disturbance to any Wetland Resource Areas Site Design Practices (e.g. clustered development, reduced frontage setbacks) Reduced Impervious Area (Redevelopment Only) Minimizing disturbance to existing trees and shrubs LID Site Design Credit Requested: Credit 1 Credit 2 Credit 3 Use of “country drainage” versus curb and gutter conveyance and pipe Bioretention Cells (includes Rain Gardens) Constructed Stormwater Wetlands (includes Gravel Wetlands designs) Treebox Filter Water Quality Swale Grass Channel Green Roof Other (describe): Standard 1: No New Untreated Discharges No new untreated discharges Outlets have been designed so there is no erosion or scour to wetlands and waters of the Commonwealth Supporting calculations specified in Volume 3 of the Massachusetts Stormwater Handbook included. 180614 - MassDEP Stormwater Checklist.doc • 04/01/08 Stormwater Report Checklist • Page 4 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 2: Peak Rate Attenuation Standard 2 waiver requested because the project is located in land subject to coastal storm flowage and stormwater discharge is to a wetland subject to coastal flooding. Evaluation provided to determine whether off-site flooding increases during the 100-year 24-hour storm. Calculations provided to show that post-development peak discharge rates do not exceed pre- development rates for the 2-year and 10-year 24-hour storms. If evaluation shows that off-site flooding increases during the 100-year 24-hour storm, calculations are also provided to show that post-development peak discharge rates do not exceed pre-development rates for the 100-year 24- hour storm. Standard 3: Recharge Soil Analysis provided. Required Recharge Volume calculation provided. Required Recharge volume reduced through use of the LID site Design Credits. Sizing the infiltration, BMPs is based on the following method: Check the method used. Static Simple Dynamic Dynamic Field1 Runoff from all impervious areas at the site discharging to the infiltration BMP. Runoff from all impervious areas at the site is not discharging to the infiltration BMP and calculations are provided showing that the drainage area contributing runoff to the infiltration BMPs is sufficient to generate the required recharge volume. Recharge BMPs have been sized to infiltrate the Required Recharge Volume. Recharge BMPs have been sized to infiltrate the Required Recharge Volume only to the maximum extent practicable for the following reason: Site is comprised solely of C and D soils and/or bedrock at the land surface M.G.L. c. 21E sites pursuant to 310 CMR 40.0000 Solid Waste Landfill pursuant to 310 CMR 19.000 Project is otherwise subject to Stormwater Management Standards only to the maximum extent practicable. Calculations showing that the infiltration BMPs will drain in 72 hours are provided. Property includes a M.G.L. c. 21E site or a solid waste landfill and a mounding analysis is included. 1 80% TSS removal is required prior to discharge to infiltration BMP if Dynamic Field method is used. 180614 - MassDEP Stormwater Checklist.doc • 04/01/08 Stormwater Report Checklist • Page 5 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 3: Recharge (continued) The infiltration BMP is used to attenuate peak flows during storms greater than or equal to the 10- year 24-hour storm and separation to seasonal high groundwater is less than 4 feet and a mounding analysis is provided. Documentation is provided showing that infiltration BMPs do not adversely impact nearby wetland resource areas. Standard 4: Water Quality The Long-Term Pollution Prevention Plan typically includes the following:  Good housekeeping practices;  Provisions for storing materials and waste products inside or under cover;  Vehicle washing controls;  Requirements for routine inspections and maintenance of stormwater BMPs;  Spill prevention and response plans;  Provisions for maintenance of lawns, gardens, and other landscaped areas;  Requirements for storage and use of fertilizers, herbicides, and pesticides;  Pet waste management provisions;  Provisions for operation and management of septic systems;  Provisions for solid waste management;  Snow disposal and plowing plans relative to Wetland Resource Areas;  Winter Road Salt and/or Sand Use and Storage restrictions;  Street sweeping schedules;  Provisions for prevention of illicit discharges to the stormwater management system;  Documentation that Stormwater BMPs are designed to provide for shutdown and containment in the event of a spill or discharges to or near critical areas or from LUHPPL;  Training for staff or personnel involved with implementing Long-Term Pollution Prevention Plan;  List of Emergency contacts for implementing Long-Term Pollution Prevention Plan. A Long-Term Pollution Prevention Plan is attached to Stormwater Report and is included as an attachment to the Wetlands Notice of Intent. Treatment BMPs subject to the 44% TSS removal pretreatment requirement and the one inch rule for calculating the water quality volume are included, and discharge: is within the Zone II or Interim Wellhead Protection Area is near or to other critical areas is within soils with a rapid infiltration rate (greater than 2.4 inches per hour) involves runoff from land uses with higher potential pollutant loads. The Required Water Quality Volume is reduced through use of the LID site Design Credits. Calculations documenting that the treatment train meets the 80% TSS removal requirement and, if applicable, the 44% TSS removal pretreatment requirement, are provided. 180614 - MassDEP Stormwater Checklist.doc • 04/01/08 Stormwater Report Checklist • Page 6 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 4: Water Quality (continued) The BMP is sized (and calculations provided) based on: The ½” or 1” Water Quality Volume or The equivalent flow rate associated with the Water Quality Volume and documentation is provided showing that the BMP treats the required water quality volume. The applicant proposes to use proprietary BMPs, and documentation supporting use of proprietary BMP and proposed TSS removal rate is provided. This documentation may be in the form of the propriety BMP checklist found in Volume 2, Chapter 4 of the Massachusetts Stormwater Handbook and submitting copies of the TARP Report, STEP Report, and/or other third party studies verifying performance of the proprietary BMPs. A TMDL exists that indicates a need to reduce pollutants other than TSS and documentation showing that the BMPs selected are consistent with the TMDL is provided. Standard 5: Land Uses With Higher Potential Pollutant Loads (LUHPPLs) The NPDES Multi-Sector General Permit covers the land use and the Stormwater Pollution Prevention Plan (SWPPP) has been included with the Stormwater Report. The NPDES Multi-Sector General Permit covers the land use and the SWPPP will be submitted prior to the discharge of stormwater to the post-construction stormwater BMPs. The NPDES Multi-Sector General Permit does not cover the land use. LUHPPLs are located at the site and industry specific source control and pollution prevention measures have been proposed to reduce or eliminate the exposure of LUHPPLs to rain, snow, snow melt and runoff, and been included in the long term Pollution Prevention Plan. All exposure has been eliminated. All exposure has not been eliminated and all BMPs selected are on MassDEP LUHPPL list. The LUHPPL has the potential to generate runoff with moderate to higher concentrations of oil and grease (e.g. all parking lots with >1000 vehicle trips per day) and the treatment train includes an oil grit separator, a filtering bioretention area, a sand filter or equivalent. Standard 6: Critical Areas The discharge is near or to a critical area and the treatment train includes only BMPs that MassDEP has approved for stormwater discharges to or near that particular class of critical area. Critical areas and BMPs are identified in the Stormwater Report. 180614 - MassDEP Stormwater Checklist.doc • 04/01/08 Stormwater Report Checklist • Page 7 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 7: Redevelopments and Other Projects Subject to the Standards only to the maximum extent practicable The project is subject to the Stormwater Management Standards only to the maximum Extent Practicable as a: Limited Project Small Residential Projects: 5-9 single family houses or 5-9 units in a multi-family development provided there is no discharge that may potentially affect a critical area. Small Residential Projects: 2-4 single family houses or 2-4 units in a multi-family development with a discharge to a critical area Marina and/or boatyard provided the hull painting, service and maintenance areas are protected from exposure to rain, snow, snow melt and runoff Bike Path and/or Foot Path Redevelopment Project Redevelopment portion of mix of new and redevelopment. Certain standards are not fully met (Standard No. 1, 8, 9, and 10 must always be fully met) and an explanation of why these standards are not met is contained in the Stormwater Report. The project involves redevelopment and a description of all measures that have been taken to improve existing conditions is provided in the Stormwater Report. The redevelopment checklist found in Volume 2 Chapter 3 of the Massachusetts Stormwater Handbook may be used to document that the proposed stormwater management system (a) complies with Standards 2, 3 and the pretreatment and structural BMP requirements of Standards 4-6 to the maximum extent practicable and (b) improves existing conditions. Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan must include the following information:  Narrative;  Construction Period Operation and Maintenance Plan;  Names of Persons or Entity Responsible for Plan Compliance;  Construction Period Pollution Prevention Measures;  Erosion and Sedimentation Control Plan Drawings;  Detail drawings and specifications for erosion control BMPs, including sizing calculations;  Vegetation Planning;  Site Development Plan;  Construction Sequencing Plan;  Sequencing of Erosion and Sedimentation Controls;  Operation and Maintenance of Erosion and Sedimentation Controls;  Inspection Schedule;  Maintenance Schedule;  Inspection and Maintenance Log Form. A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan containing the information set forth above has been included in the Stormwater Report. 180614 - MassDEP Stormwater Checklist.doc • 04/01/08 Stormwater Report Checklist • Page 8 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control (continued) The project is highly complex and information is included in the Stormwater Report that explains why it is not possible to submit the Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan with the application. A Construction Period Pollution Prevention and Erosion and Sedimentation Control has not been included in the Stormwater Report but will be submitted before land disturbance begins. The project is not covered by a NPDES Construction General Permit. The project is covered by a NPDES Construction General Permit and a copy of the SWPPP is in the Stormwater Report. The project is covered by a NPDES Construction General Permit but no SWPPP been submitted. The SWPPP will be submitted BEFORE land disturbance begins. Standard 9: Operation and Maintenance Plan The Post Construction Operation and Maintenance Plan is included in the Stormwater Report and includes the following information: Name of the stormwater management system owners; Party responsible for operation and maintenance; Schedule for implementation of routine and non-routine maintenance tasks; Plan showing the location of all stormwater BMPs maintenance access areas; Description and delineation of public safety features; Estimated operation and maintenance budget; and Operation and Maintenance Log Form. The responsible party is not the owner of the parcel where the BMP is located and the Stormwater Report includes the following submissions: A copy of the legal instrument (deed, homeowner’s association, utility trust or other legal entity) that establishes the terms of and legal responsibility for the operation and maintenance of the project site stormwater BMPs; A plan and easement deed that allows site access for the legal entity to operate and maintain BMP functions. Standard 10: Prohibition of Illicit Discharges The Long-Term Pollution Prevention Plan includes measures to prevent illicit discharges; An Illicit Discharge Compliance Statement is attached; NO Illicit Discharge Compliance Statement is attached but will be submitted prior to the discharge of any stormwater to post-construction BMPs. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Appendix B: Soils Information - NRCS Soils Report - Soil Evaluation Logs United States Department of Agriculture A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Hampshire County, Massachusetts, Central Part Easthampton Road Natural Resources Conservation Service August 14, 2018 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/ portal/nrcs/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/? cid=nrcs142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require 2 alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 3 Contents Preface....................................................................................................................2 How Soil Surveys Are Made..................................................................................5 Soil Map..................................................................................................................8 Soil Map................................................................................................................9 Legend................................................................................................................10 Map Unit Legend................................................................................................12 Map Unit Descriptions........................................................................................12 Hampshire County, Massachusetts, Central Part...........................................14 225B—Belgrade silt loam, 3 to 8 percent slopes........................................14 253B—Hinckley loamy sand, 3 to 8 percent slopes....................................15 References............................................................................................................17 4 How Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity. Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA. The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape. Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries. Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil 5 scientists classified and named the soils in the survey area, they compared the individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil-landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil-landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape. Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and Custom Soil Resource Report 6 identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately. Custom Soil Resource Report 7 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 8 9 Custom Soil Resource Report Soil Map 468475046847804684810468484046848704684900468493046849604684990468502046850504684780468481046848404684870468490046849304684960468499046850204685050692870 692900 692930 692960 692990 693020 693050 693080 692870 692900 692930 692960 692990 693020 693050 693080 42° 17' 38'' N 72° 39' 38'' W42° 17' 38'' N72° 39' 27'' W42° 17' 27'' N 72° 39' 38'' W42° 17' 27'' N 72° 39' 27'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 18N WGS84 0 50 100 200 300 Feet 0 20 40 80 120 Meters Map Scale: 1:1,530 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 Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features 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 1:15,800. 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: Hampshire County, Massachusetts, Central Part Survey Area Data: Version 12, Oct 6, 2017 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Sep 29, 2013—Oct 16, 2016 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background Custom Soil Resource Report 10 MAP LEGEND MAP INFORMATION imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report 11 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 225B Belgrade silt loam, 3 to 8 percent slopes 7.2 85.6% 253B Hinckley loamy sand, 3 to 8 percent slopes 1.2 14.4% Totals for Area of Interest 8.5 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, Custom Soil Resource Report 12 onsite investigation is needed to define and locate the soils and miscellaneous areas. An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Custom Soil Resource Report 13 Hampshire County, Massachusetts, Central Part 225B—Belgrade silt loam, 3 to 8 percent slopes Map Unit Setting National map unit symbol: 99z4 Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 140 to 240 days Farmland classification: All areas are prime farmland Map Unit Composition Belgrade and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Belgrade Setting Landform: Terraces Landform position (two-dimensional): Summit Landform position (three-dimensional): Tread Down-slope shape: Convex Across-slope shape: Convex Parent material: Coarse-silty glaciolacustrine deposits Typical profile H1 - 0 to 10 inches: silt loam H2 - 10 to 51 inches: very fine sandy loam H3 - 51 to 60 inches: loamy very fine sand Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Moderately well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat): Moderately low to high (0.06 to 2.00 in/hr) Depth to water table: About 18 to 42 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: High (about 10.7 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2w Hydrologic Soil Group: C Hydric soil rating: No Minor Components Raynham Percent of map unit: 15 percent Landform: Depressions Hydric soil rating: Yes Custom Soil Resource Report 14 253B—Hinckley loamy sand, 3 to 8 percent slopes Map Unit Setting National map unit symbol: 2svm8 Elevation: 0 to 1,430 feet Mean annual precipitation: 36 to 53 inches Mean annual air temperature: 39 to 55 degrees F Frost-free period: 140 to 250 days Farmland classification: Farmland of statewide importance Map Unit Composition Hinckley and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Hinckley Setting Landform: Eskers, moraines, outwash plains, kames, kame terraces, outwash terraces, outwash deltas Landform position (two-dimensional): Summit, shoulder, backslope, footslope Landform position (three-dimensional): Nose slope, side slope, base slope, crest, tread, riser Down-slope shape: Linear, convex, concave Across-slope shape: Convex, linear, concave Parent material: Sandy and gravelly glaciofluvial deposits derived from gneiss and/or granite and/or schist Typical profile Oe - 0 to 1 inches: moderately decomposed plant material A - 1 to 8 inches: loamy sand Bw1 - 8 to 11 inches: gravelly loamy sand Bw2 - 11 to 16 inches: gravelly loamy sand BC - 16 to 19 inches: very gravelly loamy sand C - 19 to 65 inches: very gravelly sand Properties and qualities Slope: 3 to 8 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Excessively drained Runoff class: Very low Capacity of the most limiting layer to transmit water (Ksat): Moderately high to very high (1.42 to 99.90 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Salinity, maximum in profile: Nonsaline (0.0 to 1.9 mmhos/cm) Available water storage in profile: Very low (about 3.0 inches) Custom Soil Resource Report 15 Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3s Hydrologic Soil Group: A Hydric soil rating: No Minor Components Windsor Percent of map unit: 8 percent Landform: Eskers, moraines, outwash plains, kames, kame terraces, outwash terraces, outwash deltas Landform position (two-dimensional): Summit, shoulder, backslope, footslope Landform position (three-dimensional): Nose slope, side slope, base slope, crest, tread, riser Down-slope shape: Linear, convex, concave Across-slope shape: Convex, linear, concave Hydric soil rating: No Sudbury Percent of map unit: 5 percent Landform: Moraines, outwash plains, kame terraces, outwash terraces, outwash deltas Landform position (two-dimensional): Backslope, footslope Landform position (three-dimensional): Side slope, base slope, head slope, tread Down-slope shape: Concave, linear Across-slope shape: Linear, concave Hydric soil rating: No Agawam Percent of map unit: 2 percent Landform: Eskers, moraines, outwash plains, kames, kame terraces, outwash terraces, outwash deltas Landform position (two-dimensional): Summit, shoulder, backslope, footslope Landform position (three-dimensional): Nose slope, side slope, base slope, crest, tread, riser Down-slope shape: Linear, convex, concave Across-slope shape: Convex, linear, concave Hydric soil rating: No Custom Soil Resource Report 16 References American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31. Federal Register. July 13, 1994. Changes in hydric soils of the United States. Federal Register. September 18, 2002. Hydric soils of the United States. Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/national/soils/?cid=nrcs142p2_054262 Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580 Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section. United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ home/?cid=nrcs142p2_053374 United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 17 United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/soils/scientists/?cid=nrcs142p2_054242 United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/? cid=nrcs142p2_053624 United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf Custom Soil Resource Report 18 Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Appendix C: Pre- and Post- Development Hydrologic Analysis (2, 10 & 100 Year Storm Events) ES-1 ES-2ES-3 DP-1 Ex. Drainage System DP-2 Offsite West Routing Diagram for 180614 - PRE Prepared by R Levesque Associates Inc., Printed 10/19/2018 HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Subcat Reach Pond Link Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - PRE Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 2HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 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=89,879 sf 0.00% Impervious Runoff Depth=0.54"Subcatchment ES-1: Flow Length=439' Tc=20.2 min CN=66 Runoff=0.68 cfs 4,081 cf Runoff Area=200,572 sf 0.00% Impervious Runoff Depth=0.40"Subcatchment ES-2: Flow Length=366' Tc=16.9 min CN=62 Runoff=0.96 cfs 6,657 cf Runoff Area=82,832 sf 0.00% Impervious Runoff Depth=0.71"Subcatchment ES-3: Flow Length=192' Tc=14.1 min CN=70 Runoff=1.06 cfs 4,930 cf Inflow=1.64 cfs 10,738 cfLink DP-1: Ex. Drainage System Primary=1.64 cfs 10,738 cf Inflow=1.06 cfs 4,930 cfLink DP-2: Offsite West Primary=1.06 cfs 4,930 cf Total Runoff Area = 373,282 sf Runoff Volume = 15,668 cf Average Runoff Depth = 0.50" 100.00% Pervious = 373,282 sf 0.00% Impervious = 0 sf Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - PRE Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 3HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment ES-1: Runoff =0.68 cfs @ 12.36 hrs, Volume=4,081 cf, Depth=0.54" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00" Area (sf)CN Description 9,099 30 Woods, Good, HSG A 80,780 70 Woods, Good, HSG C 89,879 66 Weighted Average 89,879 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 16.8 100 0.0400 0.10 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 3.4 339 0.1136 1.69 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 20.2 439 Total Subcatchment ES-1: Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (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 2-Year Rainfall=3.00" Runoff Area=89,879 sf Runoff Volume=4,081 cf Runoff Depth=0.54" Flow Length=439' Tc=20.2 min CN=66 0.68 cfs Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - PRE Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 4HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment ES-2: Runoff =0.96 cfs @ 12.36 hrs, Volume=6,657 cf, Depth=0.40" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00" Area (sf)CN Description 40,123 30 Woods, Good, HSG A 160,448 70 Woods, Good, HSG C 200,572 62 Weighted Average 200,572 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 14.3 100 0.0600 0.12 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 2.6 266 0.1165 1.71 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 16.9 366 Total Subcatchment ES-2: Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)1 0 Type III 24-hr 2-Year Rainfall=3.00" Runoff Area=200,572 sf Runoff Volume=6,657 cf Runoff Depth=0.40" Flow Length=366' Tc=16.9 min CN=62 0.96 cfs Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - PRE Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 5HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment ES-3: Runoff =1.06 cfs @ 12.22 hrs, Volume=4,930 cf, Depth=0.71" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00" Area (sf)CN Description 82,832 70 Woods, Good, HSG C 82,832 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 12.4 49 0.0204 0.07 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 0.3 39 0.1795 2.12 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 1.4 104 0.0625 1.25 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 14.1 192 Total Subcatchment ES-3: Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)1 0 Type III 24-hr 2-Year Rainfall=3.00" Runoff Area=82,832 sf Runoff Volume=4,930 cf Runoff Depth=0.71" Flow Length=192' Tc=14.1 min CN=70 1.06 cfs Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - PRE Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 6HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Link DP-1: Ex. Drainage System Inflow Area =290,451 sf,0.00% Impervious, Inflow Depth = 0.44" for 2-Year event Inflow =1.64 cfs @ 12.36 hrs, Volume=10,738 cf Primary =1.64 cfs @ 12.36 hrs, Volume=10,738 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Link DP-1: Ex. Drainage System Inflow Primary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)1 0 Inflow Area=290,451 sf 1.64 cfs 1.64 cfs Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - PRE Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 7HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Link DP-2: Offsite West Inflow Area =82,832 sf,0.00% Impervious, Inflow Depth = 0.71" for 2-Year event Inflow =1.06 cfs @ 12.22 hrs, Volume=4,930 cf Primary =1.06 cfs @ 12.22 hrs, Volume=4,930 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Link DP-2: Offsite West Inflow Primary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)1 0 Inflow Area=82,832 sf 1.06 cfs 1.06 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - PRE Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 8HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 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=89,879 sf 0.00% Impervious Runoff Depth=1.40"Subcatchment ES-1: Flow Length=439' Tc=20.2 min CN=66 Runoff=2.11 cfs 10,459 cf Runoff Area=200,572 sf 0.00% Impervious Runoff Depth=1.14"Subcatchment ES-2: Flow Length=366' Tc=16.9 min CN=62 Runoff=3.90 cfs 19,055 cf Runoff Area=82,832 sf 0.00% Impervious Runoff Depth=1.67"Subcatchment ES-3: Flow Length=192' Tc=14.1 min CN=70 Runoff=2.78 cfs 11,553 cf Inflow=5.95 cfs 29,515 cfLink DP-1: Ex. Drainage System Primary=5.95 cfs 29,515 cf Inflow=2.78 cfs 11,553 cfLink DP-2: Offsite West Primary=2.78 cfs 11,553 cf Total Runoff Area = 373,282 sf Runoff Volume = 41,068 cf Average Runoff Depth = 1.32" 100.00% Pervious = 373,282 sf 0.00% Impervious = 0 sf Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - PRE Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 9HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment ES-1: Runoff =2.11 cfs @ 12.31 hrs, Volume=10,459 cf, Depth=1.40" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50" Area (sf)CN Description 9,099 30 Woods, Good, HSG A 80,780 70 Woods, Good, HSG C 89,879 66 Weighted Average 89,879 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 16.8 100 0.0400 0.10 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 3.4 339 0.1136 1.69 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 20.2 439 Total Subcatchment ES-1: Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)2 1 0 Type III 24-hr 10-Year Rainfall=4.50" Runoff Area=89,879 sf Runoff Volume=10,459 cf Runoff Depth=1.40" Flow Length=439' Tc=20.2 min CN=66 2.11 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - PRE Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 10HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment ES-2: Runoff =3.90 cfs @ 12.27 hrs, Volume=19,055 cf, Depth=1.14" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50" Area (sf)CN Description 40,123 30 Woods, Good, HSG A 160,448 70 Woods, Good, HSG C 200,572 62 Weighted Average 200,572 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 14.3 100 0.0600 0.12 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 2.6 266 0.1165 1.71 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 16.9 366 Total Subcatchment ES-2: Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)4 3 2 1 0 Type III 24-hr 10-Year Rainfall=4.50" Runoff Area=200,572 sf Runoff Volume=19,055 cf Runoff Depth=1.14" Flow Length=366' Tc=16.9 min CN=62 3.90 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - PRE Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 11HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment ES-3: Runoff =2.78 cfs @ 12.21 hrs, Volume=11,553 cf, Depth=1.67" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50" Area (sf)CN Description 82,832 70 Woods, Good, HSG C 82,832 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 12.4 49 0.0204 0.07 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 0.3 39 0.1795 2.12 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 1.4 104 0.0625 1.25 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 14.1 192 Total Subcatchment ES-3: Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)3 2 1 0 Type III 24-hr 10-Year Rainfall=4.50" Runoff Area=82,832 sf Runoff Volume=11,553 cf Runoff Depth=1.67" Flow Length=192' Tc=14.1 min CN=70 2.78 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - PRE Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 12HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Link DP-1: Ex. Drainage System Inflow Area =290,451 sf,0.00% Impervious, Inflow Depth = 1.22" for 10-Year event Inflow =5.95 cfs @ 12.28 hrs, Volume=29,515 cf Primary =5.95 cfs @ 12.28 hrs, Volume=29,515 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Link DP-1: Ex. Drainage System Inflow Primary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)6 5 4 3 2 1 0 Inflow Area=290,451 sf 5.95 cfs 5.95 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - PRE Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 13HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Link DP-2: Offsite West Inflow Area =82,832 sf,0.00% Impervious, Inflow Depth = 1.67" for 10-Year event Inflow =2.78 cfs @ 12.21 hrs, Volume=11,553 cf Primary =2.78 cfs @ 12.21 hrs, Volume=11,553 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Link DP-2: Offsite West Inflow Primary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)3 2 1 0 Inflow Area=82,832 sf 2.78 cfs 2.78 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - PRE Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 14HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 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=89,879 sf 0.00% Impervious Runoff Depth=2.74"Subcatchment ES-1: Flow Length=439' Tc=20.2 min CN=66 Runoff=4.36 cfs 20,526 cf Runoff Area=200,572 sf 0.00% Impervious Runoff Depth=2.37"Subcatchment ES-2: Flow Length=366' Tc=16.9 min CN=62 Runoff=8.86 cfs 39,589 cf Runoff Area=82,832 sf 0.00% Impervious Runoff Depth=3.13"Subcatchment ES-3: Flow Length=192' Tc=14.1 min CN=70 Runoff=5.34 cfs 21,577 cf Inflow=13.16 cfs 60,115 cfLink DP-1: Ex. Drainage System Primary=13.16 cfs 60,115 cf Inflow=5.34 cfs 21,577 cfLink DP-2: Offsite West Primary=5.34 cfs 21,577 cf Total Runoff Area = 373,282 sf Runoff Volume = 81,692 cf Average Runoff Depth = 2.63" 100.00% Pervious = 373,282 sf 0.00% Impervious = 0 sf Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - PRE Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 15HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment ES-1: Runoff =4.36 cfs @ 12.29 hrs, Volume=20,526 cf, Depth=2.74" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Area (sf)CN Description 9,099 30 Woods, Good, HSG A 80,780 70 Woods, Good, HSG C 89,879 66 Weighted Average 89,879 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 16.8 100 0.0400 0.10 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 3.4 339 0.1136 1.69 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 20.2 439 Total Subcatchment ES-1: Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)4 3 2 1 0 Type III 24-hr 100-Year Rainfall=6.40" Runoff Area=89,879 sf Runoff Volume=20,526 cf Runoff Depth=2.74" Flow Length=439' Tc=20.2 min CN=66 4.36 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - PRE Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 16HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment ES-2: Runoff =8.86 cfs @ 12.25 hrs, Volume=39,589 cf, Depth=2.37" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Area (sf)CN Description 40,123 30 Woods, Good, HSG A 160,448 70 Woods, Good, HSG C 200,572 62 Weighted Average 200,572 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 14.3 100 0.0600 0.12 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 2.6 266 0.1165 1.71 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 16.9 366 Total Subcatchment ES-2: Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)9 8 7 6 5 4 3 2 1 0 Type III 24-hr 100-Year Rainfall=6.40" Runoff Area=200,572 sf Runoff Volume=39,589 cf Runoff Depth=2.37" Flow Length=366' Tc=16.9 min CN=62 8.86 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - PRE Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 17HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment ES-3: Runoff =5.34 cfs @ 12.20 hrs, Volume=21,577 cf, Depth=3.13" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Area (sf)CN Description 82,832 70 Woods, Good, HSG C 82,832 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 12.4 49 0.0204 0.07 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 0.3 39 0.1795 2.12 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 1.4 104 0.0625 1.25 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 14.1 192 Total Subcatchment ES-3: Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)5 4 3 2 1 0 Type III 24-hr 100-Year Rainfall=6.40" Runoff Area=82,832 sf Runoff Volume=21,577 cf Runoff Depth=3.13" Flow Length=192' Tc=14.1 min CN=70 5.34 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - PRE Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 18HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Link DP-1: Ex. Drainage System Inflow Area =290,451 sf,0.00% Impervious, Inflow Depth = 2.48" for 100-Year event Inflow =13.16 cfs @ 12.26 hrs, Volume=60,115 cf Primary =13.16 cfs @ 12.26 hrs, Volume=60,115 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Link DP-1: Ex. Drainage System Inflow Primary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=290,451 sf 13.16 cfs 13.16 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - PRE Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 19HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Link DP-2: Offsite West Inflow Area =82,832 sf,0.00% Impervious, Inflow Depth = 3.13" for 100-Year event Inflow =5.34 cfs @ 12.20 hrs, Volume=21,577 cf Primary =5.34 cfs @ 12.20 hrs, Volume=21,577 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Link DP-2: Offsite West Inflow Primary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)5 4 3 2 1 0 Inflow Area=82,832 sf 5.34 cfs 5.34 cfs PS-1 Subcat PS-1 PS-2A Subcat PS-2A PS-2B Subcat PS-2BPS-2C Subcat PS-2C PS-2D Subcat PS-2D PS-2E Subcat PS-2E PS-3A Subcat PS-3A PS-3B Subcat PS-3B 1P Bio Basin #1 2P Det. Basin #2 3P Bio Basin #3 4P Det. Basin #4 DP-1 Ex. Drainage System DP-2 Offsite West Routing Diagram for 180614 - POST Prepared by R Levesque Associates Inc., Printed 10/19/2018 HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Subcat Reach Pond Link Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 2HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 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=35,840 sf 8.07% Impervious Runoff Depth=0.91"Subcatchment PS-1: Subcat PS-1 Flow Length=438' Tc=27.4 min CN=74 Runoff=0.48 cfs 2,713 cf Runoff Area=60,933 sf 29.52% Impervious Runoff Depth=1.07"Subcatchment PS-2A: Subcat PS-2A Flow Length=717' Tc=6.0 min CN=77 Runoff=1.67 cfs 5,438 cf Runoff Area=57,807 sf 0.00% Impervious Runoff Depth=0.76"Subcatchment PS-2B: Subcat PS-2B Flow Length=305' Tc=15.2 min CN=71 Runoff=0.78 cfs 3,663 cf Runoff Area=55,388 sf 62.84% Impervious Runoff Depth=1.90"Subcatchment PS-2C: Subcat PS-2C Flow Length=293' Tc=11.5 min CN=89 Runoff=2.34 cfs 8,769 cf Runoff Area=44,692 sf 98.11% Impervious Runoff Depth=2.77"Subcatchment PS-2D: Subcat PS-2D Tc=6.0 min CN=98 Runoff=2.91 cfs 10,310 cf Runoff Area=24,007 sf 32.03% Impervious Runoff Depth=1.38"Subcatchment PS-2E: Subcat PS-2E Tc=6.0 min CN=82 Runoff=0.87 cfs 2,759 cf Runoff Area=65,744 sf 77.31% Impervious Runoff Depth=2.16"Subcatchment PS-3A: Subcat PS-3A Tc=6.0 min CN=92 Runoff=3.67 cfs 11,840 cf Runoff Area=28,871 sf 0.00% Impervious Runoff Depth=0.76"Subcatchment PS-3B: Subcat PS-3B Flow Length=235' Tc=18.6 min CN=71 Runoff=0.36 cfs 1,829 cf Peak Elev=143.25' Storage=6,252 cf Inflow=3.67 cfs 11,840 cfPond 1P: Bio Basin #1 Discarded=0.07 cfs 8,348 cf Primary=0.30 cfs 3,488 cf Secondary=0.00 cfs 0 cf Outflow=0.38 cfs 11,836 cf Peak Elev=141.27' Storage=6,164 cf Inflow=3.78 cfs 13,069 cfPond 2P: Det. Basin #2 Discarded=0.07 cfs 4,328 cf Primary=0.25 cfs 8,741 cf Secondary=0.00 cfs 0 cf Outflow=0.33 cfs 13,069 cf Peak Elev=134.82' Storage=4,608 cf Inflow=2.34 cfs 8,769 cfPond 3P: Bio Basin #3 Discarded=0.08 cfs 6,518 cf Primary=0.11 cfs 2,251 cf Secondary=0.00 cfs 0 cf Outflow=0.19 cfs 8,769 cf Peak Elev=110.40' Storage=1,986 cf Inflow=1.67 cfs 7,690 cfPond 4P: Det. Basin #4 Discarded=0.03 cfs 830 cf Primary=0.27 cfs 6,859 cf Secondary=0.00 cfs 0 cf Outflow=0.29 cfs 7,690 cf Inflow=1.63 cfs 21,976 cfLink DP-1: Ex. Drainage System Primary=1.63 cfs 21,976 cf Inflow=0.52 cfs 5,317 cfLink DP-2: Offsite West Primary=0.52 cfs 5,317 cf Total Runoff Area = 373,282 sf Runoff Volume = 47,321 cf Average Runoff Depth = 1.52" 57.66% Pervious = 215,231 sf 42.34% Impervious = 158,052 sf Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 3HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-1: Subcat PS-1 Runoff =0.48 cfs @ 12.42 hrs, Volume=2,713 cf, Depth=0.91" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00" Area (sf)CN Description 11,832 74 >75% Grass cover, Good, HSG C 2,893 98 Paved parking, HSG C 21,114 70 Woods, Good, HSG C 35,840 74 Weighted Average 32,947 71 91.93% Pervious Area 2,893 98 8.07% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 21.4 168 0.0618 0.13 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 6.0 270 0.0889 0.75 Shallow Concentrated Flow, Forest w/Heavy Litter Kv= 2.5 fps 27.4 438 Total Subcatchment PS-1: Subcat PS-1 Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)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 2-Year Rainfall=3.00" Runoff Area=35,840 sf Runoff Volume=2,713 cf Runoff Depth=0.91" Flow Length=438' Tc=27.4 min CN=74 0.48 cfs Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 4HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-2A: Subcat PS-2A Runoff =1.67 cfs @ 12.10 hrs, Volume=5,438 cf, Depth=1.07" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00" Area (sf)CN Description 6,726 39 >75% Grass cover, Good, HSG A 36,217 74 >75% Grass cover, Good, HSG C 138 98 Paved parking, HSG A 17,137 98 Paved parking, HSG C 712 98 Water Surface, HSG A 2 70 Woods, Good, HSG C 60,933 77 Weighted Average 42,945 69 70.48% Pervious Area 17,987 98 29.52% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 1.1 13 0.2000 0.19 Sheet Flow, Grass: Dense n= 0.240 P2= 3.00" 3.5 704 0.0363 3.34 3.34 Trap/Vee/Rect Channel Flow, Bot.W=0.00' D=0.50' Z= 4.0 '/' Top.W=4.00' n= 0.033 4.6 717 Total, Increased to minimum Tc = 6.0 min Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 5HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Subcatchment PS-2A: Subcat PS-2A Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)1 0 Type III 24-hr 2-Year Rainfall=3.00" Runoff Area=60,933 sf Runoff Volume=5,438 cf Runoff Depth=1.07" Flow Length=717' Tc=6.0 min CN=77 1.67 cfs Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 6HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-2B: Subcat PS-2B Runoff =0.78 cfs @ 12.24 hrs, Volume=3,663 cf, Depth=0.76" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00" Area (sf)CN Description 14,852 74 >75% Grass cover, Good, HSG C 42,955 70 Woods, Good, HSG C 57,807 71 Weighted Average 57,807 71 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 13.4 100 0.0700 0.12 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 1.8 205 0.1415 1.88 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 15.2 305 Total Subcatchment PS-2B: Subcat PS-2B Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type III 24-hr 2-Year Rainfall=3.00" Runoff Area=57,807 sf Runoff Volume=3,663 cf Runoff Depth=0.76" Flow Length=305' Tc=15.2 min CN=71 0.78 cfs Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 7HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-2C: Subcat PS-2C Runoff =2.34 cfs @ 12.16 hrs, Volume=8,769 cf, Depth=1.90" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00" Area (sf)CN Description 18,064 74 >75% Grass cover, Good, HSG C 31,241 98 Paved parking, HSG C 1,600 98 Unconnected roofs, HSG C 1,968 98 Water Surface, HSG C 2,516 70 Woods, Good, HSG C 55,388 89 Weighted Average 20,580 74 37.16% Pervious Area 34,808 98 62.84% Impervious Area 1,600 4.60% Unconnected Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 9.5 39 0.0256 0.07 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 1.1 15 0.2670 0.22 Sheet Flow, Grass: Dense n= 0.240 P2= 3.00" 0.5 138 0.0580 4.22 4.22 Trap/Vee/Rect Channel Flow, Bot.W=0.00' D=0.50' Z= 4.0 '/' Top.W=4.00' n= 0.033 Stream, clean & straight 0.4 101 0.0100 4.54 3.56 Pipe Channel, 12.0" Round Area= 0.8 sf Perim= 3.1' r= 0.25' n= 0.013 Corrugated PE, smooth interior 11.5 293 Total Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 8HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Subcatchment PS-2C: Subcat PS-2C Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)2 1 0 Type III 24-hr 2-Year Rainfall=3.00" Runoff Area=55,388 sf Runoff Volume=8,769 cf Runoff Depth=1.90" Flow Length=293' Tc=11.5 min CN=89 2.34 cfs Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 9HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-2D: Subcat PS-2D Runoff =2.91 cfs @ 12.09 hrs, Volume=10,310 cf, Depth=2.77" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00" Area (sf)CN Description 727 74 >75% Grass cover, Good, HSG C 14,248 98 Paved parking, HSG C 29,600 98 Unconnected roofs, HSG C 117 70 Woods, Good, HSG C 44,692 98 Weighted Average 844 73 1.89% Pervious Area 43,848 98 98.11% Impervious Area 29,600 67.51% Unconnected Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment PS-2D: Subcat PS-2D Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)3 2 1 0 Type III 24-hr 2-Year Rainfall=3.00" Runoff Area=44,692 sf Runoff Volume=10,310 cf Runoff Depth=2.77" Tc=6.0 min CN=98 2.91 cfs Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 10HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-2E: Subcat PS-2E Runoff =0.87 cfs @ 12.10 hrs, Volume=2,759 cf, Depth=1.38" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00" Area (sf)CN Description 15,303 74 >75% Grass cover, Good, HSG C 3,991 98 Paved parking, HSG C 3,699 98 Water Surface, HSG C 1,015 70 Woods, Good, HSG C 24,007 82 Weighted Average 16,318 74 67.97% Pervious Area 7,689 98 32.03% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment PS-2E: Subcat PS-2E Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)0.95 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 2-Year Rainfall=3.00" Runoff Area=24,007 sf Runoff Volume=2,759 cf Runoff Depth=1.38" Tc=6.0 min CN=82 0.87 cfs Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 11HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-3A: Subcat PS-3A Runoff =3.67 cfs @ 12.09 hrs, Volume=11,840 cf, Depth=2.16" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00" Area (sf)CN Description 12,624 74 >75% Grass cover, Good, HSG C 13,307 98 Paved parking, HSG C 33,600 98 Unconnected roofs, HSG C 3,918 98 Water Surface, HSG C 2,295 70 Woods, Good, HSG C 65,744 92 Weighted Average 14,919 73 22.69% Pervious Area 50,826 98 77.31% Impervious Area 33,600 66.11% Unconnected Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment PS-3A: Subcat PS-3A Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)4 3 2 1 0 Type III 24-hr 2-Year Rainfall=3.00" Runoff Area=65,744 sf Runoff Volume=11,840 cf Runoff Depth=2.16" Tc=6.0 min CN=92 3.67 cfs Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 12HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-3B: Subcat PS-3B Runoff =0.36 cfs @ 12.30 hrs, Volume=1,829 cf, Depth=0.76" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.00" Area (sf)CN Description 9,650 74 >75% Grass cover, Good, HSG C 19,221 70 Woods, Good, HSG C 28,871 71 Weighted Average 28,871 71 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 16.8 100 0.0400 0.10 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 1.8 135 0.0630 1.25 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 18.6 235 Total Subcatchment PS-3B: Subcat PS-3B Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)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 2-Year Rainfall=3.00" Runoff Area=28,871 sf Runoff Volume=1,829 cf Runoff Depth=0.76" Flow Length=235' Tc=18.6 min CN=71 0.36 cfs Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 13HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Pond 1P: Bio Basin #1 Inflow Area =65,744 sf,77.31% Impervious, Inflow Depth = 2.16" for 2-Year event Inflow =3.67 cfs @ 12.09 hrs, Volume=11,840 cf Outflow =0.38 cfs @ 12.90 hrs, Volume=11,836 cf, Atten= 90%, Lag= 48.5 min Discarded =0.07 cfs @ 12.90 hrs, Volume=8,348 cf Primary =0.30 cfs @ 12.90 hrs, Volume=3,488 cf Secondary =0.00 cfs @ 0.00 hrs, Volume=0 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 143.25' @ 12.90 hrs Surf.Area= 6,109 sf Storage= 6,252 cf Plug-Flow detention time= 571.5 min calculated for 11,824 cf (100% of inflow) Center-of-Mass det. time= 572.2 min ( 1,372.3 - 800.1 ) Volume Invert Avail.Storage Storage Description #1 142.00'19,750 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim.Inc.Store Cum.Store Wet.Area (feet)(sq-ft)(feet)(cubic-feet)(cubic-feet)(sq-ft) 142.00 3,918 512.0 0 0 3,918 143.00 5,674 597.0 4,769 4,769 11,440 144.00 7,496 617.0 6,564 11,333 13,465 145.00 9,374 636.0 8,418 19,750 15,460 Device Routing Invert Outlet Devices #1 Primary 140.00'12.0" Round Culvert L= 36.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 140.00' / 139.00' S= 0.0278 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf #2 Device 1 143.00'9.0" W x 18.0" H Vert. Orifice/Grate C= 0.600 #3 Device 1 144.50'48.0" x 48.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Secondary 145.00'10.0' long x 20.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 #5 Discarded 142.00'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.07 cfs @ 12.90 hrs HW=143.25' (Free Discharge) 5=Exfiltration (Exfiltration Controls 0.07 cfs) Primary OutFlow Max=0.30 cfs @ 12.90 hrs HW=143.25' (Free Discharge) 1=Culvert (Passes 0.30 cfs of 7.45 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.30 cfs @ 1.61 fps) 3=Orifice/Grate ( Controls 0.00 cfs) Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=142.00' (Free Discharge) 4=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 14HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Pond 1P: Bio Basin #1 Inflow Outflow Discarded Primary Secondary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)4 3 2 1 0 Inflow Area=65,744 sf Peak Elev=143.25' Storage=6,252 cf 3.67 cfs 0.38 cfs 0.07 cfs0.30 cfs 0.00 cfs Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 15HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Pond 2P: Det. Basin #2 Inflow Area =68,699 sf,75.02% Impervious, Inflow Depth = 2.28" for 2-Year event Inflow =3.78 cfs @ 12.09 hrs, Volume=13,069 cf Outflow =0.33 cfs @ 13.06 hrs, Volume=13,069 cf, Atten= 91%, Lag= 58.2 min Discarded =0.07 cfs @ 13.06 hrs, Volume=4,328 cf Primary =0.25 cfs @ 13.06 hrs, Volume=8,741 cf Secondary =0.00 cfs @ 0.00 hrs, Volume=0 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 141.27' @ 13.06 hrs Surf.Area= 6,070 sf Storage= 6,164 cf Plug-Flow detention time= 214.6 min calculated for 13,069 cf (100% of inflow) Center-of-Mass det. time= 214.0 min ( 989.1 - 775.0 ) Volume Invert Avail.Storage Storage Description #1 140.00'30,471 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim.Inc.Store Cum.Store Wet.Area (feet)(sq-ft)(feet)(cubic-feet)(cubic-feet)(sq-ft) 140.00 3,699 251.0 0 0 3,699 141.00 5,557 293.0 4,597 4,597 5,537 142.00 7,574 328.0 6,540 11,136 7,295 143.00 9,667 361.0 8,599 19,735 9,137 144.00 11,841 396.0 10,736 30,471 11,279 Device Routing Invert Outlet Devices #1 Primary 139.00'12.0" Round Culvert L= 55.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 139.00' / 135.00' S= 0.0727 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf #2 Device 1 140.00'3.0" Vert. Orifice/Grate C= 0.600 #3 Secondary 144.00'10.0' long x 20.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 #4 Discarded 140.00'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.07 cfs @ 13.06 hrs HW=141.27' (Free Discharge) 4=Exfiltration (Exfiltration Controls 0.07 cfs) Primary OutFlow Max=0.25 cfs @ 13.06 hrs HW=141.27' (Free Discharge) 1=Culvert (Passes 0.25 cfs of 6.29 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.25 cfs @ 5.15 fps) Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=140.00' (Free Discharge) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 16HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Pond 2P: Det. Basin #2 Inflow Outflow Discarded Primary Secondary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)4 3 2 1 0 Inflow Area=68,699 sf Peak Elev=141.27' Storage=6,164 cf 3.78 cfs 0.33 cfs 0.07 cfs0.25 cfs 0.00 cfs Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 17HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Pond 3P: Bio Basin #3 Inflow Area =55,388 sf,62.84% Impervious, Inflow Depth = 1.90" for 2-Year event Inflow =2.34 cfs @ 12.16 hrs, Volume=8,769 cf Outflow =0.19 cfs @ 13.88 hrs, Volume=8,769 cf, Atten= 92%, Lag= 102.9 min Discarded =0.08 cfs @ 13.88 hrs, Volume=6,518 cf Primary =0.11 cfs @ 13.88 hrs, Volume=2,251 cf Secondary =0.00 cfs @ 0.00 hrs, Volume=0 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 134.82' @ 13.88 hrs Surf.Area= 6,818 sf Storage= 4,608 cf Plug-Flow detention time= 404.1 min calculated for 8,760 cf (100% of inflow) Center-of-Mass det. time= 404.5 min ( 1,223.2 - 818.8 ) Volume Invert Avail.Storage Storage Description #1 134.00'14,787 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim.Inc.Store Cum.Store Wet.Area (feet)(sq-ft)(feet)(cubic-feet)(cubic-feet)(sq-ft) 134.00 4,457 658.0 0 0 4,457 135.00 7,389 739.0 5,862 5,862 13,489 136.00 10,555 783.0 8,925 14,787 18,872 Device Routing Invert Outlet Devices #1 Primary 132.00'12.0" Round Culvert L= 33.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 132.00' / 129.00' S= 0.0909 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf #2 Device 1 134.50'3.0" Vert. Orifice/Grate C= 0.600 #3 Secondary 135.00'10.0' long x 20.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 #4 Discarded 134.00'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.08 cfs @ 13.88 hrs HW=134.82' (Free Discharge) 4=Exfiltration (Exfiltration Controls 0.08 cfs) Primary OutFlow Max=0.11 cfs @ 13.88 hrs HW=134.82' (Free Discharge) 1=Culvert (Passes 0.11 cfs of 7.21 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.11 cfs @ 2.14 fps) Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=134.00' (Free Discharge) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 18HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Pond 3P: Bio Basin #3 Inflow Outflow Discarded Primary Secondary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)2 1 0 Inflow Area=55,388 sf Peak Elev=134.82' Storage=4,608 cf 2.34 cfs 0.19 cfs 0.08 cfs 0.11 cfs 0.00 cfs Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 19HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Pond 4P: Det. Basin #4 Inflow Area =116,321 sf,45.39% Impervious, Inflow Depth = 0.79" for 2-Year event Inflow =1.67 cfs @ 12.10 hrs, Volume=7,690 cf Outflow =0.29 cfs @ 13.05 hrs, Volume=7,690 cf, Atten= 82%, Lag= 57.0 min Discarded =0.03 cfs @ 13.05 hrs, Volume=830 cf Primary =0.27 cfs @ 13.05 hrs, Volume=6,859 cf Secondary =0.00 cfs @ 0.00 hrs, Volume=0 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 110.40' @ 13.05 hrs Surf.Area= 2,125 sf Storage= 1,986 cf Plug-Flow detention time= 82.3 min calculated for 7,682 cf (100% of inflow) Center-of-Mass det. time= 82.3 min ( 965.8 - 883.5 ) Volume Invert Avail.Storage Storage Description #1 109.00'6,600 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim.Inc.Store Cum.Store Wet.Area (feet)(sq-ft)(feet)(cubic-feet)(cubic-feet)(sq-ft) 109.00 712 251.0 0 0 712 110.00 1,789 287.0 1,210 1,210 2,277 111.00 2,689 313.0 2,224 3,434 3,554 112.00 3,668 340.0 3,166 6,600 4,994 Device Routing Invert Outlet Devices #1 Primary 108.20'12.0" Round Culvert L= 46.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 108.20' / 108.00' S= 0.0043 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf #2 Device 1 109.00'3.0" Vert. Orifice/Grate C= 0.600 #3 Secondary 110.50'10.0' long x 20.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 #4 Discarded 109.00'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.03 cfs @ 13.05 hrs HW=110.40' (Free Discharge) 4=Exfiltration (Exfiltration Controls 0.03 cfs) Primary OutFlow Max=0.27 cfs @ 13.05 hrs HW=110.40' (Free Discharge) 1=Culvert (Passes 0.27 cfs of 4.58 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.27 cfs @ 5.43 fps) Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=109.00' (Free Discharge) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 20HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Pond 4P: Det. Basin #4 Inflow Outflow Discarded Primary Secondary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)1 0 Inflow Area=116,321 sf Peak Elev=110.40' Storage=1,986 cf 1.67 cfs 0.29 cfs 0.03 cfs 0.27 cfs 0.00 cfs Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 21HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Link DP-1: Ex. Drainage System Inflow Area =278,667 sf,38.48% Impervious, Inflow Depth = 0.95" for 2-Year event Inflow =1.63 cfs @ 12.31 hrs, Volume=21,976 cf Primary =1.63 cfs @ 12.31 hrs, Volume=21,976 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Link DP-1: Ex. Drainage System Inflow Primary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)1 0 Inflow Area=278,667 sf 1.63 cfs 1.63 cfs Easthampton Road Type III 24-hr 2-Year Rainfall=3.00"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 22HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Link DP-2: Offsite West Inflow Area =94,616 sf,53.72% Impervious, Inflow Depth = 0.67" for 2-Year event Inflow =0.52 cfs @ 12.50 hrs, Volume=5,317 cf Primary =0.52 cfs @ 12.50 hrs, Volume=5,317 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Link DP-2: Offsite West Inflow Primary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)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=94,616 sf 0.52 cfs 0.52 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 23HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 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=35,840 sf 8.07% Impervious Runoff Depth=1.97"Subcatchment PS-1: Subcat PS-1 Flow Length=438' Tc=27.4 min CN=74 Runoff=1.10 cfs 5,891 cf Runoff Area=60,933 sf 29.52% Impervious Runoff Depth=2.21"Subcatchment PS-2A: Subcat PS-2A Flow Length=717' Tc=6.0 min CN=77 Runoff=3.55 cfs 11,225 cf Runoff Area=57,807 sf 0.00% Impervious Runoff Depth=1.75"Subcatchment PS-2B: Subcat PS-2B Flow Length=305' Tc=15.2 min CN=71 Runoff=1.98 cfs 8,413 cf Runoff Area=55,388 sf 62.84% Impervious Runoff Depth=3.30"Subcatchment PS-2C: Subcat PS-2C Flow Length=293' Tc=11.5 min CN=89 Runoff=3.99 cfs 15,209 cf Runoff Area=44,692 sf 98.11% Impervious Runoff Depth=4.26"Subcatchment PS-2D: Subcat PS-2D Tc=6.0 min CN=98 Runoff=4.40 cfs 15,881 cf Runoff Area=24,007 sf 32.03% Impervious Runoff Depth=2.64"Subcatchment PS-2E: Subcat PS-2E Tc=6.0 min CN=82 Runoff=1.67 cfs 5,274 cf Runoff Area=65,744 sf 77.31% Impervious Runoff Depth=3.60"Subcatchment PS-3A: Subcat PS-3A Tc=6.0 min CN=92 Runoff=5.95 cfs 19,735 cf Runoff Area=28,871 sf 0.00% Impervious Runoff Depth=1.75"Subcatchment PS-3B: Subcat PS-3B Flow Length=235' Tc=18.6 min CN=71 Runoff=0.91 cfs 4,202 cf Peak Elev=143.71' Storage=9,235 cf Inflow=5.95 cfs 19,735 cfPond 1P: Bio Basin #1 Discarded=0.08 cfs 9,069 cf Primary=1.44 cfs 10,643 cf Secondary=0.00 cfs 0 cf Outflow=1.52 cfs 19,712 cf Peak Elev=141.96' Storage=10,808 cf Inflow=6.07 cfs 21,154 cfPond 2P: Det. Basin #2 Discarded=0.09 cfs 6,105 cf Primary=0.32 cfs 15,049 cf Secondary=0.00 cfs 0 cf Outflow=0.41 cfs 21,154 cf Peak Elev=135.12' Storage=6,796 cf Inflow=3.99 cfs 15,209 cfPond 3P: Bio Basin #3 Discarded=0.09 cfs 7,707 cf Primary=0.17 cfs 4,635 cf Secondary=1.17 cfs 2,869 cf Outflow=1.43 cfs 15,211 cf Peak Elev=110.69' Storage=2,649 cf Inflow=3.61 cfs 18,728 cfPond 4P: Det. Basin #4 Discarded=0.03 cfs 1,170 cf Primary=0.30 cfs 10,815 cf Secondary=2.24 cfs 6,730 cf Outflow=2.57 cfs 18,715 cf Inflow=5.55 cfs 46,897 cfLink DP-1: Ex. Drainage System Primary=5.55 cfs 46,897 cf Inflow=2.22 cfs 14,845 cfLink DP-2: Offsite West Primary=2.22 cfs 14,845 cf Total Runoff Area = 373,282 sf Runoff Volume = 85,828 cf Average Runoff Depth = 2.76" 57.66% Pervious = 215,231 sf 42.34% Impervious = 158,052 sf Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 24HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-1: Subcat PS-1 Runoff =1.10 cfs @ 12.40 hrs, Volume=5,891 cf, Depth=1.97" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50" Area (sf)CN Description 11,832 74 >75% Grass cover, Good, HSG C 2,893 98 Paved parking, HSG C 21,114 70 Woods, Good, HSG C 35,840 74 Weighted Average 32,947 71 91.93% Pervious Area 2,893 98 8.07% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 21.4 168 0.0618 0.13 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 6.0 270 0.0889 0.75 Shallow Concentrated Flow, Forest w/Heavy Litter Kv= 2.5 fps 27.4 438 Total Subcatchment PS-1: Subcat PS-1 Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)1 0 Type III 24-hr 10-Year Rainfall=4.50" Runoff Area=35,840 sf Runoff Volume=5,891 cf Runoff Depth=1.97" Flow Length=438' Tc=27.4 min CN=74 1.10 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 25HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-2A: Subcat PS-2A Runoff =3.55 cfs @ 12.09 hrs, Volume=11,225 cf, Depth=2.21" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50" Area (sf)CN Description 6,726 39 >75% Grass cover, Good, HSG A 36,217 74 >75% Grass cover, Good, HSG C 138 98 Paved parking, HSG A 17,137 98 Paved parking, HSG C 712 98 Water Surface, HSG A 2 70 Woods, Good, HSG C 60,933 77 Weighted Average 42,945 69 70.48% Pervious Area 17,987 98 29.52% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 1.1 13 0.2000 0.19 Sheet Flow, Grass: Dense n= 0.240 P2= 3.00" 3.5 704 0.0363 3.34 3.34 Trap/Vee/Rect Channel Flow, Bot.W=0.00' D=0.50' Z= 4.0 '/' Top.W=4.00' n= 0.033 4.6 717 Total, Increased to minimum Tc = 6.0 min Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 26HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Subcatchment PS-2A: Subcat PS-2A Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)3 2 1 0 Type III 24-hr 10-Year Rainfall=4.50" Runoff Area=60,933 sf Runoff Volume=11,225 cf Runoff Depth=2.21" Flow Length=717' Tc=6.0 min CN=77 3.55 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 27HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-2B: Subcat PS-2B Runoff =1.98 cfs @ 12.22 hrs, Volume=8,413 cf, Depth=1.75" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50" Area (sf)CN Description 14,852 74 >75% Grass cover, Good, HSG C 42,955 70 Woods, Good, HSG C 57,807 71 Weighted Average 57,807 71 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 13.4 100 0.0700 0.12 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 1.8 205 0.1415 1.88 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 15.2 305 Total Subcatchment PS-2B: Subcat PS-2B Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)2 1 0 Type III 24-hr 10-Year Rainfall=4.50" Runoff Area=57,807 sf Runoff Volume=8,413 cf Runoff Depth=1.75" Flow Length=305' Tc=15.2 min CN=71 1.98 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 28HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-2C: Subcat PS-2C Runoff =3.99 cfs @ 12.16 hrs, Volume=15,209 cf, Depth=3.30" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50" Area (sf)CN Description 18,064 74 >75% Grass cover, Good, HSG C 31,241 98 Paved parking, HSG C 1,600 98 Unconnected roofs, HSG C 1,968 98 Water Surface, HSG C 2,516 70 Woods, Good, HSG C 55,388 89 Weighted Average 20,580 74 37.16% Pervious Area 34,808 98 62.84% Impervious Area 1,600 4.60% Unconnected Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 9.5 39 0.0256 0.07 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 1.1 15 0.2670 0.22 Sheet Flow, Grass: Dense n= 0.240 P2= 3.00" 0.5 138 0.0580 4.22 4.22 Trap/Vee/Rect Channel Flow, Bot.W=0.00' D=0.50' Z= 4.0 '/' Top.W=4.00' n= 0.033 Stream, clean & straight 0.4 101 0.0100 4.54 3.56 Pipe Channel, 12.0" Round Area= 0.8 sf Perim= 3.1' r= 0.25' n= 0.013 Corrugated PE, smooth interior 11.5 293 Total Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 29HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Subcatchment PS-2C: Subcat PS-2C Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)4 3 2 1 0 Type III 24-hr 10-Year Rainfall=4.50" Runoff Area=55,388 sf Runoff Volume=15,209 cf Runoff Depth=3.30" Flow Length=293' Tc=11.5 min CN=89 3.99 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 30HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-2D: Subcat PS-2D Runoff =4.40 cfs @ 12.09 hrs, Volume=15,881 cf, Depth=4.26" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50" Area (sf)CN Description 727 74 >75% Grass cover, Good, HSG C 14,248 98 Paved parking, HSG C 29,600 98 Unconnected roofs, HSG C 117 70 Woods, Good, HSG C 44,692 98 Weighted Average 844 73 1.89% Pervious Area 43,848 98 98.11% Impervious Area 29,600 67.51% Unconnected Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment PS-2D: Subcat PS-2D Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)4 3 2 1 0 Type III 24-hr 10-Year Rainfall=4.50" Runoff Area=44,692 sf Runoff Volume=15,881 cf Runoff Depth=4.26" Tc=6.0 min CN=98 4.40 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 31HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-2E: Subcat PS-2E Runoff =1.67 cfs @ 12.09 hrs, Volume=5,274 cf, Depth=2.64" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50" Area (sf)CN Description 15,303 74 >75% Grass cover, Good, HSG C 3,991 98 Paved parking, HSG C 3,699 98 Water Surface, HSG C 1,015 70 Woods, Good, HSG C 24,007 82 Weighted Average 16,318 74 67.97% Pervious Area 7,689 98 32.03% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment PS-2E: Subcat PS-2E Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)1 0 Type III 24-hr 10-Year Rainfall=4.50" Runoff Area=24,007 sf Runoff Volume=5,274 cf Runoff Depth=2.64" Tc=6.0 min CN=82 1.67 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 32HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-3A: Subcat PS-3A Runoff =5.95 cfs @ 12.09 hrs, Volume=19,735 cf, Depth=3.60" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50" Area (sf)CN Description 12,624 74 >75% Grass cover, Good, HSG C 13,307 98 Paved parking, HSG C 33,600 98 Unconnected roofs, HSG C 3,918 98 Water Surface, HSG C 2,295 70 Woods, Good, HSG C 65,744 92 Weighted Average 14,919 73 22.69% Pervious Area 50,826 98 77.31% Impervious Area 33,600 66.11% Unconnected Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment PS-3A: Subcat PS-3A Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)6 5 4 3 2 1 0 Type III 24-hr 10-Year Rainfall=4.50" Runoff Area=65,744 sf Runoff Volume=19,735 cf Runoff Depth=3.60" Tc=6.0 min CN=92 5.95 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 33HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-3B: Subcat PS-3B Runoff =0.91 cfs @ 12.27 hrs, Volume=4,202 cf, Depth=1.75" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.50" Area (sf)CN Description 9,650 74 >75% Grass cover, Good, HSG C 19,221 70 Woods, Good, HSG C 28,871 71 Weighted Average 28,871 71 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 16.8 100 0.0400 0.10 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 1.8 135 0.0630 1.25 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 18.6 235 Total Subcatchment PS-3B: Subcat PS-3B Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)1 0 Type III 24-hr 10-Year Rainfall=4.50" Runoff Area=28,871 sf Runoff Volume=4,202 cf Runoff Depth=1.75" Flow Length=235' Tc=18.6 min CN=71 0.91 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 34HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Pond 1P: Bio Basin #1 Inflow Area =65,744 sf,77.31% Impervious, Inflow Depth = 3.60" for 10-Year event Inflow =5.95 cfs @ 12.09 hrs, Volume=19,735 cf Outflow =1.52 cfs @ 12.46 hrs, Volume=19,712 cf, Atten= 74%, Lag= 22.4 min Discarded =0.08 cfs @ 12.46 hrs, Volume=9,069 cf Primary =1.44 cfs @ 12.46 hrs, Volume=10,643 cf Secondary =0.00 cfs @ 0.00 hrs, Volume=0 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 143.71' @ 12.46 hrs Surf.Area= 6,940 sf Storage= 9,235 cf Plug-Flow detention time= 392.4 min calculated for 19,712 cf (100% of inflow) Center-of-Mass det. time= 391.7 min ( 1,177.7 - 786.1 ) Volume Invert Avail.Storage Storage Description #1 142.00'19,750 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim.Inc.Store Cum.Store Wet.Area (feet)(sq-ft)(feet)(cubic-feet)(cubic-feet)(sq-ft) 142.00 3,918 512.0 0 0 3,918 143.00 5,674 597.0 4,769 4,769 11,440 144.00 7,496 617.0 6,564 11,333 13,465 145.00 9,374 636.0 8,418 19,750 15,460 Device Routing Invert Outlet Devices #1 Primary 140.00'12.0" Round Culvert L= 36.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 140.00' / 139.00' S= 0.0278 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf #2 Device 1 143.00'9.0" W x 18.0" H Vert. Orifice/Grate C= 0.600 #3 Device 1 144.50'48.0" x 48.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Secondary 145.00'10.0' long x 20.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 #5 Discarded 142.00'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.08 cfs @ 12.46 hrs HW=143.71' (Free Discharge) 5=Exfiltration (Exfiltration Controls 0.08 cfs) Primary OutFlow Max=1.44 cfs @ 12.46 hrs HW=143.71' (Free Discharge) 1=Culvert (Passes 1.44 cfs of 7.95 cfs potential flow) 2=Orifice/Grate (Orifice Controls 1.44 cfs @ 2.70 fps) 3=Orifice/Grate ( Controls 0.00 cfs) Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=142.00' (Free Discharge) 4=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 35HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Pond 1P: Bio Basin #1 Inflow Outflow Discarded Primary Secondary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)6 5 4 3 2 1 0 Inflow Area=65,744 sf Peak Elev=143.71' Storage=9,235 cf 5.95 cfs 1.52 cfs 0.08 cfs 1.44 cfs 0.00 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 36HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Pond 2P: Det. Basin #2 Inflow Area =68,699 sf,75.02% Impervious, Inflow Depth = 3.70" for 10-Year event Inflow =6.07 cfs @ 12.09 hrs, Volume=21,154 cf Outflow =0.41 cfs @ 13.59 hrs, Volume=21,154 cf, Atten= 93%, Lag= 90.1 min Discarded =0.09 cfs @ 13.59 hrs, Volume=6,105 cf Primary =0.32 cfs @ 13.59 hrs, Volume=15,049 cf Secondary =0.00 cfs @ 0.00 hrs, Volume=0 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 141.96' @ 13.59 hrs Surf.Area= 7,479 sf Storage= 10,808 cf Plug-Flow detention time= 298.9 min calculated for 21,154 cf (100% of inflow) Center-of-Mass det. time= 298.5 min ( 1,066.0 - 767.5 ) Volume Invert Avail.Storage Storage Description #1 140.00'30,471 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim.Inc.Store Cum.Store Wet.Area (feet)(sq-ft)(feet)(cubic-feet)(cubic-feet)(sq-ft) 140.00 3,699 251.0 0 0 3,699 141.00 5,557 293.0 4,597 4,597 5,537 142.00 7,574 328.0 6,540 11,136 7,295 143.00 9,667 361.0 8,599 19,735 9,137 144.00 11,841 396.0 10,736 30,471 11,279 Device Routing Invert Outlet Devices #1 Primary 139.00'12.0" Round Culvert L= 55.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 139.00' / 135.00' S= 0.0727 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf #2 Device 1 140.00'3.0" Vert. Orifice/Grate C= 0.600 #3 Secondary 144.00'10.0' long x 20.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 #4 Discarded 140.00'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.09 cfs @ 13.59 hrs HW=141.96' (Free Discharge) 4=Exfiltration (Exfiltration Controls 0.09 cfs) Primary OutFlow Max=0.32 cfs @ 13.59 hrs HW=141.96' (Free Discharge) 1=Culvert (Passes 0.32 cfs of 7.41 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.32 cfs @ 6.52 fps) Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=140.00' (Free Discharge) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 37HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Pond 2P: Det. Basin #2 Inflow Outflow Discarded Primary Secondary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)6 5 4 3 2 1 0 Inflow Area=68,699 sf Peak Elev=141.96' Storage=10,808 cf 6.07 cfs 0.41 cfs 0.09 cfs0.32 cfs 0.00 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 38HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Pond 3P: Bio Basin #3 Inflow Area =55,388 sf,62.84% Impervious, Inflow Depth = 3.30" for 10-Year event Inflow =3.99 cfs @ 12.16 hrs, Volume=15,209 cf Outflow =1.43 cfs @ 12.51 hrs, Volume=15,211 cf, Atten= 64%, Lag= 21.2 min Discarded =0.09 cfs @ 12.51 hrs, Volume=7,707 cf Primary =0.17 cfs @ 12.51 hrs, Volume=4,635 cf Secondary =1.17 cfs @ 12.51 hrs, Volume=2,869 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 135.12' @ 12.51 hrs Surf.Area= 7,750 sf Storage= 6,796 cf Plug-Flow detention time= 321.5 min calculated for 15,195 cf (100% of inflow) Center-of-Mass det. time= 322.1 min ( 1,125.4 - 803.2 ) Volume Invert Avail.Storage Storage Description #1 134.00'14,787 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim.Inc.Store Cum.Store Wet.Area (feet)(sq-ft)(feet)(cubic-feet)(cubic-feet)(sq-ft) 134.00 4,457 658.0 0 0 4,457 135.00 7,389 739.0 5,862 5,862 13,489 136.00 10,555 783.0 8,925 14,787 18,872 Device Routing Invert Outlet Devices #1 Primary 132.00'12.0" Round Culvert L= 33.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 132.00' / 129.00' S= 0.0909 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf #2 Device 1 134.50'3.0" Vert. Orifice/Grate C= 0.600 #3 Secondary 135.00'10.0' long x 20.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 #4 Discarded 134.00'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.09 cfs @ 12.51 hrs HW=135.12' (Free Discharge) 4=Exfiltration (Exfiltration Controls 0.09 cfs) Primary OutFlow Max=0.17 cfs @ 12.51 hrs HW=135.12' (Free Discharge) 1=Culvert (Passes 0.17 cfs of 7.66 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.17 cfs @ 3.40 fps) Secondary OutFlow Max=1.16 cfs @ 12.51 hrs HW=135.12' (Free Discharge) 3=Broad-Crested Rectangular Weir (Weir Controls 1.16 cfs @ 0.94 fps) Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 39HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Pond 3P: Bio Basin #3 Inflow Outflow Discarded Primary Secondary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)4 3 2 1 0 Inflow Area=55,388 sf Peak Elev=135.12' Storage=6,796 cf 3.99 cfs 1.43 cfs 0.09 cfs 0.17 cfs 1.17 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 40HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Pond 4P: Det. Basin #4 Inflow Area =116,321 sf,45.39% Impervious, Inflow Depth = 1.93" for 10-Year event Inflow =3.61 cfs @ 12.10 hrs, Volume=18,728 cf Outflow =2.57 cfs @ 12.19 hrs, Volume=18,715 cf, Atten= 29%, Lag= 5.7 min Discarded =0.03 cfs @ 12.19 hrs, Volume=1,170 cf Primary =0.30 cfs @ 12.19 hrs, Volume=10,815 cf Secondary =2.24 cfs @ 12.19 hrs, Volume=6,730 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 110.69' @ 12.19 hrs Surf.Area= 2,391 sf Storage= 2,649 cf Plug-Flow detention time= 63.3 min calculated for 18,696 cf (100% of inflow) Center-of-Mass det. time= 62.9 min ( 931.9 - 869.0 ) Volume Invert Avail.Storage Storage Description #1 109.00'6,600 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim.Inc.Store Cum.Store Wet.Area (feet)(sq-ft)(feet)(cubic-feet)(cubic-feet)(sq-ft) 109.00 712 251.0 0 0 712 110.00 1,789 287.0 1,210 1,210 2,277 111.00 2,689 313.0 2,224 3,434 3,554 112.00 3,668 340.0 3,166 6,600 4,994 Device Routing Invert Outlet Devices #1 Primary 108.20'12.0" Round Culvert L= 46.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 108.20' / 108.00' S= 0.0043 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf #2 Device 1 109.00'3.0" Vert. Orifice/Grate C= 0.600 #3 Secondary 110.50'10.0' long x 20.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 #4 Discarded 109.00'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.03 cfs @ 12.19 hrs HW=110.69' (Free Discharge) 4=Exfiltration (Exfiltration Controls 0.03 cfs) Primary OutFlow Max=0.30 cfs @ 12.19 hrs HW=110.69' (Free Discharge) 1=Culvert (Passes 0.30 cfs of 5.04 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.30 cfs @ 6.02 fps) Secondary OutFlow Max=2.20 cfs @ 12.19 hrs HW=110.69' (Free Discharge) 3=Broad-Crested Rectangular Weir (Weir Controls 2.20 cfs @ 1.17 fps) Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 41HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Pond 4P: Det. Basin #4 Inflow Outflow Discarded Primary Secondary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)4 3 2 1 0 Inflow Area=116,321 sf Peak Elev=110.69' Storage=2,649 cf 3.61 cfs 2.57 cfs 0.03 cfs0.30 cfs 2.24 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 42HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Link DP-1: Ex. Drainage System Inflow Area =278,667 sf,38.48% Impervious, Inflow Depth = 2.02" for 10-Year event Inflow =5.55 cfs @ 12.21 hrs, Volume=46,897 cf Primary =5.55 cfs @ 12.21 hrs, Volume=46,897 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Link DP-1: Ex. Drainage System Inflow Primary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)6 5 4 3 2 1 0 Inflow Area=278,667 sf 5.55 cfs 5.55 cfs Easthampton Road Type III 24-hr 10-Year Rainfall=4.50"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 43HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Link DP-2: Offsite West Inflow Area =94,616 sf,53.72% Impervious, Inflow Depth = 1.88" for 10-Year event Inflow =2.22 cfs @ 12.34 hrs, Volume=14,845 cf Primary =2.22 cfs @ 12.34 hrs, Volume=14,845 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Link DP-2: Offsite West Inflow Primary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)2 1 0 Inflow Area=94,616 sf 2.22 cfs 2.22 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 44HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 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=35,840 sf 8.07% Impervious Runoff Depth=3.52"Subcatchment PS-1: Subcat PS-1 Flow Length=438' Tc=27.4 min CN=74 Runoff=2.00 cfs 10,525 cf Runoff Area=60,933 sf 29.52% Impervious Runoff Depth=3.83"Subcatchment PS-2A: Subcat PS-2A Flow Length=717' Tc=6.0 min CN=77 Runoff=6.15 cfs 19,451 cf Runoff Area=57,807 sf 0.00% Impervious Runoff Depth=3.22"Subcatchment PS-2B: Subcat PS-2B Flow Length=305' Tc=15.2 min CN=71 Runoff=3.75 cfs 15,532 cf Runoff Area=55,388 sf 62.84% Impervious Runoff Depth=5.12"Subcatchment PS-2C: Subcat PS-2C Flow Length=293' Tc=11.5 min CN=89 Runoff=6.07 cfs 23,649 cf Runoff Area=44,692 sf 98.11% Impervious Runoff Depth=6.16"Subcatchment PS-2D: Subcat PS-2D Tc=6.0 min CN=98 Runoff=6.29 cfs 22,947 cf Runoff Area=24,007 sf 32.03% Impervious Runoff Depth=4.36"Subcatchment PS-2E: Subcat PS-2E Tc=6.0 min CN=82 Runoff=2.72 cfs 8,716 cf Runoff Area=65,744 sf 77.31% Impervious Runoff Depth=5.46"Subcatchment PS-3A: Subcat PS-3A Tc=6.0 min CN=92 Runoff=8.82 cfs 29,931 cf Runoff Area=28,871 sf 0.00% Impervious Runoff Depth=3.22"Subcatchment PS-3B: Subcat PS-3B Flow Length=235' Tc=18.6 min CN=71 Runoff=1.73 cfs 7,757 cf Peak Elev=144.17' Storage=12,637 cf Inflow=8.82 cfs 29,931 cfPond 1P: Bio Basin #1 Discarded=0.09 cfs 9,629 cf Primary=3.05 cfs 20,243 cf Secondary=0.00 cfs 0 cf Outflow=3.14 cfs 29,872 cf Peak Elev=142.75' Storage=17,375 cf Inflow=9.01 cfs 31,663 cfPond 2P: Det. Basin #2 Discarded=0.11 cfs 8,429 cf Primary=0.38 cfs 23,235 cf Secondary=0.00 cfs 0 cf Outflow=0.49 cfs 31,663 cf Peak Elev=135.28' Storage=8,051 cf Inflow=6.07 cfs 23,649 cfPond 3P: Bio Basin #3 Discarded=0.10 cfs 8,502 cf Primary=0.19 cfs 5,759 cf Secondary=4.00 cfs 9,385 cf Outflow=4.29 cfs 23,647 cf Peak Elev=110.90' Storage=3,179 cf Inflow=7.33 cfs 34,596 cfPond 4P: Det. Basin #4 Discarded=0.03 cfs 1,429 cf Primary=0.32 cfs 13,467 cf Secondary=6.92 cfs 19,701 cf Outflow=7.27 cfs 34,597 cf Inflow=12.89 cfs 82,460 cfLink DP-1: Ex. Drainage System Primary=12.89 cfs 82,460 cf Inflow=4.72 cfs 28,000 cfLink DP-2: Offsite West Primary=4.72 cfs 28,000 cf Total Runoff Area = 373,282 sf Runoff Volume = 138,508 cf Average Runoff Depth = 4.45" 57.66% Pervious = 215,231 sf 42.34% Impervious = 158,052 sf Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 45HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-1: Subcat PS-1 Runoff =2.00 cfs @ 12.38 hrs, Volume=10,525 cf, Depth=3.52" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Area (sf)CN Description 11,832 74 >75% Grass cover, Good, HSG C 2,893 98 Paved parking, HSG C 21,114 70 Woods, Good, HSG C 35,840 74 Weighted Average 32,947 71 91.93% Pervious Area 2,893 98 8.07% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 21.4 168 0.0618 0.13 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 6.0 270 0.0889 0.75 Shallow Concentrated Flow, Forest w/Heavy Litter Kv= 2.5 fps 27.4 438 Total Subcatchment PS-1: Subcat PS-1 Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)2 1 0 Type III 24-hr 100-Year Rainfall=6.40" Runoff Area=35,840 sf Runoff Volume=10,525 cf Runoff Depth=3.52" Flow Length=438' Tc=27.4 min CN=74 2.00 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 46HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-2A: Subcat PS-2A Runoff =6.15 cfs @ 12.09 hrs, Volume=19,451 cf, Depth=3.83" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Area (sf)CN Description 6,726 39 >75% Grass cover, Good, HSG A 36,217 74 >75% Grass cover, Good, HSG C 138 98 Paved parking, HSG A 17,137 98 Paved parking, HSG C 712 98 Water Surface, HSG A 2 70 Woods, Good, HSG C 60,933 77 Weighted Average 42,945 69 70.48% Pervious Area 17,987 98 29.52% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 1.1 13 0.2000 0.19 Sheet Flow, Grass: Dense n= 0.240 P2= 3.00" 3.5 704 0.0363 3.34 3.34 Trap/Vee/Rect Channel Flow, Bot.W=0.00' D=0.50' Z= 4.0 '/' Top.W=4.00' n= 0.033 4.6 717 Total, Increased to minimum Tc = 6.0 min Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 47HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Subcatchment PS-2A: Subcat PS-2A Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)6 5 4 3 2 1 0 Type III 24-hr 100-Year Rainfall=6.40" Runoff Area=60,933 sf Runoff Volume=19,451 cf Runoff Depth=3.83" Flow Length=717' Tc=6.0 min CN=77 6.15 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 48HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-2B: Subcat PS-2B Runoff =3.75 cfs @ 12.21 hrs, Volume=15,532 cf, Depth=3.22" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Area (sf)CN Description 14,852 74 >75% Grass cover, Good, HSG C 42,955 70 Woods, Good, HSG C 57,807 71 Weighted Average 57,807 71 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 13.4 100 0.0700 0.12 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 1.8 205 0.1415 1.88 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 15.2 305 Total Subcatchment PS-2B: Subcat PS-2B Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)4 3 2 1 0 Type III 24-hr 100-Year Rainfall=6.40" Runoff Area=57,807 sf Runoff Volume=15,532 cf Runoff Depth=3.22" Flow Length=305' Tc=15.2 min CN=71 3.75 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 49HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-2C: Subcat PS-2C Runoff =6.07 cfs @ 12.16 hrs, Volume=23,649 cf, Depth=5.12" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Area (sf)CN Description 18,064 74 >75% Grass cover, Good, HSG C 31,241 98 Paved parking, HSG C 1,600 98 Unconnected roofs, HSG C 1,968 98 Water Surface, HSG C 2,516 70 Woods, Good, HSG C 55,388 89 Weighted Average 20,580 74 37.16% Pervious Area 34,808 98 62.84% Impervious Area 1,600 4.60% Unconnected Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 9.5 39 0.0256 0.07 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 1.1 15 0.2670 0.22 Sheet Flow, Grass: Dense n= 0.240 P2= 3.00" 0.5 138 0.0580 4.22 4.22 Trap/Vee/Rect Channel Flow, Bot.W=0.00' D=0.50' Z= 4.0 '/' Top.W=4.00' n= 0.033 Stream, clean & straight 0.4 101 0.0100 4.54 3.56 Pipe Channel, 12.0" Round Area= 0.8 sf Perim= 3.1' r= 0.25' n= 0.013 Corrugated PE, smooth interior 11.5 293 Total Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 50HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Subcatchment PS-2C: Subcat PS-2C Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)6 5 4 3 2 1 0 Type III 24-hr 100-Year Rainfall=6.40" Runoff Area=55,388 sf Runoff Volume=23,649 cf Runoff Depth=5.12" Flow Length=293' Tc=11.5 min CN=89 6.07 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 51HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-2D: Subcat PS-2D Runoff =6.29 cfs @ 12.09 hrs, Volume=22,947 cf, Depth=6.16" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Area (sf)CN Description 727 74 >75% Grass cover, Good, HSG C 14,248 98 Paved parking, HSG C 29,600 98 Unconnected roofs, HSG C 117 70 Woods, Good, HSG C 44,692 98 Weighted Average 844 73 1.89% Pervious Area 43,848 98 98.11% Impervious Area 29,600 67.51% Unconnected Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment PS-2D: Subcat PS-2D Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)7 6 5 4 3 2 1 0 Type III 24-hr 100-Year Rainfall=6.40" Runoff Area=44,692 sf Runoff Volume=22,947 cf Runoff Depth=6.16" Tc=6.0 min CN=98 6.29 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 52HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-2E: Subcat PS-2E Runoff =2.72 cfs @ 12.09 hrs, Volume=8,716 cf, Depth=4.36" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Area (sf)CN Description 15,303 74 >75% Grass cover, Good, HSG C 3,991 98 Paved parking, HSG C 3,699 98 Water Surface, HSG C 1,015 70 Woods, Good, HSG C 24,007 82 Weighted Average 16,318 74 67.97% Pervious Area 7,689 98 32.03% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment PS-2E: Subcat PS-2E Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)3 2 1 0 Type III 24-hr 100-Year Rainfall=6.40" Runoff Area=24,007 sf Runoff Volume=8,716 cf Runoff Depth=4.36" Tc=6.0 min CN=82 2.72 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 53HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-3A: Subcat PS-3A Runoff =8.82 cfs @ 12.09 hrs, Volume=29,931 cf, Depth=5.46" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Area (sf)CN Description 12,624 74 >75% Grass cover, Good, HSG C 13,307 98 Paved parking, HSG C 33,600 98 Unconnected roofs, HSG C 3,918 98 Water Surface, HSG C 2,295 70 Woods, Good, HSG C 65,744 92 Weighted Average 14,919 73 22.69% Pervious Area 50,826 98 77.31% Impervious Area 33,600 66.11% Unconnected Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment PS-3A: Subcat PS-3A Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)9 8 7 6 5 4 3 2 1 0 Type III 24-hr 100-Year Rainfall=6.40" Runoff Area=65,744 sf Runoff Volume=29,931 cf Runoff Depth=5.46" Tc=6.0 min CN=92 8.82 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 54HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment PS-3B: Subcat PS-3B Runoff =1.73 cfs @ 12.26 hrs, Volume=7,757 cf, Depth=3.22" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=6.40" Area (sf)CN Description 9,650 74 >75% Grass cover, Good, HSG C 19,221 70 Woods, Good, HSG C 28,871 71 Weighted Average 28,871 71 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 16.8 100 0.0400 0.10 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.00" 1.8 135 0.0630 1.25 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 18.6 235 Total Subcatchment PS-3B: Subcat PS-3B Runoff Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)1 0 Type III 24-hr 100-Year Rainfall=6.40" Runoff Area=28,871 sf Runoff Volume=7,757 cf Runoff Depth=3.22" Flow Length=235' Tc=18.6 min CN=71 1.73 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 55HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Pond 1P: Bio Basin #1 Inflow Area =65,744 sf,77.31% Impervious, Inflow Depth = 5.46" for 100-Year event Inflow =8.82 cfs @ 12.09 hrs, Volume=29,931 cf Outflow =3.14 cfs @ 12.35 hrs, Volume=29,872 cf, Atten= 64%, Lag= 15.9 min Discarded =0.09 cfs @ 12.35 hrs, Volume=9,629 cf Primary =3.05 cfs @ 12.35 hrs, Volume=20,243 cf Secondary =0.00 cfs @ 0.00 hrs, Volume=0 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 144.17' @ 12.35 hrs Surf.Area= 7,801 sf Storage= 12,637 cf Plug-Flow detention time= 288.1 min calculated for 29,841 cf (100% of inflow) Center-of-Mass det. time= 288.0 min ( 1,063.3 - 775.3 ) Volume Invert Avail.Storage Storage Description #1 142.00'19,750 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim.Inc.Store Cum.Store Wet.Area (feet)(sq-ft)(feet)(cubic-feet)(cubic-feet)(sq-ft) 142.00 3,918 512.0 0 0 3,918 143.00 5,674 597.0 4,769 4,769 11,440 144.00 7,496 617.0 6,564 11,333 13,465 145.00 9,374 636.0 8,418 19,750 15,460 Device Routing Invert Outlet Devices #1 Primary 140.00'12.0" Round Culvert L= 36.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 140.00' / 139.00' S= 0.0278 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf #2 Device 1 143.00'9.0" W x 18.0" H Vert. Orifice/Grate C= 0.600 #3 Device 1 144.50'48.0" x 48.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Secondary 145.00'10.0' long x 20.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 #5 Discarded 142.00'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.09 cfs @ 12.35 hrs HW=144.17' (Free Discharge) 5=Exfiltration (Exfiltration Controls 0.09 cfs) Primary OutFlow Max=3.05 cfs @ 12.35 hrs HW=144.17' (Free Discharge) 1=Culvert (Passes 3.05 cfs of 8.43 cfs potential flow) 2=Orifice/Grate (Orifice Controls 3.05 cfs @ 3.47 fps) 3=Orifice/Grate ( Controls 0.00 cfs) Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=142.00' (Free Discharge) 4=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 56HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Pond 1P: Bio Basin #1 Inflow Outflow Discarded Primary Secondary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)9 8 7 6 5 4 3 2 1 0 Inflow Area=65,744 sf Peak Elev=144.17' Storage=12,637 cf 8.82 cfs 3.14 cfs 0.09 cfs 3.05 cfs 0.00 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 57HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Pond 2P: Det. Basin #2 Inflow Area =68,699 sf,75.02% Impervious, Inflow Depth = 5.53" for 100-Year event Inflow =9.01 cfs @ 12.09 hrs, Volume=31,663 cf Outflow =0.49 cfs @ 14.05 hrs, Volume=31,663 cf, Atten= 95%, Lag= 117.5 min Discarded =0.11 cfs @ 14.05 hrs, Volume=8,429 cf Primary =0.38 cfs @ 14.05 hrs, Volume=23,235 cf Secondary =0.00 cfs @ 0.00 hrs, Volume=0 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 142.75' @ 14.05 hrs Surf.Area= 9,117 sf Storage= 17,375 cf Plug-Flow detention time= 397.1 min calculated for 31,630 cf (100% of inflow) Center-of-Mass det. time= 397.5 min ( 1,158.8 - 761.3 ) Volume Invert Avail.Storage Storage Description #1 140.00'30,471 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim.Inc.Store Cum.Store Wet.Area (feet)(sq-ft)(feet)(cubic-feet)(cubic-feet)(sq-ft) 140.00 3,699 251.0 0 0 3,699 141.00 5,557 293.0 4,597 4,597 5,537 142.00 7,574 328.0 6,540 11,136 7,295 143.00 9,667 361.0 8,599 19,735 9,137 144.00 11,841 396.0 10,736 30,471 11,279 Device Routing Invert Outlet Devices #1 Primary 139.00'12.0" Round Culvert L= 55.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 139.00' / 135.00' S= 0.0727 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf #2 Device 1 140.00'3.0" Vert. Orifice/Grate C= 0.600 #3 Secondary 144.00'10.0' long x 20.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 #4 Discarded 140.00'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.11 cfs @ 14.05 hrs HW=142.75' (Free Discharge) 4=Exfiltration (Exfiltration Controls 0.11 cfs) Primary OutFlow Max=0.38 cfs @ 14.05 hrs HW=142.75' (Free Discharge) 1=Culvert (Passes 0.38 cfs of 8.52 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.38 cfs @ 7.80 fps) Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=140.00' (Free Discharge) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 58HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Pond 2P: Det. Basin #2 Inflow Outflow Discarded Primary Secondary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)10 9 8 7 6 5 4 3 2 1 0 Inflow Area=68,699 sf Peak Elev=142.75' Storage=17,375 cf 9.01 cfs 0.49 cfs 0.11 cfs0.38 cfs 0.00 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 59HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Pond 3P: Bio Basin #3 Inflow Area =55,388 sf,62.84% Impervious, Inflow Depth = 5.12" for 100-Year event Inflow =6.07 cfs @ 12.16 hrs, Volume=23,649 cf Outflow =4.29 cfs @ 12.28 hrs, Volume=23,647 cf, Atten= 29%, Lag= 7.7 min Discarded =0.10 cfs @ 12.28 hrs, Volume=8,502 cf Primary =0.19 cfs @ 12.28 hrs, Volume=5,759 cf Secondary =4.00 cfs @ 12.28 hrs, Volume=9,385 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 135.28' @ 12.28 hrs Surf.Area= 8,221 sf Storage= 8,051 cf Plug-Flow detention time= 239.7 min calculated for 23,622 cf (100% of inflow) Center-of-Mass det. time= 240.3 min ( 1,031.5 - 791.2 ) Volume Invert Avail.Storage Storage Description #1 134.00'14,787 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim.Inc.Store Cum.Store Wet.Area (feet)(sq-ft)(feet)(cubic-feet)(cubic-feet)(sq-ft) 134.00 4,457 658.0 0 0 4,457 135.00 7,389 739.0 5,862 5,862 13,489 136.00 10,555 783.0 8,925 14,787 18,872 Device Routing Invert Outlet Devices #1 Primary 132.00'12.0" Round Culvert L= 33.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 132.00' / 129.00' S= 0.0909 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf #2 Device 1 134.50'3.0" Vert. Orifice/Grate C= 0.600 #3 Secondary 135.00'10.0' long x 20.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 #4 Discarded 134.00'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.10 cfs @ 12.28 hrs HW=135.28' (Free Discharge) 4=Exfiltration (Exfiltration Controls 0.10 cfs) Primary OutFlow Max=0.19 cfs @ 12.28 hrs HW=135.28' (Free Discharge) 1=Culvert (Passes 0.19 cfs of 7.88 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.19 cfs @ 3.89 fps) Secondary OutFlow Max=3.97 cfs @ 12.28 hrs HW=135.28' (Free Discharge) 3=Broad-Crested Rectangular Weir (Weir Controls 3.97 cfs @ 1.42 fps) Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 60HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Pond 3P: Bio Basin #3 Inflow Outflow Discarded Primary Secondary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)6 5 4 3 2 1 0 Inflow Area=55,388 sf Peak Elev=135.28' Storage=8,051 cf 6.07 cfs 4.29 cfs 0.10 cfs 0.19 cfs 4.00 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 61HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Pond 4P: Det. Basin #4 Inflow Area =116,321 sf,45.39% Impervious, Inflow Depth = 3.57" for 100-Year event Inflow =7.33 cfs @ 12.17 hrs, Volume=34,596 cf Outflow =7.27 cfs @ 12.22 hrs, Volume=34,597 cf, Atten= 1%, Lag= 3.2 min Discarded =0.03 cfs @ 12.22 hrs, Volume=1,429 cf Primary =0.32 cfs @ 12.22 hrs, Volume=13,467 cf Secondary =6.92 cfs @ 12.22 hrs, Volume=19,701 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 110.90' @ 12.22 hrs Surf.Area= 2,594 sf Storage= 3,179 cf Plug-Flow detention time= 44.5 min calculated for 34,561 cf (100% of inflow) Center-of-Mass det. time= 44.6 min ( 886.7 - 842.1 ) Volume Invert Avail.Storage Storage Description #1 109.00'6,600 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim.Inc.Store Cum.Store Wet.Area (feet)(sq-ft)(feet)(cubic-feet)(cubic-feet)(sq-ft) 109.00 712 251.0 0 0 712 110.00 1,789 287.0 1,210 1,210 2,277 111.00 2,689 313.0 2,224 3,434 3,554 112.00 3,668 340.0 3,166 6,600 4,994 Device Routing Invert Outlet Devices #1 Primary 108.20'12.0" Round Culvert L= 46.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 108.20' / 108.00' S= 0.0043 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf #2 Device 1 109.00'3.0" Vert. Orifice/Grate C= 0.600 #3 Secondary 110.50'10.0' long x 20.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 #4 Discarded 109.00'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.03 cfs @ 12.22 hrs HW=110.90' (Free Discharge) 4=Exfiltration (Exfiltration Controls 0.03 cfs) Primary OutFlow Max=0.32 cfs @ 12.22 hrs HW=110.90' (Free Discharge) 1=Culvert (Passes 0.32 cfs of 5.35 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.32 cfs @ 6.42 fps) Secondary OutFlow Max=6.90 cfs @ 12.22 hrs HW=110.90' (Free Discharge) 3=Broad-Crested Rectangular Weir (Weir Controls 6.90 cfs @ 1.71 fps) Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 62HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Pond 4P: Det. Basin #4 Inflow Outflow Discarded Primary Secondary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)8 7 6 5 4 3 2 1 0 Inflow Area=116,321 sf Peak Elev=110.90' Storage=3,179 cf 7.33 cfs 7.27 cfs 0.03 cfs0.32 cfs 6.92 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 63HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Link DP-1: Ex. Drainage System Inflow Area =278,667 sf,38.48% Impervious, Inflow Depth = 3.55" for 100-Year event Inflow =12.89 cfs @ 12.24 hrs, Volume=82,460 cf Primary =12.89 cfs @ 12.24 hrs, Volume=82,460 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Link DP-1: Ex. Drainage System Inflow Primary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=278,667 sf 12.89 cfs 12.89 cfs Easthampton Road Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. Page 64HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Summary for Link DP-2: Offsite West Inflow Area =94,616 sf,53.72% Impervious, Inflow Depth = 3.55" for 100-Year event Inflow =4.72 cfs @ 12.29 hrs, Volume=28,000 cf Primary =4.72 cfs @ 12.29 hrs, Volume=28,000 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Link DP-2: Offsite West Inflow Primary Hydrograph Time (hours) 484644424038363432302826242220181614121086420Flow (cfs)5 4 3 2 1 0 Inflow Area=94,616 sf 4.72 cfs 4.72 cfs Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Appendix D: Hydraulic Analysis Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Appendix E: MassDEP Calculations - Impervious Area Calculations - Water Quality Calculations – PWQU-1 - Water Quality Calculations – PWQU-2 - Water Quality Flow Rate Conversion Table - CDS Water Quality Unit Detail – CDS 2015-4-C - Bioretention Area #1 Stage-Storage Chart - TSS Removal Worksheet - Bioretention Area #1 - TSS Removal Worksheet - Detention Basin #2 - TSS Removal Worksheet - Bioretention Area #3 - TSS Removal Worksheet - Detention Basin #4 - Drawdown Calculations - Sediment Forebay Sizing Calculations - Contech – Hydrodynamic Separation Products Overview Proposed Self-Storage Facility Stormwater Drainage Report Easthampton Road Northampton, Massachusetts Standard 3: Recharge Calculations Impervious Area Calculations Existing Total Impervious Area Sub-Catchment Roof (sf) Other Impervious (sf) Sum (sf) ES-1 0 0 0 ES-2 0 0 0 ES-3 0 0 0 0 0 0 Proposed Total Impervious Area Sub-Catchment Roof (sf) Other Impervious (sf) Sum (sf) PS-1 0 2893 2893 PS-2A 0 17275 17275 Tributary to Detention Basin #4 PS-2B 0 0 0 PS-2C 1600 31241 32841 Tributary to Bio Basin #3 PS-2D 29600 14248 43848 PS-2E 0 3991 3991 PS-3A 33600 13307 46907 Tributary to Bio Basin #1 PS-3B 0 0 0 64800 82955 147755 Summary Table 0 SF 147755 SF 147755 SF 46907 SF Tributary to Detention Basin #2 Total New Impervious Area Total Existing Impervious Area Total Proposed Impervious Area Total Impervious Area Tributary to Recharge Facilities Proposed Self-Storage Facility Stormwater Drainage Report Easthampton Road Northampton, Massachusetts Standard 4: Water Quality - PWQU-1 Water Quality Volume Conversion to Flow Rate Note: Required water quality volume based on 0.5-inch of runoff Q = (qu) (A) (WQV) where: Q = peak flow rate associated with first 0.5-inch of runoff (c.f.s.)* qu = unit peak discharge (csm/in) - value taken from table based on tc A = impervious surface drainage area (sq. mi.) WQV = water quality volume in watershed inches (0.5-inch) · Proposed Water Quality Unit (PWQU-1) tc =0.100 hrs qu =752 csm/in (from table) A =0.00172 sq. mi.** WQV =0.5 inch Q0.5 = 0.65 c.f.s The Contech CDS 2015-4-C provides treatment of flows up to 1.40 c.f.s. * Water quality depth shall equal 1-inch for discharges within a Zone II or Interim Wellhead Protection Area, to or near another critical area, runoff from a LUHPPL, or exfiltration to soils with infiltration rate greater than 2.4 inches/hour or greater; ½-inch for discharges near or to other areas ** Only includes impervious area tributary to water quality unit. Proposed Self-Storage Facility Stormwater Drainage Report Easthampton Road Northampton, Massachusetts Standard 4: Water Quality - PWQU-2 Water Quality Volume Conversion to Flow Rate Note: Required water quality volume based on 0.5-inch of runoff Q = (qu) (A) (WQV) where: Q = peak flow rate associated with first 0.5-inch of runoff (c.f.s.)* qu = unit peak discharge (csm/in) - value taken from table based on tc A = impervious surface drainage area (sq. mi.)** WQV = water quality volume in watershed inches (0.5-inch) · Proposed Water Quality Unit (PWQU-1) tc =0.100 hrs qu =752 csm/in (from table) A =0.00062 sq. mi.* WQV =0.5 inch Q0.5 = 0.23 c.f.s The Contech CDS 2015-4-C provides treatment of flows up to 1.40 c.f.s. * Water quality depth shall equal 1-inch for discharges within a Zone II or Interim Wellhead Protection Area, to or near another critical area, runoff from a LUHPPL, or exfiltration to soils with infiltration rate greater than 2.4 inches/hour or greater; ½-inch for discharges near or to other areas ** Only includes impervious area tributary to water quality unit. MassDEP Q Rate - Sept. 10, 2013 - Page 4 Figure 2: For First ½-inch of Runoff, Table of qu values for Ia/P Curve = 0.0.058, listed by tc, for Type III Storm Distribution Tc qu Tc qu Tc qu Tc qu (Hours) (csm/in) (Hours) (csm/in) (Hours) (csm/in) (Hours) (csm/in) 0.01 821 1.8 246 5.3 116 8.8 77 0.03 821 1.9 238 5.4 115 8.9 76 0.05 813 2 230 5.5 113 9 76 0.067 794 2.1 223 5.6 112 9.1 75 0.083 773 2.2 217 5.7 110 9.2 74 0.1 752 2.3 211 5.8 109 9.3 74 0.116 733 2.4 205 5.9 107 9.4 73 0.133 713 2.5 200 6 106 9.5 72 0.15 694 2.6 194 6.1 104 9.6 72 0.167 677 2.7 190 6.2 103 9.7 71 0.183 662 2.8 185 6.3 102 9.8 70 0.2 646 2.9 181 6.4 100 9.9 70 0.217 632 3 176 6.5 99 10 69 0.233 619 3.1 173 6.6 98 0.25 606 3.2 169 6.7 97 0.3 572 3.3 165 6.8 96 0.333 552 3.4 162 6.9 94 0.35 542 3.5 158 7 93 0.4 516 3.6 155 7.1 92 0.416 508 3.7 152 7.2 91 0.5 472 3.8 149 7.3 90 0.583 443 3.9 147 7.4 89 0.6 437 4 144 7.5 88 0.667 417 4.1 141 7.6 87 0.7 408 4.2 139 7.7 86 0.8 383 4.3 136 7.8 85 0.9 361 4.4 134 7.9 84 1 342 4.5 132 8 84 1.1 325 4.6 130 8.1 83 1.2 311 4.7 128 8.2 82 1.3 297 4.8 126 8.3 81 1.4 285 4.9 124 8.4 80 1.5 274 5 122 8.5 79 1.6 264 5.1 120 8.6 79 1.7 254 5.2 118 8.7 78 Type III 24-hr 100-Year Rainfall=6.40"180614 - POST Printed 10/19/2018Prepared by R Levesque Associates Inc. HydroCAD® 10.00-22 s/n 02175 © 2018 HydroCAD Software Solutions LLC Stage-Area-Storage for Pond 1P: Basin #1 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 142.00 3,918 0 142.05 3,998 198 142.10 4,079 400 142.15 4,161 606 142.20 4,243 816 142.25 4,327 1,030 142.30 4,411 1,249 142.35 4,496 1,471 142.40 4,581 1,698 142.45 4,668 1,929 142.50 4,755 2,165 142.55 4,844 2,405 142.60 4,933 2,649 142.65 5,023 2,898 142.70 5,113 3,152 142.75 5,205 3,410 142.80 5,297 3,672 142.85 5,390 3,939 142.90 5,484 4,211 142.95 5,579 4,488 143.00 5,674 4,769 143.05 5,759 5,055 143.10 5,845 5,345 143.15 5,931 5,639 143.20 6,018 5,938 143.25 6,106 6,241 143.30 6,194 6,549 143.35 6,283 6,861 143.40 6,372 7,177 143.45 6,463 7,498 143.50 6,553 7,823 143.55 6,645 8,153 143.60 6,737 8,488 143.65 6,829 8,827 143.70 6,923 9,171 143.75 7,017 9,519 143.80 7,111 9,872 143.85 7,207 10,230 143.90 7,302 10,593 143.95 7,399 10,961 144.00 7,496 11,333 144.05 7,585 11,710 144.10 7,674 12,091 144.15 7,764 12,477 144.20 7,855 12,868 144.25 7,946 13,263 144.30 8,037 13,662 144.35 8,129 14,067 144.40 8,222 14,475 144.45 8,315 14,889 144.50 8,409 15,307 144.55 8,503 15,730 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 144.60 8,598 16,157 144.65 8,693 16,589 144.70 8,789 17,026 144.75 8,885 17,468 144.80 8,982 17,915 144.85 9,079 18,366 144.90 9,177 18,823 144.95 9,275 19,284 145.00 9,374 19,750 Proposed Self-Storage Facility Stormwater Drainage Report Easthampton Road Northampton, Massachusetts TSS Removal Form - Bioretention Basin #1 BMP TSS Removal Starting TSS Amount Remaining Rate Load Removed Load Bioretention Basin #1 Total TSS Removal =90%Total TSS Removal0.90 1.00 0.90 0.10 Proposed Self-Storage Facility Stormwater Drainage Report Easthampton Road Northampton, Massachusetts TSS Removal Form - Detention Basin #2 BMP TSS Removal Starting TSS Amount Remaining Rate Load Removed Load Deep Sump Hooded Catch Basins Proprietary Sedimentation Device Total TSS Removal =85% TSS Removal Form - Detention Basin #2 BMP TSS Removal Starting TSS Amount Remaining Rate Load Removed Load Deep-Sump Hooded Catch Basins Proprietary Sedimentation Device Extended Dry Detention Basin Total TSS Removal =93% 0.15 0.08 0.08 Total TSS Removal0.25 1.00 0.25 0.75 0.80 0.75 0.60 0.15 0.50Pre-Treatment0.25 1.00 0.25 0.75 0.80 0.75 0.60 0.15 Proposed Self-Storage Facility Stormwater Drainage Report Easthampton Road Northampton, Massachusetts TSS Removal Form - Bioretention Basin #3 BMP TSS Removal Starting TSS Amount Remaining Rate Load Removed Load Bioretention Basin #3 Total TSS Removal =90%Total TSS Removal0.90 1.00 0.90 0.10 Proposed Self-Storage Facility Stormwater Drainage Report Easthampton Road Northampton, Massachusetts TSS Removal Form - Detention Basin #4 BMP TSS Removal Starting TSS Amount Remaining Rate Load Removed Load Deep Sump Hooded Catch Basins Proprietary Sedimentation Device Total TSS Removal =85% TSS Removal Form - Detention Basin #4 BMP TSS Removal Starting TSS Amount Remaining Rate Load Removed Load Deep-Sump Hooded Catch Basins Proprietary Sedimentation Device Extended Dry Detention Basin Total TSS Removal =93% 0.15 0.08 0.08 Total TSS Removal0.25 1.00 0.25 0.75 0.80 0.75 0.60 0.15 0.50Pre-Treatment0.25 1.00 0.25 0.75 0.80 0.75 0.60 0.15 Proposed Self-Storage Facility Stormwater Drainage Report Easthampton Road Northampton, Massachusetts Drawdown Analysis RV KA where: TDRAWDOWN = time in hours RV = required recharge volume (cu. ft.) K = Rawls rate 8.27 inches/hour (A-soils)* 0.52 inches/hour (B-soils)* 0.27 inches/hour (C-soils)* A = bottom area of recharge facility (sq. ft.) *Most conservative Rawls rate values for given soil type used for analysis purposes Bio-Retention Area #1 RV =4,769 cu. ft. A =5,674 sq. ft. TDRAWDOWN =37.4 hours < 72 hours (C-soils) TDRAWDOWN = Proposed Self-Storage Facility Stormwater Drainage Report Easthampton Road Northampton, Massachusetts Sediment Forebay #1 Sizing - Detention Basin #2 0.1-inch Impervious Acre where: VSF (required) = required volume of the sediment forebay (cu. ft.) Impervious Acre =amount of impervious area tributary to forebay (acres) =0.42 acres * VSF (required) = 152 cu.ft. VSF (provided) = 1,181 cu. ft. Sediment Forebay #2 Sizing - Detention Basin #4 0.1-inch Impervious Acre where: VSF (required) = required volume of the sediment forebay (cu. ft.) Impervious Acre =amount of impervious area tributary to forebay (acres) =0.40 acres * VSF (required) = 144 cu.ft. VSF (provided) = 253 cu. ft. VSF (required) = * Only includes impervious area tributary to sediment forebay #1. VSF (required) = * Only includes impervious area tributary to sediment forebay #2. Learn more at www.ContechES.com/HDS|Page 1 VortSentry® HS Hydrodynamic Separation Products Overview Massachusetts ENGINEERED SOLUTIONS PDF compression, OCR, web optimization using a watermarked evaluation copy of CVISION PDFCompressor Page 2 | Learn more at www.ContechES.com/HDS Patented continuous deflection separation (CDS) technology Using patented continuous deflective separation technology, the CDS system screens, separates and traps sediment, debris, and oil and grease from stormwater runoff. The indirect screening capability of the system allows for 100% removal of floatables and neutrally buoyant material without blinding. Flow and screening controls physically separate captured solids, and minimize the re-suspension and release of previously trapped pollutants. Available in precast or cast-in-place. Offline units can treat flows from 30 to 8500 L/s (1 to 300 cfs). Inline units can treat up to 170 L/s (7.5 cfs), and internally bypass larger flows in excess of 1420 L/s (50 cfs). The pollutant removal capability of the CDS system has been proven in the lab and field. How does it work? Stormwater enters the CDS unit’s diversion chamber where the diversion weir guides the flow into the unit’s separation chamber and pollutants are removed. All flows up to the system’s treatment design capacity enter the separation chamber. Swirl concentration and screen deflection forces floatables and solids to the center of the separation chamber where 100% of floatables and neutrally buoyant debris larger than the screen apertures are trapped. Stormwater then moves through the separation screen, under the oil baffle and exits the system. The separation screen remains clog free due to continuous deflection. During flow events exceeding the design capacity, the diversion weir bypasses excessive flows around the separation chamber, so captured pollutants will not wash out. CDS • Removes sediment, trash and free oil and grease • Patented screening technology captures and retains 100% of floatables, including neutrally buoyant and all other material larger than the screen aperture • Operation independent of flow • Performance verified through lab and field testing • Unobstructed maintenance access • Customizable/flexible design and multiple configurations available • Separates and confines pollutants from outlet flow • Inline, offline, grate inlet and drop inlet configurations available • Multiple screen aperture sizes available • Allows for multiple inlet pipes CDS® GRATE INLET(CAST IRON HOOD FORCURB INLET OPENING) CREST OF BYPASS WEIR(ONE EACH SIDE) INLET(MULTIPLE PIPES POSSIBLE) OIL BAFFLE SUMP STORAGESEPARATION SLAB TREATMENT SCREEN OUTLET INLET FLUME SEPARATION CYLINDER CLEAN OUT(REQUIRED) DEFLECTION PAN, 3 SIDED(GRATE INLET DESIGN) PDF compression, OCR, web optimization using a watermarked evaluation copy of CVISION PDFCompressor Learn more at www.ContechES.com/HDS|Page 3 High performance hydrodynamic separation The Vortechs system is a high-performance hydrodynamic separator that effectively removes finer sediment, oil and grease, and floating and sinking debris. Its swirl concentrator and flow controls work together to minimize turbulence and provide stable storage of captured pollutants. The design also allows for easy inspection and unobstructed maintenance access. With comprehensive lab and field testing, the system delivers proven results and site-specific solutions. Precast models can treat peak design flows up to 25 cfs; cast-in-place models handle even greater flows. A typical system is sized to provide an 80% load reduction based on laboratory- verified removal efficiencies for varying particle size distributions such as 50-micron sediment particles. How does it work? Water enters the swirl chamber at a tangent, inducing a gentle swirling flow pattern and enhancing gravitational separation. Sinking pollutants stay in the swirl chamber while floating pollutants are stopped at the baffle wall. Typically Vortechs systems are sized such that 80% or more of runoff through the system will be controlled exclusively by the low flow control. This orifice effectively reduces inflow velocity and turbulence by inducing a slight backwater appropriate to the site. During larger storms, the water level rises above the low flow control and begins to flow through the high flow control. The layer of floating pollutants is elevated above the influent pipe, preventing re-entrainment. Swirling action increases in relation to the storm intensity, which helps prevent re-suspension. When the storm drain is flowing at peak capacity, the water surface in the system approaches the top of the high flow control. The Vortechs system will be sized large enough so that previously captured pollutants are retained in the system even during these infrequent events. As a storm subsides, treated runoff decants out of the Vortechs system at a controlled rate, restoring the water level to a dry-weather level equal to the invert of the inlet and outlet pipes. The low water level facilitates easier inspection and cleaning, and significantly reduces maintenance costs by reducing pump-out volume. FLOATABLES BAFFLE WALLFLOATABLES CHAMBER LOW FLOW CONTROL OUTLET CHAMBER SWIRL CHAMBER HIGH FLOW CONTROL INLET PIPE OUTLET PIPE Vortechs • Proven performance speeds approval process • Treats peak flows without bypassing • Flow controls reduce inflow velocity and increase residence time • Unobstructed access simplifies maintenance • Shallow system profile makes installation easier and less expensive • Very low headloss • Flexible design fits multiple site constraints Vortechs® PDF compression, OCR, web optimization using a watermarked evaluation copy of CVISION PDFCompressor Page 4 | Learn more at www.ContechES.com/HDS VortSentry® HS VortSentry HS • Helical flow pattern enhances trapping and containment of pollutants • High treatment and bypass capacities • Compact footprint ideal for congested sites • Lightweight design easy to install • Available in both inline and grate inlet configurations • Quick manufacturing turnaround time Engineered performance and installation simplicity The VortSentry HS system employs a helical flow pattern that enhances trapping and containment of pollutants and provides effective removal of settleable solids and floating contaminants from urban runoff. With the ability to accept a wide range of pipe sizes, the VortSentry HS can treat and convey flows from small to large sites. A unique internal bypass design means higher flows can be diverted without the use of external bypass structures. The design of the VortSentry HS minimizes adverse velocities or turbulence in the treatment chamber. This helps to prevent the washout of previously captured pollutants even during peak conditions. The VortSentry HS is also available in a grate inlet configuration, which is ideal for retrofits. How does it work? Flows from low intensity storms, which are most frequent, are directed into the treatment chamber through the primary inlet. The tangentially oriented downward pipe induces a swirling motion in the treatment chamber that increases capture and containment abilities. Moderate storm flows are directed into the treatment chamber through the secondary inlet, which allows for capture of floating trash and debris. The secondary inlet also provides for treatment of higher flows without significantly increasing the velocity or turbulence in the treatment chamber. This allows for a more quiescent separation environment. Settleable solids and floating pollutants are captured and contained in the treatment chamber. Flow exits the treatment chamber through the outlet flow control, which manages the amount of flow that is treated and helps maintain the helical flow patterns developed within the treatment chamber. Flows exceeding the system’s rated treatment flow are diverted away from the treatment chamber by the flow partition. Internal diversion of high flows eliminates the need for external bypass structures. During bypass, the head equalizing baffle applies head on the outlet flow control to limit the flow through the treatment chamber. This helps prevent re-suspension of previously captured pollutants. OUTLETPIPE INLET PIPE PRIMARY INLET TREATMENT CHAMBER OUTLET FLOW CONTROL FRAME GRATE FLOW PARTITION SECONDARY INLET GRATE INLET HEAD EQUALIZING BAFFLE SEDIMENT STORAGE SUMP PDF compression, OCR, web optimization using a watermarked evaluation copy of CVISION PDFCompressor Learn more at www.ContechES.com/HDS|Page 5 Available Models CDS Model Typical Internal MH Diameter or Equivalent ID1 (ft) Typical Depth2 Below Pipe Invert (ft) Treatment Capacity3 (cfs) Screen Diameter/ Height (ft) Maximum Sediment Storage Capacity (CF) 2015_4 4 4.5 1.4 2.0/1.5 50 w/ 1' added sump 4 5.5 1.4 2.0/1.5 63 w/ 2' added sump 4 6.5 1.4 2.0/1.5 75 w/ 3' added sump 4 7.5 1.4 2.0/1.5 88 2015 5 4.7 1.4 2.0/1.5 79 w/ 1' added sump 5 5.7 1.4 2.0/1.5 98 w/ 2' added sump 5 6.7 1.4 2.0/1.5 118 2020 5 5.3 2.2 2.0/2.0 90 w/ 1' added sump 5 6.3 2.2 2.0/2.0 110 w/ 2' added sump 5 7.3 2.2 2.0/2.0 129 2025 5 5.6 3.2 2.0/2.5 97 w/ 1' added sump 5 6.6 3.2 2.0/2.5 117 w/ 2' added sump 5 7.6 3.2 2.0/2.5 136 3020 6 5.4 3.9 3.0/2.0 134 w/ 1' added sump 6 6.4 3.9 3.0/2.0 163 w/ 2' added sump 6 7.4 3.9 3.0/2.0 191 3030 6 6.2 6.1 3.0/3.0 157 w/ 1' added sump 6 7.2 6.1 3.0/3.0 185 w/ 2' added sump 6 8.2 6.1 3.0/3.0 213 4030 8 7.2 7.9 4.0/3.0 329 w/ 1' added sump 8 8.2 7.9 4.0/3.0 379 w/ 2' added sump 8 9.2 7.9 4.0/3.0 429 4040 8 8.3 12.4 4.0/4.0 381 w/ 1' added sump 8 9.3 12.4 4.0/4.0 431 w/ 2' added sump 8 10.3 12.4 4.0/4.0 482 1. Structure diameter represents the typical inside dimension of the concrete structure. Offline systems will require additional concrete diversion components 2. Depth below pipe can vary to accommodate site specific design. Depth below pipe invert represents the depth from the pipe invert to the inside bottom of concrete structure. 3. Treatment Capacity is based on laboratory testing using OK-110 (average d50 particle size of approximately 100 microns) and a 2400 micron screen. Sediment Depths Indicating Required Servicing* CDS Model Sediment Depth (in.) 2015_4 18" 2015 18" 2020 18" 2025 18"3020 18" 3030 18" 4030 27" 4040 27" Every 1' of added sump depth Add 9" * Based on 75% capacity of isolated sump. PDF compression, OCR, web optimization using a watermarked evaluation copy of CVISION PDFCompressor Page 6 | Learn more at www.ContechES.com/HDS Vortechs Model Swirl Chamber Diameter Internal Length Peak Treatment Flow1 Sediment Storage2 ft m ft m cfs L/s yd3 m3 1000 3 0.9 9 2.7 1.6 45.3 0.7 0.5 2000 4 1.2 10 3 2.8 79.3 1.2 0.9 3000 5 1.5 11 3.4 4.5 127.4 1.8 1.4 4000 6 1.8 12 3.7 6 169.9 2.4 1.8 5000 7 2.1 13 4 8.5 240.7 3.2 2.4 7000 8 2.4 14 4.3 11 311.5 4 3.1 9000 9 2.7 15 4.6 14 396.4 4.8 3.7 11000 10 3 16 4.9 17.5 495.5 5.6 4.3 16000 12 3.7 18 5.5 25 707.9 7.1 5.4 1. Peak Treatment Flow is maximum flow treated for each unit listed. This flow represents an infrequent storm event such as a 10 or 25 yr storm. Standard Vortechs System depth below invert is 3’ for all precast models. Cast-in-place system are available to treat higher flows. Check with your local representatives for specifications. 2. Maintenance recommended when sediment depth has accumulated to within 12-18 inches of the dry weather water surface elevation. VortSentry HS Model Swirl Chamber Diameter (ft) Typical Depth Below Invert (ft) Treatment Capacity (cfs)1 Max. Inlet/Outlet Pipe Diameter (in) Maximum Sediment Storage Capacity (CF) VortSentry HS36*3 5.6 0.55 18 39 w/ 1' added sump 3 6.6 0.55 18 47 w/ 2' added sump 3 7.6 0.55 18 54 w/ 3' added sump 3 8.6 0.55 18 61 w/ 4' added sump 3 9.6 0.55 18 68 w/ 5' added sump 3 10.6 0.55 18 75 VortSentry HS48**4 6.8 1.2 24 85 w/ 1' added sump 4 7.8 1.2 24 97 w/ 2' added sump 4 8.8 1.2 24 110 w/ 3' added sump 4 9.8 1.2 24 123 w/ 4' added sump 4 10.8 1.2 24 135 VortSentry HS60***5 8.0 2.2 30 156 w/ 1' added sump 5 9.0 2.2 30 176 w/ 2' added sump 5 10.0 2.2 30 196 w/ 3' added sump 5 11.0 2.2 30 215 *maintenance recommended when sediment reaches a height of 3’-7” below water surface elevation in sump. **maintenance recommended when sediment reaches a height of 4’-9” below water surface elevation in sump. ***maintenance recommended when sediment reaches a height of 6.0’ below water surface elevation in sump. 1. Design Flow Rate is based on 80% removal of particle size distribution with an average particle size of 240 micron. This flow also represents the maximum flow prior to which bypass occurs. Notes: Systems can be sized based on a water quality flow (e.g. 1 inch storm) or on a net annual basis depending on the local regulatory requirement. When sizing based on a water quality storm, the required flow to be treated should be equal or less than the listed water quality flow for the selected system. Systems sized based on a water quality storm are generally more conservatively sized. Additional particle size distributions are available for sizing purposes upon request. Depth below invert is measured to the inside bottom of the system. This depth can be adjusted to meet specific storage or maintenance requirements. Contact our support staff for the most cost effective sizing for your area. Available Models PDF compression, OCR, web optimization using a watermarked evaluation copy of CVISION PDFCompressor Learn more at www.ContechES.com/HDS|Page 7 Customer Support Installation Contech products are some of the easiest to install in the industry. We provide comprehensive installation drawings, details and instructions, as well as full technical support on every project. Maintenance Maintenance of Contech Stormwater Solutions products is cost effective, straightforward and efficient. We offer a complete range of engineering planning, design and drawing, and construction services that can be tailored to your specific site needs. Inspection Contech has created a network of Certified Maintenance Providers (CCMP’s) to provide maintenance on your stormwater BMP’s. CCMP’s agree to: • Inspect and maintain systems in accordance to the manufacturer’s specifications • Provide maintenance only when necessary to avoid undue costs to system owners • Utilize only OEM replacement cartridges • Provide quality reports to system owners • Allow Contech to audit maintenance events to ensure quality • Maintain the highest level of service standards FactoryCertifiedMaintenanceProvider PDF compression, OCR, web optimization using a watermarked evaluation copy of CVISION PDFCompressor Page 8 | Learn more at www.ContechES.com/HDS 800.338.1122 www.ContechES.com ©2014 Contech Engineered Solutions LLC Contech Engineered Solutions provides site solutions for the civil engineering industry. Contech’s portfolio includes bridges, drainage, sanitary sewer, stormwater and earth stabilization products. For information on other Contech division offerings, visit ContechES.com or call 800.338.1122. NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS AN EXPRESSED WARRANTY OR AN IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE. SEE THE CONTECH STANDARD CONDITION OF SALES (VIEWABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. The product(s) described may be protected by one or more of the following US patents: 5,322,629; 5,624,576; 5,707,527; 5,759,415; 5,788,848; 5,985,157; 6,027,639; 6,350,374; 6,406,218; 6,641,720; 6,511,595; 6,649,048; 6,991,114; 6,998,038; 7,186,058; 7,296,692; 7,297,266 related foreign patents or other patents pending. Vortechs, VortSentry HS, and CDS are trademarks, registered trademarks, or licensed trademarks of Contech Engineered Solutions LLC Support • Drawings and specifications are available at www.ContechES.com. • Site-specific design support is available from our professional engineering staff engineers. ENGINEERED SOLUTIONS HDS Products-4 PDF 03/14PDF compression, OCR, web optimization using a watermarked evaluation copy of CVISION PDFCompressor Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Appendix F: Construction Period Erosion Control Plan R LEVESQUE ASSOCIATES, INC A L AND PL ANNING SERVICES COMPANY 40 School Street · Westfield, MA 01085 p 413.568.0985 · f 413.568.0986 · www.rlaland.com Construction Period Erosion Control Plan Proposed Self Storage Facility Easthampton Road Northampton, Massachusetts (Parcel: 44-031-001) Applicant: Platinum Self Storage 2100 Main St. Suite 106 Irvine, CA 92614 Owner: Robert D. Raymond P.O. Box Easthampton, MA 01027 RLA Project File: 180614 Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 1 The project shall implement a construction period erosion control plan. The following provides descriptions and guidelines to ensure that the areas surrounding the project site will be protected from excessive sedimentation and runoff during construction. 1.1 Construction Period Pollution Prevention And Erosion Control Measures 1.1.1 Preconstruction Notifications And Meetings Prior to the start of construction, the contractor shall call together a pre-construction meeting including a representative from the City/Town, the design engineer, contractor, and any pertinent persons that should be in attendance. These requirements shall be the responsibility of the Contractor to arrange, attend, and document. 1.1.2 Sediment Barrier And Work Limit Before installation of the sediment barriers, the location shall be staked in the field for review and approval by the owner or their representative. To facilitate sediment barrier installation, woody vegetation may then be removed and any required trench may be cut by machine, provided all other ground cover is left intact. No excavation, grading, filling, or removal of vegetative ground cover shall begin until sediment barriers have been installed as shown on the plans and have been inspected by the owner or their representative. 1.1.3 Silt Fence The bottom of the fence shall be trenched into the ground a minimum of 6" and back-filled with compacted soil. Where trenching is not feasible, silt fence skirt shall be covered with compacted soil or crushed stone. The top of the fabric shall be stretched as tightly as is practical, with intermediate stakes added to correct excessive sags. Stakes shall be driven at least 12" into the ground. Splices between sections shall be made by rolling end stakes together one complete turn and driving into the ground together. 1.1.4 Straw Bales Straw bales may be used as temporary and moveable control measures, temporary check dams, or as reinforcement for silt fence in areas of concentrated runoff or high fills. Bales shall be tightly butted and staked 12" into the ground. Where used without silt fence in front, the bales shall be trenched 4" into the ground, back-filled with compacted soil, and the spaces between bales shall be chinked with loose hay. 1.1.5 Filter Sock (Filtrexx Or Equivalent) In areas of expected sheet flow, filter sock may be placed directly on the ground without trenching or stakes. In areas of expected concentrated flow, mulch or crushed stone shall be placed along the up-slope face to control and filter underflow. Additional layers of Filter Sock may be required for adequate freeboard. The filter sock shall be staked at 10 feet on-center or in cases where they cannot be staked, utilize heavy concrete blocks to hold in place. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 2 1.1.6 Temporary Sedimentation Basins Temporary sediment basins may be excavations or bermed stormwater detention structures (depending on grading) that will retain runoff for a sufficient period of time to allow suspended soil particles to settle out prior to discharge. These temporary basins will be located based on construction needs as determined by the contractor and outlet devices will be designed to control velocity and sediment. Points of discharge from sediment basins will be stabilized to minimize erosion. If the temporary basin is to be located within an area of future infiltration as part of the stormwater management system, the excavation shall be limited to one foot above final grade of the infiltration structure. 1.1.7 Stocking Additional Materials A stock of additional erosion control materials shall be available on the site for emergency repairs and temporary measures. Stock shall be replenished when decreased to 50% of the numbers below. Stock shall include: Straw Bales – 10 (kept dry) with 20 oak stakes Or Silt Fence – 30 Linear feet. Or Filter Sock – 4 – 8 foot sections (kept dry) Washed Stone – One (1) cubic yard, ¾” to 2” diameter 1.1.8 Trench Protection Open trenches shall be protected from accumulation of surface water or groundwater that could result in erosion of the trench and discharge of sediment. Where feasible, spoil shall be stockpiled on the up-slope side of the trench to prevent entrance of surface runoff. Backfill shall be crowned to allow for settlement and to avoid concentration of runoff on top of the trench. 1.1.9 Site Stabilization – Temporary Where a portion of the site will not be subject to construction activity for over 14 days, measures shall be taken to provide temporary stabilization of that inactive portion of the site, within 14 days of the cessation of construction activity. Stabilization measures may include seeding for temporary cover, mulching, or other measures to protect exposed soil from erosion and prevent sediment movement. 1.1.10 Site Stabilization – Permanent Within 14 days of completion of loaming and finish grading on any portion of the site, that area shall be seeded or planted for permanent cover (season permitting) in accordance with USDA NRCS guidelines or equivalent. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 3 1.1.11 Roadway Sweeping The entrance to the site and affected portions of the access drive or paved project areas shall be swept as needed to control sediment runoff into storm drains or waterways and to control blowing dust. 1.2 Short-Term Erosion Control Maintenance The following provides short-term erosion control maintenance guidelines and requirements. 1. The contractor or subcontractor will be responsible for implementing each control shown on the sedimentation and erosion control plan. 2. All erosion and sediment control devices shall be properly maintained during all phases of construction until the completion of all construction activities and all disturbed areas have been stabilized. Additional control measures will be installed during construction in order to control erosion and/or off-site sedimentation if deemed necessary by on-site inspection. 3. Effective erosion control measures shall be initiated prior to the commencement of clearing, grading, excavation, or other operations that will disturb the natural protection. 4. All sediment and erosion control devices shall be inspected at least once every seven (7) calendar days and after any storm event greater than 0.5 inches of precipitation during any 24-hour period, and the inspection shall be documented in writing. Damaged or ineffective devices shall be repaired or replaced, as necessary. 5. The contractor shall take all reasonable precautions to avoid excess erosion of the site due to the construction of this project. 6. Silt shall be removed from behind barriers if greater than 6-inches deep or as needed. Sediment that is collected in structures shall be disposed of properly and covered if stored on-site 7. Damaged or deteriorated items will be repaired immediately after identification. 8. All ditches shall be stabilized as soon as is practicable to minimize erosion. 9. The contractor shall maintain all erosion control devices in a good, working state of repair. Upon complete stabilization of any tributary areas, the erosion control devices shall be removed and disposed of so as to cause no off-site siltation. 10. Inspect and maintain construction entrance stone such that sediment does not track onto the street. Any sediment tracked onto the street shall be swept daily. 11. After catch basins have been constructed, the contractor shall protect the inlets by constructing inlet protection as shown on the plans. 12. Once the site has been paved, all catch basin inlets shall receive a silt sack type protection. 13. Erosion control measures shall remain in place until all disturbed earth has been substantially stabilized. After removal of structures, disturbed areas shall be regraded and stabilized as necessary. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Appendix G: Long-Term Operation and Maintenance Plan - Long-Term Operation & Maintenance Plan - CDS Inspection and Maintenance Guide & Inspection Log - O&M Checklist R LEVESQUE ASSOCIATES, INC A L AND PL ANNING SERVICES COMPANY 40 School Street · Westfield, MA 01085 p 413.568.0985 · f 413.568.0986 · www.rlaland.com Long-Term Operation & Maintenance Plan Proposed Self Storage Facility Easthampton Road Northampton, Massachusetts (Parcel: 44-031-001) Applicant: Platinum Self Storage 2100 Main St. Suite 106 Irvine, CA 92614 Owner: Robert D. Raymond P.O. Box Easthampton, MA 01027 RLA Project File: 180614 Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 1 1. Long-Term Stormwater Maintenance Program: This Long-Term Operation and Maintenance Plan (O&M) identifies inspection and maintenance requirements for the proposed stormwater management system. The O&M references guidelines set forth by the Stormwater Management Handbook developed by the Massachusetts Department of Environmental Protection. Owner: Robert D. Raymond P.O. Box Easthampton, MA 01027 Responsible Party*: Platinum Self Storage 2100 Main St. Suite 106 Irvine, CA 92614 *The party listed shall be responsible for implementation and record keeping of the requirements listed in this operation and maintenance plan. Upon sale of property or any other transition of ownership, the responsible party shall be reinstated as the new owner or any other group created as determined by the owner. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 2 2. Inspection and Maintenance Program: Regular inspection and routine maintenance are necessary to ensure that the stormwater management system continues to control and treat runoff. The following lists the inspection schedule and maintenance procedures for the proposed stormwater Best Management Practices: BMP Inspection Schedule Maintenance Schedule Maintenance Procedures Bituminous Concrete Pavement Four times per year Twice per year  Roadway to be swept in March or April following snow melt and again in late November or early December to remove fallen leaves and debris Deep-Sump Catch Basins Four times per year Four times per year  Remove sediment once deposits reach one half the depth from the bottom sump to the lowest invert. Stormwater Piping Once per year Once per year  Inspect pipe entrances in catch basins and manholes and remove any blockages Roof Leaders Once per year Once per year  Inspect downspout connections at grade and remove any blockages  Open and inspect cleanout locations and remove any blockages CDS Water Quality Unit* As specified by the manufacturer As specified by the manufacturer  Clean the unit using the method specified by the manufacturer. Vactor trucks are typically used to clean these units. Sediment Forebay Monthly Four times per year  Remove sediment when it reaches six inches;  Mow the grass to no less than 3 inches and no greater than 6 inches;  Replace vegetation damaged during sediment removal. Extended Dry Detention Basin  After every major storm for the first three months;  Twice per year thereafter. Twice Per year  Check for signs of differential settlement, cracking, erosion, leakage in the embankments, tree growth, riprap condition, sediment accumulation, and health of the turf;  Mow side slopes and basin bottom and remove clippings;  Remove accumulated trash and debris. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 3 BMP Inspection Schedule Maintenance Schedule Maintenance Procedures Flared End Section Four times per year As Needed  Remove any debris or vegetation around the flared end section such that flow out of the structure is not impeded. Bio-Retention Areas Once per month Twice per year (Spring and Fall)  Inspect bio-retention areas for sediment build- up, structural damage, and standing water;  Inspect and repair eroded areas monthly;  Re-mulch void areas as needed;  Remove litter and debris monthly;  Treat diseased or distressed vegetation as needed;  Remove and replace dead vegetation twice per year (Spring and Fall);  Inspect for and remove invasive species as needed;  Replace mulch every two years. *See attached Device Operation and Maintenance Guides See the attached Long-Term O&M Inspection Checklist for record keeping purposes. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 4 3. Additional Long-Term Operation and Maintenance Items The following is a list of additional operation and maintenance items to be implemented by the owner/governing group to maintain the features proposed in this project. A. Proper storage, use, and disposal of hazardous chemicals, including automobile fluids, pesticides, paints, solvents, etc. shall be required. Information should be provided on chemicals of concern, proper use, and disposal options. Recycling programs for used motor oil, antifreeze, and other products should be developed. B. Vehicle Washing. This management measure involves educating the owner on the water quality impacts of the outdoor washing of vehicles and how to avoid allowing polluted runoff to enter the storm drain system. Outdoor vehicle washing has the potential to result in high loads of nutrients, metals, and hydrocarbons which is conveyed by the detergent-rich water into storm drains. C. Recycling, spill prevention and response plans, and proper material storage and disposal of potentially hazardous materials shall be implemented. It will be the responsibility of the owner to contain and legally remove any materials that are spilled onsite. The use of dry floor cleaners and absorbent materials and limiting the use of water to clean pavement is encouraged. Care should be taken to avoid accidental disposal of hazardous materials. D. Provisions for storing trash and waste products shall be implemented. The waste materials shall be collected by the owner and all materials shall be properly disposed of. E. Requirements for routine inspections and maintenance of stormwater best management practices. Routine inspections shall be performed to ensure the correct functioning of stormwater best management practices. See the specific maintenance criteria for detail regarding inspections and maintenance frequency. F. Requirements for Storage and Use of Fertilizers, Herbicides, and Pesticides. Fertilizers, pesticides, herbicides, lawn care chemicals, or other leachable materials shall be used in accordance with the Lawn Care Regulations of the Massachusetts Pesticide Board, 33 CMR 10.03 (30,31), as amended, with manufacturer’s label instructions and all other necessary precautions to minimize adverse impacts on surface and groundwater. The storage of any such materials shall be within structure designed to prevent the escape of contaminated runoff or leachate. G. Provisions for prevention of illicit discharges to the stormwater management system shall be implemented. Any illicit discharges to the stormwater management system shall be prohibited. It will be the owner’s responsibility to ensure compliance with the legal disposal of all materials and containment/cleanup of any illicit discharges. H. Training for staff or personnel involved with implementation of the Long-Term Pollution Prevention Plan shall be required. The owner/governing group will be responsible for the implementation of the measures set forth in the Long-Term Pollution Prevention Plan. Documentation that personnel and owners involved with the implementation of the Long-Term Pollution Prevention Plan have been trained to conduct such tasks shall be documented. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 5 4. Winter and Snow Conditions The following is a list of additional operation and maintenance items to be implemented by the owner during winter and snow conditions. A. Snowfall shall be stored on the grassed areas surrounding the pavement areas, excluding any areas utilized for stormwater management practices. As needed, any snow that cannot be stored on site shall be trucked off site and disposed of properly. B. Winter road salt and/or sand use and storage restrictions shall be implemented based on any restrictions issued for the project. Sodium chloride for ice control shall be used at the minimum salt to sand ratio which is consistent with the Massachusetts Department of Environmental Protections guidelines. Sodium chloride, calcium chloride, chemically treated abrasives or other chemicals used for the removal of ice and snow on roads/drives shall not be stored on site. 5. Public Safety Features The proposed site design utilizes the following features which have been incorporated to ensure the safety of the public: A. Control and collection of stormwater runoff through positive drainage and curbing directing it towards the drainage inlets; B. Heavy-duty stormwater drain manhole covers and catch basin grates have been designed to withstand H20 loading; C. Reduction of peak discharge rates from the site in the post-development condition as compared to the pre-developed conditions; D. Development and implementation of an Operations & Maintenance Plan to ensure the stormwater management system continues to function as designed. 6. Invasive Species Management The proposed site design utilizes bio-retention areas, planted with native species, which should be monitored for the establishment of invasive species which can create a monoculture and decrease the functionality of the system. The bio-retention areas shall be inspected monthly for the presence of invasive species by a person with knowledge/training in invasive species identification. Any invasive species found shall be removed by cutting or removal of the entire plant if necessary or as recommended for the specific plant by the Massachusetts Invasive Plant Advisory Group’s “Strategic Recommendations for Managing Invasive Plants in Massachusetts”. Invasive species cuttings shall be removed and disposed of outside of the bio retention area in a manner as to not encourage regrowth from seeds or cut fragments. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 6 7. Estimated Cost of Maintenance The following budget was prepared as an estimate of inspection and maintenance costs for the stormwater management system. The budget is an estimate only as the costs may vary depending on the level of sediment accumulation and frequency of maintenance tasks required. BMP Inspections Number of Occurrences Maintenance Cost Number of Structures Sum Catch Basin 4/year $30 7 $840 CDS Water Quality Unit 2/year $100 2 $400 Sediment Forebay 2/year $50 2 $200 Detention Basin 2/year $75 2 $300 Bio-Retention Area 12/year $50 2 $1,200 Total Estimated Annual Cost of Inspections $2,940 BMP Maintenance Number of Occurrences Maintenance Cost Number of Structures Sum Catch Basin 4/year $100 7 $2,800 CDS Water Quality Unit 2/year $500 2 $2,000 Sediment Forebay 2/year $300 2 $1,200 Detention Basin 2/year $500 2 $2,000 Bio-Retention Area 2/year $300 2 $1,200 Total Estimated Annual Cost of Maintenance $9,200 CDS® Inspection and Maintenance Guide ENGINEERED SOLUTIONS Maintenance The CDS system should be inspected at regular intervals and maintained when necessary to ensure optimum performance. The rate at which the system collects pollutants will depend more heavily on site activities than the size of the unit. For example, unstable soils or heavy winter sanding will cause the grit chamber to fill more quickly but regular sweeping of paved surfaces will slow accumulation. Inspection Inspection is the key to effective maintenance and is easily performed. Pollutant transport and deposition may vary from year to year and regular inspections will help ensure that the system is cleaned out at the appropriate time. At a minimum, inspections should be performed twice per year (e.g. spring and fall) however more frequent inspections may be necessary in climates where winter sanding operations may lead to rapid accumulations, or in equipment washdown areas. Installations should also be inspected more frequently where excessive amounts of trash are expected. The visual inspection should ascertain that the system components are in working order and that there are no blockages or obstructions in the inlet and separation screen. The inspection should also quantify the accumulation of hydrocarbons, trash, and sediment in the system. Measuring pollutant accumulation can be done with a calibrated dipstick, tape measure or other measuring instrument. If absorbent material is used for enhanced removal of hydrocarbons, the level of discoloration of the sorbent material should also be identified during inspection. It is useful and often required as part of an operating permit to keep a record of each inspection. A simple form for doing so is provided. Access to the CDS unit is typically achieved through two manhole access covers. One opening allows for inspection and cleanout of the separation chamber (cylinder and screen) and isolated sump. The other allows for inspection and cleanout of sediment captured and retained outside the screen. For deep units, a single manhole access point would allows both sump cleanout and access outside the screen. The CDS system should be cleaned when the level of sediment has reached 75% of capacity in the isolated sump or when an appreciable level of hydrocarbons and trash has accumulated. If absorbent material is used, it should be replaced when significant discoloration has occurred. Performance will not be impacted until 100% of the sump capacity is exceeded however it is recommended that the system be cleaned prior to that for easier removal of sediment. The level of sediment is easily determined by measuring from finished grade down to the top of the sediment pile. To avoid underestimating the level of sediment in the chamber, the measuring device must be lowered to the top of the sediment pile carefully. Particles at the top of the pile typically offer less resistance to the end of the rod than consolidated particles toward the bottom of the pile. Once this measurement is recorded, it should be compared to the as-built drawing for the unit to determine weather the height of the sediment pile off the bottom of the sump floor exceeds 75% of the total height of isolated sump. Cleaning Cleaning of a CDS systems should be done during dry weather conditions when no flow is entering the system. The use of a vacuum truck is generally the most effective and convenient method of removing pollutants from the system. Simply remove the manhole covers and insert the vacuum hose into the sump. The system should be completely drained down and the sump fully evacuated of sediment. The area outside the screen should also be cleaned out if pollutant build-up exists in this area. In installations where the risk of petroleum spills is small, liquid contaminants may not accumulate as quickly as sediment. However, the system should be cleaned out immediately in the event of an oil or gasoline spill should be cleaned out immediately. Motor oil and other hydrocarbons that accumulate on a more routine basis should be removed when an appreciable layer has been captured. To remove these pollutants, it may be preferable to use absorbent pads since they are usually less expensive to dispose than the oil/water emulsion that may be created by vacuuming the oily layer. Trash and debris can be netted out to separate it from the other pollutants. The screen should be power washed to ensure it is free of trash and debris. Manhole covers should be securely seated following cleaning activities to prevent leakage of runoff into the system from above and also to ensure that proper safety precautions have been followed. Confined space entry procedures need to be followed if physical access is required. Disposal of all material removed from the CDS system should be done in accordance with local regulations. In many jurisdictions, disposal of the sediments may be handled in the same manner as the disposal of sediments removed from catch basins or deep sump manholes. CDS Diameter Distance from Water Surface Sediment Model to Top of Sediment Pile Storage Capacity ft m ft m yd3 m3 CDS2015-4 4 1.2 3.0 0.9 0.9 0.7 CDS2015 5 1.5 3.0 0.9 1.3 1.0 CDS2020 5 1.5 3.5 1.1 1.3 1.0 CDS2025 5 1.5 4.0 1.2 1.3 1.0 CDS3020 6 1.8 4.0 1.2 2.1 1.6 CDS3030 6 1.8 4.6 1.4 2.1 1.6 CDS3035 6 1.8 5.0 1.5 2.1 1.6 CDS4030 8 2.4 4.6 1.4 5.6 4.3 CDS4040 8 2.4 5.7 1.7 5.6 4.3 CDS4045 8 2.4 6.2 1.9 5.6 4.3 CDS5640 10 3.0 6.3 1.9 8.7 6.7 CDS5653 10 3.0 7.7 2.3 8.7 6.7 CDS5668 10 3.0 9.3 2.8 8.7 6.7 CDS5678 10 3.0 10.3 3.1 8.7 6.7 Table 1: CDS Maintenance Indicators and Sediment Storage Capacities 800.925.5240www.ContechES.com Support• Drawings and specifications are available at www.contechstormwater.com. • Site-specific design support is available from our engineers. ©2014 Contech Engineered Solutions LLC Contech Engineered Solutions LLC provides site solutions for the civil engineering industry. Contech’s portfolio includes bridges, drainage, sanitary sewer, stormwater, earth stabilization and wastewater treament products. For information, visit www.ContechES.com or call 800.338.1122 NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS AN EXPRESSED WARRANTY OR AN IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE. SEE THE CONTECH STANDARD CONDITION OF SALES (VIEWABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. The product(s) described may be protected by one or more of the following US patents: 5,322,629; 5,624,576; 5,707,527; 5,759,415; 5,788,848; 5,985,157; 6,027,639; 6,350,374; 6,406,218; 6,641,720; 6,511,595; 6,649,048; 6,991,114; 6,998,038; 7,186,058; 7,296,692; 7,297,266; 7,517,450 related foreign patents or other patents pending. cdsMaintenance 11/14 ENGINEERED SOLUTIONS CDS Inspection & Maintenance Log CDS Model: Location: Water Floatable Describe Maintenance Date depth to Layer Maintenance Personnel Comments sediment 1 Thickness 2 Performed —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— 1. The water depth to sediment is determined by taking two measurements with a stadia rod: one measurement from the manhole opening to the top of the sediment pile and the other from the manhole opening to the water surface. If the difference between these measurements is less than the values listed in table 1 the system should be cleaned out. Note: to avoid underestimating the volume of sediment in the chamber, the measuring device must be carefully lowered to the top of the sediment pile. 2. For optimum performance, the system should be cleaned out when the floating hydrocarbon layer accumulates to an appreciable thickness. In the event of an oil spill, the system should be cleaned immediately. Project: Responsible Party: Address: Date: BPM Name:Page: 1 of 3 Operation & Maintenance Inspection Checklist BMP Element:Potential Problem:Pass Fail Recommended Remediation Bituminous Concrete Roadway Build-up of sediment over the winter months and collection of leaves during the fall months. Deep-Sump Catch Basins Sediment has accumulated to a depth greater than the original design depth for sediment storage, approximately 2-feet of sediment. Stormwater Piping Blockage of inlet/outlet pipes due to debris or sediment accumulation. Downspout connections have been damaged or disconnected. Roof leaders are surcharging at the downspout connections CDS Water Quality Units Sediment has accumulated to a depth greater that the original design depth for sediment storage. Inspector's Signature Date Resolution: Sweep roadway using a high-efficiency street sweeper. Remove the sediment and dispose of in accordance with local and state regulations. Remove any debris and sediment via proper means. Dispose of debris/sediment in accordance with local & state regulations. Open and insepct at cleanout locations and remove any blockages. Roof Leaders Repair and reconnect downspout connections. Remove sediment and disposed of in accordance with local and state regulations. Project: Responsible Party: Address: Date: BPM Name:Page: 2 of 3 Operation & Maintenance Inspection Checklist BMP Element:Potential Problem:Pass Fail Recommended Remediation Excessive sediment accumulation. Erosion is occuring on the side slope or around the flared end section. Debris has collected inside the basin. Sediment has accumulated to 6" or above. Standing water inside basin. Erosion is occuring on the side slope or around the flared end section. Trees/Shrubs are starting to grow within the basin. Debris has collected inside the basin. Vegetation has started to grow within the riprap area. Accumulation of sediment/debris at the culvert inlet. Erosion is occuring where riprap has been dislodged. Inspector's Signature Date Sediment Forebay Remove sediment and debris. Remedy scoured area and/or replace riprap immediately. Remove debris and remedy any damage Remove the sediment and restablish the sediment forebay with vegetaion to the original bottom elevation Detention Basin Remedy scoured area and replace vegetation. Remove trees/shrubs and vegetate with grass. Flared End Sections Remove vegetation immediately. Remedy scoured area and replace riprap immediately. Remove sediment or debris such that the culvert has free flow. Resolution: Verify that sediment is not entering the basin. Remove collected sediment and scour basin bottom. Replace damaged vegetation Remove debris and remedy any damage caused. Project: Responsible Party: Address: Date: BPM Name:Page: 3 of 3 Operation & Maintenance Inspection Checklist BMP Element:Potential Problem:Pass Fail Recommended Remediation Sediment has accumulated over mulched surface. Erosion has occurred at inlets. Areas are devoid of mulch. Litter and/or debris has accumulated in bio-retention area. Vegetation has died or is distressed. Inspector's Signature Date Resolution: Bio-Retention Area Remove sediment and mulch mixture and replace mulch. Repair any eroded areas and replace with appropriate materials. Replace mulch as necessary. Remove litter and/or debris. Replace vegetation as necessary. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Appendix H: Illicit Discharge Compliance Statement Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts Illicit Discharge Compliance Statement The owners of the land/responsible party will be responsible for prohibiting illicit discharges to the stormwater management system during construction and during its life of operation. The stormwater management system is comprised of the components for conveying, treating, and infiltrating stormwater runoff on-site, including stormwater best management practices and any pipes intended to transport stormwater to the groundwater, a surface water, or municipal separate storm sewer system. An illicit discharge shall constitute any connection or discharge to the stormwater management system including, but not limited to, wastewater discharges, discharge of stormwater contaminated by contact with process wastes, raw materials, toxic pollutants, hazardous substances, oil, or grease. Responsible Party*: Platinum Self Storage 2100 Main St. Suite 106 Irvine, CA 92614 *The party listed shall be responsible for implementation and record keeping of the requirements listed in this operation and maintenance plan. Upon sale of property or any other transition of ownership, the responsible party shall be reinstated as the new owner or any other group created as determined by the owner. Signature of Responsible Party Representative Date Signature of Responsible Party Representative** Date **Required upon transfer of ownership Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Appendix I: Northampton DPW Inspection Schedule Northampton DPW Inspection Schedule Sign-Off Sheet Inspection Schedule Description Date of Inspection Inspector Passed Failed Notes Initial Inspection Prior to approval of any plan. After site clearing Rough Grading Final Grading Bury Inspection Prior to backfilling of any underground drainage or stormwater conveyance structures. Final Inspection Conducted when all work, inlcuding construction of stormwater management facilities and landscaping have been completed. Final inspection shall include a full, dated TV inspcetion of all stormwater pipes installed. Erosion and Sediment Control Inspections Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Appendix J: Low Impact Development Alternatives Analysis Narrative R LEVESQUE ASSOCIATES, INC A L AND PL ANNING SERVICES COMPANY 40 School Street · Westfield, MA 01085 p 413.568.0985 · f 413.568.0986 · www.rlaland.com Low Impact Development Considerations Proposed Self Storage Facility Easthampton Road Northampton, Massachusetts (Parcel: 44-031-001) Applicant: Platinum Self Storage 2100 Main St. Suite 106 Irvine, CA 92614 Owner: Robert D. Raymond P.O. Box Easthampton, MA 01027 RLA Project File: 180614 Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 1 Introduction Per the Massachusetts Stormwater Handbook, project proponents must consider environmentally sensitive site design and low impact development techniques to effectively manage stormwater runoff. As part of the proposed project, the proponent has considered a number of environmentally sensitive, low impact development techniques to prevent the generation of stormwater and non- point source pollution. Due to site design constraints, options for low-impact development best management practice techniques were limited. However, the proposed stormwater management system design was able to incorporate some LID techniques throughout the project. The LID stormwater best management practices include a proprietary sedimentation device, surface detention basins with sediment forebays, and bioretention areas. The proposed stormwater management system has been designed to meet City of Northampton Stormwater Management Ordinance as well as the Massachusetts Department of Environmental Protection Stormwater Management Handbook. This letter serves to describe the relationship between the requirements of the MassDEP Handbook and “environmentally sensitive site design” considerations as well as the analysis of alternatives to any “point source” of “stormwater discharge” which may be regulated. The following sections provide detailed descriptions for the consideration of low impact development measures as listed by the MassDEP. Environmentally Sensitive Site Design Considerations The Department’s requirement for the inclusion of Environmentally Sensitive Site Design was considered as part of the design of the stormwater management system. These considerations include review of low impact development techniques to prevent the generation of stormwater and non-point source pollution by reducing impervious surfaces, disconnecting stormwater sheet flow paths and treating stormwater at its source, maximizing open space, minimizing disturbance, protecting natural features and processes, and/or enhancing wildlife habitat. The stormwater management system was designed to meet City of Northampton Stormwater Management Ordinance as well as the Massachusetts Department of Environmental Protection Stormwater Management Handbook. The proposed stormwater management system does not introduce any new point source discharges to resource areas. A. Disconnecting stormwater sheet flow paths and treating stormwater at its source The stormwater that is generated within the paved areas is collected reasonably close to their respective sources by the proposed catch basins. Collected stormwater is discharged to one of the four detention basins/bioretention area dispersed throughout the site in an effort to treat stormwater at it’s respective source. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 2 B. Maximizing open space Open space areas have been provided to the maximum extent practicable. The open spaces were located as efficiently as possible while still achieving functionality across the site for the applicant. Additionally, disturbed areas such as the bioretention area and landscape islands will be densely planted with native species with high wildlife characteristics. Proposed open space areas, as defined by Northampton zoning ordinance, is approximately 60% of the parcel area. This represents a significant increase over the Northampton zoning ordinance requirement of 20% minimum open space. C. Minimizing disturbance No disturbance to wetland resource areas or NHESP habitat is proposed as part of this project. D. Protecting natural features and processes The proposed stormwater management system has been designed to mimic the existing drainage patterns of the site while increasing water quality and groundwater recharge and reducing peak discharge rates. E. Enhancing wildlife habitat Impacts to wildlife habitat have been limited to functional minimums. Additionally, the proposed bioretention area and proposed landscaped areas have been densely planted with native species with high wildlife characteristics. Point Source Stormwater Discharge Alternatives Analysis Under the Department’s Outreach Document for 310 CMR 10.05(6)(k) through (q) and 314 CMR 9.06(5) & (6)(a) through (f), a list of considerations is provided for use in developing an Alternatives Analysis to point source stormwater discharge within Departmental jurisdiction. In the case of the currently proposed project, there are no new point source discharges being proposed. For ease of review, the aforementioned list is repeated below in italics with responses after each item: a. Removal of all proposed work and/or impervious surfaces from the Department’s jurisdiction; No work is proposed within Departments jurisdictional areas. b. Division of the upper portion of the subject catchments into smaller subcatchments, where resultant stormwater discharges should be completely infiltrated and/or retained; The proposed stormwater management infrastructure layout was designed in such a manner that it achieves this requirement to a logical extent. The four proposed detention basins/bioretention areas have been dispersed throughout the site in an effort to create smaller subcatchments. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 3 c. Maintaining existing drainage patterns and not mixing country drainage with untreated stormwater; The intent of this item has been achieved with the proposed layout of the stormwater management system by maintaining the existing drainage patterns of the site. d. Treatment of remaining stormwater at or proximate to its source within these subcatchments; The intent of this requirement has been achieved. Treatment of stormwater will occur within the proprietary sedimentation device and/or bioretention areas which are located proximate to source collection. e. Installation of “qualifying pervious areas” to accept stormwater discharge from roads and driveways within each subcatchment; Due to the commercial nature of the site, and the proposed use, this BMP was not implemented. f. Installation of dry wells for acceptance of roof drainage; Infiltration/attenuation of roof runoff from the proposed buildings is achieved within the proposed detention basins/bioretention areas. Due to the size of the proposed buildings and depth to groundwater dry wells were not a feasible solution for roof runoff. When considering environmental sensitive site design criteria, the use of a bioretention area for stormwater runoff is preferable to dry wells due to the increase in wildlife habitat and increase in functional lifespan. g. Disconnection of roof drainage; Due to the size of the proposed buildings, depth to groundwater and soil characteristics, infiltrating roof drainage at its respective source was impractical. h. Installation of discrete structural Best Management Practices at relatively high elevations in each subcatchment; No new point source discharges are being proposed within jurisdictional wetland resource areas. i. Further describe: 1. Reduction in impervious surfaces; Impervious surfaces are limited to the proposed buildings and the minimum paved area for required drive aisles, parking, and walkway to service for the proposed use. 2. Road width and length reductions; The access drive width is at the minimum acceptable dimension in order to provide a functional site design. 3. Clustering of impervious surfaces; The impervious surfaces have been clustered to the maximum functional extent. 4. Addition of planted materials and landscaped areas; All pervious areas are to be planted, seeded, or landscaped. Platinum Self Storage Stormwater Drainage Report Easthampton Road Northampton, Massachusetts R Levesque Associates, Inc. Page 4 5. Re-grading of landscaped areas away from jurisdictional Resource Areas and their Buffer Zones; and The general drainage patterns of the site have been maintained by the proposed site improvements and a stormwater management system has been designed to mitigate the impacts imposed by the development. No new point source discharges are being proposed within jurisdictional wetland resource areas. 6. Preservation of vegetated areas within the Buffer Zone, and immediately proximate to jurisdictional resource areas. The development area has been consolidated and no impacts to wetland areas, or their associated buffer areas, are proposed.