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HomeMy WebLinkAbout221205-Stormwater Report_21080 COMPILED STORMWATER ANALYSIS AND DRAINAGE REPORT Armstrong Kelley Park Osterville, Massachusetts Prepared for: The Trustees of Reservations 830 Drift Road Westport, MA 02790 Prepared by:   December 2022 Stormwater Analysis and Drainage Report Horsley Witten Group, Inc. Armstrong Kelley Park Project, Osterville, MA December 2022 i TABLE OF CONTENTS Page STORMWATER CHECKLIST 1.0 STORMWATER AND DRAINAGE NARRATIVE .............................................................. 1  1.1. Existing Conditions ......................................................................................................... 1  1.2. Proposed Conditions ...................................................................................................... 3  2.0 DRAINAGE DESIGN METHODOLOGY AND ANALYSIS ................................................ 5  3.0 COMPLIANCE WITH MADEP STORMWATER STANDARDS ........................................ 7  4.0 CONSTRUCTION ACTIVITIES AND GENERAL CONSTRUCTION SEQUENCE ......... 11  5.0 POLLUTANT CONTROLS DURING CONSTRUCTION ................................................. 11  5.1. Structural Practices ...................................................................................................... 11  5.2. Stabilization Practices .................................................................................................. 13  5.3. Other Types of Controls ............................................................................................... 13  6.0 STORMWATER OPERATION AND MAINTENANCE .................................................... 16  7.0 REFERENCES ................................................................................................................. 16  FIGURES Figure 1: USGS Locus Figure 2: Aerial Map Figure 3: FEMA National Flood Hazard Layer Figure 4: Existing Site Constraints Figure 5: NRCS Soils Map APPENDICES Appendix A: Site Soil Evaluations Appendix B: Drainage Area Maps Appendix C: GSI Sizing Calculations Appendix D: HydroCAD® Modeling Appendix E: TSS and Recharge Calculations Appendix F: Groundwater Mounding Armstrong Kelley-swcheck-21080.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. Armstrong Kelley-swcheck-21080.doc • 04/01/08 Stormwater Report Checklist • Page 2 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report B. Stormwater Checklist and Certification The following checklist is intended to serve as a guide for applicants as to the elements that ordinarily need to be addressed in a complete Stormwater Report. The checklist is also intended to provide conservation commissions and other reviewing authorities with a summary of the components necessary for a comprehensive Stormwater Report that addresses the ten Stormwater Standards. Note: Because stormwater requirements vary from project to project, it is possible that a complete Stormwater Report may not include information on some of the subjects specified in the Checklist. If it is determined that a specific item does not apply to the project under review, please note that the item is not applicable (N.A.) and provide the reasons for that determination. A complete checklist must include the Certification set forth below signed by the Registered Professional Engineer who prepared the Stormwater Report. Registered Professional Engineer’s Certification I have reviewed the Stormwater Report, including the soil evaluation, computations, Long-term Pollution Prevention Plan, the Construction Period Erosion and Sedimentation Control Plan (if included), the Long- term Post-Construction Operation and Maintenance Plan, the Illicit Discharge Compliance Statement (if included) and the plans showing the stormwater management system, and have determined that they have been prepared in accordance with the requirements of the Stormwater Management Standards as further elaborated by the Massachusetts Stormwater Handbook. I have also determined that the information presented in the Stormwater Checklist is accurate and that the information presented in the Stormwater Report accurately reflects conditions at the site as of the date of this permit application. Registered Professional Engineer Block and Signature Signature and Date Checklist Project Type: Is the application for new development, redevelopment, or a mix of new and redevelopment? New development Redevelopment Mix of New Development and Redevelopment 12/05/2022 Armstrong Kelley-swcheck-21080.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): Infiltration chambers, use of natural depression to manage runoff 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. Armstrong Kelley-swcheck-21080.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. Armstrong Kelley-swcheck-21080.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. Armstrong Kelley-swcheck-21080.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. Armstrong Kelley-swcheck-21080.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. Armstrong Kelley-swcheck-21080.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. Stormwater Analysis and Drainage Report Horsley Witten Group, Inc. Armstrong Kelley Park December 2022 Page 1 1.0 STORMWATER AND DRAINAGE NARRATIVE This Stormwater Analysis and Drainage Report provides a summary of the proposed stormwater management for the Armstrong Kelley Park revitalization project proposed by The Trustees of Reservations. The purpose of this report is to describe the pre- and post- development site conditions and the practices to be used for reducing stormwater runoff and pollutants during and after construction. The proposed project has been developed to incorporate a series of green stormwater infrastructure (GSI) practices into the overall site and landscape design. The design includes surface GSI bioretention facilities for pre-treatment, recharge and water quality management for 1” of runoff from impervious surfaces. An existing depression and an underground infiltration chamber system provide storage for peak flow attenuation for the 2-year, 10-year, and 100-year storms. The proposed site design conforms to the Massachusetts Stormwater Standards (MASWS) (revised in January 2008) by providing stormwater runoff treatment or the first 1-inch runoff from proposed impervious areas contributing to site runoff. On-site attenuation and infiltration are proposed to match or reduce peak runoff conditions for the 2, 10 and 100-year storm events. The proposed stormwater controls will be maintained during and after construction as part of the development regular landscape maintenance and as described further in the stand alone Stormwater Management Operation and Maintenance Plan. 1.1. Existing Conditions The project site is located at 675 Main Street in the village of Osterville (part of the Town of Barnstable), Massachusetts (Latitude 41.627941, Longitude -70.380323). The Town of Barnstable identifies the Subject Property as Map 141 Lot 38. Refer to Figures 1 and 2 for regional location and general layout of the Subject Property, respectively. According to the Town of Barnstable Assessors Office, the Subject Property consists of 8.5- acres of land. The Subject Property is a privately owned public park consisting of a gravel driveway, a garden area, woodlands, and a network of boardwalks and trails. The garden area consists of lawn, flower beds, and a variety of rare tree species. There is an isolated wetland in the southeast corner of the property that is approximately 3,500 square feet in size. There are two sheds for maintenance equipment located on the property. Wetland resource areas were identified and delineated by Horsley Witten Group, Inc. on July 14, 2021. Wetland resource areas were determined in accordance with methods developed by Massachusetts Department of Environmental Protection (MassDEP), the Massachusetts Wetlands Protection Act regulations. The site is located in the watershed of East Bay. According to MassDEP’s – Final Massachusetts Integrated List of Waters for the Clean Water Act 2018/2020 Reporting Cycle, Centerville River, including East Bay is listed as an impaired waterbody for estuarine bioassessments, fecal coliform, and total nitrogen. MassDEP developed Total Maximum Daily Loads (TMDL) for total nitrogen for Centerville River- East Bay System (December 18, 2007). Stormwater Analysis and Drainage Report Horsley Witten Group, Inc. Armstrong Kelley Park December 2022 Page 2 1.1.1. Existing Drainage The existing drainage area is 8.0 acres (350,480 square feet) and is comprised of the following land cover: Table 1: Existing Land Coverage Coverage Area (ft2) Area (acres) % Roadway 10,243 0.235 3% Roof 4,749 0.109 1% Woods 305,306 7.009 87% Grass 29,868 0.686 9% TOTAL 350,166 8.039 100 The site is divided into three sub catchments, DA1a, DA1b, and DA2. DA1a and DA1b flow to localized depression, D1. DA2 discharges via overland flow to Study Point 1 (SP1). The Existing Drainage Map is provided in Appendix B. SP1 is at the isolated wetlands in the southeastern corner of the site. DA1a is approximately 1.96 acre and drains to D1, where it infiltrates into the existing soils. In extreme storm events excess runoff would flow overland to the road (Main Street). D1 is at the southern edge of the site, west of the park entrance. The majority of the drainage area is woodlands with grass, flower beds and half of the gravel driveway. The western end of the drainage area has slopes of approximately 20% that decrease closer to the depression. DA1b is approximately 4.46 acres and drains to localized depression, D2, where it infiltrates into existing soils. Any excess runoff would flow overland to D1. DA1b is comprised of mainly woodlands with a small amount of grass. The northwestern end of the drainage area has slopes of approximately 20% that decrease closer to the depression. DA2 is approximately 1.63 acres and drains to the wetland, SP1. This drainage area consists of half of the gravel driveway, grassed area, flowerbeds, woodlands, and a portion of the adjacent residential property. 1.1.2. Soils According to the Commonwealth of Massachusetts Bureau of Geographical Information (“MassGIS”), soils underlying the Subject Property are classified as Carver Coarse Sand (HSG A) soils (Figure 5). The United States Department of Agriculture Soil Conservation Service identifies these soils as well drained to excessively drained. The NRCS Soil Map is located in Appendix A. Stormwater Analysis and Drainage Report Horsley Witten Group, Inc. Armstrong Kelley Park December 2022 Page 3 1.2. Proposed Conditions The proposed project includes the enhancement and revitalization of Armstrong Kelley Park. Elements of the project include improving parking, expanding the gardens, upgrading and extending the boardwalks and path network, removing the two existing maintenance sheds and constructing a single maintenance shed. A new parking lot is proposed, consisting of a new dense grade gravel driveway with 13 parking spaces. Site features include:  A total of 13 dense grade parking spaces  ADA accessible sidewalks and parking space  A 11,500 SF dense grade driveway  Expanded fish pond  Upgraded path network  400 SF maintenance shed  Interior landscaped areas and garden beds. 1.2.1. Stormwater Management The proposed stormwater management includes a GSI approach to capture, treat, infiltrate, and detain runoff, when applicable and to the maximum extent practicable, by using the following Stormwater Control Measures (SCM)s. Sediment Forebays Sediment forebays are provided at bioretention areas for pretreatment of surface water runoff from the proposed pavement and concrete surfaces to allow for sediment to settle from the incoming stormwater runoff prior to conveyance to the bioretention and infiltration basin/chamber systems. The forebays are designed to provide 0.1” of runoff volume as required by the Massachusetts Stormwater Standards. The sediment forebays are designed to be easily accessed on a regular basis for cleanout and sediment removal. See the Stormwater Management Operation and Maintenance Plan. Bioretention Areas (BIO) A bioretention area (sometimes referred to as a “rain garden” or a “biofilter”) is a stormwater management practice to manage and treat stormwater runoff using a conditioned planting soil bed or “filter” media and plants to filter runoff captured in a shallow depression. The method combines physical filtering and adsorption with bio-geochemical processes to remove pollutants. The system consists of an inflow component, a pretreatment element, an overflow structure, a shallow ponding area (6 inches deep), a well-drained planting soil bed, and plants. The two proposed bioretention areas have been designed with enhanced nitrogen removal features. Stormwater Analysis and Drainage Report Horsley Witten Group, Inc. Armstrong Kelley Park December 2022 Page 4 Infiltration Basins (IB) The infiltration basins are surface stormwater facilities designed to collect and temporarily store runoff before infiltration into the subsoil. The infiltration basins allow stored water to infiltrate and recharge groundwater. Infiltration basins only receive runoff from adjacent pervious and rooftop areas, and after treatment of the one-inch runoff from upgradient bioretention areas. Underground Infiltration Chambers (UIC) Underground infiltration chambers capture, and store stormwater collected from the parking area. Riser pipes, curb cuts, and/or drainage structures direct surface stormwater to subsurface interconnected storage units. When site conditions are appropriate, stored water is released directly into the ground mimicking pre-development conditions. Use of stormwater infiltration chambers allows stored water to infiltrate and recharge groundwater. 1.2.2. Drainage Areas The proposed improvements will occur within an approximately 2.5 acre area of the southern part of the 8.5 acre property. Stormwater management is proposed for the driveway and parking spaces. Table 2: Proposed Land Coverage Coverage Area (ft2) Area (acres) % Roadway 15,714 0.36 4.5% Roof 4,495 0.10 1.3% Pond/SW 1,219 0.03 0.3% Forest 285,738 6.56 81.6% Grass 43,000 0.99 12.3% Total 350,166 8.04 The proposed site drainage is divided into five subcatchments: DA1a, DA1b, DA1c, DA2, and DA3. The Proposed Drainage map is provided in Appendix B. DA1a is approximately 1.75 acre and drains to localized depression, D1, where it infiltrates into the existing soils. The majority of the drainage area is woodlands with a portion of grass and flower beds. The western end of the drainage area has slopes of approximately 20% that decrease closer to the depression. DA1b is approximately 4.28 acres and drains to localized depression, D2, where it infiltrates into existing soils. Any excess runoff would flow overland to D1. DA1b is comprised of mainly woodlands with a small amount of grass. The northwestern end of the drainage area has slopes of approximately 20% that decrease closer to the depression. DA1c is approximately 0.58 acres and consists of the proposed 20’ dense grade driveway, grassed area, flower beds, and stone dust paths. Runoff drains first to Bioretention area, BIO1, which overflows to D1 for infiltration. Stormwater Analysis and Drainage Report Horsley Witten Group, Inc. Armstrong Kelley Park December 2022 Page 5 DA2 is approximately 1.12 acres and drains to the wetland, SP1. This drainage area consists of grassed area, flowerbeds, woodlands, and a portion of the adjacent residential property. DA3 is approximately 0.32 acres and consists of the dense grade parking area, the maintenance shed, and some landscaped area. Runoff drains first to Bioretention area, BIO2, which overflows to underground infiltration chamber system, UIC1 for infiltration. 2.0 DRAINAGE DESIGN METHODOLOGY AND ANALYSIS The drainage design was completed by performing the following series of tasks:  Site soil evaluations (3 test pits) (Appendix A)  Delineation of drainage areas and sub catchments (Appendix B)  Sizing the bioretention areas and underground infiltration chamber system (Appendix C)  Modeling the proposed drainage network with HydroCAD® software (Appendix D)  TSS and Recharge calculations (Appendix E)  Stormwater Management Operation and Maintenance Plan Three soil test pits were excavated on the site to assess the subsurface conditions and determine its suitability for the construction of stormwater management practices. The soil test pit data and memo are included in Appendix A. All three test pits are located within proposed locations of stormwater management practices. The Stormwater Management System has been designed to accomplish the following major objectives:  To capture and treat, at a minimum, the “first flush” (first one-inch of stormwater runoff) from the impervious surfaces to maintain or improve water quality conditions when compared to existing conditions.  To provide groundwater recharge to the greatest extent practicable in conformance with the Massachusetts Department of Environmental Protection groundwater recharge criteria.  To meet or reduce peak flow rates for post-developed conditions as compared to pre- developed conditions at the study point.  To maximize nitrogen removal in compliance with the Mass DEP’s TMDL for total nitrogen for Centerville River- East Bay System (December 18, 2007). Stormwater Analysis and Drainage Report Horsley Witten Group, Inc. Armstrong Kelley Park December 2022 Page 6 These objectives are met through the use of the following stormwater management measures:  Bioretention systems sized to treat the first one-inch of stormwater runoff for water quality treatment of runoff from the driveway and parking area. The systems are equipped with overflows to convey runoff from larger storm events into either underground infiltration chambers or an infiltration area. Additionally, nitrogen reducing elements are incorporated in the bioretention design to maximize nitrogen removal by creating a low dissolved oxygen environment coupled with organic matter. These elements include slowing infiltration in the bioretention areas by adding a layer of loam under the bioretention and setting the outlets of the underdrains higher in the bioretention subsurface layers. (Appendix C)  Underground infiltration chambers sized to infiltrate and detain onsite runoff.  Existing infiltration area utilized to infiltrate and detain onsite runoff. The proposed Stormwater Management System was designed to accommodate pre- development site hydrologic conditions as well as reduce stormwater pollution from the proposed site conditions. Stormwater runoff quantity was evaluated for the 2-year, 10-year, 25- year, and 100-year Type III, 24-hour storm events for both pre-development and post- development conditions. Pre-development and post-development conditions were modeled using HydroCAD software, which combines USDA Soil Conservation Service hydrology and hydraulic techniques (commonly known as SCS TR-55 and TR-20) to generate hydrographs (See Appendix B for both “Existing" and "Proposed" Drainage Area Maps). The rainfall amounts used for calculating runoff for the storm events are the NOAA+ values (NOAA Atlas 14 90% Upper Confidence value multiplied by 0.9). Rainfall values are listed below in Table 4. A summary table of pre- and post-development runoff peak flow rates and volumes is provided in Table 5. Table 4: Precipitation Values for Design and Hydrological/Hydraulic Analysis Storm Frequency (24- hour – Type III Storm) Precipitation Value (inches) (NOAA+) Water Quality Event (WQv) 1” per impervious acre1 2-year 3.63 10-Year 5.32 25-Year 6.57 100-Year 8.60 Stormwater Analysis and Drainage Report Horsley Witten Group, Inc. Armstrong Kelley Park December 2022 Page 7 Stormwater runoff quality was evaluated to ensure that pollutant export from the project site was minimized to the maximum extent practicable. The stormwater management system for the site was designed in accordance with the MASWS and the applicable criteria within the Town’s Subdivision Regulations and Zoning Bylaw. Table 5: Peak Flow and Volume Comparison STUDY POINT 1 – Wetland DESIGN STORM PRE-DEVELOPMENT POST-DEVELOPMENT PERCENT REDUCTION PEAK FLOW (CFS) VOLUME (AF) PEAK FLOW (CFS) VOLUME (AF) PEAK FLOW VOLUME 2 YR 0.00 0.003 0.00 0.002 0% 33% 10 YR 0.15 0.042 0.10 0.029 33% 31% 25 YR 0.53 0.093 0.36 0.063 32% 32% 100 YR 1.78 0.206 1.20 0.141 33% 32% 3.0 COMPLIANCE WITH MADEP STORMWATER STANDARDS The Massachusetts Stormwater Standards were revised in February 2008 to include ten stormwater management standards, established jointly by the DEP and the Office of Coastal Zone Management, and published in the 2008 update of the Stormwater Management Handbook. Projects that are within the jurisdiction of the Wetlands Protection Act Regulations, 310 CMR 10.00 are subjected to these Stormwater Management Standards. For this project, adherence to the Handbook is required as the project is within the jurisdiction of the Wetlands Protection Act. Therefore, the stormwater management system was designed in accordance with the MASWS. The following is a list of Stormwater Management Standards and accompanying documentation describing compliance of the proposed retrofit project with each 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 stormwater management system was designed so that no untreated stormwater runoff associated with the project will be directed to wetland areas. Stormwater runoff will flow through the GSI practices before being infiltrated. No additional flows up to the 100-year storm event are discharged to wetland areas. 2. Stormwater management systems shall be designed so that post-development peak discharge rates do not exceed pre-development peak discharge rates. Discharge rates for pre and post-development were calculated using HydroCAD v10.10-4a, and SCS-TR20 based stormwater modeling computer program (Appendix D). To replicate predeveloped conditions all flows up to the 100-year storm event are infiltrated within the site via Stormwater Analysis and Drainage Report Horsley Witten Group, Inc. Armstrong Kelley Park December 2022 Page 8 the underground infiltration chamber system and the existing infiltrating area at the front of the site. A summary table of these precipitation events is provided in Table 5. Updated rainfall values from NOAA Atlas 14 Upper Confidence Limit were utilized for this analysis. 3. Loss of annual recharge to groundwater shall be eliminated or minimized through the use of infiltration measures including environmentally sensitive site design, low impact development techniques, stormwater best management practices, 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 recharge volume as determined in accordance with the Massachusetts Stormwater Handbook. Under the proposed design, the stormwater runoff up to the 100-year storm event is being directed to surface infiltrating bioretention, underground infiltration chambers, and the existing surface infiltration area. Recharge calculations are provided in Appendix E. The site is characterized with a high infiltration rate (greater than 2.4 in/hr.), so at least 44% of the total suspended solids must be removed prior to discharge to the infiltration structure. The required TSS pretreatment will be done through bioretention practices. TSS calculations are provided in Appendix E. Storms equal to or great than the 10-year storm are being infiltrated into soils with a separation distance to the seasonal high groundwater elevation of less than four feet, so a groundwater mounding analysis is provided in Appendix F. 4. Stormwater management systems shall be designed to remove 80% of the average annual post-construction load of Total Suspended Solids (TSS). This Standard is met when:  Suitable practices for source control and pollution prevention are identified in a long-term pollution prevention plan, and thereafter are implemented and maintained;  Structural stormwater best management practices are sized to capture the required water quality volume determined in accordance with the Massachusetts Stormwater Handbook; and  Pretreatment is provided in accordance with the Massachusetts Stormwater Handbook. The stormwater management practices are sized to capture the required water quality volume (Appendix C). The stormwater management pretreatment and treatment systems for the sites have been selected and sized for the most removal of the average annual load of TSS possible. The following removal rates were taken MA Stormwater Handbook: Bioretention (with sediment forebay): Recommended design rate: 90% Infiltration Basin (with adequate pretreatment) Recommended design rate: 80% Underground Infiltration Chambers Recommended design rate: 80% Stormwater Analysis and Drainage Report Horsley Witten Group, Inc. Armstrong Kelley Park December 2022 Page 9 (when combined with a pretreatment BMP) TSS calculations are provided in Appendix E. Source controls and pollution prevention will be controlled by the methods outlined in Sections 5.0 and 6.0. The proposed stand alone Stormwater Management Operation and Maintenance Plan was developed to ensure that the stormwater system continues to function as it was designed into the future. 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 SCMs determined by the Department 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. The site is not considered a LUHPPL; thus, this standard is not applicable. 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 best management practices determined by the Department 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. The project site is not located within a Zone II but is considered a Nitrogen Sensitive Area The project proposes to use stormwater pretreatment, treatment, and infiltration SCMs identified in Standard 6 for discharges within sensitive areas. Infiltrated stormwater likely drains to East Bay, which has been identified a nitrogen sensitive in MassDEP’s Final Massachusetts Integrated List of Waters for the Clean Water Act 2018/2020 Reporting Cycle. MassDEP developed Total Maximum Daily Loads (TMDL) for total nitrogen for Centerville River- East Bay System (December 18, 2007). Sediment forebays with filtering bioretention areas are approved treatment SCMs with 44% TSS reduction prior to infiltration occurring, and subsurface structures, and infiltration basins are approved infiltration SCMs. All are appropriate to Stormwater Analysis and Drainage Report Horsley Witten Group, Inc. Armstrong Kelley Park December 2022 Page 10 maximize nitrogen removal. Additionally, nitrogen reducing elements are incorporated in the bioretention design to maximize nitrogen removal. 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 best management practice 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. At least a portion of the project is considered redevelopment, allowing some aspects to only meet the Stormwater Standards to the maximum extent practicable. However, the project has been designed to meet the Stormwater Standards fully. 8. A plan to control construction-related impacts including erosion, sedimentation and other pollutant sources during construction and land disturbance activities (construction period erosion, sedimentation, and pollution prevention plan) shall be developed and implemented. An Erosion and Sediment Control Plan is included in construction documents, and a Pollutant Prevention Plan is included in this Report. Silt fence and/or silt socks are proposed at the limit of work; silt socks are proposed along the downgradient edges of the area of disturbance. Disturbed areas will be stabilized with seeding and mulching, as soon as possible to minimize erosion and sedimentation. Additional pollutant controls during construction are described in Section 5.0 and on the plans. A Stormwater Pollution Plan (SWPPP) is required as part of the NPDES Construction General Permit and will be submitted prior to construction. The contractor will be required to establish erosion controls prior to beginning any other project- related work. The Erosion and Sediment Control Plan will also establish the limit of work, beyond which the contractor will not be allowed to perform any project work. It is the contractor’s responsibility to monitor and correct erosion control practices throughout the duration of the project. Erosion control measures will not be removed until the project reaches completion as directed by the project engineer or landscape architect. 9. A long-term operation and maintenance plan shall be developed and implemented to ensure that stormwater management systems function as designed. The long-term stormwater operation and maintenance plan for each stormwater best management practice is discussed in Section 6.0. 10. All illicit discharges to the stormwater management system are prohibited. There will be no illicit discharges to the stormwater management system. The Long-Term Pollution Prevention Plan provided includes measures to prevent illicit discharges. Stormwater Analysis and Drainage Report Horsley Witten Group, Inc. Armstrong Kelley Park December 2022 Page 11 4.0 CONSTRUCTION ACTIVITIES AND GENERAL CONSTRUCTION SEQUENCE Construction activities will involve site preparation and earthwork necessary for construction of the proposed project. These activities primarily include the following:  Erosion control installation  Clearing and grubbing of existing vegetation within the proposed limits of work  Excavation stockpiling, and hauling of excavated foundation, topsoil and subsoils  Rough grading of all disturbed areas  Construction of stormwater management system  Construction of driveway and parking lot  Finish grading, final site stabilization and landscaping Erosion and sediment control (ESC) measures will be installed per the construction plans prior to commencement of any soil disturbing activities. ESC measures will remain in place until final site stabilization is complete. Topsoil will be separated from the remaining soil and stockpiled on-site for use during site finish grading. The stockpiled topsoil will be protected to prevent erosion and sedimentation. 5.0 POLLUTANT CONTROLS DURING CONSTRUCTION Controls will be used to reduce erosion during the construction period. Perimeter controls and sediment settling devices will be installed during construction to minimize sediment movement in stormwater and to protect the adjacent properties and buffers on the property. 5.1. Structural Practices The following are the structural practices that will be implemented as part of the construction activity.  Silt Fence & Sediment Silt Sock Barrier will be installed prior to commencement of construction. This type of practice creates erosion control barriers to intercept sediment in diffuse runoff. The Town will be informed upon installation so that they may inspect these barriers prior to construction. Portions of the erosion control barriers will be replaced and/or repaired as necessary to prevent erosion. Barriers will be installed parallel to land slope at the perimeter of the work site. In addition, silt fence barriers will be installed around the bioretention areas during construction.  Silt Sacks (or approved equivalent) will be installed at identified existing catch basins and structure following construction of the proposed catch basins to prevent sedimentation during the any additional construction. The Silt Sack will be replaced and disposed of off-site if damage is observed. Stormwater Analysis and Drainage Report Horsley Witten Group, Inc. Armstrong Kelley Park December 2022 Page 12  Bioretention Area(s) will be graded to within one foot of design elevations until site is fully stabilized to capture sediment during construction. Heavy equipment will not be allowed to operate on the surface location where the systems are planned because soil compaction would adversely impact their long-term performance. Silt fence will be utilized around the perimeter of the bioretention systems during construction. Light earth- moving equipment will be used for excavation and construction of the systems. All excavated materials from the area will be removed and disposed of in an approved location. All bioretention areas will be inspected at least once every seven calendar days and immediately after storm events by the Site Superintendent.  Slope Stabilization will be installed immediately upon obtaining final grades as shown on the project site plans. Areas that fail to stabilize will be re-graded to final grade and stabilized as necessary. Amount of land disturbed will be minimized to reduce potential for erosion and sedimentation. Stabilization measures shall be initiated within 14 days following the end of construction at each portion of the site and as soon as practicable. The entire stormwater management systems including overflow spillways and sediment forebays will be inspected upon completion of construction. Sediment will be removed from all elements of the stormwater management system. All control measures must be installed and maintained in accordance with manufacturer’s specifications, good engineering practices, and in accordance with this Plan (every seven calendar days and after storm events). If inspections show that a control has failed or been installed incorrectly, the Operator must replace or modify it within 24 hours. Structural controls will be regularly inspected to ensure proper performance. The following operation and maintenance provisions will be provided:  Silt fences will be inspected for depth of sediment, tears, to determine if the fabric is securely attached to the fence posts, and to determine if the fence posts are firmly in the ground. Silt fence will be replaced when necessary.  Silt Socks shall be inspected for depth of sediment and any breaches will promptly be repaired or replaced when necessary.  Sediment shall be removed where accumulation reaches one-third the above ground height of any barrier.  Once each workday structural control measures receiving flows from areas that have not been stabilized shall be inspected.  Remedial action shall be taken in areas where temporary and permanent seeding is deemed inefficient through weekly inspections to establish a stabilized surface.  All SCMs will be cleared of accumulated foreign debris, including leaves and lawn cuttings.  All SCMs will be inspected for slope integrity and erosion. Stormwater Analysis and Drainage Report Horsley Witten Group, Inc. Armstrong Kelley Park December 2022 Page 13  All control measures will be inspected at least once every 7-calendar days and within 24 hours after storm events of 0.5 inches or more.  All measures will be maintained in good working order, if a repair is necessary, it will be initiated within 24 hours of discovery. 5.2. Stabilization Practices The amount of land disturbed during construction will be minimized to reduce the potential for erosion and sedimentation. Prompt surface stabilization will be practiced to control erosion in areas where disturbances cannot be avoided during construction. Stabilization measures shall be initiated within 14 days following the end of construction at each portion of the site. Exceptions to this requirement are allowable when snow cover prevents the initiation of stabilization within 14 days, in which case such measures shall be undertaken as soon as possible. Stabilization measures that may be used during construction are described below:  Temporary Seeding – Temporary seeding of disturbed surfaces with fast-growing grasses (annual rye) to provide greater resistance to stormwater runoff and/or wind erosion for areas where construction has temporarily ceased.  Permanent Seeding – Permanent seeding of surfaces with vegetation, including but not limited to grass, trees, bushes, and shrubs, to stabilize the soil. Establishing a permanent and sustainable ground cover at a site stabilizes the soil while reducing the sediment content in runoff.  Permanent Planting – the contractor shall install and adequately establish all planting as required at the completion of the project.  Mulching/Hydro mulching – hydro mulch will be placed on the soil surface to cover and hold in place disturbed soils. Temporary seeding or other soil stabilization measures will be provided where construction activities have ceased at the site. Topsoil stockpiles will be temporarily seeded or covered to prevent erosion and will be surrounded with silt fence. When the site’s final grade has been established, permanent vegetation will be planted on the disturbed areas. The vegetation will consist of grass, shrubs, bushes, and trees. 5.3. Other Types of Controls Additional controls/practices will be undertaken to reduce pollution in stormwater runoff flows which include, but are not limited to, control of off-site mud tracking from construction site, dust suppression, proper sanitary waste disposal, earthwork procedures timed and conducted in manners aimed to minimize erosion and sedimentation, snow removal plans, proper management of waste materials, proper management of hazardous waste, proper material stockpiling, and spill prevention and control measures. Stormwater Analysis and Drainage Report Horsley Witten Group, Inc. Armstrong Kelley Park December 2022 Page 14  Dust Suppression – Water sprays shall be used to control dust during extended dry periods during construction.  Sanitary Wastes – All sanitary wastes will be collected from the portable units by a licensed sanitary waste management contractor (as required by local regulations).  Earthwork – The exposure of disturbed surfaces to stormwater and potential stormwater erosion will be minimized by well-organized earthwork procedures. Stabilization procedures shall be undertaken in accordance with this report. Grubbing during wet seasons will be avoided if feasible.  Snow Removal Plan – Plowed snow collected from the parking areas will be deposited onto free draining, pervious surfaces, away from the site’s drainage conveyance structures to maximize infiltration. Snowmelt runoff that is not infiltrated will be directed to the site’s stormwater management system. Snow is not to be plowed or piled onto the stormwater management facility or wetlands.  Waste Materials – Dumpsters rented from a licensed solid waste management company will be used to store solid waste and debris that cannot be recycled, reused or salvaged. The dumpsters will meet all local and state solid waste management regulations. Dumpsters will be covered when refuse is not being directly deposited or withdrawn from. Potentially hazardous wastes will be separated from normal wastes, including segregation of storage areas and proper labeling of containers. Removal of all waste from the site will be performed by licensed contractors in accordance with applicable regulatory requirements and disposed of at either local or regional approved facilities. Waste materials will not be buried on-site. All site personnel will be instructed regarding the correct procedures for waste disposal. Notices stating these procedures will be posted at the site. Solvents and flushing materials used during construction and pre- operational cleaning will be provided, handled, managed, and removed by the contractor for appropriate off-site disposal.  Hazardous Waste Materials – Any disposal of hazardous materials will be completed using the required paperwork. Copies will be provided to the Engineer and to the Town.  Spill Prevention and Control Measures – To minimize the risk of spills or other accidental exposure of materials and substances to stormwater runoff, the following material management practices will be used throughout the project: o An effort will be made to store only enough products required to do the job. o All materials stored on-site will be stored in a neat, orderly manner in their appropriate containers and, if possible, under a roof or other enclosure. o Products will be kept in their original containers with the original manufacturer’s label. o Substances will not be mixed with one another unless recommended by the manufacturer. o Whenever possible, the maximum amount of a product will be used before disposing of the container. Stormwater Analysis and Drainage Report Horsley Witten Group, Inc. Armstrong Kelley Park December 2022 Page 15 o Manufacturers’ recommendations for proper use and disposal will be followed. o The site superintendent will conduct daily inspections to ensure proper use and disposal of materials. To reduce the risk associated with hazardous materials used on the site, the following practices will be used: o Products will be kept in original containers unless they are not resealable. o Original labels and material safety data sheets will be retained and kept on-site; they contain important product information. o If surplus product must be disposed of, manufacturers’ or local and state recommended methods for proper disposal will be followed.  Materials List - Materials or substances listed below are expected to be present on-site during construction: - Concrete - Fertilizers - Asphalt - Petroleum Based Products - Paints (enamel and latex) - Cleaning Solvents - Metal Studs - Wood - Concrete - Tar - Sealants - Adhesives The following product-specific practices will be followed on-site:  Petroleum Products - All on-site vehicles will be monitored for leaks and receive preventative maintenance to reduce the chance of leakage. Petroleum products will be stored in tightly sealed containers which area clearly labeled. Any asphalt substances used on-site will be applied according to the manufacturers’ recommendations.  Fertilizers – Fertilizers used will be applied only in the minimum amounts recommended by the manufacturer. Once applied, fertilizer will be worked into the soil to limit exposure to stormwater. Products will be stored in a covered shed. The contents of any partially used bags of fertilizer will be transferred to a sealable plastic bin to avoid spills.  Paints – All containers will be tightly sealed and stored indoors when not required for use. Excess paint will not be discharged to the storm sewer system but will be properly disposed of according to the manufacturers’ instructions or state and local regulations.  Concrete Trucks – Concrete trucks will not be allowed to wash out or discharge surplus concrete or drum wash water on the site. In addition to the good housekeeping and material management practices discussed in the previous sections of this plan, the following practices will be followed for spill prevention and cleanup: Stormwater Analysis and Drainage Report Horsley Witten Group, Inc. Armstrong Kelley Park December 2022 Page 16  Manufacturers’ recommended methods for spill cleanup will be clearly posted, and site personnel will be made aware of the procedures and location of the information and cleanup supplies.  Materials and equipment necessary for spill cleanup will be kept in the material storage area on-site. Equipment and materials will include, but not be limited to, brooms, dustpans, mops, rags, gloves, goggles, speedi-dry, sand, sawdust, and plastic and metal trash containers specifically for this purpose.  All spills will be cleaned up immediately after discovery. Spills large enough to reach the storm water system will be reported to the National Response Center at 1-800-424- 8802.  The spill area will be kept well ventilated and personnel will wear appropriate protective clothing to prevent injury from contact with a hazardous substance.  Spills of toxic or hazardous material will be reported to the appropriate state or local government agency, regardless of the size.  The site superintendent responsible for the day-to-day site operations will be the spill prevention and clean-up coordinator. He will designate at least three other site personnel who will receive spill prevention and cleanup training. These individuals will each become responsible for a particular phase of prevention and cleanup. The names of responsible spill personnel will be posted in the material storage area and in the on-site office trailer. 6.0 STORMWATER OPERATION AND MAINTENANCE All stormwater management measures and controls identified in this report shall be operated and maintained appropriately during the construction phase of the project and during regular operation of the site in the post-construction period as required on the construction drawings and the stand alone Stormwater Management Operation and Maintenance Plan. 7.0 REFERENCES 1. MADEP (Massachusetts Department of Environmental Protection). 2008. Massachusetts Stormwater Standards Manual. 2. NOAA’s National Weather Service: Hydrometeorological Design Studies Center, Precipitation Frequency Data Server for Atlas 14 Point Precipitation Frequency Estimates: MA https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html?bkmrk=ma FIGURES Path: H:\Projects\2021\21080 Armstrong Kelley Park\GIS\Maps\USGS_Locus.mxd Figure 1 USGS Locus Armstrong Kelley ParkMunicipal Boundary Date:2/2/2022Data Sources:Bureau of GeographicInformation (MassGIS), ESRI This map is for informational purposes andmay not be suitable for legal, engineering,or surveying purposes. Service Layer Credits: USGS Topographic Map Hyannis and Cotuit Quadrangles 0 1,000500 FeetI Barnstable Sandwich Armstrong Kelley Park 675 Main Street Osterville, MA 02655 MAIN STREET OLDMILLROAD OLDMILLROADE A S T B A Y R O A D HIN C K L E Y C IR C L E MAINSTREETFINGER LANELINDEN LANEWESTBAYROADT OWE R H I L L R O A D Path: H:\Projects\2021\21080 Armstrong Kelley Park\GIS\Maps\Aerial.mxd Figure 2Aerial Armstrong Kelley ParkParcels Date:2/8/2022Data Sources:Bureau of GeographicInformation (MassGIS), ESRI This map is for informational purposes andmay not be suitable for legal, engineering,or surveying purposes. 0 200100 FeetI Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS UserCommunity Armstrong Kelley Park675 Main StreetOsterville, MA 02655 MAIN STREET OLDMILLROAD OLDMILL ROADE A S T B A Y R O A D HIN C K L E Y C IR C L E MAINSTREETFINGER LANELINDEN LANEWESTBAYROADT OWE R H I L L R OA D Path: H:\Projects\2021\21080 Armstrong Kelley Park\GIS\Maps\FEMA.mxd Figure 3 FEMA National Flood Hazard Layer Armstrong Kelley ParkParcels FEMA National Flood Hazard Layer Flood Zone DesignationsAE: 1% Annual Chance of Flooding, with BFEX: 0.2% Annual Chance of Flooding Date:2/8/2022Data Sources:Bureau of GeographicInformation (MassGIS), ESRI This map is for informational purposes andmay not be suitable for legal, engineering,or surveying purposes. 0 200100 FeetI Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS UserCommunity Armstrong Kelley Park675 Main StreetOsterville, MA 02655 Zone X - Area of Minimal Flood Hazard Zone X - Area of Minimal Flood Hazard M AIN STREET OLDMILLROAD OLDMILLROADE A S T B A Y R O A D HIN C K LE Y C IR C LE MAINSTREETFINGER LANELINDEN LANEWESTBAYROADTOWE R H I L L R OA D BarnstableWaterSupply Land Armstrong-kelleyPark East Bay RoadConservationArea Barnstable-ostervilleHillside Cemetery Path: H:\Projects\2021\21080 Armstrong Kelley Park\GIS\Maps\Existing_Constraints.mxd Fig ure 4Existing Constraints Date:2/8/2022Data Sources:Bureau of GeographicInformation (MassGIS), ESRI This map is for informational purposesand may not be suitable for legal,engineering, or surveying purposes. 0 200100 FeetI Service Layer Credits: Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User CommunityEsri, HERE, Garmin, (c) OpenStreetMap contributors, and the GIS user community Armstrong Kelley Park675 Main StreetOsterville, M A 026 55 Armstrong Kelley ParkParcels Land Trust !(National Register of Historic Places EPA Designated Sole Source Aquifer DEP Approved Zone II Wetland LimitClosure LineMarsh/BogWooded marsh Protected and Recreational Open SpaceMunicipal DEP Wetlands !(Inventoried Property (MHC) Medium Yield Non Potential Drinking Water Source Area Ch. 91 Jurisdiction MAIN STREET OLDMILLROAD OLDMILLROADE A S T B A Y R O A D HIN C K L E Y C IR C L E MAINSTREETFINGER LANELINDEN LANEWESTBAYROADT OWE R H I L L R O A D 1 252C665 252B 252B Path: H:\Projects\2021\21080 Armstrong Kelley Park\GIS\Maps\Soils.mxd Figure 5NRCS Soils MUSYM, compname, hydgrp1, Water, <Null>252B, Carver, A252C, Carver, A665, Udipsamments, A Armstrong Kelley ParkParcels Date:2/8/2022Data Sources:Bureau of GeographicInformation (MassGIS), ESRI This map is for informational purposes andmay not be suitable for legal, engineering,or surveying purposes.0 200100 FeetI Service Layer Credits: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS UserCommunity Armstrong Kelley Park675 Main StreetOsterville, MA 02655 APPENDIX A Site Soil Evaluations MEMORANDUM To: Elizabeth Keary Soule, RLA Structures & Landscapes Project Manager The Trustees of Reservations From: Eliza Hoffman, EIT, MA Licensed Soil Evaluator Date: March 1, 2022 Re: Armstrong Kelley Park Site Soil Evaluation cc: Brian Kuchar, RLA, P.E. The Horsley Witten Group, Inc. (HW) completed site soil evaluations at the Armstrong Kelley Park in Barnstable, Massachusetts on February 16, 2022. The work consisted of three deep hole soil evaluation test pits. The test pit evaluations were completed to determine the Estimated Seasonal High Groundwater (ESHGW) and infiltration rate for the design of the stormwater management system for the proposed park improvement. The test pit logs and a map of the locations are attached. ESHGW is determined based on the presence of groundwater within the test pit or redoximorphic features, which are color patterns in the soil that indicate intermittent periods of saturation. This saturation is often an indication of groundwater. The redoximorphic features include areas where material (usually iron oxide) has accumulated, giving them a bright orange color, and may also include areas where material has been depleted and the soil is dull or grey in color. The infiltration rate is determined based on the soil textural class. Soils According to the USDA Natural Resources Conservation Service Soil Map, the entirety of the site’s underlying native soils consist of Carver coarse sand at varying slopes. This soil group is excessively drained and has an estimated depth to water table of more than 80 inches. The site is categorized as Hydrologic Soil Group A. The first test pit (TP-1) was excavated in the existing depression to the west of the entrance driveway. The ground surface elevation of TP-1 is estimated to be 10.0 feet. TP-1 was excavated to a depth of 5.5 feet (66 inches); the subsurface material began caving in at depths greater than 5.5 feet and this prevented further excavation. The topsoil (likely including imported topsoil) extended to 18 inches below grade. The subsoil was encountered at a depth of 18 inches and consisted of coarse sand. No redoximorphic features were encountered, but groundwater began weeping at a depth of 60 inches. The pit was left open for approximately 10 minutes and groundwater pooled at the bottom but did not increase above the 60-inch depth. Elizabeth Keary Soule, RLA Structures & Landscapes Project Manager The Trustees of Reservations March 1, 2022 Page 2 of 3 H:\Projects\2021\21080 Armstrong Kelley Park\Field Data\Test Pits\220217_Test Pit Memo-21080.doc The second test pit (TP-2) was also excavated west of the entrance driveway, approximately 50 ft north and uphill of TP-1. The ground surface elevation of TP-2 is 12.5 feet. TP-2 was excavated to a depth of 7.5 feet (90 inches); the subsurface material began caving in at depths greater than 7.5 feet and this prevented further excavation. The topsoil extended to 12 inches below grade. The subsoil was encountered at a depth of 12 inches and consisted of coarse sand. Redoximorphic features were detected at 56 inches deep. The final test pit (TP-3) was excavated behind the existing shed and boardwalk, between the evergreen trees. The ground surface elevation of TP-3 is 18.5 feet. TP-3 was excavated to a depth of 8.0 feet (96 inches); the excavator was unable to excavate further than 8.0 feet. The topsoil and organic matter extended to 8 inches below grade. The subsoil was encountered at a depth of 8 inches and consisted of medium and coarse sand. A brightly colored layer from 30-45 inches in depth was observed on two of the four sides of the pit. Due to the shallow depth and the fact that this layer was not consistent around the entire pit, it was determined not to be indicative of groundwater. Infiltration Based on the test pit observations, the subsurface material present in the location of the proposed parking lot expansion is extremely well drained and suitable for stormwater infiltration. An infiltration rate of 8.27 inches/hour is recommended for all proposed stormwater infiltration areas. This rate is the so-called “Rawls Rate” for sandy soils as required by the Massachusetts Stormwater Handbook. Groundwater Groundwater was observed in TP-1 and redoximorphic features were observed in TP-2. The groundwater in TP-1 was observed at elevation 5.0 feet. The redoximorphic features were observed in TP-2 at elevation 7.8 feet. Due to the proximity of TP-1 and TP-2, the sandy nature of the site, and consistent material throughout the test pits, the redoximorphic features observed at elevation 7.8 feet in TP-2 are the indicator of groundwater in TP-1 and TP-2, as shown in the table below. No groundwater indicators were observed in TP-3, so ESHGW is considered to be at elevation 10.5 feet for design purposes. This is a conservative estimate as actual groundwater is likely to be lower, but HW has designed the proposed stormwater management system to ensure separation to an ESHGW of 10.5 feet. Elizabeth Keary Soule, RLA Structures & Landscapes Project Manager The Trustees of Reservations March 1, 2022 Page 3 of 3 H:\Projects\2021\21080 Armstrong Kelley Park\Field Data\Test Pits\220217_Test Pit Memo-21080.doc Summary of Findings Below is a summary of the pertinent data from the test pits: Date Test Pit Number Surface Elevation (NAVD88) Bottom Elevation (NAVD88) ESHGW Elevation (NAVD88) Infiltration Soil Texture Recommended Design Infiltration Rate (in/hr) 2/16/22 1 10.0 4.5 7.8 Sand 8.27 2 12.5 5.0 7.8 Sand 8.27 3 18.5 10.5 10.5* Sand 8.27 *Conservative ESHGW for design purposes only—not indicative of actual groundwater. Based upon the results of on-site soil evaluations, conditions observed at all test pits are acceptable for stormwater infiltration due to the high infiltration capacity of sand, and enough groundwater separation to proposed practices. Attached Test Pit Locations Test Pit Logs C. On-Site Review: Armstrong Kelley Park Deep Observation Hole Number: Date Time Weather 1. Location Ground Elevation at Surface of Hole Location (Identify on Plan ) 2. Land Use: (e.g. woodland, agricultural field, vacant lot, etc.) Surface Stones Slope (%) Vegetation Landform Position on landscape (attach sheet) 3. Distances from: Open Water Body Drainage Way Possible Wet Area feet feet feet Property Line Drinking Water Well Other feet feet 4 Parent Material: Outwash Unsuitable Materials Present: Yes No X If Yes: Disturbed Soil Fill Material Impervious Layer(s) Weathered/Fractured Rock Bedrock 5 Groundwater Observed: Yes X No If Yes: Depth Weeping from Pit Depth Standing Water in Hole inches Estimated Depth to High Groundwater: inches elevation Deep Observation Hole Number: Additional Notes . Weeping at 60". Let sit for ~10 min and level did not get higher than 60". Buried electric cable at ~18". Ended pit at 66" due to cave in 5.0 - <5 Massive16-48 10 YR 4/6 - 10 ColorDepth 60 Grass sunny, cold, snow on ground10:30 AM1 In existing depression to west of driveway ~50 ft 16-Feb-22 1-5%N/A Soil Horizon/ Layer Other imported topsoil Loose TP-1 - Very Friable >100 ft >100 ft unknown >100 ft Percent Soil Consistence (Moist) Soil Texture (USDA)Gravel Cobbles & Stones Depth (in) Soil Matrix: Color - Moist (Munsell) Redoximorphic Features 0-16 10 YR 3/2 Coarse Sand Massive Loose 60 60 ---- - - Coarse Fragments by % Volume 48-66 - - <5 - Medium SandA Bw C Coarse Sand 10 YR 4/3 - Granular Soil Structure DEP Form 11 Soil Suitability Assessment for On-Site Sewage Disposal Page 1 of 3 C. On-Site Review: Armstrong Kelley Park Deep Observation Hole Number: Date Time Weather 1. Location Ground Elevation at Surface of Hole Location (Identify on Plan ) 2. Land Use: (e.g. woodland, agricultural field, vacant lot, etc.) Surface Stones Slope (%) Vegetation Landform Position on landscape (attach sheet) 3. Distances from: Open Water Body Drainage Way Possible Wet Area feet feet feet Property Line Drinking Water Well Other feet feet 4 Parent Material: Outwash Unsuitable Materials Present: Yes No X If Yes: Disturbed Soil Fill Material Impervious Layer(s) Weathered/Fractured Rock Bedrock 5 Groundwater Observed: Yes No X If Yes: Depth Weeping from Pit Depth Standing Water in Hole Estimated Depth to High Groundwater: inches elevation Deep Observation Hole Number: Additional Notes Ended pit at 90" due to cave in. 2 16-Feb-22 9:30 AM sunny, cold, snow on ground 12.5 West side of driveway, uphill from TP 1 Grass N/A 5-10% >100 ft >100 ft unknown ~100 ft N/A N/A 56 7.8 >100 ft TP-2 Depth (in) Soil Horizon/ Layer Soil Texture (USDA) Soil Matrix: Color - Moist (Munsell) Redoximorphic Features Coarse Fragments by % Volume Soil Structure Soil Consistence (Moist) Other Depth Color Percent Gravel Cobbles & Stones 0-12 A Medium Sand 10 YR 3/3 - - - - - Granular Very Friable 12-66 Bw Coarse Sand 10 YR 5/6 56 7.5 YR 4/6 10 YR 6/1 >25% <5 - Massive Loose old iron water pipe (?) at 18" 66-90 C Coarse Sand 10 YR 5/3 - - - <5 - Massive Loose moist soil at bottom of pit DEP Form 11 Soil Suitability Assessment for On-Site Sewage Disposal Page 2 of 3 C. On-Site Review: Armstrong Kelley Park Deep Observation Hole Number: Date Time Weather 1. Location Ground Elevation at Surface of Hole Location (Identify on Plan ) 2. Land Use: (e.g. woodland, agricultural field, vacant lot, etc.) Surface Stones Slope (%) Vegetation Landform Position on landscape (attach sheet) 3. Distances from: Open Water Body Drainage Way Possible Wet Area feet feet feet Property Line Drinking Water Well Other feet feet 4 Parent Material: Outwash Unsuitable Materials Present: Yes No X If Yes: Disturbed Soil Fill Material Impervious Layer(s) Weathered/Fractured Rock Bedrock 5 Groundwater Observed: Yes No If Yes: Depth Weeping from Pit Depth Standing Water in Hole Estimated Depth to High Groundwater: inches elevation Deep Observation Hole Number: Additional Notes C1 layer was only visible on two sides of pit and not consistant, so was determined to not be redox. Pit ended at 96" due to machine 3 16-Feb-22 11:15 AM sunny, cold, snow on ground 18.5 Behind shed/boardwalk area, between large pines/spruces. Woodland N/A 1% leaf litter >100 ft >100 ft unknown >100 ft N/A N/A 96 10.5 >100 ft TP-3 Depth (in) Soil Horizon/ Layer Soil Texture (USDA) Soil Matrix: Color - Moist (Munsell) Redoximorphic Features Coarse Fragments by % Volume Soil Structure Soil Consistence (Moist) Other Depth Color Percent Gravel Cobbles & Stones 0-8 A Medium Sand 10 YR 2/1 - - - - - Granular Very Friable 8-30 Bw Medium Sand 10 YR 5/8 - - - - - Massive Loose 30-45 C1 Coarse Sand 5 YR 5/8 - - - 5 2 Massive Loose This layer was only visible on 2 walls of pit. 45-96 C2 Coarse Sand 10 YR 5/4 - - - 10 5 Massive Loose DEP Form 11 Soil Suitability Assessment for On-Site Sewage Disposal Page 3 of 3 CEDAR CANOPYCEDAR CANOPYPINEBLUE SPRUCEWEEPING SPRUCEJAPANESE MAPLECANOPYCROCKERMEMORIALBEECHPINEDOG FOUNTAINMISC. FLOWERS &HYDRANGEASHYDRANGEASHYDRANGEAS & RHODODENDRONSMISC. BUSHESDAFFODILS& HOSTASMAIN STREET656 MAIN STREETMAP 141 LOT39-3N/FGIATRELIS19 OLD MILL ROADMAP 141 LOT 40N/FCOMMONWEALTH ELECTRIC675 MAIN STREETMAP 141 LOT 38CAPE COD HORTICULTURAL SOCIETY716 MAIN STREETMAP 141 LOT 37MASS STATE PLANEPONDRHODODENDRONSHYACINTHS & HOSTASPANICLE HYDRANGEASROSA BEDSLILLIES & HOLLYMISC. BUSHESRHODODENDRONSHEATHERRHODODENDRONSJAPANESE SKIMMIARHODODENDRONS& HEATHERLEMON BALM, CHIVES,FEVERFEWBARRENWORTMISC. FLOWERS &HYDRANGEASBLEEDING HEARTSTOKES ASTERWITCHAZELIVY71089118910 111213141516141312111011121314151617 1 8 1 9 17 18191 8 1 9 20 2 1 22 2 3 2 4 2 5 1918 171918171615141318171 4 1 5 16171 8 13ISOLATED VEGETATIVEWETLANDSIDEWALKVERTICAL GRANITE CURBSIDEWALKLAWNHEATHER& IVYIRR. CONTROL BOXCBDH FNDEL: 9.95'CBDH FNDEL: 15.48'CONC. POSTSBEE HIVESLIAM'STRAINLAWNSHEDSHEDRET. WALLHOLLYRET. WALLMUMS &CHERRY BELLSHYACINTHLAWNRIM: 9.85'RIM: 9.86'RIM: 9.58'RIM: 12.42'RIM: 12.37'RIM: 19.24'RIM: 12.75'ARBORVITAERAMPRAMPPATHPROPERTY LINEPROPERTY LINEFLAGPOLE10-JAPANESE-STEWARTIA"10-WINTER-JASMINE"MH10-GOLDEN-RAIN"EM16-CHINESE-ELM"16-UMBRELLA-MAGNOLIA"14-PINE"24-PINE"20-PINE"EB28-OAK"16-PINE"HYD18-PINE"16-PINE"24-PINE"10-PINE"32-MAPLE"30-MAPLE"24-MAPLE"12-PINE"20-PINE"30-OAK"6-PINE"20-OAK"10-HOLLY"10-HOLLY"16-HOLLY"20-DOGWOOD"20-DOGWOOD"22-PINE"24-OAK"30-OAK"26-OAK"20-OAK"10-BIRCH"10-ELM"10-STEWARTIA"32-PINE"22-PINE"22-PINE"26-PINE"20-DOUBLE-HOLLY"8-HOLLY"10-HOLLY"20-PINE"22-PINE"14-HOLLY"20-OAK"18-PINE"24-PINE"22-PINE"20-TRIPLE-MAPLE"28-MAPLE"8-PINE"12-PINE"18-PINE"20-PINE"8-PINE"12-PINE"14-OAK"18-OAK"16-OAK"10-OAK"24-OAK"36-MAPLE"12-OAK"16-OAK"12-OAK"22-OAK"22-OAK"22-PINE"FRANKLIN"WF IVW 110-DOGWOOD"WF IVW 13WF IVW 12WF IVW 11WF IVW 7WF IVW 6WF IVW 5WF IVW 8WF IVW 9WF IVW 1022-OAK"16-OAK"24-OAK"32-PINE"8-PINE"10-PINE"12-PINE"22-PINE"EM22-PINE"28-OAK"14-PINE"16-PINE"14-OAK"10-PINE"24-PINE"18-OAK"12-PINE"16-PINE"10-OAK"14-PINE"12-PINE"28-PINE-DOUBLE"14-OAK"14-OAK"20-OAK"14-OAK"12-OAK"18-PINE"10-PINE"16-OAK"14-MAPLE"20-OAK"18-PINE"18-OAK"12-PINE"10-OAK"12-PINE"28-PINE-DOUBLE"24-PINE"12-PINE"14-PINE"26-OAK"16-PINE"16-PINE"16-PINE"8-MAPLE"18-OAK"18-OAK"22-PINE"20-PINE"16-PINE"32-WHITE-CEDAR"8-PINE"8-PINE"24-OAK"10-OAK"6-PINE"16-OAK"12-DOGWOOD"20-PINE"18-PINE"18-PINE"12-HOLLY"18-PINE"12-HOLLY"6-WEEPING-CEDAR"8-MAGNOLIA"30-MAPLE"14-MAGNOLIA"32-REDWOOD"12-SASSAFRAS"16-HOLLY"36"32-DOGWOOD-DOUBLE"DD14-JAPANESE"18-CEDAR"8-JAPANESE"12-HOLLY"IVYARBORVITAERHODODENDRONSHYDRANGEAS50' WETLAND BUFFER100' WETLAND BUFFERWF IVW 2WF IVW 3WF IVW 4EL:12.19EL:14.31GENERAL GAVINMEMORIALLIDAR TOPOGRAPHYRevisions Appr.Rev.Date By Description 1 2 3 4 5 6 7EXISTING CONDITIONS PLAN ARMSTRONG KELLEY PARK PERMITTING BARNSTABLE, MA Survey Provided By:Sheet Number:Project Number:Registration:Prepared For:Plan Set: Plan Title:Sheet :1C -Horsley Witten Group, Inc. 90 Route 6A Sandwich, MA 02563 Phone: (508) 833-6600 Fax: (508) 833-3150 Dated: JULY 2021 The Trustees of Reservations 830 Drift Road Westport, MA 02790 Phone: ---- Fax: ----1321080oflast modified: 01/27/22 printed: 02/07/22 by jv H:\Projects\2021\21080 Armstrong Kelley Park\Drawings\21080 EX.dwg ------------ ------------ ------------ ------------ ------------ ------------ ------------(in feet)GRAPHIC SCALE020102040801 INCH = 20 FEETJuly 26, 2021 JDP DWM Checked By:Designed By:Date:Drawn By: Sustainable Environmental Solutions www.horsleywitten.com 90 Route 6A Sandwich, MA 02563 508-833-6600 voice 508-833-3150 fax Horsley Witten Group, Inc.DRAFTNOT FORCONSTRUCTION SURVEY NOTES1.THE TOPOGRAPHY AND EXISTING SITE CONDITIONS DEPICTED HEREON ARE THE RESULT OF AN ON THE GROUND FIELDSURVEY CONDUCTED BY THE HORSLEY WITTEN GROUP, INC. JULY 19, 2021.2.HORIZONTAL DATUM IS MASS STATE PLANE COORDINATE SYSTEM. DATUM ESTABLISHED BY GPS RTK.3.THE ELEVATIONS DEPICTED HEREON WERE BASED ON THE NORTH AMERICAN VERTICAL DATUM (NAVD) OF 1988.4.THE PROPERTY LINES AND RIGHTS OF WAYS DEPICTED ARE APPROXIMATE ONLY.5.PROPERTY LINES FOR ABUTTING PROPERTY OWNERS ARE APPROXIMATE ONLY.6.THE LOCATION AND/OR ELEVATION OF EXISTING UTILITIES AND STRUCTURES AS SHOWN ON THESE PLANS ARE BASED ONRECORDS OF VARIOUS UTILITY COMPANIES, AND WHEREVER POSSIBLE, MEASUREMENTS TAKEN IN THE FIELD. THISINFORMATION IS NOT TO BE RELIED UPON AS BEING EXACT OR COMPLETE. THE LOCATION OF ALL UNDERGROUNDUTILITIES AND STRUCTURES SHALL BE VERIFIED IN THE FIELD PRIOR TO THE START OF ANY CONSTRUCTION. THECONTRACTOR MUST CONTACT THE APPROPRIATE UTILITY COMPANY, ANY GOVERNING PERMITTING AUTHORITY IN THETOWN OF BARNSTABLE, AND "DIGSAFE" (1-888-344-7233) AT LEAST 72 HOURS PRIOR TO ANY EXCAVATION WORK INPREVIOUSLY UNALTERED AREAS TO REQUEST EXACT FIELD LOCATION OF UTILITIES.7.UTILITY PROVIDERS: ELECTRIC - EVERSOURCE ELECTRIC WATER - C.O.M.M. WATER DEPARTMENT (MUNICIPAL)8.THE PROPERTY IS LOCATED WITHIN F.I.R.M ZONES AE (EL. 12) AND X, AS SHOWN ON COMMUNITY PANEL NO, 25001C0544JDATED JULY 15, 2014.9.THE WETLAND DELINEATION SHOWN HEREON WAS CONDUCTED BY THE HORSLEY WITTEN GROUP, INC. ON JULY 14, 2021.LEGEND:CONTOUR - MAJORDRAIN PIPEEDGE OF PAVEMENTCURBBOARDWALKWALL - RETAININGFENCE - WOODGRAVELOVERHEAD WIRECONTOUR - MINORPLANT BEDGENERALUTILITIESWATER LINEBUILDINGSYMBOLSDRAIN MANHOLEELECTRIC BOXGVWVEXISTING TREEHYDRANTSIGNLIGHT POSTGAS VALVEELECTRIC METERWATER VALVECATCHBASINCONCRETEMANHOLEMHDHYD 4445EBEMBUSHES/BRUSHCANOPYTREE LINEBRICK WALKWETLAND BOUNDARYWETLAND FLAGGUYWETLAND 50' BUFFERWETLAND 100' BUFFER APPENDIX B Drainage Area Maps MAIN STREET6 1015 19 1617 1 8 20253035363940 45 50556051545550454 0 35 3 0 2 5 2 0 1 0 12 1 2 15 Prepared For:Survey Provided By: Fax:Registration:Sheet Number:Project Number:Date:Drawn By:Design By:Checked By: Revisions Rev. Date By Appr. Description last modified: 11/28/22 printed: 12/05/22 by jv H:\Projects\2021\21080 Armstrong Kelley Park\Drawings\MISC\21080 DR.dwg Plan Set: Plan Title:of1210802Horsley Witten Group, Inc. 90 Route 6A (508) 833-6600Phone: (508) 833-3150 Dated:JULY 2021 The Trustees of Reservations Fax: Phone: 830 Drift Road Westport, MA 02790 ---- ----252 CARVER COARSE SAND (HSG A)252 CARVER COARSE SAND (HSG A)0SCALE IN FEET100Horsley Witten Group, Inc. Sustainable Environmental Solutions 90 Route 6A Sandwich, MA 02563 508-833-6600 voice 508-833-3150 faxPONDP1 EXISTING DRAINAGE MAP ARMSTRONG KELLEY PARK PERMITTING PLANS BARNSTABLE, MA DECEMBER 6, 2022 JLV JLV BRKSOIL TYPESLEGEND252BDA1SP1STUDY POINTDRAINAGE AREA5,00015,000SOIL BOUNDARYTIME OF CONCENTRATIONFLOW PATH1' MINOR CONTOURDRAINAGEAREABOUNDARYWOODSROOFTOPSGRASSPAVEMENTIMP. AREATOTAL AREA(SQUARE FEET)252C252B252CDA1aD1D2DA1bDA2252BSP12,88385,1590194,24012,10970,767 151515 16 1413 14 15 16 171617161514181 312 111216 1 4 1 5 191817 1819191 81716151413 18 192 01817 19 1 3MAIN STREET6 1015 19 1617 1 8 20253035363940 45 50 55605 1545550 4 5 4 0 35 3 0 2 5 2 0 1 0 12 1 2 15 Prepared For:Survey Provided By: Fax:Registration:Sheet Number:Project Number:Date:Drawn By:Design By:Checked By: Revisions Rev. Date By Appr. Description last modified: 11/28/22 printed: 12/05/22 by jv H:\Projects\2021\21080 Armstrong Kelley Park\Drawings\MISC\21080 DR.dwg Plan Set: Plan Title:of2210802Horsley Witten Group, Inc. 90 Route 6A (508) 833-6600Phone: (508) 833-3150 Dated:JULY 2021 The Trustees of Reservations Fax: Phone: 830 Drift Road Westport, MA 02790 ---- ----252 CARVER COARSE SAND (HSG A)252 CARVER COARSE SAND (HSG A)0SCALE IN FEET100Horsley Witten Group, Inc. Sustainable Environmental Solutions 90 Route 6A Sandwich, MA 02563 508-833-6600 voice 508-833-3150 faxPONDP1 PROPOSED DRAINAGE MAP ARMSTRONG KELLEY PARK PERMITTING PLANS BARNSTABLE, MA DECEMBER 6, 2022 JLV JLV BRKSOIL TYPESLEGEND252BDA1SP1STUDY POINTDRAINAGE AREA5,00015,000SOIL BOUNDARYTIME OF CONCENTRATIONFLOW PATH1' MINOR CONTOURDRAINAGEAREABOUNDARYWOODSROOFTOPSGRASSPAVEMENTIMP. AREATOTAL AREA(SQUARE FEET)252C252B252CDA1aD1DA3DA1cBIO1BIO2DA1bDA2SP1D2076,1397,02225,4078,68248,6265,72413,8060186,452UIC1 APPENDIX C GSI Sizing Calculations Project: Project No:21080Instructions: Enter values in cells only. All other cells are formulas or linksProject Location: and do not need to be edited. See cell comments for descriptions and formulas used.Calculated By: JLVChecked By:RACDate : 12/5/2022Water Quality Volume (WQv)Based upon 1-inch of rainfall times the contributing impervious area contributing impervious areaWQv (cf) = (1" rainfall/12) * Imp. Area (sf) Storm Type:1Inch % Imp.WQv Required*WQv required%sfacsfaccfaf1c Entrance25% 25,4070.586,3330.155280.0123 Parking35% 13,8570.324,7940.114000.009TOTALS39264 0.58 11,127 0.15 9270.021Required Surface Area (sf) = (WQv) (df) / [(k) (hf + df) (tf)] Where: df = Filter bed depth (ft) k = Coefficient of permeability of filter media (ft/day) hf = Ave. height of water above filter bed (ft) tf = Design filter bed drain time (days) Bio AreaDrainage Area NameWQv Required(af)df (ft)K (ft/day)hmax-Height of water above filter(in.)hf=avg of above (ft) tf (days)Surface Area Required (sf)Surface Area Provided (sf)Sediment Forebay Required 0.066 WQv sf)Sediment Forebay Provided (sf)WQV Treatment Provided(af)1 1c 0.012 1.00 0.5 6 0.25 1.67 506 600 35 780.0142 3 0.009 1.00 0.5 6 0.25 1.67 383 425 26 2440.010TOTALS0.021 888 1025 61 322 0.025Percentage of Treatment Provided 115% 526% 115%Bioretention Sizing CalculationsBIORETENTION SIZING:Armstrong Kelley ParkOsterville, MASizing Equations: BioretentionDADescriptionDrainage Area Imp. AreaH:\Projects\2021\21080 Armstrong Kelley Park\Design\Calculations\21080 Bio Sizing.xls1of 1 APPENDIX D HydroCAD Modeling DA1a WEST DA1b NORTH DA2 WETLAND D1 Storage D2 Storage SP1 Study Point 1 Routing Diagram for 21080 EX Prepared by Horsley Witten Inc, Printed 11/29/2022 HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Subcat Reach Pond Link 21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 2HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Rainfall Events Listing (selected events) Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC 1 2 YR Type III 24-hr Default 24.00 1 3.63 2 2 10 YR Type III 24-hr Default 24.00 1 5.32 2 3 25 YR Type III 24-hr Default 24.00 1 6.57 2 4 100YR 14+ Type III 24-hr Default 24.00 1 8.60 2 21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 3HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (acres) CN Description (subcatchment-numbers) 0.686 39 >75% Grass cover, Good, HSG A (DA1a, DA1b, DA2) 0.066 98 Gravel Road (DA1a) 0.169 98 Road (DA2) 0.109 98 Unconnected roofs, HSG A (DA2) 7.009 30 Woods, Good, HSG A (DA1a, DA1b, DA2) 8.039 34 TOTAL AREA 21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 4HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Ground Covers (all nodes) HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers 0.686 0.000 0.000 0.000 0.000 0.686 >75% Grass cover, Good DA1a, DA1b, DA2 0.000 0.000 0.000 0.000 0.066 0.066 Gravel Road DA1a 0.000 0.000 0.000 0.000 0.169 0.169 Road DA2 0.109 0.000 0.000 0.000 0.000 0.109 Unconnected roofs DA2 7.009 0.000 0.000 0.000 0.000 7.009 Woods, Good DA1a, DA1b, DA2 7.804 0.000 0.000 0.000 0.235 8.039 TOTAL AREA Type III 24-hr 2 YR Rainfall=3.63"21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 5HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment DA1a: WEST [45] Hint: Runoff=Zero Runoff = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af, Depth= 0.00" Routed to Pond D1 : Storage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Type III 24-hr 2 YR Rainfall=3.63" Area (sf) CN Description 19,711 39 >75% Grass cover, Good, HSG A 62,565 30 Woods, Good, HSG A * 2,883 98 Gravel Road 85,159 34 Weighted Average 82,276 32 96.61% Pervious Area 2,883 98 3.39% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.5 50 0.0600 0.11 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.63" 6.2 530 0.0800 1.41 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 13.7 580 Total Summary for Subcatchment DA1b: NORTH [45] Hint: Runoff=Zero Runoff = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af, Depth= 0.00" Routed to Pond D2 : Storage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Type III 24-hr 2 YR Rainfall=3.63" Area (sf) CN Description 3,315 39 >75% Grass cover, Good, HSG A 190,925 30 Woods, Good, HSG A 194,240 30 Weighted Average 194,240 30 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.1 50 0.1000 0.14 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.63" 7.9 616 0.0680 1.30 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 14.0 666 Total Type III 24-hr 2 YR Rainfall=3.63"21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 6HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment DA2: WETLAND Runoff = 0.00 cfs @ 17.22 hrs, Volume= 0.003 af, Depth= 0.03" Routed to Pond SP1 : Study Point 1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Type III 24-hr 2 YR Rainfall=3.63" Area (sf) CN Adj Description 6,842 39 >75% Grass cover, Good, HSG A 51,816 30 Woods, Good, HSG A * 7,360 98 Road 4,749 98 Unconnected roofs, HSG A 70,767 43 40 Weighted Average, UI Adjusted 58,658 31 31 82.89% Pervious Area 12,109 98 98 17.11% Impervious Area 4,749 39.22% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.0 50 0.0100 0.12 Sheet Flow, Grass: Short n= 0.150 P2= 3.63" 4.7 283 0.0400 1.00 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 11.7 333 Total Summary for Pond D1: Storage Inflow Area = 6.414 ac, 1.03% Impervious, Inflow Depth = 0.00" for 2 YR event Inflow = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Outflow = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Discarded = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Peak Elev= 10.00' @ 0.50 hrs Surf.Area= 530 sf Storage= 0 cf Plug-Flow detention time= (not calculated: initial storage exceeds outflow) Center-of-Mass det. time= (not calculated: no inflow) Volume Invert Avail.Storage Storage Description #1 10.00' 5,102 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 10.00 530 0 0 11.00 2,300 1,415 1,415 11.40 3,000 1,060 2,475 12.00 5,500 2,550 5,025 12.01 10,000 77 5,102 Type III 24-hr 2 YR Rainfall=3.63"21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 7HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Device Routing Invert Outlet Devices #1 Discarded 10.00'2.410 in/hr Exfiltration over Surface area #2 Primary 11.40'10.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=0.00 cfs @ 0.50 hrs HW=10.00' (Free Discharge) 1=Exfiltration (Passes 0.00 cfs of 0.03 cfs potential flow) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=10.00' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond D2: Storage Inflow Area = 4.459 ac, 0.00% Impervious, Inflow Depth = 0.00" for 2 YR event Inflow = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Outflow = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Discarded = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routed to Pond D1 : Storage Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Peak Elev= 16.50' @ 0.50 hrs Surf.Area= 370 sf Storage= 0 cf Plug-Flow detention time= (not calculated: initial storage exceeds outflow) Center-of-Mass det. time= (not calculated: no inflow) Volume Invert Avail.Storage Storage Description #1 16.50' 7,901 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 16.50 370 0 0 17.00 2,000 593 593 18.00 6,350 4,175 4,768 18.35 10,400 2,931 7,699 18.36 30,000 202 7,901 Device Routing Invert Outlet Devices #1 Discarded 16.50'2.410 in/hr Exfiltration over Surface area #2 Primary 18.34'40.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Type III 24-hr 2 YR Rainfall=3.63"21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 8HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Discarded OutFlow Max=0.00 cfs @ 0.50 hrs HW=16.50' (Free Discharge) 1=Exfiltration (Passes 0.00 cfs of 0.02 cfs potential flow) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=16.50' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond SP1: Study Point 1 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.625 ac, 17.11% Impervious, Inflow Depth = 0.03" for 2 YR event Inflow = 0.00 cfs @ 17.22 hrs, Volume= 0.003 af Primary = 0.00 cfs @ 17.22 hrs, Volume= 0.003 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Type III 24-hr 10 YR Rainfall=5.32"21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 9HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment DA1a: WEST Runoff = 0.03 cfs @ 15.13 hrs, Volume= 0.016 af, Depth= 0.10" Routed to Pond D1 : Storage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Type III 24-hr 10 YR Rainfall=5.32" Area (sf) CN Description 19,711 39 >75% Grass cover, Good, HSG A 62,565 30 Woods, Good, HSG A * 2,883 98 Gravel Road 85,159 34 Weighted Average 82,276 32 96.61% Pervious Area 2,883 98 3.39% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.5 50 0.0600 0.11 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.63" 6.2 530 0.0800 1.41 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 13.7 580 Total Summary for Subcatchment DA1b: NORTH Runoff = 0.01 cfs @ 22.14 hrs, Volume= 0.007 af, Depth= 0.02" Routed to Pond D2 : Storage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Type III 24-hr 10 YR Rainfall=5.32" Area (sf) CN Description 3,315 39 >75% Grass cover, Good, HSG A 190,925 30 Woods, Good, HSG A 194,240 30 Weighted Average 194,240 30 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.1 50 0.1000 0.14 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.63" 7.9 616 0.0680 1.30 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 14.0 666 Total Type III 24-hr 10 YR Rainfall=5.32"21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 10HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment DA2: WETLAND Runoff = 0.15 cfs @ 12.48 hrs, Volume= 0.042 af, Depth= 0.31" Routed to Pond SP1 : Study Point 1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Type III 24-hr 10 YR Rainfall=5.32" Area (sf) CN Adj Description 6,842 39 >75% Grass cover, Good, HSG A 51,816 30 Woods, Good, HSG A * 7,360 98 Road 4,749 98 Unconnected roofs, HSG A 70,767 43 40 Weighted Average, UI Adjusted 58,658 31 31 82.89% Pervious Area 12,109 98 98 17.11% Impervious Area 4,749 39.22% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.0 50 0.0100 0.12 Sheet Flow, Grass: Short n= 0.150 P2= 3.63" 4.7 283 0.0400 1.00 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 11.7 333 Total Summary for Pond D1: Storage Inflow Area = 6.414 ac, 1.03% Impervious, Inflow Depth = 0.03" for 10 YR event Inflow = 0.03 cfs @ 15.13 hrs, Volume= 0.016 af Outflow = 0.03 cfs @ 15.24 hrs, Volume= 0.016 af, Atten= 0%, Lag= 6.8 min Discarded = 0.03 cfs @ 15.24 hrs, Volume= 0.016 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Peak Elev= 10.02' @ 15.24 hrs Surf.Area= 559 sf Storage= 9 cf Plug-Flow detention time= 5.8 min calculated for 0.016 af (100% of inflow) Center-of-Mass det. time= 5.8 min ( 1,092.1 - 1,086.3 ) Volume Invert Avail.Storage Storage Description #1 10.00' 5,102 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 10.00 530 0 0 11.00 2,300 1,415 1,415 11.40 3,000 1,060 2,475 12.00 5,500 2,550 5,025 12.01 10,000 77 5,102 Type III 24-hr 10 YR Rainfall=5.32"21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 11HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Device Routing Invert Outlet Devices #1 Discarded 10.00'2.410 in/hr Exfiltration over Surface area #2 Primary 11.40'10.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=0.03 cfs @ 15.24 hrs HW=10.02' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.03 cfs) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=10.00' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond D2: Storage Inflow Area = 4.459 ac, 0.00% Impervious, Inflow Depth = 0.02" for 10 YR event Inflow = 0.01 cfs @ 22.14 hrs, Volume= 0.007 af Outflow = 0.01 cfs @ 22.17 hrs, Volume= 0.007 af, Atten= 0%, Lag= 1.9 min Discarded = 0.01 cfs @ 22.17 hrs, Volume= 0.007 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routed to Pond D1 : Storage Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Peak Elev= 16.51' @ 22.17 hrs Surf.Area= 400 sf Storage= 3 cf Plug-Flow detention time= 5.2 min calculated for 0.007 af (100% of inflow) Center-of-Mass det. time= 5.2 min ( 1,242.1 - 1,237.0 ) Volume Invert Avail.Storage Storage Description #1 16.50' 7,901 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 16.50 370 0 0 17.00 2,000 593 593 18.00 6,350 4,175 4,768 18.35 10,400 2,931 7,699 18.36 30,000 202 7,901 Device Routing Invert Outlet Devices #1 Discarded 16.50'2.410 in/hr Exfiltration over Surface area #2 Primary 18.34'40.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Type III 24-hr 10 YR Rainfall=5.32"21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 12HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Discarded OutFlow Max=0.02 cfs @ 22.17 hrs HW=16.51' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.02 cfs) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=16.50' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond SP1: Study Point 1 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.625 ac, 17.11% Impervious, Inflow Depth = 0.31" for 10 YR event Inflow = 0.15 cfs @ 12.48 hrs, Volume= 0.042 af Primary = 0.15 cfs @ 12.48 hrs, Volume= 0.042 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Type III 24-hr 25 YR Rainfall=6.57"21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 13HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment DA1a: WEST Runoff = 0.15 cfs @ 12.55 hrs, Volume= 0.053 af, Depth= 0.33" Routed to Pond D1 : Storage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Type III 24-hr 25 YR Rainfall=6.57" Area (sf) CN Description 19,711 39 >75% Grass cover, Good, HSG A 62,565 30 Woods, Good, HSG A * 2,883 98 Gravel Road 85,159 34 Weighted Average 82,276 32 96.61% Pervious Area 2,883 98 3.39% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.5 50 0.0600 0.11 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.63" 6.2 530 0.0800 1.41 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 13.7 580 Total Summary for Subcatchment DA1b: NORTH Runoff = 0.09 cfs @ 14.98 hrs, Volume= 0.053 af, Depth= 0.14" Routed to Pond D2 : Storage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Type III 24-hr 25 YR Rainfall=6.57" Area (sf) CN Description 3,315 39 >75% Grass cover, Good, HSG A 190,925 30 Woods, Good, HSG A 194,240 30 Weighted Average 194,240 30 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.1 50 0.1000 0.14 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.63" 7.9 616 0.0680 1.30 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 14.0 666 Total Type III 24-hr 25 YR Rainfall=6.57"21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 14HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment DA2: WETLAND Runoff = 0.53 cfs @ 12.35 hrs, Volume= 0.093 af, Depth= 0.69" Routed to Pond SP1 : Study Point 1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Type III 24-hr 25 YR Rainfall=6.57" Area (sf) CN Adj Description 6,842 39 >75% Grass cover, Good, HSG A 51,816 30 Woods, Good, HSG A * 7,360 98 Road 4,749 98 Unconnected roofs, HSG A 70,767 43 40 Weighted Average, UI Adjusted 58,658 31 31 82.89% Pervious Area 12,109 98 98 17.11% Impervious Area 4,749 39.22% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.0 50 0.0100 0.12 Sheet Flow, Grass: Short n= 0.150 P2= 3.63" 4.7 283 0.0400 1.00 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 11.7 333 Total Summary for Pond D1: Storage Inflow Area = 6.414 ac, 1.03% Impervious, Inflow Depth = 0.10" for 25 YR event Inflow = 0.15 cfs @ 12.55 hrs, Volume= 0.053 af Outflow = 0.07 cfs @ 15.55 hrs, Volume= 0.053 af, Atten= 53%, Lag= 180.2 min Discarded = 0.07 cfs @ 15.55 hrs, Volume= 0.053 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Peak Elev= 10.42' @ 15.55 hrs Surf.Area= 1,272 sf Storage= 378 cf Plug-Flow detention time= 61.7 min calculated for 0.053 af (100% of inflow) Center-of-Mass det. time= 61.6 min ( 1,060.5 - 998.9 ) Volume Invert Avail.Storage Storage Description #1 10.00' 5,102 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 10.00 530 0 0 11.00 2,300 1,415 1,415 11.40 3,000 1,060 2,475 12.00 5,500 2,550 5,025 12.01 10,000 77 5,102 Type III 24-hr 25 YR Rainfall=6.57"21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 15HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Device Routing Invert Outlet Devices #1 Discarded 10.00'2.410 in/hr Exfiltration over Surface area #2 Primary 11.40'10.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=0.07 cfs @ 15.55 hrs HW=10.42' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.07 cfs) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=10.00' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond D2: Storage Inflow Area = 4.459 ac, 0.00% Impervious, Inflow Depth = 0.14" for 25 YR event Inflow = 0.09 cfs @ 14.98 hrs, Volume= 0.053 af Outflow = 0.07 cfs @ 16.20 hrs, Volume= 0.053 af, Atten= 16%, Lag= 73.1 min Discarded = 0.07 cfs @ 16.20 hrs, Volume= 0.053 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routed to Pond D1 : Storage Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Peak Elev= 16.78' @ 16.20 hrs Surf.Area= 1,283 sf Storage= 232 cf Plug-Flow detention time= 40.7 min calculated for 0.053 af (100% of inflow) Center-of-Mass det. time= 40.7 min ( 1,112.6 - 1,072.0 ) Volume Invert Avail.Storage Storage Description #1 16.50' 7,901 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 16.50 370 0 0 17.00 2,000 593 593 18.00 6,350 4,175 4,768 18.35 10,400 2,931 7,699 18.36 30,000 202 7,901 Device Routing Invert Outlet Devices #1 Discarded 16.50'2.410 in/hr Exfiltration over Surface area #2 Primary 18.34'40.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Type III 24-hr 25 YR Rainfall=6.57"21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 16HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Discarded OutFlow Max=0.07 cfs @ 16.20 hrs HW=16.78' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.07 cfs) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=16.50' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond SP1: Study Point 1 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.625 ac, 17.11% Impervious, Inflow Depth = 0.69" for 25 YR event Inflow = 0.53 cfs @ 12.35 hrs, Volume= 0.093 af Primary = 0.53 cfs @ 12.35 hrs, Volume= 0.093 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Type III 24-hr 100YR 14+ Rainfall=8.60"21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 17HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment DA1a: WEST Runoff = 0.85 cfs @ 12.37 hrs, Volume= 0.150 af, Depth= 0.92" Routed to Pond D1 : Storage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Type III 24-hr 100YR 14+ Rainfall=8.60" Area (sf) CN Description 19,711 39 >75% Grass cover, Good, HSG A 62,565 30 Woods, Good, HSG A * 2,883 98 Gravel Road 85,159 34 Weighted Average 82,276 32 96.61% Pervious Area 2,883 98 3.39% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.5 50 0.0600 0.11 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.63" 6.2 530 0.0800 1.41 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 13.7 580 Total Summary for Subcatchment DA1b: NORTH Runoff = 0.83 cfs @ 12.49 hrs, Volume= 0.211 af, Depth= 0.57" Routed to Pond D2 : Storage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Type III 24-hr 100YR 14+ Rainfall=8.60" Area (sf) CN Description 3,315 39 >75% Grass cover, Good, HSG A 190,925 30 Woods, Good, HSG A 194,240 30 Weighted Average 194,240 30 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.1 50 0.1000 0.14 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.63" 7.9 616 0.0680 1.30 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 14.0 666 Total Type III 24-hr 100YR 14+ Rainfall=8.60"21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 18HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment DA2: WETLAND Runoff = 1.78 cfs @ 12.21 hrs, Volume= 0.206 af, Depth= 1.52" Routed to Pond SP1 : Study Point 1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Type III 24-hr 100YR 14+ Rainfall=8.60" Area (sf) CN Adj Description 6,842 39 >75% Grass cover, Good, HSG A 51,816 30 Woods, Good, HSG A * 7,360 98 Road 4,749 98 Unconnected roofs, HSG A 70,767 43 40 Weighted Average, UI Adjusted 58,658 31 31 82.89% Pervious Area 12,109 98 98 17.11% Impervious Area 4,749 39.22% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.0 50 0.0100 0.12 Sheet Flow, Grass: Short n= 0.150 P2= 3.63" 4.7 283 0.0400 1.00 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 11.7 333 Total Summary for Pond D1: Storage Inflow Area = 6.414 ac, 1.03% Impervious, Inflow Depth = 0.28" for 100YR 14+ event Inflow = 0.85 cfs @ 12.37 hrs, Volume= 0.150 af Outflow = 0.16 cfs @ 15.65 hrs, Volume= 0.150 af, Atten= 81%, Lag= 196.4 min Discarded = 0.16 cfs @ 15.65 hrs, Volume= 0.150 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Peak Elev= 11.31' @ 15.65 hrs Surf.Area= 2,843 sf Storage= 2,214 cf Plug-Flow detention time= 184.7 min calculated for 0.150 af (100% of inflow) Center-of-Mass det. time= 184.7 min ( 1,124.2 - 939.5 ) Volume Invert Avail.Storage Storage Description #1 10.00' 5,102 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 10.00 530 0 0 11.00 2,300 1,415 1,415 11.40 3,000 1,060 2,475 12.00 5,500 2,550 5,025 12.01 10,000 77 5,102 Type III 24-hr 100YR 14+ Rainfall=8.60"21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 19HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Device Routing Invert Outlet Devices #1 Discarded 10.00'2.410 in/hr Exfiltration over Surface area #2 Primary 11.40'10.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=0.16 cfs @ 15.65 hrs HW=11.31' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.16 cfs) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=10.00' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond D2: Storage Inflow Area = 4.459 ac, 0.00% Impervious, Inflow Depth = 0.57" for 100YR 14+ event Inflow = 0.83 cfs @ 12.49 hrs, Volume= 0.211 af Outflow = 0.25 cfs @ 15.78 hrs, Volume= 0.211 af, Atten= 70%, Lag= 197.3 min Discarded = 0.25 cfs @ 15.78 hrs, Volume= 0.211 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routed to Pond D1 : Storage Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs Peak Elev= 17.56' @ 15.78 hrs Surf.Area= 4,416 sf Storage= 2,374 cf Plug-Flow detention time= 131.2 min calculated for 0.211 af (100% of inflow) Center-of-Mass det. time= 131.3 min ( 1,107.5 - 976.2 ) Volume Invert Avail.Storage Storage Description #1 16.50' 7,901 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 16.50 370 0 0 17.00 2,000 593 593 18.00 6,350 4,175 4,768 18.35 10,400 2,931 7,699 18.36 30,000 202 7,901 Device Routing Invert Outlet Devices #1 Discarded 16.50'2.410 in/hr Exfiltration over Surface area #2 Primary 18.34'40.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Type III 24-hr 100YR 14+ Rainfall=8.60"21080 EX Printed 11/29/2022Prepared by Horsley Witten Inc Page 20HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Discarded OutFlow Max=0.25 cfs @ 15.78 hrs HW=17.56' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.25 cfs) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=16.50' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond SP1: Study Point 1 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.625 ac, 17.11% Impervious, Inflow Depth = 1.52" for 100YR 14+ event Inflow = 1.78 cfs @ 12.21 hrs, Volume= 0.206 af Primary = 1.78 cfs @ 12.21 hrs, Volume= 0.206 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.05 hrs DA1a WEST DA1b NORTH DA1c ENTRANCE DA2 WETLAND DA3 PARKING BIO1 BIO 1 BIO2 BIO 2 D1 Storage D2 Storage SP1 Study Point 1 UIC1 Chambers Routing Diagram for 21080 PR Prepared by Horsley Witten Inc, Printed 11/29/2022 HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Subcat Reach Pond Link 21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 2HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Rainfall Events Listing (selected events) Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC 1 2YR Type III 24-hr Default 24.00 1 3.63 2 2 10YR Type III 24-hr Default 24.00 1 5.32 2 3 25YR Type III 24-hr Default 24.00 1 6.57 2 4 100YR 14+ Type III 24-hr Default 24.00 1 8.60 2 21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 3HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (acres) CN Description (subcatchment-numbers) 0.987 39 >75% Grass cover, Good, HSG A (DA1a, DA1b, DA1c, DA2, DA3) 0.255 96 Gravel parking, HSG A (DA1c, DA3) 0.105 98 Road (DA2) 0.103 98 Unconnected roofs, HSG A (DA2, DA3) 0.012 98 Water Surface, 0% imp, HSG A (DA3) 0.016 98 Water Surface, HSG A (DA1c) 6.560 30 Woods, Good, HSG A (DA1a, DA1b, DA2, DA3) 8.039 35 TOTAL AREA 21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 4HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Ground Covers (all nodes) HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers 0.987 0.000 0.000 0.000 0.000 0.987 >75% Grass cover, Good DA1a, DA1b, DA1c, DA2, DA3 0.255 0.000 0.000 0.000 0.000 0.255 Gravel parking DA1c, DA3 0.000 0.000 0.000 0.000 0.105 0.105 Road DA2 0.103 0.000 0.000 0.000 0.000 0.103 Unconnected roofs DA2, DA3 0.016 0.000 0.000 0.000 0.000 0.016 Water Surface DA1c 0.012 0.000 0.000 0.000 0.000 0.012 Water Surface, 0% imp DA3 6.560 0.000 0.000 0.000 0.000 6.560 Woods, Good DA1a, DA1b, DA2, DA3 7.933 0.000 0.000 0.000 0.105 8.039 TOTAL AREA Type III 24-hr 2YR Rainfall=3.63"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 5HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment DA1a: WEST [45] Hint: Runoff=Zero Runoff = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af, Depth= 0.00" Routed to Pond D1 : Storage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 2YR Rainfall=3.63" Area (sf) CN Description 62,253 30 Woods, Good, HSG A 13,886 39 >75% Grass cover, Good, HSG A 76,139 32 Weighted Average 76,139 32 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.1 50 0.0600 0.10 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.07" 6.2 530 0.0800 1.41 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 14.3 580 Total Summary for Subcatchment DA1b: NORTH [45] Hint: Runoff=Zero Runoff = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af, Depth= 0.00" Routed to Pond D2 : Storage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 2YR Rainfall=3.63" Area (sf) CN Description 3,058 39 >75% Grass cover, Good, HSG A 183,394 30 Woods, Good, HSG A 186,452 30 Weighted Average 186,452 30 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.6 50 0.1000 0.13 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.07" 7.9 616 0.0680 1.30 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 14.5 666 Total Type III 24-hr 2YR Rainfall=3.63"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 6HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment DA1c: ENTRANCE Runoff = 0.13 cfs @ 12.13 hrs, Volume= 0.019 af, Depth= 0.39" Routed to Pond BIO1 : BIO 1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 2YR Rainfall=3.63" Area (sf) CN Description * 6,333 96 Gravel parking, HSG A 18,385 39 >75% Grass cover, Good, HSG A 689 98 Water Surface, HSG A 25,407 55 Weighted Average 24,718 54 97.29% Pervious Area 689 98 2.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment DA2: WETLAND Runoff = 0.00 cfs @ 17.26 hrs, Volume= 0.002 af, Depth= 0.03" Routed to Pond SP1 : Study Point 1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 2YR Rainfall=3.63" Area (sf) CN Adj Description 2,072 39 >75% Grass cover, Good, HSG A 37,559 30 Woods, Good, HSG A * 4,587 98 Road 4,095 98 Unconnected roofs, HSG A 48,313 43 40 Weighted Average, UI Adjusted 39,631 30 30 82.03% Pervious Area 8,682 98 98 17.97% Impervious Area 4,095 47.17% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.6 50 0.0100 0.11 Sheet Flow, Grass: Short n= 0.150 P2= 3.07" 4.7 283 0.0400 1.00 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 12.3 333 Total Type III 24-hr 2YR Rainfall=3.63"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 7HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment DA3: PARKING Runoff = 0.16 cfs @ 12.10 hrs, Volume= 0.016 af, Depth= 0.59" Routed to Pond BIO2 : BIO 2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 2YR Rainfall=3.63" Area (sf) CN Adj Description * 4,794 96 Gravel parking, HSG A 5,601 39 >75% Grass cover, Good, HSG A 400 98 Unconnected roofs, HSG A 530 98 Water Surface, 0% imp, HSG A 2,532 30 Woods, Good, HSG A 13,857 61 60 Weighted Average, UI Adjusted 13,457 60 60 97.11% Pervious Area 400 98 98 2.89% Impervious Area 400 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Pond BIO1: BIO 1 Inflow Area = 0.583 ac, 2.71% Impervious, Inflow Depth = 0.39" for 2YR event Inflow = 0.13 cfs @ 12.13 hrs, Volume= 0.019 af Outflow = 0.02 cfs @ 14.68 hrs, Volume= 0.019 af, Atten= 81%, Lag= 153.2 min Discarded = 0.01 cfs @ 14.68 hrs, Volume= 0.016 af Primary = 0.02 cfs @ 14.68 hrs, Volume= 0.003 af Routed to Pond D1 : Storage Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 11.76' @ 14.68 hrs Surf.Area= 757 sf Storage= 343 cf Plug-Flow detention time= 400.3 min calculated for 0.019 af (100% of inflow) Center-of-Mass det. time= 400.3 min ( 1,331.5 - 931.2 ) Volume Invert Avail.Storage Storage Description #1 11.25' 556 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 11.25 600 0 0 11.75 750 338 338 12.00 1,000 219 556 Device Routing Invert Outlet Devices #1 Discarded 11.25'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' #2 Primary 11.75'10.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 Type III 24-hr 2YR Rainfall=3.63"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 8HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=0.01 cfs @ 14.68 hrs HW=11.76' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=0.01 cfs @ 14.68 hrs HW=11.76' (Free Discharge) 2=Broad-Crested Rectangular Weir (Weir Controls 0.01 cfs @ 0.20 fps) Summary for Pond BIO2: BIO 2 Inflow Area = 0.318 ac, 2.89% Impervious, Inflow Depth = 0.59" for 2YR event Inflow = 0.16 cfs @ 12.10 hrs, Volume= 0.016 af Outflow = 0.02 cfs @ 15.20 hrs, Volume= 0.016 af, Atten= 90%, Lag= 186.0 min Discarded = 0.01 cfs @ 15.20 hrs, Volume= 0.014 af Primary = 0.01 cfs @ 15.20 hrs, Volume= 0.002 af Routed to Pond UIC1 : Chambers Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 16.00' @ 15.20 hrs Surf.Area= 425 sf Storage= 374 cf Plug-Flow detention time= 702.0 min calculated for 0.016 af (100% of inflow) Center-of-Mass det. time= 702.1 min ( 1,605.7 - 903.7 ) Volume Invert Avail.Storage Storage Description #1 16.00' 8,064 cf Custom Stage Data (Prismatic) Listed below (Recalc) #2 13.33' 374 cf Subsurface (Prismatic) Listed below (Recalc) 8,438 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 16.00 425 0 0 16.50 640 266 266 17.00 850 373 639 18.00 3,000 1,925 2,564 19.00 8,000 5,500 8,064 Elevation Surf.Area Voids Inc.Store Cum.Store (feet) (sq-ft) (%) (cubic-feet) (cubic-feet) 13.33 425 0.0 0 0 13.92 425 33.0 83 83 14.00 425 33.0 11 94 14.50 425 33.0 70 164 15.17 425 33.0 94 258 15.50 425 33.0 46 304 16.00 425 33.0 70 374 Type III 24-hr 2YR Rainfall=3.63"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 9HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Device Routing Invert Outlet Devices #1 Device 3 14.00'4.0" Horiz. Underdrain C= 0.600 Limited to weir flow at low heads #2 Device 3 16.50'24.0" Horiz. Rim C= 0.600 Limited to weir flow at low heads #3 Primary 14.50'12.0" Round Outlet pipe L= 30.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 14.50' / 14.35' S= 0.0050 '/' Cc= 0.900 n= 0.013 Concrete pipe, bends & connections, Flow Area= 0.79 sf #4 Device 1 14.33'2.410 in/hr Bio Exfiltration over Surface area above 14.33' Excluded Surface area = 425 sf Phase-In= 0.01' #5 Discarded 13.33'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.01 cfs @ 15.20 hrs HW=16.00' (Free Discharge) 5=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=0.00 cfs @ 15.20 hrs HW=16.00' (Free Discharge) 3=Outlet pipe (Passes 0.00 cfs of 2.98 cfs potential flow) 1=Underdrain (Passes 0.00 cfs of 0.51 cfs potential flow) 4=Bio Exfiltration (Exfiltration Controls 0.00 cfs) 2=Rim ( Controls 0.00 cfs) Summary for Pond D1: Storage Inflow Area = 6.612 ac, 0.24% Impervious, Inflow Depth = 0.00" for 2YR event Inflow = 0.02 cfs @ 14.68 hrs, Volume= 0.003 af Outflow = 0.01 cfs @ 14.92 hrs, Volume= 0.003 af, Atten= 5%, Lag= 14.5 min Discarded = 0.01 cfs @ 14.92 hrs, Volume= 0.003 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 10.01' @ 14.92 hrs Surf.Area= 552 sf Storage= 7 cf Plug-Flow detention time= 7.7 min calculated for 0.003 af (100% of inflow) Center-of-Mass det. time= 7.7 min ( 966.6 - 958.9 ) Volume Invert Avail.Storage Storage Description #1 10.00' 10,755 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 10.00 530 0 0 11.00 2,300 1,415 1,415 11.50 3,000 1,325 2,740 12.00 5,400 2,100 4,840 12.70 11,500 5,915 10,755 Device Routing Invert Outlet Devices #1 Discarded 10.00'2.410 in/hr Exfiltration over Surface area #2 Primary 12.00'10.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Type III 24-hr 2YR Rainfall=3.63"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 10HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Discarded OutFlow Max=0.03 cfs @ 14.92 hrs HW=10.01' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.03 cfs) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=10.00' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond D2: Storage Inflow Area = 4.280 ac, 0.00% Impervious, Inflow Depth = 0.00" for 2YR event Inflow = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Outflow = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Discarded = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routed to Pond D1 : Storage Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 16.50' @ 0.50 hrs Surf.Area= 370 sf Storage= 0 cf Plug-Flow detention time= (not calculated: initial storage exceeds outflow) Center-of-Mass det. time= (not calculated: no inflow) Volume Invert Avail.Storage Storage Description #1 16.50' 7,901 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 16.50 370 0 0 17.00 2,000 593 593 18.00 6,350 4,175 4,768 18.35 10,400 2,931 7,699 18.36 30,000 202 7,901 Device Routing Invert Outlet Devices #1 Discarded 16.50'2.410 in/hr Exfiltration over Surface area #2 Primary 18.34'40.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=0.00 cfs @ 0.50 hrs HW=16.50' (Free Discharge) 1=Exfiltration (Passes 0.00 cfs of 0.02 cfs potential flow) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=16.50' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 2YR Rainfall=3.63"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 11HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Pond SP1: Study Point 1 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.109 ac, 17.97% Impervious, Inflow Depth = 0.03" for 2YR event Inflow = 0.00 cfs @ 17.26 hrs, Volume= 0.002 af Primary = 0.00 cfs @ 17.26 hrs, Volume= 0.002 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Summary for Pond UIC1: Chambers Inflow Area = 0.318 ac, 2.89% Impervious, Inflow Depth = 0.06" for 2YR event Inflow = 0.01 cfs @ 15.20 hrs, Volume= 0.002 af Outflow = 0.01 cfs @ 15.28 hrs, Volume= 0.002 af, Atten= 3%, Lag= 4.8 min Discarded = 0.01 cfs @ 15.28 hrs, Volume= 0.002 af Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs / 2 Peak Elev= 11.50' @ 15.28 hrs Surf.Area= 0.016 ac Storage= 0.000 af Plug-Flow detention time= 1.3 min calculated for 0.002 af (100% of inflow) Center-of-Mass det. time= 1.3 min ( 1,029.9 - 1,028.6 ) Volume Invert Avail.Storage Storage Description #1A 11.50' 0.018 af 11.25'W x 60.58'L x 4.50'H Field A 0.070 af Overall - 0.017 af Embedded = 0.054 af x 33.0% Voids #2A 12.50' 0.017 af ADS_StormTech SC-740 +Cap x 16 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 16 Chambers in 2 Rows 0.035 af Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 11.50'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.13 cfs @ 15.28 hrs HW=11.50' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.13 cfs) Type III 24-hr 10YR Rainfall=5.32"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 12HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment DA1a: WEST Runoff = 0.01 cfs @ 16.86 hrs, Volume= 0.007 af, Depth= 0.05" Routed to Pond D1 : Storage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 10YR Rainfall=5.32" Area (sf) CN Description 62,253 30 Woods, Good, HSG A 13,886 39 >75% Grass cover, Good, HSG A 76,139 32 Weighted Average 76,139 32 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.1 50 0.0600 0.10 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.07" 6.2 530 0.0800 1.41 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 14.3 580 Total Summary for Subcatchment DA1b: NORTH Runoff = 0.01 cfs @ 22.12 hrs, Volume= 0.006 af, Depth= 0.02" Routed to Pond D2 : Storage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 10YR Rainfall=5.32" Area (sf) CN Description 3,058 39 >75% Grass cover, Good, HSG A 183,394 30 Woods, Good, HSG A 186,452 30 Weighted Average 186,452 30 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.6 50 0.1000 0.13 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.07" 7.9 616 0.0680 1.30 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 14.5 666 Total Summary for Subcatchment DA1c: ENTRANCE Runoff = 0.68 cfs @ 12.09 hrs, Volume= 0.056 af, Depth= 1.14" Routed to Pond BIO1 : BIO 1 Type III 24-hr 10YR Rainfall=5.32"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 13HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 10YR Rainfall=5.32" Area (sf) CN Description * 6,333 96 Gravel parking, HSG A 18,385 39 >75% Grass cover, Good, HSG A 689 98 Water Surface, HSG A 25,407 55 Weighted Average 24,718 54 97.29% Pervious Area 689 98 2.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment DA2: WETLAND Runoff = 0.10 cfs @ 12.49 hrs, Volume= 0.029 af, Depth= 0.31" Routed to Pond SP1 : Study Point 1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 10YR Rainfall=5.32" Area (sf) CN Adj Description 2,072 39 >75% Grass cover, Good, HSG A 37,559 30 Woods, Good, HSG A * 4,587 98 Road 4,095 98 Unconnected roofs, HSG A 48,313 43 40 Weighted Average, UI Adjusted 39,631 30 30 82.03% Pervious Area 8,682 98 98 17.97% Impervious Area 4,095 47.17% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.6 50 0.0100 0.11 Sheet Flow, Grass: Short n= 0.150 P2= 3.07" 4.7 283 0.0400 1.00 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 12.3 333 Total Summary for Subcatchment DA3: PARKING Runoff = 0.53 cfs @ 12.08 hrs, Volume= 0.040 af, Depth= 1.49" Routed to Pond BIO2 : BIO 2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 10YR Rainfall=5.32" Type III 24-hr 10YR Rainfall=5.32"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 14HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Area (sf) CN Adj Description * 4,794 96 Gravel parking, HSG A 5,601 39 >75% Grass cover, Good, HSG A 400 98 Unconnected roofs, HSG A 530 98 Water Surface, 0% imp, HSG A 2,532 30 Woods, Good, HSG A 13,857 61 60 Weighted Average, UI Adjusted 13,457 60 60 97.11% Pervious Area 400 98 98 2.89% Impervious Area 400 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Pond BIO1: BIO 1 Inflow Area = 0.583 ac, 2.71% Impervious, Inflow Depth = 1.14" for 10YR event Inflow = 0.68 cfs @ 12.09 hrs, Volume= 0.056 af Outflow = 0.46 cfs @ 12.19 hrs, Volume= 0.056 af, Atten= 33%, Lag= 5.9 min Discarded = 0.01 cfs @ 12.19 hrs, Volume= 0.017 af Primary = 0.45 cfs @ 12.19 hrs, Volume= 0.038 af Routed to Pond D1 : Storage Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 11.82' @ 12.19 hrs Surf.Area= 821 sf Storage= 393 cf Plug-Flow detention time= 150.5 min calculated for 0.056 af (100% of inflow) Center-of-Mass det. time= 150.6 min ( 1,036.6 - 886.0 ) Volume Invert Avail.Storage Storage Description #1 11.25' 556 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 11.25 600 0 0 11.75 750 338 338 12.00 1,000 219 556 Device Routing Invert Outlet Devices #1 Discarded 11.25'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' #2 Primary 11.75'10.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Type III 24-hr 10YR Rainfall=5.32"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 15HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Discarded OutFlow Max=0.01 cfs @ 12.19 hrs HW=11.82' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=0.44 cfs @ 12.19 hrs HW=11.82' (Free Discharge) 2=Broad-Crested Rectangular Weir (Weir Controls 0.44 cfs @ 0.62 fps) Summary for Pond BIO2: BIO 2 Inflow Area = 0.318 ac, 2.89% Impervious, Inflow Depth = 1.49" for 10YR event Inflow = 0.53 cfs @ 12.08 hrs, Volume= 0.040 af Outflow = 0.10 cfs @ 12.61 hrs, Volume= 0.040 af, Atten= 82%, Lag= 31.4 min Discarded = 0.01 cfs @ 12.61 hrs, Volume= 0.018 af Primary = 0.08 cfs @ 12.61 hrs, Volume= 0.021 af Routed to Pond UIC1 : Chambers Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 16.51' @ 12.61 hrs Surf.Area= 1,070 sf Storage= 649 cf Plug-Flow detention time= 330.0 min calculated for 0.040 af (100% of inflow) Center-of-Mass det. time= 330.2 min ( 1,200.1 - 870.0 ) Volume Invert Avail.Storage Storage Description #1 16.00' 8,064 cf Custom Stage Data (Prismatic) Listed below (Recalc) #2 13.33' 374 cf Subsurface (Prismatic) Listed below (Recalc) 8,438 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 16.00 425 0 0 16.50 640 266 266 17.00 850 373 639 18.00 3,000 1,925 2,564 19.00 8,000 5,500 8,064 Elevation Surf.Area Voids Inc.Store Cum.Store (feet) (sq-ft) (%) (cubic-feet) (cubic-feet) 13.33 425 0.0 0 0 13.92 425 33.0 83 83 14.00 425 33.0 11 94 14.50 425 33.0 70 164 15.17 425 33.0 94 258 15.50 425 33.0 46 304 16.00 425 33.0 70 374 Device Routing Invert Outlet Devices #1 Device 3 14.00'4.0" Horiz. Underdrain C= 0.600 Limited to weir flow at low heads #2 Device 3 16.50'24.0" Horiz. Rim C= 0.600 Limited to weir flow at low heads #3 Primary 14.50'12.0" Round Outlet pipe L= 30.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 14.50' / 14.35' S= 0.0050 '/' Cc= 0.900 n= 0.013 Concrete pipe, bends & connections, Flow Area= 0.79 sf Type III 24-hr 10YR Rainfall=5.32"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 16HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC #4 Device 1 14.33'2.410 in/hr Bio Exfiltration over Surface area above 14.33' Excluded Surface area = 425 sf Phase-In= 0.01' #5 Discarded 13.33'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.01 cfs @ 12.61 hrs HW=16.51' (Free Discharge) 5=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=0.06 cfs @ 12.61 hrs HW=16.51' (Free Discharge) 3=Outlet pipe (Passes 0.06 cfs of 3.67 cfs potential flow) 1=Underdrain (Passes 0.04 cfs of 0.60 cfs potential flow) 4=Bio Exfiltration (Exfiltration Controls 0.04 cfs) 2=Rim (Weir Controls 0.03 cfs @ 0.36 fps) Summary for Pond D1: Storage Inflow Area = 6.612 ac, 0.24% Impervious, Inflow Depth = 0.08" for 10YR event Inflow = 0.45 cfs @ 12.19 hrs, Volume= 0.046 af Outflow = 0.08 cfs @ 13.25 hrs, Volume= 0.046 af, Atten= 82%, Lag= 63.9 min Discarded = 0.08 cfs @ 13.25 hrs, Volume= 0.046 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 10.50' @ 13.25 hrs Surf.Area= 1,411 sf Storage= 483 cf Plug-Flow detention time= 66.8 min calculated for 0.046 af (100% of inflow) Center-of-Mass det. time= 66.7 min ( 987.6 - 920.8 ) Volume Invert Avail.Storage Storage Description #1 10.00' 10,755 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 10.00 530 0 0 11.00 2,300 1,415 1,415 11.50 3,000 1,325 2,740 12.00 5,400 2,100 4,840 12.70 11,500 5,915 10,755 Device Routing Invert Outlet Devices #1 Discarded 10.00'2.410 in/hr Exfiltration over Surface area #2 Primary 12.00'10.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=0.08 cfs @ 13.25 hrs HW=10.50' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.08 cfs) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=10.00' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 10YR Rainfall=5.32"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 17HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Pond D2: Storage Inflow Area = 4.280 ac, 0.00% Impervious, Inflow Depth = 0.02" for 10YR event Inflow = 0.01 cfs @ 22.12 hrs, Volume= 0.006 af Outflow = 0.01 cfs @ 22.16 hrs, Volume= 0.006 af, Atten= 0%, Lag= 2.4 min Discarded = 0.01 cfs @ 22.16 hrs, Volume= 0.006 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routed to Pond D1 : Storage Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 16.51' @ 22.16 hrs Surf.Area= 398 sf Storage= 3 cf Plug-Flow detention time= 5.2 min calculated for 0.006 af (100% of inflow) Center-of-Mass det. time= 5.2 min ( 1,242.6 - 1,237.4 ) Volume Invert Avail.Storage Storage Description #1 16.50' 7,901 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 16.50 370 0 0 17.00 2,000 593 593 18.00 6,350 4,175 4,768 18.35 10,400 2,931 7,699 18.36 30,000 202 7,901 Device Routing Invert Outlet Devices #1 Discarded 16.50'2.410 in/hr Exfiltration over Surface area #2 Primary 18.34'40.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=0.02 cfs @ 22.16 hrs HW=16.51' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.02 cfs) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=16.50' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond SP1: Study Point 1 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.109 ac, 17.97% Impervious, Inflow Depth = 0.31" for 10YR event Inflow = 0.10 cfs @ 12.49 hrs, Volume= 0.029 af Primary = 0.10 cfs @ 12.49 hrs, Volume= 0.029 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 10YR Rainfall=5.32"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 18HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Pond UIC1: Chambers Inflow Area = 0.318 ac, 2.89% Impervious, Inflow Depth = 0.81" for 10YR event Inflow = 0.08 cfs @ 12.61 hrs, Volume= 0.021 af Outflow = 0.08 cfs @ 12.64 hrs, Volume= 0.021 af, Atten= 2%, Lag= 2.1 min Discarded = 0.08 cfs @ 12.64 hrs, Volume= 0.021 af Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs / 2 Peak Elev= 11.53' @ 12.64 hrs Surf.Area= 0.016 ac Storage= 0.000 af Plug-Flow detention time= 1.3 min calculated for 0.021 af (100% of inflow) Center-of-Mass det. time= 1.3 min ( 940.6 - 939.3 ) Volume Invert Avail.Storage Storage Description #1A 11.50' 0.018 af 11.25'W x 60.58'L x 4.50'H Field A 0.070 af Overall - 0.017 af Embedded = 0.054 af x 33.0% Voids #2A 12.50' 0.017 af ADS_StormTech SC-740 +Cap x 16 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 16 Chambers in 2 Rows 0.035 af Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 11.50'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.13 cfs @ 12.64 hrs HW=11.53' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.13 cfs) Type III 24-hr 25YR Rainfall=6.57"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 19HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment DA1a: WEST Runoff = 0.06 cfs @ 13.78 hrs, Volume= 0.033 af, Depth= 0.23" Routed to Pond D1 : Storage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 25YR Rainfall=6.57" Area (sf) CN Description 62,253 30 Woods, Good, HSG A 13,886 39 >75% Grass cover, Good, HSG A 76,139 32 Weighted Average 76,139 32 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.1 50 0.0600 0.10 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.07" 6.2 530 0.0800 1.41 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 14.3 580 Total Summary for Subcatchment DA1b: NORTH Runoff = 0.08 cfs @ 14.97 hrs, Volume= 0.051 af, Depth= 0.14" Routed to Pond D2 : Storage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 25YR Rainfall=6.57" Area (sf) CN Description 3,058 39 >75% Grass cover, Good, HSG A 183,394 30 Woods, Good, HSG A 186,452 30 Weighted Average 186,452 30 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.6 50 0.1000 0.13 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.07" 7.9 616 0.0680 1.30 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 14.5 666 Total Summary for Subcatchment DA1c: ENTRANCE Runoff = 1.21 cfs @ 12.08 hrs, Volume= 0.090 af, Depth= 1.86" Routed to Pond BIO1 : BIO 1 Type III 24-hr 25YR Rainfall=6.57"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 20HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 25YR Rainfall=6.57" Area (sf) CN Description * 6,333 96 Gravel parking, HSG A 18,385 39 >75% Grass cover, Good, HSG A 689 98 Water Surface, HSG A 25,407 55 Weighted Average 24,718 54 97.29% Pervious Area 689 98 2.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment DA2: WETLAND Runoff = 0.36 cfs @ 12.36 hrs, Volume= 0.063 af, Depth= 0.69" Routed to Pond SP1 : Study Point 1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 25YR Rainfall=6.57" Area (sf) CN Adj Description 2,072 39 >75% Grass cover, Good, HSG A 37,559 30 Woods, Good, HSG A * 4,587 98 Road 4,095 98 Unconnected roofs, HSG A 48,313 43 40 Weighted Average, UI Adjusted 39,631 30 30 82.03% Pervious Area 8,682 98 98 17.97% Impervious Area 4,095 47.17% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.6 50 0.0100 0.11 Sheet Flow, Grass: Short n= 0.150 P2= 3.07" 4.7 283 0.0400 1.00 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 12.3 333 Total Summary for Subcatchment DA3: PARKING Runoff = 0.86 cfs @ 12.08 hrs, Volume= 0.061 af, Depth= 2.30" Routed to Pond BIO2 : BIO 2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 25YR Rainfall=6.57" Type III 24-hr 25YR Rainfall=6.57"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 21HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Area (sf) CN Adj Description * 4,794 96 Gravel parking, HSG A 5,601 39 >75% Grass cover, Good, HSG A 400 98 Unconnected roofs, HSG A 530 98 Water Surface, 0% imp, HSG A 2,532 30 Woods, Good, HSG A 13,857 61 60 Weighted Average, UI Adjusted 13,457 60 60 97.11% Pervious Area 400 98 98 2.89% Impervious Area 400 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Pond BIO1: BIO 1 Inflow Area = 0.583 ac, 2.71% Impervious, Inflow Depth = 1.86" for 25YR event Inflow = 1.21 cfs @ 12.08 hrs, Volume= 0.090 af Outflow = 1.16 cfs @ 12.11 hrs, Volume= 0.090 af, Atten= 4%, Lag= 1.4 min Discarded = 0.01 cfs @ 12.11 hrs, Volume= 0.017 af Primary = 1.15 cfs @ 12.11 hrs, Volume= 0.073 af Routed to Pond D1 : Storage Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 11.88' @ 12.11 hrs Surf.Area= 884 sf Storage= 447 cf Plug-Flow detention time= 94.7 min calculated for 0.090 af (100% of inflow) Center-of-Mass det. time= 94.6 min ( 964.2 - 869.5 ) Volume Invert Avail.Storage Storage Description #1 11.25' 556 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 11.25 600 0 0 11.75 750 338 338 12.00 1,000 219 556 Device Routing Invert Outlet Devices #1 Discarded 11.25'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' #2 Primary 11.75'10.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Type III 24-hr 25YR Rainfall=6.57"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 22HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Discarded OutFlow Max=0.01 cfs @ 12.11 hrs HW=11.88' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=1.15 cfs @ 12.11 hrs HW=11.88' (Free Discharge) 2=Broad-Crested Rectangular Weir (Weir Controls 1.15 cfs @ 0.86 fps) Summary for Pond BIO2: BIO 2 Inflow Area = 0.318 ac, 2.89% Impervious, Inflow Depth = 2.30" for 25YR event Inflow = 0.86 cfs @ 12.08 hrs, Volume= 0.061 af Outflow = 0.51 cfs @ 12.19 hrs, Volume= 0.061 af, Atten= 41%, Lag= 6.8 min Discarded = 0.01 cfs @ 12.19 hrs, Volume= 0.020 af Primary = 0.49 cfs @ 12.19 hrs, Volume= 0.042 af Routed to Pond UIC1 : Chambers Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 16.58' @ 12.19 hrs Surf.Area= 1,097 sf Storage= 691 cf Plug-Flow detention time= 225.5 min calculated for 0.061 af (100% of inflow) Center-of-Mass det. time= 225.5 min ( 1,081.8 - 856.3 ) Volume Invert Avail.Storage Storage Description #1 16.00' 8,064 cf Custom Stage Data (Prismatic) Listed below (Recalc) #2 13.33' 374 cf Subsurface (Prismatic) Listed below (Recalc) 8,438 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 16.00 425 0 0 16.50 640 266 266 17.00 850 373 639 18.00 3,000 1,925 2,564 19.00 8,000 5,500 8,064 Elevation Surf.Area Voids Inc.Store Cum.Store (feet) (sq-ft) (%) (cubic-feet) (cubic-feet) 13.33 425 0.0 0 0 13.92 425 33.0 83 83 14.00 425 33.0 11 94 14.50 425 33.0 70 164 15.17 425 33.0 94 258 15.50 425 33.0 46 304 16.00 425 33.0 70 374 Device Routing Invert Outlet Devices #1 Device 3 14.00'4.0" Horiz. Underdrain C= 0.600 Limited to weir flow at low heads #2 Device 3 16.50'24.0" Horiz. Rim C= 0.600 Limited to weir flow at low heads #3 Primary 14.50'12.0" Round Outlet pipe L= 30.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 14.50' / 14.35' S= 0.0050 '/' Cc= 0.900 n= 0.013 Concrete pipe, bends & connections, Flow Area= 0.79 sf Type III 24-hr 25YR Rainfall=6.57"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 23HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC #4 Device 1 14.33'2.410 in/hr Bio Exfiltration over Surface area above 14.33' Excluded Surface area = 425 sf Phase-In= 0.01' #5 Discarded 13.33'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.01 cfs @ 12.19 hrs HW=16.58' (Free Discharge) 5=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=0.47 cfs @ 12.19 hrs HW=16.58' (Free Discharge) 3=Outlet pipe (Passes 0.47 cfs of 3.75 cfs potential flow) 1=Underdrain (Passes 0.04 cfs of 0.61 cfs potential flow) 4=Bio Exfiltration (Exfiltration Controls 0.04 cfs) 2=Rim (Weir Controls 0.44 cfs @ 0.91 fps) Summary for Pond D1: Storage Inflow Area = 6.612 ac, 0.24% Impervious, Inflow Depth = 0.19" for 25YR event Inflow = 1.15 cfs @ 12.11 hrs, Volume= 0.106 af Outflow = 0.13 cfs @ 14.80 hrs, Volume= 0.106 af, Atten= 89%, Lag= 161.5 min Discarded = 0.13 cfs @ 14.80 hrs, Volume= 0.106 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 11.02' @ 14.80 hrs Surf.Area= 2,327 sf Storage= 1,459 cf Plug-Flow detention time= 145.2 min calculated for 0.106 af (100% of inflow) Center-of-Mass det. time= 145.1 min ( 1,060.9 - 915.8 ) Volume Invert Avail.Storage Storage Description #1 10.00' 10,755 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 10.00 530 0 0 11.00 2,300 1,415 1,415 11.50 3,000 1,325 2,740 12.00 5,400 2,100 4,840 12.70 11,500 5,915 10,755 Device Routing Invert Outlet Devices #1 Discarded 10.00'2.410 in/hr Exfiltration over Surface area #2 Primary 12.00'10.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=0.13 cfs @ 14.80 hrs HW=11.02' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.13 cfs) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=10.00' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 25YR Rainfall=6.57"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 24HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Pond D2: Storage Inflow Area = 4.280 ac, 0.00% Impervious, Inflow Depth = 0.14" for 25YR event Inflow = 0.08 cfs @ 14.97 hrs, Volume= 0.051 af Outflow = 0.07 cfs @ 16.17 hrs, Volume= 0.051 af, Atten= 15%, Lag= 72.0 min Discarded = 0.07 cfs @ 16.17 hrs, Volume= 0.051 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routed to Pond D1 : Storage Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 16.77' @ 16.17 hrs Surf.Area= 1,240 sf Storage= 215 cf Plug-Flow detention time= 38.7 min calculated for 0.051 af (100% of inflow) Center-of-Mass det. time= 38.7 min ( 1,111.1 - 1,072.4 ) Volume Invert Avail.Storage Storage Description #1 16.50' 7,901 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 16.50 370 0 0 17.00 2,000 593 593 18.00 6,350 4,175 4,768 18.35 10,400 2,931 7,699 18.36 30,000 202 7,901 Device Routing Invert Outlet Devices #1 Discarded 16.50'2.410 in/hr Exfiltration over Surface area #2 Primary 18.34'40.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=0.07 cfs @ 16.17 hrs HW=16.77' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.07 cfs) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=16.50' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond SP1: Study Point 1 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.109 ac, 17.97% Impervious, Inflow Depth = 0.69" for 25YR event Inflow = 0.36 cfs @ 12.36 hrs, Volume= 0.063 af Primary = 0.36 cfs @ 12.36 hrs, Volume= 0.063 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 25YR Rainfall=6.57"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 25HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Pond UIC1: Chambers Inflow Area = 0.318 ac, 2.89% Impervious, Inflow Depth = 1.57" for 25YR event Inflow = 0.49 cfs @ 12.19 hrs, Volume= 0.042 af Outflow = 0.13 cfs @ 12.16 hrs, Volume= 0.042 af, Atten= 73%, Lag= 0.0 min Discarded = 0.13 cfs @ 12.16 hrs, Volume= 0.042 af Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs / 2 Peak Elev= 12.71' @ 12.64 hrs Surf.Area= 0.016 ac Storage= 0.008 af Plug-Flow detention time= 14.7 min calculated for 0.042 af (100% of inflow) Center-of-Mass det. time= 14.7 min ( 911.7 - 897.0 ) Volume Invert Avail.Storage Storage Description #1A 11.50' 0.018 af 11.25'W x 60.58'L x 4.50'H Field A 0.070 af Overall - 0.017 af Embedded = 0.054 af x 33.0% Voids #2A 12.50' 0.017 af ADS_StormTech SC-740 +Cap x 16 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 16 Chambers in 2 Rows 0.035 af Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 11.50'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.13 cfs @ 12.16 hrs HW=11.57' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.13 cfs) Type III 24-hr 100YR 14+ Rainfall=8.60"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 26HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment DA1a: WEST Runoff = 0.52 cfs @ 12.44 hrs, Volume= 0.108 af, Depth= 0.74" Routed to Pond D1 : Storage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 100YR 14+ Rainfall=8.60" Area (sf) CN Description 62,253 30 Woods, Good, HSG A 13,886 39 >75% Grass cover, Good, HSG A 76,139 32 Weighted Average 76,139 32 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.1 50 0.0600 0.10 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.07" 6.2 530 0.0800 1.41 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 14.3 580 Total Summary for Subcatchment DA1b: NORTH Runoff = 0.79 cfs @ 12.50 hrs, Volume= 0.202 af, Depth= 0.57" Routed to Pond D2 : Storage Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 100YR 14+ Rainfall=8.60" Area (sf) CN Description 3,058 39 >75% Grass cover, Good, HSG A 183,394 30 Woods, Good, HSG A 186,452 30 Weighted Average 186,452 30 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.6 50 0.1000 0.13 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.07" 7.9 616 0.0680 1.30 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 14.5 666 Total Summary for Subcatchment DA1c: ENTRANCE Runoff = 2.20 cfs @ 12.08 hrs, Volume= 0.156 af, Depth= 3.20" Routed to Pond BIO1 : BIO 1 Type III 24-hr 100YR 14+ Rainfall=8.60"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 27HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 100YR 14+ Rainfall=8.60" Area (sf) CN Description * 6,333 96 Gravel parking, HSG A 18,385 39 >75% Grass cover, Good, HSG A 689 98 Water Surface, HSG A 25,407 55 Weighted Average 24,718 54 97.29% Pervious Area 689 98 2.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment DA2: WETLAND Runoff = 1.20 cfs @ 12.21 hrs, Volume= 0.141 af, Depth= 1.52" Routed to Pond SP1 : Study Point 1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 100YR 14+ Rainfall=8.60" Area (sf) CN Adj Description 2,072 39 >75% Grass cover, Good, HSG A 37,559 30 Woods, Good, HSG A * 4,587 98 Road 4,095 98 Unconnected roofs, HSG A 48,313 43 40 Weighted Average, UI Adjusted 39,631 30 30 82.03% Pervious Area 8,682 98 98 17.97% Impervious Area 4,095 47.17% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.6 50 0.0100 0.11 Sheet Flow, Grass: Short n= 0.150 P2= 3.07" 4.7 283 0.0400 1.00 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 12.3 333 Total Summary for Subcatchment DA3: PARKING Runoff = 1.45 cfs @ 12.08 hrs, Volume= 0.100 af, Depth= 3.79" Routed to Pond BIO2 : BIO 2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr 100YR 14+ Rainfall=8.60" Type III 24-hr 100YR 14+ Rainfall=8.60"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 28HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Area (sf) CN Adj Description * 4,794 96 Gravel parking, HSG A 5,601 39 >75% Grass cover, Good, HSG A 400 98 Unconnected roofs, HSG A 530 98 Water Surface, 0% imp, HSG A 2,532 30 Woods, Good, HSG A 13,857 61 60 Weighted Average, UI Adjusted 13,457 60 60 97.11% Pervious Area 400 98 98 2.89% Impervious Area 400 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Pond BIO1: BIO 1 Inflow Area = 0.583 ac, 2.71% Impervious, Inflow Depth = 3.20" for 100YR 14+ event Inflow = 2.20 cfs @ 12.08 hrs, Volume= 0.156 af Outflow = 2.15 cfs @ 12.10 hrs, Volume= 0.156 af, Atten= 2%, Lag= 1.0 min Discarded = 0.01 cfs @ 12.10 hrs, Volume= 0.018 af Primary = 2.14 cfs @ 12.10 hrs, Volume= 0.137 af Routed to Pond D1 : Storage Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 11.95' @ 12.10 hrs Surf.Area= 953 sf Storage= 510 cf Plug-Flow detention time= 56.9 min calculated for 0.156 af (100% of inflow) Center-of-Mass det. time= 57.0 min ( 909.5 - 852.5 ) Volume Invert Avail.Storage Storage Description #1 11.25' 556 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 11.25 600 0 0 11.75 750 338 338 12.00 1,000 219 556 Device Routing Invert Outlet Devices #1 Discarded 11.25'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' #2 Primary 11.75'10.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Type III 24-hr 100YR 14+ Rainfall=8.60"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 29HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Discarded OutFlow Max=0.01 cfs @ 12.10 hrs HW=11.95' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=2.14 cfs @ 12.10 hrs HW=11.95' (Free Discharge) 2=Broad-Crested Rectangular Weir (Weir Controls 2.14 cfs @ 1.05 fps) Summary for Pond BIO2: BIO 2 Inflow Area = 0.318 ac, 2.89% Impervious, Inflow Depth = 3.79" for 100YR 14+ event Inflow = 1.45 cfs @ 12.08 hrs, Volume= 0.100 af Outflow = 1.42 cfs @ 12.10 hrs, Volume= 0.100 af, Atten= 2%, Lag= 1.0 min Discarded = 0.01 cfs @ 12.10 hrs, Volume= 0.021 af Primary = 1.40 cfs @ 12.10 hrs, Volume= 0.079 af Routed to Pond UIC1 : Chambers Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 16.66' @ 12.10 hrs Surf.Area= 1,133 sf Storage= 751 cf Plug-Flow detention time= 147.6 min calculated for 0.100 af (100% of inflow) Center-of-Mass det. time= 147.6 min ( 989.0 - 841.4 ) Volume Invert Avail.Storage Storage Description #1 16.00' 8,064 cf Custom Stage Data (Prismatic) Listed below (Recalc) #2 13.33' 374 cf Subsurface (Prismatic) Listed below (Recalc) 8,438 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 16.00 425 0 0 16.50 640 266 266 17.00 850 373 639 18.00 3,000 1,925 2,564 19.00 8,000 5,500 8,064 Elevation Surf.Area Voids Inc.Store Cum.Store (feet) (sq-ft) (%) (cubic-feet) (cubic-feet) 13.33 425 0.0 0 0 13.92 425 33.0 83 83 14.00 425 33.0 11 94 14.50 425 33.0 70 164 15.17 425 33.0 94 258 15.50 425 33.0 46 304 16.00 425 33.0 70 374 Device Routing Invert Outlet Devices #1 Device 3 14.00'4.0" Horiz. Underdrain C= 0.600 Limited to weir flow at low heads #2 Device 3 16.50'24.0" Horiz. Rim C= 0.600 Limited to weir flow at low heads #3 Primary 14.50'12.0" Round Outlet pipe L= 30.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 14.50' / 14.35' S= 0.0050 '/' Cc= 0.900 n= 0.013 Concrete pipe, bends & connections, Flow Area= 0.79 sf Type III 24-hr 100YR 14+ Rainfall=8.60"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 30HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC #4 Device 1 14.33'2.410 in/hr Bio Exfiltration over Surface area above 14.33' Excluded Surface area = 425 sf Phase-In= 0.01' #5 Discarded 13.33'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.01 cfs @ 12.10 hrs HW=16.66' (Free Discharge) 5=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=1.39 cfs @ 12.10 hrs HW=16.66' (Free Discharge) 3=Outlet pipe (Passes 1.39 cfs of 3.85 cfs potential flow) 1=Underdrain (Passes 0.04 cfs of 0.62 cfs potential flow) 4=Bio Exfiltration (Exfiltration Controls 0.04 cfs) 2=Rim (Weir Controls 1.35 cfs @ 1.32 fps) Summary for Pond D1: Storage [81] Warning: Exceeded Pond BIO1 by 0.11' @ 14.96 hrs Inflow Area = 6.612 ac, 0.24% Impervious, Inflow Depth = 0.44" for 100YR 14+ event Inflow = 2.17 cfs @ 12.10 hrs, Volume= 0.245 af Outflow = 0.27 cfs @ 14.83 hrs, Volume= 0.245 af, Atten= 88%, Lag= 163.7 min Discarded = 0.27 cfs @ 14.83 hrs, Volume= 0.245 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 11.89' @ 14.83 hrs Surf.Area= 4,851 sf Storage= 4,253 cf Plug-Flow detention time= 234.9 min calculated for 0.245 af (100% of inflow) Center-of-Mass det. time= 234.9 min ( 1,131.6 - 896.7 ) Volume Invert Avail.Storage Storage Description #1 10.00' 10,755 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 10.00 530 0 0 11.00 2,300 1,415 1,415 11.50 3,000 1,325 2,740 12.00 5,400 2,100 4,840 12.70 11,500 5,915 10,755 Device Routing Invert Outlet Devices #1 Discarded 10.00'2.410 in/hr Exfiltration over Surface area #2 Primary 12.00'10.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Type III 24-hr 100YR 14+ Rainfall=8.60"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 31HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Discarded OutFlow Max=0.27 cfs @ 14.83 hrs HW=11.89' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.27 cfs) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=10.00' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond D2: Storage Inflow Area = 4.280 ac, 0.00% Impervious, Inflow Depth = 0.57" for 100YR 14+ event Inflow = 0.79 cfs @ 12.50 hrs, Volume= 0.202 af Outflow = 0.24 cfs @ 15.75 hrs, Volume= 0.202 af, Atten= 70%, Lag= 195.3 min Discarded = 0.24 cfs @ 15.75 hrs, Volume= 0.202 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routed to Pond D1 : Storage Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 17.53' @ 15.75 hrs Surf.Area= 4,285 sf Storage= 2,243 cf Plug-Flow detention time= 127.7 min calculated for 0.202 af (100% of inflow) Center-of-Mass det. time= 127.7 min ( 1,104.4 - 976.7 ) Volume Invert Avail.Storage Storage Description #1 16.50' 7,901 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 16.50 370 0 0 17.00 2,000 593 593 18.00 6,350 4,175 4,768 18.35 10,400 2,931 7,699 18.36 30,000 202 7,901 Device Routing Invert Outlet Devices #1 Discarded 16.50'2.410 in/hr Exfiltration over Surface area #2 Primary 18.34'40.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=0.24 cfs @ 15.75 hrs HW=17.53' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.24 cfs) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=16.50' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 100YR 14+ Rainfall=8.60"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 32HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Pond SP1: Study Point 1 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.109 ac, 17.97% Impervious, Inflow Depth = 1.52" for 100YR 14+ event Inflow = 1.20 cfs @ 12.21 hrs, Volume= 0.141 af Primary = 1.20 cfs @ 12.21 hrs, Volume= 0.141 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Summary for Pond UIC1: Chambers [79] Warning: Submerged Pond BIO2 Primary device # 3 INLET by 0.56' Inflow Area = 0.318 ac, 2.89% Impervious, Inflow Depth = 2.99" for 100YR 14+ event Inflow = 1.40 cfs @ 12.10 hrs, Volume= 0.079 af Outflow = 0.13 cfs @ 12.01 hrs, Volume= 0.079 af, Atten= 91%, Lag= 0.0 min Discarded = 0.13 cfs @ 12.01 hrs, Volume= 0.079 af Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs / 2 Peak Elev= 15.06' @ 13.07 hrs Surf.Area= 0.016 ac Storage= 0.030 af Plug-Flow detention time= 88.5 min calculated for 0.079 af (100% of inflow) Center-of-Mass det. time= 88.5 min ( 955.9 - 867.5 ) Volume Invert Avail.Storage Storage Description #1A 11.50' 0.018 af 11.25'W x 60.58'L x 4.50'H Field A 0.070 af Overall - 0.017 af Embedded = 0.054 af x 33.0% Voids #2A 12.50' 0.017 af ADS_StormTech SC-740 +Cap x 16 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 16 Chambers in 2 Rows 0.035 af Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 11.50'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.13 cfs @ 12.01 hrs HW=11.55' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.13 cfs) 21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 1HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Rainfall Events Listing (selected events) Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC 1 WQV Type III 24-hr Default 24.00 1 1.21 2 Type III 24-hr WQV Rainfall=1.21"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 2HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment DA1a: WEST [45] Hint: Runoff=Zero Runoff = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af, Depth= 0.00" Routed to Pond D1 : Storage Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr WQV Rainfall=1.21" Area (sf) CN Description 62,253 30 Woods, Good, HSG A 13,886 39 >75% Grass cover, Good, HSG A 76,139 Weighted Average 76,139 32 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.1 50 0.0600 0.10 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.07" 6.2 530 0.0800 1.41 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 14.3 580 Total Summary for Subcatchment DA1b: NORTH [45] Hint: Runoff=Zero Runoff = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af, Depth= 0.00" Routed to Pond D2 : Storage Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr WQV Rainfall=1.21" Area (sf) CN Description 3,058 39 >75% Grass cover, Good, HSG A 183,394 30 Woods, Good, HSG A 186,452 Weighted Average 186,452 30 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.6 50 0.1000 0.13 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.07" 7.9 616 0.0680 1.30 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 14.5 666 Total Type III 24-hr WQV Rainfall=1.21"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 3HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment DA1c: ENTRANCE Runoff = 0.16 cfs @ 12.07 hrs, Volume= 0.011 af, Depth= 0.23" Routed to Pond BIO1 : BIO 1 Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr WQV Rainfall=1.21" Area (sf) CN Description * 6,333 96 Gravel parking, HSG A 18,385 39 >75% Grass cover, Good, HSG A 689 98 Water Surface, HSG A 25,407 Weighted Average 24,718 54 97.29% Pervious Area 689 98 2.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment DA2: WETLAND Runoff = 0.18 cfs @ 12.16 hrs, Volume= 0.017 af, Depth= 0.18" Routed to Pond SP1 : Study Point 1 Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr WQV Rainfall=1.21" Area (sf) CN Adj Description 2,072 39 39 >75% Grass cover, Good, HSG A 37,559 30 30 Woods, Good, HSG A * 4,587 98 98 Road 4,095 98 98 Unconnected roofs, HSG A 48,313 Weighted Average 39,631 30 30 82.03% Pervious Area 8,682 98 98 17.97% Impervious Area 4,095 47.17% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.6 50 0.0100 0.11 Sheet Flow, Grass: Short n= 0.150 P2= 3.07" 4.7 283 0.0400 1.00 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 12.3 333 Total Type III 24-hr WQV Rainfall=1.21"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 4HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment DA3: PARKING Runoff = 0.13 cfs @ 12.07 hrs, Volume= 0.009 af, Depth= 0.35" Routed to Pond BIO2 : BIO 2 Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Type III 24-hr WQV Rainfall=1.21" Area (sf) CN Adj Description * 4,794 96 96 Gravel parking, HSG A 5,601 39 39 >75% Grass cover, Good, HSG A 400 98 98 Unconnected roofs, HSG A 530 98 98 Water Surface, 0% imp, HSG A 2,532 30 30 Woods, Good, HSG A 13,857 Weighted Average 13,457 60 60 97.11% Pervious Area 400 98 98 2.89% Impervious Area 400 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Pond BIO1: BIO 1 Inflow Area = 0.583 ac, 2.71% Impervious, Inflow Depth = 0.23" for WQV event Inflow = 0.16 cfs @ 12.07 hrs, Volume= 0.011 af Outflow = 0.01 cfs @ 14.17 hrs, Volume= 0.011 af, Atten= 95%, Lag= 126.1 min Discarded = 0.01 cfs @ 14.17 hrs, Volume= 0.011 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routed to Pond D1 : Storage Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 11.62' @ 14.17 hrs Surf.Area= 710 sf Storage= 240 cf Plug-Flow detention time= 275.6 min calculated for 0.011 af (100% of inflow) Center-of-Mass det. time= 275.6 min ( 1,078.4 - 802.8 ) Volume Invert Avail.Storage Storage Description #1 11.25' 556 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 11.25 600 0 0 11.75 750 338 338 12.00 1,000 219 556 Device Routing Invert Outlet Devices #1 Discarded 11.25'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' #2 Primary 11.75'10.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 Type III 24-hr WQV Rainfall=1.21"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 5HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=0.01 cfs @ 14.17 hrs HW=11.62' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=11.25' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond BIO2: BIO 2 Inflow Area = 0.318 ac, 2.89% Impervious, Inflow Depth = 0.35" for WQV event Inflow = 0.13 cfs @ 12.07 hrs, Volume= 0.009 af Outflow = 0.01 cfs @ 10.88 hrs, Volume= 0.009 af, Atten= 96%, Lag= 0.0 min Discarded = 0.01 cfs @ 10.88 hrs, Volume= 0.009 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routed to Pond UIC1 : Chambers Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 14.91' @ 15.32 hrs Surf.Area= 425 sf Storage= 222 cf Plug-Flow detention time= 416.7 min calculated for 0.009 af (100% of inflow) Center-of-Mass det. time= 416.7 min ( 1,217.6 - 800.9 ) Volume Invert Avail.Storage Storage Description #1 16.00' 8,064 cf Custom Stage Data (Prismatic) Listed below (Recalc) #2 13.33' 374 cf Subsurface (Prismatic) Listed below (Recalc) 8,438 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 16.00 425 0 0 16.50 640 266 266 17.00 850 373 639 18.00 3,000 1,925 2,564 19.00 8,000 5,500 8,064 Elevation Surf.Area Voids Inc.Store Cum.Store (feet) (sq-ft) (%) (cubic-feet) (cubic-feet) 13.33 425 0.0 0 0 13.92 425 33.0 83 83 14.00 425 33.0 11 94 14.50 425 33.0 70 164 15.17 425 33.0 94 258 15.50 425 33.0 46 304 16.00 425 33.0 70 374 Type III 24-hr WQV Rainfall=1.21"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 6HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Device Routing Invert Outlet Devices #1 Device 3 14.00'4.0" Horiz. Underdrain C= 0.600 Limited to weir flow at low heads #2 Device 3 16.50'24.0" Horiz. Rim C= 0.600 Limited to weir flow at low heads #3 Primary 14.50'12.0" Round Outlet pipe L= 30.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 14.50' / 14.35' S= 0.0050 '/' Cc= 0.900 n= 0.013 Concrete pipe, bends & connections, Flow Area= 0.79 sf #4 Device 1 14.33'2.410 in/hr Bio Exfiltration over Surface area above 14.33' Excluded Surface area = 425 sf Phase-In= 0.01' #5 Discarded 13.33'0.520 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.01 cfs @ 10.88 hrs HW=13.39' (Free Discharge) 5=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=13.33' (Free Discharge) 3=Outlet pipe ( Controls 0.00 cfs) 1=Underdrain ( Controls 0.00 cfs) 4=Bio Exfiltration ( Controls 0.00 cfs) 2=Rim ( Controls 0.00 cfs) Summary for Pond D1: Storage Inflow Area = 6.612 ac, 0.24% Impervious, Inflow Depth = 0.00" for WQV event Inflow = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Outflow = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Discarded = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 10.00' @ 0.50 hrs Surf.Area= 530 sf Storage= 0 cf Plug-Flow detention time= (not calculated: initial storage exceeds outflow) Center-of-Mass det. time= (not calculated: no inflow) Volume Invert Avail.Storage Storage Description #1 10.00' 10,755 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 10.00 530 0 0 11.00 2,300 1,415 1,415 11.50 3,000 1,325 2,740 12.00 5,400 2,100 4,840 12.70 11,500 5,915 10,755 Device Routing Invert Outlet Devices #1 Discarded 10.00'2.410 in/hr Exfiltration over Surface area #2 Primary 12.00'10.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Type III 24-hr WQV Rainfall=1.21"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 7HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Discarded OutFlow Max=0.00 cfs @ 0.50 hrs HW=10.00' (Free Discharge) 1=Exfiltration (Passes 0.00 cfs of 0.03 cfs potential flow) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=10.00' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond D2: Storage Inflow Area = 4.280 ac, 0.00% Impervious, Inflow Depth = 0.00" for WQV event Inflow = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Outflow = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Discarded = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Primary = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routed to Pond D1 : Storage Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Peak Elev= 16.50' @ 0.50 hrs Surf.Area= 370 sf Storage= 0 cf Plug-Flow detention time= (not calculated: initial storage exceeds outflow) Center-of-Mass det. time= (not calculated: no inflow) Volume Invert Avail.Storage Storage Description #1 16.50' 7,901 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 16.50 370 0 0 17.00 2,000 593 593 18.00 6,350 4,175 4,768 18.35 10,400 2,931 7,699 18.36 30,000 202 7,901 Device Routing Invert Outlet Devices #1 Discarded 16.50'2.410 in/hr Exfiltration over Surface area #2 Primary 18.34'40.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=0.00 cfs @ 0.50 hrs HW=16.50' (Free Discharge) 1=Exfiltration (Passes 0.00 cfs of 0.02 cfs potential flow) Primary OutFlow Max=0.00 cfs @ 0.50 hrs HW=16.50' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr WQV Rainfall=1.21"21080 PR Printed 11/29/2022Prepared by Horsley Witten Inc Page 8HydroCAD® 10.20-2g s/n 01445 © 2022 HydroCAD Software Solutions LLC Summary for Pond SP1: Study Point 1 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.109 ac, 17.97% Impervious, Inflow Depth = 0.18" for WQV event Inflow = 0.18 cfs @ 12.16 hrs, Volume= 0.017 af Primary = 0.18 cfs @ 12.16 hrs, Volume= 0.017 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs Summary for Pond UIC1: Chambers Inflow Area = 0.318 ac, 2.89% Impervious, Inflow Depth = 0.00" for WQV event Inflow = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Outflow = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Discarded = 0.00 cfs @ 0.50 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.50-72.00 hrs, dt= 0.01 hrs / 2 Peak Elev= 11.50' @ 0.50 hrs Surf.Area= 0.016 ac Storage= 0.000 af Plug-Flow detention time= (not calculated: initial storage exceeds outflow) Center-of-Mass det. time= (not calculated: no inflow) Volume Invert Avail.Storage Storage Description #1A 11.50' 0.018 af 11.25'W x 60.58'L x 4.50'H Field A 0.070 af Overall - 0.017 af Embedded = 0.054 af x 33.0% Voids #2A 12.50' 0.017 af ADS_StormTech SC-740 +Cap x 16 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 16 Chambers in 2 Rows 0.035 af Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 11.50'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.00 cfs @ 0.50 hrs HW=11.50' (Free Discharge) 1=Exfiltration (Passes 0.00 cfs of 0.13 cfs potential flow) Project Name: Project No: 21080 Calculated by:JLV STANDARD 3-RECHARGE REQUIREMENTS Checked:RAC Date:11/29/2022 350166 sf Soil Type Target Depth (in) Target Depth (ft) 8.04 acres A 0.6 0.05 5217 sf B 0.35 0.029 0.12 acres C 0.25 0.021 TOTAL IMPERVIOUS DIRECTED TO RECHARGE 5,217 sf D 0.1 0.008 0.12 acres Rawls Table 100 % Texture Class Infiltration Rate Inches/Hour SOIL TYPE A Sand A 8.27 RECHARGE VOLUME REQUIRED (Rv)261 cft Loamy Sand A 2.41 2.41 in/hr Sandy Loam B 1.02 BOTTOM SURFACE AREA OF INFILTRATING PRACTICES 1,212 sf Loam B 0.52 ESTIMATED DRAWDOWN TIME FOR Rv* 1.07 hr Silt Loam C 0.27 Sandy Clay C 0.17 Clay Loam D 0.09 RECHARGE VOLUMES Silty Clay D 0.06 1in Sandy Clay D 0.05 VOLUME OF INFILTRATION CHAMBERS 1,525 cf Silty Clay D 0.04 VOLUME OF INFILTRATION AREA 4,840 cf Clay D 0.02 TOTAL RECHARGE VOLUME PROVIDED 6,365 cf TOTAL RECHARGE VOLUME REQUIRED 261 cf Armstrong Kelley Park TOTAL DRAINAGE AREA TOTAL NEW IMPERVIOUS AREA NRCS Hydrologic Soil Group (HSG) RAINFALL INFILTRATION RATE *Must be less than 72 HRS % IMPERVIOUS TO BE RECHARGED APPENDIX E TSS and Recharge Calculations VINSTRUCTIONS:Version 1, Automated: Mar. 4, 20081. In BMP Column, click on Blue Cell to Activate Drop Down Menu2. Select BMP from Drop Down Menu3. After BMP is selected, TSS Removal and other Columns are automatically completed.Location: BCDEFTSS Removal Starting TSS Amount RemainingBMP1Rate1Load* Removed (C*D) Load (D-E)Bioretention Area 0.901.00 0.90 0.10Infiltration Basin 0.800.10 0.08 0.020.000.02 0.00 0.020.000.02 0.00 0.020.000.02 0.00 0.02Total TSS Removal =98%Separate Form Needs to be Completed for Each Outlet or BMP TrainProject:21080Prepared By:JLV*Equals remaining load from previous BMP (E)Date:11/29/2022which enters the BMPTSS Removal Calculation WorksheetDA1cNon-automated TSS Calculation Sheetmust be used if Proprietary BMP Proposed1. From MassDEP Stormwater Handbook Vol. 1Mass. Dept. of Environmental Protection VINSTRUCTIONS:Version 1, Automated: Mar. 4, 20081. In BMP Column, click on Blue Cell to Activate Drop Down Menu2. Select BMP from Drop Down Menu3. After BMP is selected, TSS Removal and other Columns are automatically completed.Location: BCDEFTSS Removal Starting TSS Amount RemainingBMP1Rate1Load* Removed (C*D) Load (D-E)Bioretention Area 0.901.00 0.90 0.10Subsurface Infiltration Structure 0.800.10 0.08 0.020.000.02 0.00 0.020.000.02 0.00 0.020.000.02 0.00 0.02Total TSS Removal =98%Separate Form Needs to be Completed for Each Outlet or BMP TrainProject:21080Prepared By:JLV*Equals remaining load from previous BMP (E)Date:11/29/2022which enters the BMPDA3TSS Removal Calculation WorksheetNon-automated TSS Calculation Sheetmust be used if Proprietary BMP Proposed1. From MassDEP Stormwater Handbook Vol. 1Mass. Dept. of Environmental Protection APPENDIX F Groundwater Mounding use consistent units (e.g. feet & days or inches & hours)Conversion Table Input Values inch/hour feet/day 2.5900 R Recharge (infiltration) rate (feet/day)0.67 1.33 0.200 Sy Specific yield, Sy (dimensionless, between 0 and 1) 90.00 K Horizontal hydraulic conductivity, Kh  (feet/day)*2.00 4.00 25.000 x 1/2 length of basin (x direction, in feet) 15.000 y 1/2 width of basin (y direction, in feet)hours days 3.000 t duration of infiltration period (days)36 1.50 10.000 hi(0)initial thickness of saturated zone (feet) 11.632 h(max)maximum thickness of saturated zone (beneath center of basin at end of infiltration period) 1.632 Δh(max)maximum groundwater mounding (beneath center of basin at end of infiltration period) Ground‐ water  Mounding, in  feet Distance from  center of basin  in x direction, in  feet 1.632 0 1.448 20 1.027 40 0.881 50 0.765 60 0.669 70 0.587 80 0.518 90 0.457 100 0.358 120 Disclaimer This spreadsheet solving the Hantush (1967) equation for ground-water mounding beneath an infiltration basin is made available to the general public as a convenience for those wishing to replicate values documented in the USGS Scientific Investigations Report 2010-5102 "Groundwater mounding beneath hypothetical stormwater infiltration basins" or to calculate values based on user-specified site conditions. Any changes made to the spreadsheet (other than values identified as user-specified) after transmission from the USGS could have unintended, undesirable consequences. These consequences could include, but may not be limited to: erroneous output, numerical instabilities, and violations of underlying assumptions that are inherent in results presented in the accompanying USGS published report. The USGS assumes no responsibility for the consequences of any changes made to the spreadsheet. If changes are made to the spreadsheet, the user is responsible for documenting the changes and justifying the results and conclusions. This spreadsheet will calculate the height of a groundwater mound beneath a stormwater infiltration basin.   More information can be found in the U.S. Geological Survey  Scientific Investigations Report 2010‐5102 "Simulation of groundwater mounding beneath hypothetical stormwater infiltration basins". The user must specify infiltration rate (R), specific yield (Sy), horizontal hydraulic conductivity (Kh),  basin dimensions (x, y), duration of infiltration period (t), and the initial  thickness of the saturated zone (hi(0), height of the water table if the bottom of the aquifer is the datum).  For a square basin the half width equals the half length (x = y).   For a rectangular basin, if the user wants the water‐table changes perpendicular to the long side, specify x as the short dimension and y as the long dimension.  Conversely,  if the user wants the values perpendicular to the short side, specify y as the short dimension, x as the long dimension.  All distances are from the center of the basin.    Users can change the distances from the center of the basin at which water‐table aquifer thickness are calculated. Cells highlighted in yellow are values that can be changed by the user.  Cells highlighted in red are output values based on user‐specified inputs.  The user MUST click the  blue "Re‐Calculate Now" button each time ANY of the user‐specified inputs are changed  otherwise necessary iterations to converge on the correct solution will not be  done and values shown will be incorrect.  Use consistent units for all input values (for example, feet and days) In the report accompanying this spreadsheet  (USGS SIR 2010‐5102), vertical soil permeability  (ft/d) is assumed to be one‐tenth horizontal  hydraulic conductivity (ft/d).  Re‐Calculate Now 0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 1.600 1.800 0 20 40 60 80 100 120 140 Groundwater Mounding, in feet Groundwater Modeling for Existing Basin (D1) Initial separation to groundwater is 2.2 ft. Mound is 1.63 ft, leaving 0.57 ft separation. use consistent units (e.g. feet & days or inches & hours)Conversion Table Input Values inch/hour feet/day 5.0500 R Recharge (infiltration) rate (feet/day)0.67 1.33 0.200 Sy Specific yield, Sy (dimensionless, between 0 and 1) 90.00 K Horizontal hydraulic conductivity, Kh  (feet/day)*2.00 4.00 15.000 x 1/2 length of basin (x direction, in feet) 5.000 y 1/2 width of basin (y direction, in feet)hours days 3.000 t duration of infiltration period (days)36 1.50 10.000 hi(0)initial thickness of saturated zone (feet) 10.829 h(max)maximum thickness of saturated zone (beneath center of basin at end of infiltration period) 0.829 Δh(max)maximum groundwater mounding (beneath center of basin at end of infiltration period) Ground‐ water  Mounding, in  feet Distance from  center of basin  in x direction, in  feet 0.829 0 0.618 20 0.424 40 0.366 50 0.319 60 0.281 70 0.249 80 0.222 90 0.198 100 0.159 120 Disclaimer This spreadsheet solving the Hantush (1967) equation for ground-water mounding beneath an infiltration basin is made available to the general public as a convenience for those wishing to replicate values documented in the USGS Scientific Investigations Report 2010-5102 "Groundwater mounding beneath hypothetical stormwater infiltration basins" or to calculate values based on user-specified site conditions. Any changes made to the spreadsheet (other than values identified as user-specified) after transmission from the USGS could have unintended, undesirable consequences. These consequences could include, but may not be limited to: erroneous output, numerical instabilities, and violations of underlying assumptions that are inherent in results presented in the accompanying USGS published report. The USGS assumes no responsibility for the consequences of any changes made to the spreadsheet. If changes are made to the spreadsheet, the user is responsible for documenting the changes and justifying the results and conclusions. This spreadsheet will calculate the height of a groundwater mound beneath a stormwater infiltration basin.   More information can be found in the U.S. Geological Survey  Scientific Investigations Report 2010‐5102 "Simulation of groundwater mounding beneath hypothetical stormwater infiltration basins". The user must specify infiltration rate (R), specific yield (Sy), horizontal hydraulic conductivity (Kh),  basin dimensions (x, y), duration of infiltration period (t), and the initial  thickness of the saturated zone (hi(0), height of the water table if the bottom of the aquifer is the datum).  For a square basin the half width equals the half length (x = y).   For a rectangular basin, if the user wants the water‐table changes perpendicular to the long side, specify x as the short dimension and y as the long dimension.  Conversely,  if the user wants the values perpendicular to the short side, specify y as the short dimension, x as the long dimension.  All distances are from the center of the basin.    Users can change the distances from the center of the basin at which water‐table aquifer thickness are calculated. Cells highlighted in yellow are values that can be changed by the user.  Cells highlighted in red are output values based on user‐specified inputs.  The user MUST click the  blue "Re‐Calculate Now" button each time ANY of the user‐specified inputs are changed  otherwise necessary iterations to converge on the correct solution will not be  done and values shown will be incorrect.  Use consistent units for all input values (for example, feet and days) In the report accompanying this spreadsheet  (USGS SIR 2010‐5102), vertical soil permeability  (ft/d) is assumed to be one‐tenth horizontal  hydraulic conductivity (ft/d).  Re‐Calculate Now 0.000 0.100 0.200 0.300 0.400 0.500 0.600 0.700 0.800 0.900 0 20 40 60 80 100 120 140 Groundwater Mounding, in feet Groundwater Modeling for Recharger Basins (RB) Initial separation to groundwater is 2.0 ft. Mound is 0.83 ft, leaving 1.17 ft separation. 100 ‐ Year Storm Groundwater Mounding Evaluation for Two Infiltration Practices 375 Feet Apart updated 3/1/22 by EWHExisting Basin (D1)            Peak Mound Recharge Basins (RB) Peak Mound D1 Mound @ RBRB Mound @ D1Total Basin D1 MoundTotal  RB MoundBasin D1 ‐ Initial GW  SeparationBasin D1 ‐ Mounded GW  SeparationRB ‐ Initial GW  SeparationRB ‐ Mounded GW  Separation1.63 0.83 0.023 0.029 1.66 0.85 2.201.35 2.00 1.15D1 RB1.63200.82900.881500.366500.4571000.1981000.2481500.1161500.1342000.0722000.0722500.0482500.0413000.0363000.0253500.0303500.0184000.0274000.0154500.0264500.0000.2000.4000.6000.8001.0001.2001.4001.6001.8000 100 200 300 400 500Groundwater Mounding, in feetRBD1