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  • Have a question? | Philadelphia Water Stormwater Plan Review
    101 Regulations Stormwater Management Stormwater Billing Retrofits Green City Clean Waters News Contact Us About Us Development Review Contacts Have a question Check Status SEARCH 215 685 6387 pwd planreview phila gov Apply Manual Have a question Comments suggestions We value your feedback about the Guidance Manual website and plan review process We will review responses to this form regularly and post responses to common questions online First Name Last

    Original URL path: http://www.pwdplanreview.org/have-a-question (2016-04-24)
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  • Project Application Status | Philadelphia Water Stormwater Plan Review
    and Sediment Control Plan Apply Manual Development Resources Stormwater Plan Review Resources Pilot Projects Proprietary Products Additional Resources Stormwater 101 Regulations Stormwater Management Stormwater Billing Retrofits Green City Clean Waters News Contact Us About Us Development Review Contacts Have a question Check Status 215 685 6387 pwd planreview phila gov Apply Manual Project Application Status Enter Tracking Number Please include the dashes in the tracking number Project Basic Information Tracking

    Original URL path: http://www.pwdplanreview.org/apply/application/app_status (2016-04-24)
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  • ERSA Form Login | Philadelphia Water Stormwater Plan Review
    application is the initial submission for all projects requiring PWD Stormwater Plan Review approval or exemption PWD Stormwater Plan Review uses the ERSA Application to define the existing conditions of the project site to confirm the project s applicability within or exemption from the Stormwater Regulations and to confirm the project s Review Path with the applicant The ERSA Application must be completed electronically To access the online Application the user must log in to a valid PWD Stormwater Plan Review user account above If you are a new user you can create a new account On the first page of the ERSA Worksheet the applicant will be asked to enter project information Upon completion of this page a PWD Stormwater Plan Review project tracking number will be generated displayed on the following webpage and sent to the email address associated with the applicant s PWD Stormwater Plan Review user account This tracking number can be used to track the review process through the PWD Stormwater Plan Review website Log into your PWD Stormwater Plan Review user account by clicking Apply from the pwdplanreview org homepage to check the status of all of your ERSA Applications The project tracking webpage is updated daily so please check the site for the most recent information regarding your project An ERSA application consists of the following components ERSA Worksheet Site Photographs including at least one color photograph from each face of the parcel s looking into the site Existing Conditions Plan Conceptual Review Phase Submission Package determined by the project characteristics in the web form and the projects Review Path as identified in Section 2 3 of the Manual In order to submit the ERSA Application for review the applicant must click the Submit Application button at the end of the ERSA Worksheet

    Original URL path: http://www.pwdplanreview.org/apply/login (2016-04-24)
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  • Introduction | Philadelphia Water Stormwater Plan Review
    7 6 Pond and Wet Basin Maintenance Guidance Back to Chapter 4 4 8 1 Subsurface Detention Introduction 4 8 2 Subsurface Detention Components 4 8 3 Subsurface Detention Design Standards 4 8 4 Subsurface Detention Material Standards 4 8 5 Subsurface Detention Construction Guidance 4 8 6 Subsurface Detention Maintenance Guidance Back to Chapter 4 4 9 1 Media Filter Introduction 4 9 2 Media Filter Components 4 9 3 Media Filter Design Standards 4 9 4 Media Filter Material Standards 4 9 5 Media Filter Construction Guidance 4 9 6 Media Filter Maintenance Guidance Back to Chapter 4 4 10 1 Pretreatment Introduction 4 10 2 Berms and Retentive Grading 4 10 3 Filter Strips 4 10 4 Forebays 4 10 5 Swales Back to Chapter 4 4 11 1 Inlet Control Introduction 4 11 2 Flow Splitters 4 11 3 Curbless Design Curb Openings 4 11 4 Energy Dissipaters 4 11 5 Inlets Back to Chapter 4 4 12 1 Outlet Control Introduction 4 12 2 Orifices 4 12 3 Weirs 4 12 4 Risers 4 12 5 Underdrains 4 12 6 Level Spreaders 4 12 7 Impervious Liners 4 12 8 Micro Siphon Drain Belts 4 12 9 Low Flow Devices Back to Chapters 5 0 Introduction 5 1 Construction Inspection 5 2 Common Construction Issues 5 3 Construction Documentation Back to Chapter 5 5 1 1 Coordinating Inspections with Other PWD Units 5 1 2 Preconstruction Processes 5 1 3 Construction Processes 5 1 4 Final Inspection 5 1 5 Post Construction Submissions Back to Chapter 5 5 2 1 Erosion and Sediment Related Construction Issues 5 2 2 Stormwater Management Practice Related Construction Issues Back to Chapter 5 5 3 1 Construction Certification Package 5 3 2 Record Drawings Back to Chapters 6 0 Introduction 6 1 Operations and Maintenance 6 2 Stormwater Management Practice Inspection Guidance 6 3 Stormwater Credits Program Back to Chapter 6 6 1 1 Maintenance Requirements for Property Owners 6 1 2 Operations and Maintenance Agreements Back to Chapter 6 6 2 1 PWD Inspections and Enforcement 6 2 2 Property Owner Inspections Back to Chapters Appendix Index A Glossary B Abbreviations C PWD Stormwater Regulations D Watershed Maps E Plan and Report Checklists F Design Guidance Checklists G Worksheets and Infiltration Waiver H Infiltration Testing Log I Landscape Guidance J Construction Certification Package K Record Drawing Sample Back to Appendices Table E 1 General Plan Sheet Requirements Table E 2 Existing Conditions Plan Requirements Table E 3 Conceptual Stormwater Management Plan Requirements Table E 4 Erosion and Sediment Control Plan Requirements Table E 5 Standard Erosion and Sediment Control Notes Table E 6 Standard Sequence of Construction Notes Table E 7 Post Construction Stormwater Management Plan Report Requirements Table E 8 Record Drawing Requirements Back to Appendices F 1 Stormwater Regulation Compliance F 2 Post Construction Stormwater Management Plan F 3 Erosion and Sediment Control F 4 Disconnected Impervious Cover F 5 Infiltration Testing and Soil Assessment F 6 Hydrologic Model and Calculation Methods F 7 Bioinfiltration Bioretention F 8 Porous Pavement F 9 Green Roofs F 10 Subsurface Infiltration F 11 Cisterns F 12 Blue Roofs F 13 Ponds and Wet Basins F 14 Subsurface Detention F 15 Media Filters F 16 Pretreatment F 17 Inlet Controls F 18 Outlet Controls Back to Chapters Download Full Manual 80 mb Download Introduction Introduction The Philadelphia Water PWD Stormwater Management Guidance Manual the Manual or SMGM is a comprehensive resource for the development community in complying with the PWD Stormwater Regulations Stormwater Regulations The Stormwater Regulations require on site stormwater management for development projects above a certain size helping to improve the health and vitality of Philadelphia s waterways along with the City s own sizable clean water investments Other types of construction activities may also trigger portions of the Stormwater Regulations including demolition and voluntary stormwater retrofit projects At its core the Manual provides detailed guidance for the applicant on how to most quickly and efficiently comply with the Stormwater Regulations for development and other construction projects Using this Manual the applicant will be able to do the following Determine if a project is regulated under the Stormwater Regulations and if so what specific requirements need to be met Learn about new ways to incorporate green approaches to stormwater management that provide benefits for development projects and expedite the stormwater approval process Design specific stormwater management practices SMPs to meet PWD s standards Prepare and submit application materials Learn how to ensure proper installation and protection of SMPs during construction activity and Obtain information on post construction and operations and maintenance O M requirements Manual Organization and Purpose The Manual provides the development community with detailed guidance on designing stormwater management systems to meet the Stormwater Regulations understanding PWD s stormwater related requirements and approval processes and preparing submissions to the PWD Stormwater Plan Review unit The Manual also provides guidance on topics relating to the proper construction and maintenance of SMPs The Manual has six Chapters and a series of Appendices Chapters 1 through 4 focus on the stormwater design submittal and approval process while Chapters 5 and 6 discuss construction and post construction topics As design submittal and review processes are closely related the applicant will find cross referencing throughout the Manual particularly between Chapters 2 and 3 The applicant should use each Chapter as follows Table 1 How to Use the Chapters in this Manual Chapter How to Use Chapter 1 Regulatory Requirements Learn about the Stormwater Regulations determine if a project is subject to the Stormwater Regulations and find out which requirements need to be met Chapter 2 Submission Review and Approval Procedures Understand the submission and review process for a project and get detailed guidance in preparing submissions to PWD Chapter 3 Site Design and Stormwater Management Integration Learn how to perform site assessments including infiltration testing and design stormwater management controls including disconnected impervious cover and SMPs to comply with the Stormwater Regulations Chapter 4 Stormwater Management Practice Guidance Obtain SMP specific guidance on use applicability components design requirements materials specifications construction sequencing and O M Chapter 5 Construction Guidance Understand PWD s construction inspection process identify common problems with SMP and Erosion and Sediment Control E S construction and prepare a Construction Certification Package and Record Drawings Chapter 6 Post Construction and Operations Maintenance Guidance Understand PWD s SMP maintenance requirements learn how to inspect operate and maintain SMPs and other stormwater controls get detailed guidance on O M Agreements and apply for stormwater billing credits The Appendices contain additional resources including watershed and Flood Management District mapping submission checklists worksheets a sample Record Drawing and landscape guidance A list of Appendices is provided in the Manual table of contents Stormwater Regulations PWD requires that many development sites in the City implement stormwater management controls The Stormwater Regulations define the specific requirements that need to be met for various types of development in the City PWD s Stormwater Regulations fall into two categories Post Construction Stormwater Management PCSM Requirements and an E S Requirement PCSM Requirements regulate how stormwater runoff leaves a project site in the built or post development condition There are four components of PWD s PSCM Requirements Water Quality to recharge the groundwater table and reduce pollution in stormwater runoff Channel Protection to minimize channel erosion resulting from stormwater runoff by controlling the peak flow rates for medium sized storms Flood Control to prevent through peak flow rate control flooding caused by large storm events that could cause damage to life or property and Public Health and Safety Release Rate to minimize the impact of flooding in areas of the City with infrastructure capacity restrictions through peak flow rate control The E S Requirement stipulates that practices be employed during construction to reduce any erosion and sedimentation that occur as a result of development activities PWD Stormwater Plan Review PWD Stormwater Plan Review is responsible for administering the Stormwater Regulations PWD Stormwater Plan Review provides a range of services relating to the enforcement and implementation of the Stormwater Regulations including the following Reviewing development plans for compliance Ensuring that SMPs are correctly designed installed and maintained in accordance with the Stormwater Regulations Acting as PWD s link to the larger development process in the City most critically the Zoning and Building Permit process administered by the City of Philadelphia Department of Licenses and Inspections L I The applicant must receive approvals from PWD before a Zoning or Building Permit may be issued Coordinating with other reviewing entities such as the Philadelphia City Planning Commission PCPC Philadelphia Streets Department Streets Department and the Pennsylvania Department of Environmental Protection PA DEP to ensure that consistent information is provided by the applicant to all agencies Administering inspection activities to ensure that SMPs are installed according to the approved plans Conducting post construction meetings to walk the site and record information about the project s as built conditions which the applicant must incorporate into a Record Drawing Contacting PWD Stormwater Plan Review PWD Stormwater Plan Review encourages the applicant to contact staff throughout the project lifecycle from preliminary planning through O M If additional clarity or discussion is required the applicant is encouraged to request in person meetings Staff can be reached during normal business hours 8 am to 5 pm at 215 685 6387 or pwd planreview phila gov The general phone line and email account are both monitored regularly by PWD Stormwater Plan Review staff Before a reviewer has been assigned to the project the applicant should use the general email account for all inquiries to ensure an efficient response time Website The PWD Stormwater Plan Review website www pwdplanreview org is geared toward the applicant and the development community at large and is the best place to find all applicant resources Using the website the applicant can access technical resources such as process flow charts Standard Details design worksheets and informational fact sheets Copies of the Manual can be downloaded from the website The applicant may use the website to submit their application for review and monitor the review status Stormwater Management in Philadelphia Unmanaged stormwater runoff rainfall in developed areas that quickly runs off of impervious surfaces rather than soaking into the ground negatively affects the aquatic and streamside habitats of streams and rivers in Philadelphia These water bodies suffer from a variety of problems and as a result many of Philadelphia s streams do not support healthy aquatic communities Similarly pollution from unmanaged stormwater that reaches the drinking water intakes on the Schuylkill and Delaware Rivers threatens the City s potable water supply In contrast healthy streams and rivers have lower rates of erosion plenty of flow during dry periods for fish and aquatic life high water quality that supports both recreational uses such as swimming and fishing and potable water use and flood less frequently and less severely Clean healthy rivers are a valuable community amenity that attracts residents and enhances the overall quality of life for residents The goal of healthy clean rivers in Philadelphia is an ambitious one but one that PWD and its partners are aggressively working toward Stormwater and Land Development Land development activities such as the construction of new buildings roads driveways and parking lots can lead to increased stormwater runoff and pollution As land is developed increases in impervious areas hard surfaces like rooftops roads and parking lots limit the amount of rainfall infiltrating into the ground Rates of evaporation are also reduced due to a lack of vegetation Conversely in natural undeveloped conditions the majority of rainfall either infiltrates or evaporates back into the air As rainfall flows across the developed land surfaces it picks up pollutants such as sediment fertilizers pesticides bacteria metals and oils and flows directly into streams rivers or other bodies of water Every acre of impervious cover in Philadelphia produces about 1 million gallons of polluted runoff per year causing sewer overflows degraded stream habitat and water quality problems Figure 1 Effects of Urbanization on the Hydrologic Cycle These problems are not unique to Philadelphia Stormwater regulations are changing around the country to address these and similar problems These changing regulations include new approaches to stormwater management which often require improvements in stormwater quality prior to discharge reductions in the volume and rate of runoff and reductions in stormwater related erosion and sedimentation Through these regulations cities and developers are working together to prevent additional pollution and damage to waterways by controlling stormwater The updated Stormwater Regulations in Philadelphia ensure that the City has an effective comprehensive stormwater program that meets State and Federal requirements and is adaptable to a changing regulatory context PWD s Regulatory Context The City of Philadelphia is required by a series of State and Federal regulations and mandates to clean up its waterways While PWD is investing billions of dollars to implement the bulk of the required upgrades PWD through the Stormwater Regulations also requires the development community to do its part to help manage stormwater Table 2 provides an overview of the many State and Federal laws that require PWD to work toward cleaning up Philadelphia s waterways PWD s CSO Program Requirements by the Numbers 7 960 000 000 000 fewer gallons of CSO water released 85 equivalent mass capture of specific pollutants such as suspended solids and coliform bacteria which means removing the same amount of pollutants that would be removed if stormwater were to pass through a wastewater treatment plant 9 564 Greened Acres each of which represents an acre of impervious cover within the combined sewer service area that has at least the first inch of stormwater runoff managed by stormwater infrastructure Clean Water Act The Clean Water Act CWA of 1972 aims to restore and maintain the chemical physical and biological integrity of the nation s waterways PWD is primarily charged with ensuring CWA compliance in Philadelphia and does so through a variety of activities such as building and maintaining public stormwater infrastructure regulating development implementing municipal pollution prevention best practices meeting pollutant discharge standards at sewage treatment plants and monitoring industrial and commercial dischargers Combined Sewer Overflow CSO Control Policy Published by the Environmental Protection Agency EPA in 1994 this policy established a national approach for controlling CSOs through the National Pollutant Discharge Elimination System NPDES Permit program CSOs occur when combined sewers sewers that convey both stormwater and sewage in the same pipe reach capacity as a result of stormwater runoff entering the pipe network during rain and snowmelt events When this happens the PA DEP permits Philadelphia as is common with other cities containing combined sewer systems to discharge excess untreated wastewater into nearby waterbodies Communities with combined sewer systems are required to develop a Long Term Control Plan to outline steps toward full compliance with the CWA PWD submitted its original Long Term Control Plan in 1997 In 2006 PWD enacted Stormwater Regulations that included requirements to assist the City in addressing CSOs Then in June 2011 PWD and PA DEP entered into a Consent Order and Agreement CO A a binding legal agreement that outlines the water quality targets the City needs to meet to reduce CSOs Quick Tip To determine if a project lies within a CSO area of the City visit phillywatersheds org PWD prepared and submitted to PA DEP a Long Term Control Plan Update LTCPU known as Green City Clean Waters to outline specific steps needed to implement the provisions of the CO A Green City Clean Waters outlines a 25 year 2 4 billion plan to protect and enhance Philadelphia s combined sewer watersheds by managing stormwater with innovative green stormwater infrastructure PWD s approach differs from the methods used by other cities to address CSOs which typically involves building large underground tunnels and storage tanks to temporarily hold combined sewer water so that it can eventually be treated by wastewater plants In Philadelphia this approach was found to be cost prohibitive for residents it also did not meet restoration goals for the City s waterways Table 2 Summary and Objectives of PWD Regulations Regulation Objectives How PWD Meets These Objectives Clean Water Act of 1972 Restore and maintain the chemical physical and biological integrity of the nation s waterways Implementing CSO control and Municipal Separate Stormwater Sewer Systems MS4 permit programs see descriptions below Reducing the quantity of sediment to Wissahickon Creek to under the siltation Total Maximum Daily Load The Safe Drinking Water Act of 1974 To ensure safe drinking water for the public by establishing standards for water quality Investing in identifying and reducing major potential sources of contamination including stormwater runoff which could affect the drinking water supply Reducing the amount of pollutants entering Philadelphia s source waters and treatment facilities through implementation of the Stormwater Regulations The Pennsylvania Stormwater Management Act of 1978 Develop county based stormwater management plans to ensure that stormwater is managed properly particularly with regard to flooding Requiring that development activities comply with the Stormwater Regulations and other measurable benchmarks Aligning Stormwater Regulations with Act 167 Plan requirements for local waterways NPDES MS4 Stormwater Regulations Reduce and eliminate sources of pollution coming from municipally owned separate sewer systems into the Nation s water bodies Implementing public water quality improvement projects such as SMPs and stream restoration projects Implementing illicit discharge elimination programs Implementing public outreach and education programs Regulating development and Industrial dischargers Monitoring industrial and commercial dischargers CSO Control Policy Eliminate discharges of untreated wastewater through combined sewer overflows into the nation s waterbodies Implementing green stormwater practices wastewater upgrades and other improvements through Green City Clean Waters PWD s LTCPU Regulating development Applicability and Submission Process PWD s Stormwater Regulations cover a wide spectrum of development and construction projects Under the Stormwater Regulations not all projects are subject to the same requirements Some projects may need to meet multiple requirements while others may be subject to only certain portions of the Stormwater

    Original URL path: http://www.pwdplanreview.org/manual/introduction (2016-04-24)
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  • Pre-July 2015 Resources | Philadelphia Water Stormwater Plan Review
    Guidance Manual Version 2 1 and its associated supplemental materials below Projects whose ERSA Applications are submitted to PWD on or after July 1 2015 should refer to the PWD Stormwater Management Guidance Manual Version 3 0 If you are unclear on which requirements apply to your project please call Stormwater Plan Review at 215 685 6387 Download the Full Manual Full Manual Manual Version 2 1 pdf revised February 10 2014 33MB Download the Manual By Section Cover Manual Version 2 1 pdf 1MB Preface Manual Version 2 1 pdf 1MB Table of Contents Manual Version 2 1 pdf 1MB Chapter 1 Manual Version 2 1 pdf 1MB Chapter 2 Manual Version 2 1 pdf 1MB Chapter 3 Manual Version 2 1 pdf 1MB Chapter 4 Manual Version 2 1 pdf 1MB Chapter 5 Manual Version 2 1 pdf 1MB Chapter 6 Manual Version 2 1 pdf 5MB Chapter 7 Manual Version 2 1 pdf 14MB Chapter 8 Manual Version 2 1 pdf 1 5MB Appendices All Manual Version 2 1 pdf 13MB Appendices A C Manual Version 2 1 pdf 1MB Appendix D Manual Version 2 1 pdf 11MB Appendices E F Manual Version 2 1 pdf 1MB

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  • F. Design Guidance Checklists | Philadelphia Water Stormwater Plan Review
    Bioinfiltration Bioretention 4 2 Porous Pavement 4 3 Green Roofs 4 4 Subsurface Infiltration 4 5 Cisterns 4 6 Blue Roofs 4 7 Ponds and Wet Basins 4 8 Subsurface Detention 4 9 Media Filters 4 10 Pretreatment 4 11 Inlet Controls 4 12 Outlet Controls Back to Chapter 4 4 0 1 How to Use This Chapter 4 0 2 Chapter Organization 4 0 3 Design Innovation Back to Chapter 4 4 1 1 Bioinfiltration Bioretention Introduction 4 1 2 Bioinfiltration Bioretention Components 4 1 3 Bioinfiltration Bioretention Design Standards 4 1 4 Bioinfiltration Bioretention Material Standards 4 1 5 Bioinfiltration Bioretention Construction Guidance 4 1 6 Bioinfiltration Bioretention Maintenance Guidance Back to Chapter 4 4 2 1 Porous Pavement Introduction 4 2 2 Porous Pavement Components 4 2 3 Porous Pavement Design Standards 4 2 4 Porous Pavement Material Standards 4 2 5 Porous Pavement Construction Guidance 4 2 6 Porous Pavement Maintenance Guidance Back to Chapter 4 4 3 1 Green Roof Introduction 4 3 2 Green Roof Components 4 3 3 Green Roof Design Standards 4 3 4 Green Roof Material Standards 4 3 5 Green Roof Construction Guidance 4 3 6 Green Roof Maintenance Guidance Back to Chapter 4 4 4 1 Subsurface Infiltration Introduction 4 4 2 Subsurface Infiltration Components 4 4 3 Subsurface Infiltration Design Standards 4 4 4 Subsurface Infiltration Material Standards 4 4 5 Subsurface Infiltration Construction Guidance 4 4 6 Subsurface Infiltration Maintenance Guidance Back to Chapter 4 4 5 1 Cistern Introduction 4 5 2 Cistern Components 4 5 3 Cistern Design Standards 4 5 4 Cistern Material Standards 4 5 5 Cistern Construction Guidance 4 5 6 Cistern Maintenance Guidance Back to Chapter 4 4 6 1 Blue Roof Introduction 4 6 2 Blue Roof Components 4 6 3 Blue Roof Design Standards 4 6 4 Blue Roof Material Standards 4 6 5 Blue Roof Construction Guidance 4 6 6 Blue Roof Maintenance Guidance Back to Chapter 4 4 7 1 Pond and Wet Basin Introduction 4 7 2 Pond and Wet Basin Components 4 7 3 Pond and Wet Basin Design Standards 4 7 4 Pond and Wet Basin Material Standards 4 7 5 Pond and Wet Basin Construction Guidance 4 7 6 Pond and Wet Basin Maintenance Guidance Back to Chapter 4 4 8 1 Subsurface Detention Introduction 4 8 2 Subsurface Detention Components 4 8 3 Subsurface Detention Design Standards 4 8 4 Subsurface Detention Material Standards 4 8 5 Subsurface Detention Construction Guidance 4 8 6 Subsurface Detention Maintenance Guidance Back to Chapter 4 4 9 1 Media Filter Introduction 4 9 2 Media Filter Components 4 9 3 Media Filter Design Standards 4 9 4 Media Filter Material Standards 4 9 5 Media Filter Construction Guidance 4 9 6 Media Filter Maintenance Guidance Back to Chapter 4 4 10 1 Pretreatment Introduction 4 10 2 Berms and Retentive Grading 4 10 3 Filter Strips 4 10 4 Forebays 4 10 5 Swales Back

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  • Chapter 1 - Regulatory Requirements | Philadelphia Water Stormwater Plan Review
    portions of the Stormwater Regulations apply to the project 1 1 Applicability Factors This Section contains guidance on the project factors that determine which portions of the Philadelphia Water PWD Stormwater Regulations Stormwater Regulations apply to an applicant s project PWD requires submissions for all projects in the City of Philadelphia that generate earth disturbance of 5 000 square feet or more yet not all projects will need to comply with all requirements of the Stormwater Regulations There are three main factors that determine which requirements of the Stormwater Regulations apply to a project Development Type Watershed and Earth Disturbance These three project characteristics play an important role in determining how the Stormwater Regulations discussed in Section 1 2 are applied to a project The applicant will use this Section to identify the project s development type watershed and earth disturbance area This information in conjunction with the requirement specific exemptions in Section 1 2 is necessary for determining applicability and the project s Review Path in Chapter 2 Of the three key applicability factors one earth disturbance can change during the course of design and construction If the earth disturbance threshold changes the applicant must return to Section 1 1 3 to verify whether the project s applicability determinations have changed 1 1 1 Development Type Development type plays a key role in determining if and how Post Construction Stormwater Management PCSM Requirements Section 1 2 1 will apply to a project Development is defined in the Stormwater Regulations as any human induced change to improved or unimproved real estate whether public or private Development encompasses but is not limited to New Development Redevelopment Demolition and Stormwater Retrofit It includes the entire Development Site even when the project is performed in phases The development types listed below are types that PWD recognizes and it is incumbent on the applicant to determine under which type his or her project falls The applicant is encouraged to contact PWD Stormwater Plan Review for assistance in determining the project s development type if they are uncertain or believe that their project may fall under more than one category New Development New Development is defined in the Stormwater Regulations as development on an unimproved tract of land where structures or impervious surfaces were removed before January 1 1970 Redevelopment Redevelopment is defined in the Stormwater Regulations as development on an improved tract of land that includes but is not limited to the demolition or removal of existing structures or impervious surfaces and replacement with new impervious surfaces This includes replacement of impervious surfaces that have been removed on or after January 1 1970 Demolition Demolition is defined in the Stormwater Regulations as a project that is limited to the razing or destruction whether entirely or in significant part of a building structure site or object including the removal of a building structure site or object from its site or the removal or destruction of the façade or surface Stormwater Retrofit Stormwater Retrofit is defined in the Stormwater Regulations as a project that is limited to the voluntary rehabilitation and or installation of stormwater management practices SMPs on a property to better manage stormwater runoff Often the motivation to initiate a Stormwater Retrofit project is to reduce the applicant s monthly stormwater bill In addition these projects often involve stormwater grants In most circumstances projects classified as Demoltion or Stormwater Retrofits will be exempt from PCSM Requirements regardless of size However these types of projects must still comply with the Erosion Sediment Control E S requirement The applicant is referred to Chapter 2 for more information Due to historic urbanization New Development projects are uncommon in Philadelphia and must comply with the most stringent PCSM Requirements The vast majority of development projects in Philadelphia are classified as Redevelopment projects The applicant can submit supporting documentation e g photographs past permits inspection reports etc to confirm a redevelopment classification If a Redevelopment project meets certain conditions it may be exempt from the Flood Control and Channel Protection requirements The applicant is referred to Section 1 2 for the Stormwater Regulations as well as requirement specific exemptions 1 1 2 Watershed The watershed in which a project site is located plays an important role in determining how PCSM Requirements Section 1 2 1 are applied to a project For example ongoing watershed wide Pennsylvania Stormwater Management Act Act 167 planning studies determine Flood Management Districts for controlling peak rates of runoff and watershed locations are also used to determine the applicability of the Channel Protection requirement for Redevelopment projects For this reason it is important that the applicant identify the correct watershed early in the design process Watershed Maps in Appendix D provide a basic guide as well as PWD s Find Your Watershed website but the applicant can also contact PWD to verify a site s watershed location There are seven major watersheds in Philadelphia Darby and Cobbs Creeks Delaware Direct Lower Schuylkill River Pennypack Creek Poquessing Creek Tookany Tacony Frankford and Wissahickon Creek Watershed based regulations are evolving to address stormwater challenges within Philadelphia While the Stormwater Regulations apply to all projects that result in earth disturbance totals of 15 000 square feet or more Section 1 1 3 watershed specific regulations trigger the Stormwater Regulations at a lower disturbance threshold Project sites located in the Darby and Cobbs Creeks Watershed and in the Wissahickon Creek Watershed are subject to additional watershed specific stormwater management requirements The latest information about watershed specific regulations can be found on the PWD Stormwater Plan Review website Darby and Cobbs Creeks Watershed Projects located in the Darby and Cobbs Creeks Watershed are subject to the provisions of the Darby and Cobbs Creeks Watershed Act 167 Stormwater Management Plan Because the Stormwater Regulations were developed to comply with the plan for the Darby and Cobbs Creeks Watershed all projects that propose 5 000 square feet or more of earth disturbance in the Darby and Cobbs Creeks Watershed are subject to the Stormwater Regulations and their associated PCSM Requirements Section 1 2 1 Wissahickon Watershed Overlay To help reduce flooding erosion siltation and channel enlargement resulting from development within the Wissahickon Creek Watershed additional stormwater management requirements and impervious coverage limits may apply to projects within this watershed Projects located in the Wissahickon Creek Watershed are subject to the Philadelphia Code 14 510 WWO Wissahickon Watershed Overlay District The applicability of these requirements depends on the location of the project within the watershed and the amount of impervious cover proposed in comparison to the existing impervious condition A map of the Wissahickon Watershed Overlay WWO District can be found within the Code and can also be viewed using the City of Philadelphia online zoning map For projects located within the WWO District the Philadelphia City Planning Commission PCPC will determine if additional stormwater management requirements are applicable however PWD Stormwater Plan Review will be responsible for review of the Post Construction Stormwater Management Plan PCSMP The applicant is referred to Section 2 6 for more information on the WWO as it relates to project specific requirements 1 1 3 Earth Disturbance Earth disturbance is the primary factor that determines whether a project is subject to the Stormwater Regulations It is also a primary factor in determining the applicability of PCSM Requirements Section 1 2 1 and the E S requirement Section 1 2 2 As such applicants must properly and accurately assess the limits of earth disturbance associated with development projects to determine applicable requirements and the level of review required While earth disturbance of 15 000 square feet or more triggers the PCSM Requirements in most areas of the City earth disturbance of 5 000 square feet or more triggers the PCSM Requirements in the Darby and Cobbs Creek Watershed Projects located in the Wissahickon Creek Watershed may also be required to comply with PCSM Requirements at even lower earth disturbance totals The applicant is referred to Section 1 1 2 above for specific requirements regarding projects located within the Wissahickon Creek Watershed or the Darby and Cobbs Creeks Watershed Quick Tip A project may have multiple boundaries each of which is significant when determining stormwater management applicability during the development process For example the parcel boundary limits of earth disturbance and area that must be managed for stormwater may all be different Only the limit of earth disturbance is used to determine whether or not and which portions of the Stormwater Regulations apply to most projects Earth disturbance is defined in the Stormwater Regulations as any construction or other activity that disturbs the surface of land Examples of activities that consist of or can commonly involve earth disturbance include but are not limited to the following activities Excavation Embankments Land development Subdivision development Moving depositing stockpiling or storing of soil rock or earth materials except as excluded below Demolition activity that results in the disturbance of the land beneath or surrounding a structure including foundation or building slab removal Stormwater Retrofits that include ground level SMP installation Utility connections including work in the public rights of way Road maintenance activities that disturb the surface of the land New paving and full depth pavement replacement Installation of E S controls and construction related disturbance located over existing pervious areas such as establishment of rock construction entrances stockpiles silt fencing construction vehicle paths staging and fill areas Grading Clearing and grubbing and Landscaping Activities that are not typically classified as earth disturbance include the following Interior building renovations Temporary stockpiles or rock construction entrances located over existing impervious surfaces Restriping of paved areas and Milling and repaving of existing paved areas as long as the pavement subbase is not exposed during the milling process The pavement subbase is defined as the layer of aggregate material laid on the subgrade on which the base course layer is laid Some earth disturbance activities and their associated areas count toward the regulatory disturbance threshold for triggering PCSM Requirements but are not required to be managed in the post development condition Such activities include the following Replacement of existing public roads within the public right of way when stormwater runoff characteristics are not significantly altered as part of development New public roads that are constructed to the City grid as determined by the Philadelphia Department of Streets PCPC and PWD Certain road maintenance activities as determined by PWD Demolition provided the surface of the land is returned to a pervious condition Certain activities within a Waterway of the Commonwealth such as dredging stream restoration bank stabilization and erosion stabilization activities provided they are permitted under 25 Pa Code Chapter 105 Certain water features as determined by PWD such as spraygrounds swimming pools and fountains that will be chlorinated and Earth disturbance located beneath an undisturbed existing impervious superstructure such as a highway overpass There are other earth disturbance areas that do not count toward the regulatory disturbance threshold for triggering PCSM Requirements and are not required to be managed in the post development condition When calculating the total limit of earth disturbance for a development project the earth disturbance area associated with the following activities should not be counted toward the total disturbance value triggering the PCSM Requirements These areas include Replacement of existing public sidewalks within the public right of way as part of the development project and Area disturbed for Stormwater Retrofit installation Applicants who wish to claim exemption from PCSM Requirements as a result of these earth disturbance areas should delineate them separately on E S Plans submitted to PWD as part of the Conceptual Review Phase Earth disturbance activities that are exempt from PCSM Requirements are still required to comply with all appropriate E S submission and review requirements which may include PWD approval of an E S Plan The applicant is referred to Chapter 2 for more information on submission requirements Exemption of a project from PWD s PCSM Requirements does not necessarily imply that the project is also exempt from PCSM Requirements from other City and State agencies The applicant is referred to Section 2 6 and Section 2 7 for more information Being Conservative PWD often observes earth disturbances that occur during construction activity that exceed initial estimates provided on plans To avoid costly delays PWD recommends that the applicant be conservative when estimating the disturbance area at each stage of the review process Should a site inspection reveal that 15 000 or more square feet of earth disturbance has occurred the site will be required to comply with the Stormwater Regulations and will be subject to the enforcement actions outlined in the Stormwater Regulations Should a site inspection reveal that more than one acre of earth has been disturbed the site will be required to apply for a Pennsylvania Department of Environmental Protection PA DEP National Pollutant Discharge Elimination System NPDES Permit The site will be subject to the enforcement actions outlined in the Stormwater Regulations until the applicant receives a NPDES Permit The applicant is referred to Section 2 7 for more information on the interaction between PWD and PA DEP PWD Stormwater Plan Review should be contacted prior to plan submittal and before any construction activities whenever there are questions or a need for clarification regarding earth disturbance activities 1 2 Stormwater Regulations This Section provides an overview of the Philadelphia Water PWD Stormwater Regulations Stormwater Regulations their objectives and project specific exemptions After determining the project s development type watershed and earth disturbance area using Section 1 1 the applicant will use this information in conjunction with the requirement specific exemptions detailed in this Section to determine which portions of the Stormwater Regulations apply to the project The Stormwater Regulations have been developed in accordance with the Philadelphia Code 14 704 3 and they consist of four major Post Construction Stormwater Management PCSM Requirements Water Quality Channel Protection Flood Control and Public Health and Safety PHS Release Rate In addition all earth disturbance activity must comply with the Erosion and Sediment Control E S requirements of the Pennsylvania Department of Environmental Protection PA DEP as specified in 25 Pa Code 102 4 The details of the Stormwater Regulations can be found within Chapter 6 Stormwater of PWD Regulations which are available at the City of Philadelphia website 1 2 1 Post Construction Stormwater Management Requirements PCSM Requirements regulate how stormwater runoff leaves a project site in the built or post development condition PCSM Requirements have four components Water Quality Channel Protection Flood Control and PHS Release Rate requirements All projects in the City of Philadelphia that generate earth disturbance of 15 000 square feet or more or 5 000 square feet in the Darby and Cobbs Creeks Watershed are subject to the PCSM Requirements and will follow the Development Compliance Review Path The applicant is referred to Section 2 1 2 for an explanation of and further guidance regarding Review Paths Water Quality Background The objectives of the Water Quality requirement are as follows Reduce pollution in runoff Recharge the groundwater table and increase stream base flows Restore more natural site hydrology and Reduce combined sewer overflows CSOs from the City s combined sewer systems The Water Quality requirement focuses on the removal of pollutants from stormwater runoff and is similar to requirements in surrounding states and other major cities across the country Water quality benefits are provided in part by slowing water down and allowing suspended solids to settle Because some nutrients metals organics and other contaminants are bound to these sediment particles this basic treatment mechanism can have multiple benefits Generally the physical chemical and biological processes that take place in a system that incorporates soil water and plants provide the best water quality improvements Infiltration of stormwater runoff can significantly reduce pollutant loads reaching surface water and generally does not pose a threat to groundwater quality if there is sufficient separation from the water table Infiltrating stormwater runoff also has a direct impact on reducing the quantity of water in the sewer system that can contribute to CSOs and pollution of receiving waters As such infiltration is a major focus of the Water Quality requirement Attenuation of stormwater flows also contributes to water quality goals In combined sewer systems CSOs must be reduced by maintenance of a slow release rate set to match the area weighted wet weather treatment rate of PWD s Water Pollution Control Plants Therefore when infiltration is not feasible water quality improvement in combined sewer areas must be achieved not only by reducing runoff pollutant load concentrations but also by managing the quantity and timing of stormwater discharge Detention and slow release reduces peak flows in the combined sewer during wet weather events thus reducing the frequency and magnitude of CSOs Requirement The Water Quality requirement stipulates infiltration of the first 1 5 inches of runoff from all directly connected impervious area DCIA within the limits of earth disturbance This volume of stormwater runoff is referred to as the Water Quality Volume WQv If infiltration is feasible on the project site the Water Quality requirement must be met by infiltrating 100 of the WQv through stormwater management practices SMPs One strategy to address the Water Quality requirement is to minimize the amount of DCIA which reduces the WQv that must be treated on site DCIA can be reduced through the use of disconnected impervious cover DIC which includes green roofs porous pavement and rooftop pavement and tree disconnections which are outlined in greater detail in Section 3 2 Projects that propose to disconnect 95 or more of their post development impervious area qualify for an expedited Disconnection Green Review as described in Section 2 4 Quick Tip Property owners often find that by incorporating landscape elements to reduce their DCIA they simultaneously increase their property value and retail sales reduce crime and improve mental health and worker productivity For more information regarding the triple bottom line benefits of green stormwater management practices the applicant is encouraged to

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  • 4.1 Bioinfiltration/Bioretention | Philadelphia Water Stormwater Plan Review
    Control requirement May have limited opportunities for implementation based on the amount of open space available at the site Key Design Considerations for Bioinfiltration Bioretention Bioinfiltration bioretention SMPs should be considered as an alternative before designing subsurface infiltration and detention SMPs Bioinfiltration bioretention SMPs are preferred for a number of reasons including installation and maintenance cost ease of maintenance habitat creation nutrient cycling and aesthetics The pretreatment approach should be matched to site characteristics Bioinfiltration bioretention SMPs rely on flow through soil media to provide Water Quality treatment Media layers can become clogged particularly when runoff has high quantities of sediment To avoid this SMPs managing runoff from surfaces that generate high sediment loads should have adequate pretreatment to remove dirt and grit before they reach the bioinfiltration bioretention SMP The SMPs should be viewed as landscape features Viewing bioinfiltration bioretention SMPs as an integral part of a site s landscape design can help identify key implementation locations Bioinfiltration bioretention SMPs can double as landscape features on many sites providing landscape amenities and stormwater management in the same location Non basin designs can be used for small spaces Integrating bioinfiltration bioretention into flow through planter boxes or tree pits can be an effective way of incorporating bioinfiltration bioretention functions into spatially constrained sites Safety issues relating to ponding depth should be carefully considered particularly for sites where small children will be proximate to the installation Balancing cut and fill can reduce costs A berm placed on the downslope side of a mild slope can help retain stormwater and increase capacity without additional excavation For constrained sites using additional subsurface stone to meet storage volume needs should be considered Areas of soil contamination should be avoided however in some cases an impervious liner may be appropriate for separating bioinfiltration bioretention SMPs from these underlying conditions A diverse planting palette should be used A diverse community of native plants is recommended to minimize susceptibility to insect and disease infestation and reduce long term maintenance requirements A mixture of groundcover grasses shrubs and trees is generally recommended to create a microclimate that can ameliorate urban stresses discourage weed growth and reduce maintenance needs The designer should choose low maintenance plants that minimize the need for mowing pruning and irrigation The characteristics of the soil for the bioinfiltration bioretention SMP are perhaps as important as the facility location size and treatment volume The soil must be permeable enough to allow runoff to filter through the media while having characteristics suitable to promote and sustain a robust vegetative cover crop In addition much of the nutrient pollutant uptake nitrogen and phosphorus is accomplished through adsorption and microbial activity within the soil profile Therefore the soils must balance soil chemistry and physical properties to support biotic communities above and below ground Smart plant selection for the site should be a focus It is critical that plant materials are appropriate for soil hydrologic light and other site conditions The designer is referred to the list of native species in Appendix I Ponding depth drain down time sunlight salt tolerance and other conditions should be taken into consideration when selecting plants Turf grass is generally not recommended but may be acceptable provided the designer can demonstrate that it meets all applicable requirements Flow through planter box planting requires that plants be supplied with nutrients that they would otherwise receive from being part of an ecosystem Since they are cut off from these processes they must be cared for accordingly Groundcover plantings and wildflower plugs should be planted on eight to ten inch centers with triangular spacing Mulch for a bioinfiltration bioretention SMP should have a minimum depth of two inches 4 1 2 Bioinfiltration Bioretention Components Figure 4 1 1 Bioinfiltration Bioretention Basin with Typical Features Pretreatment Component Pretreatment systems capture trash sediment and or other pollutants from stormwater runoff before delivery to the storage or infiltration area Pretreatment needs will vary significantly depending on the contributing drainage area composition and use Pretreatment can include structures such as sumped and trapped inlets sediment grit chambers or separators media filters inlet inserts or other appropriate prefabricated or proprietary designs to remove sediment floatables and or hydrocarbons from stormwater runoff prior to being conveyed to a bioinfiltration bioretention SMP Pretreatment can also consist of berms and retentive grading filter strips forebays and swales The designer is referred to Section 4 10 Pretreatment for more information on pretreatment systems Inlet Control Component Inlet control systems convey and control the flow of stormwater from the contributing catchment area to a bioinfiltration bioretention SMP Inlet control needs will vary depending on the design of stormwater conveyance systems and the site layout The designer is referred to Section 3 4 2 for guidance on stormwater conveyance system design Inlet controls may include flow splitters curbless design curb openings energy dissipaters and inlets The designer is referred to Section 4 11 Inlet Controls for more information on inlet controls Storage Area Component Storage areas within bioinfiltration bioretention SMPs temporarily hold stormwater runoff until it can either infiltrate into native soils evaporate be used by plants through transpiration or be released downstream at a controlled rate depending on the SMP design Bioinfiltration bioretention SMPs can include both surface and subsurface storage areas Surface storage is typically provided by excavating an area to create a depression Surface storage for bioinfiltration bioretention SMPs can also be created using curbing or concrete structures such as flow through planter boxes It provides temporary storage of stormwater runoff before infiltration evaporation and uptake can occur within the bioinfiltration bioretention SMP Ponding time provides Water Quality benefits by allowing larger debris and sediment to settle out of the water Maximum surface ponding depth requirements are provided in order to reduce hydraulic loading on underlying soils ensure adequate drain down time and prevent standing water Figure 4 1 2 Flow Through Planter Box with Typical Features Beneath surface storage areas prepared planting soil medium provides subsurface storage capacity This storage capacity is a function of the soil depth surface area and void space The planting soil medium serves as the primary Water Quality treatment mechanism of a bioinfiltration bioretention SMP filtering runoff before it reaches the native soil for bioinfiltration SMPs or before it reaches the downstream discharge point for bioretention SMPs Many bioinfiltration bioretention SMPs include an additional subsurface storage component typically constructed of a stone filled level bottomed bed or trench The void spaces between the stones store stormwater until it can infiltrate into the surrounding soils or be released downstream A mulch or organic layer atop the planting soil medium provides a medium for biological growth decomposition of organic material and adsorption of pollutants such as heavy metals The mulch layer can also absorb some water during storms and help the planting soil retain water for plant growth during dry periods Vegetation Component Plant material in a bioinfiltration bioretention SMP removes nutrients and stormwater pollutants through vegetative uptake and microbial community support removes water through evapotranspiration creates pathways for infiltration in bioinfiltration SMPs through root development and plant growth improves aesthetics provides habitat and helps to stabilize soil The proper selection and installation of plant materials is critical to a successful bioinfiltration bioretention SMP There are essentially six zones within a bioinfiltration bioretention SMP Figure 4 1 3 The lowest elevation supports plant species adapted to standing and fluctuating water levels The middle elevation supports a slightly drier group of plants but still tolerates fluctuating water levels The outer edge is the highest elevation and generally supports plants adapted to drier conditions However plants in all of the zones should be drought tolerant Plants should also have high salt tolerance if the bioinfiltration bioretention SMP receives runoff from ground level impervious surfaces Figure 4 1 3 Hydrologic Zones of a Bioinfiltration Bioretention Basin The lowest zone hydrologic zones 2 4 contains plant species adapted to standing and fluctuating water levels and frequent inundation Frequently used native plants include the following species The designer is referred to Appendix I for a complete listing Table 4 1 1 Frequently Used Native Plants for Hydrologic Zones 2 4 Frequently Used Native Plants for Hydrologic Zones 2 4 asters Aster spp winterberry Ilex verticillata goldenrods Solidago spp arrowwood Viburnum dentatum bergamot Monarda fistulosa sweet pepperbush Clethra alnifolia blue flag iris Iris versicolor bayberry Myrica pensylvanica sedges Carex spp buttonbush Cephalanthus occidentalis ironweed Vernonia noveboracensis swamp azalea Rhododendron viscosum blue vervain Verbena hastata elderberry Sambucus canadensis joe pye weed Eupatorium spp green ash Fraxinus pennsylvanica swamp milkweed Asclepias incarnata river birch Betula nigra switchgrass Panicum virgatum sweetgum Liquidambar styraciflua shrub dogwoods Cornus spp northern white cedar Juniperus virginiana swamp rose Rosa palustris red maple Acer rubrum The middle zone hydrologic zones 4 5 is slightly drier than the lowest zone but plants should still tolerate fluctuating water levels Some commonly planted native species include the following species The designer is referred to Appendix I for a complete listing Table 4 1 2 Frequently Used Native Plants for Hydrologic Zones 4 5 Frequently Used Native Plants for Hydrologic Zones 4 5 black snakeroot Cimicifuga racemosa spicebush Lindera benzoin switchgrass Panicum virgatum hackberry Celtis occidentalis spotted joe pye weed Eupatorium maculatum willow oak Quercus phellos cutleaf coneflower Rudabeckia lacinata winterberry Ilex verticillata frosted hawthorn Crataegus pruinosa slippery elm Ulmus rubra marginal wood fern Dryopteris marginalis viburnums Viburnum spp ironwood Carpinus caroliniana witch hazel Hamamelis virginiana serviceberry Amelanchier canadensis steeplebush Spiraea tomentosa obedient plant Physostegia virginiana blueberry Vaccinium spp The outer zone hydrologic zones 5 6 generally supports plants adapted to drier conditions Examples of commonly planted native species include the following species The designer is referred to Appendix I for a complete listing Table 4 1 3 Frequently Used Native Plants for Hydrologic Zones 5 6 Frequently Used Native Plants for Hydrologic Zones 5 6 many grasses and wildflowers juniper Juniperus communis basswood Tilia americana sweet fern Comptonia peregrina white oak Quercus alba eastern red cedar Juniperus virginiana scarlet oak Quercus coccinea smooth serviceberry Amelanchier laevis black oak Quercus velutina american holly Ilex opaca american beech Fagus grandifolia sassafras Sassafras albidum black chokeberry Aronia melanocarpa white pine Pinus strobus Outlet Control Component Outlet controls within a bioinfiltration bioretention SMP can provide a range of functions including the following Controlling how much water is stored for infiltration for bioinfiltration SMPs Meeting drain down time requirements Controlling the rate of discharge from the SMP and limiting water surface elevations during various storm events and Bypassing of flows from large storm events Outlet controls may include orifices weirs risers or underdrains The designer is referred to Section 4 12 Outlet Controls for more information on outlet controls Inspection and Maintenance Access Component Safe and easy inspection and maintenance access to all major components within a bioinfiltration bioretention SMP is critical to ensuring long term performance Cleanouts provide a means to maintain any installed underdrains Mildly sloping stabilized and graded areas also provide access to surface storage areas for heavy equipment which may be needed for sediment removal 4 1 3 Bioinfiltration Bioretention Design Standards The designer is encouraged to design bioinfiltration bioretention SMPs meeting the minimum requirements set forth in the Bioinfiltration Bioretention Basin Standard Detail Figure 4 1 4 in conjunction with the Bioinfiltration Bioretention Basin Sizing Table Table 4 1 4 Basins sized as such provide Water Quality compliance in all sewersheds and regardless of infiltration feasibility with only minor modification necessary to the capped underdrain during construction As a result bioinfiltration bioretention SMPs can be designed without knowledge of infiltration feasibility Assuming a directly disconnected impervious area DCIA to SMP footprint loading ratio less than or equal to 16 1 the Bioinfiltration Bioretention Basin Sizing Table Table 4 1 4 provides an orifice diameter based on the DCIA drainage area being treated by the basin The designer may use this table to determine the orifice diameter required for Water Quality compliance where infiltration is infeasible for DCIA drainage areas less than one acre Table 4 1 4 Bioinfiltration Bioretention Sizing Table Tier DCIA Drainage Area Range square feet Orifice Diameter inches A 0 17 000 B 17 000 24 000 C 24 000 33 000 D 33 000 43 560 1 DCIA to SMP footprint loading ratio must not exceed 16 1 2 For DCIA drainage areas greater than 1 acre the designer must design the SMP to meet all applicable PWD Stormwater Regulations Basins designed to meet the minimum requirements of the Standard Detail Figure 4 1 4 and the Bioinfiltration Bioretention Basin Sizing Table Table 4 1 4 inherently meet key design requirements static storage of the Water Quality Volume WQv when infiltration is feasible Water Quality release rate requirements when infiltration is infeasible in the combined sewer area appropriate maximum ponding depths and drain down within 72 hours Accordingly calculations confirming these design requirements have been met do not need to be submitted when designing bioinfiltration bioretention SMPs for Water Quality compliance per these recommendations Design modifications may be necessary when the Flood Control Channel Protection and or Public Health and Safety requirements apply General Design Standards The maximum allowable drain down time is 72 hours The maximum allowable DCIA to SMP footprint loading ratio is 16 1 Positive overflow must be provided for large storm events up to and including the 100 year storm Overflow structures and pipes must be designed to convey at least the ten year 24 hour storm The minimum allowable distance between infiltration SMPs and any adjacent private property line is ten feet It is acceptable for SMPs to be located directly adjacent to the public right of way ROW The minimum allowable distance between infiltration SMPs and any building foundation is ten feet Infiltration Requirements The designer is referred to Section 3 3 for information on infiltration testing requirements The SMP must be located at least two feet above any poorly infiltrating soils seasonal high groundwater table bedrock or other limiting zone For hydrologic modeling infiltration must be applied to the horizontal surface area SMP footprint not the wetted area If necessary for the purpose of meeting the Water Quality requirement infiltration can be assumed through the horizontal projection of the wetted area up to the WQv water surface elevation Soils underlying infiltration practices must when tested pursuant to the infiltration testing procedure described in Section 3 3 be determined to be infiltration feasible Soils with rates in excess of ten inches per hour require soil amendments During construction upon achieving final subgrade elevations a two foot thick layer of amended soil must be placed across the entire cross section of the infiltrating SMP below the bottom elevation of the SMP and a minimum of two infiltration tests must be performed within the amended soil layer If soil amendments are installed and the tested infiltration rate is determined to be outside of the PWD allowable range or varies significantly from the design infiltration rate additional soil amendments and or an SMP redesign will be required The designer is referred to Section 3 3 for additional detail Pretreatment Design Standards Acceptable form s of pretreatment must be incorporated into design Pretreatment of runoff from all inlets is required At a minimum this can be achieved through the use of sumps and traps for inlets sump boxes with traps downstream of trench drains and filter strips for overland flow The designer is referred to Section 4 10 Pretreatment for more information on design standards for pretreatment systems Inlet Control Design Standards To prevent erosion energy dissipaters such as riprap stone must be placed at all locations of concentrated inflow Riprap aprons must be designed and stone sizing must be determined in accordance with the riprap apron design procedures in the latest edition of the Pennsylvania Department of Environmental Protection PA DEP Erosion and Sediment Pollution Control Program Manual The designer is referred to Section 4 11 Inlet Controls for more information on design standards for inlet control systems Storage Area Design Standards The storage area for a bioinfiltration SMP must provide static storage for the WQv between the bottom elevation of the SMP and the elevation of the lowest outlet including the planting soil medium and stone storage void space Bioinfiltration basins may also be sized per the Bioinfiltration Bioretention Basin Sizing Table Table 4 1 4 to ensure that storage requirements are achieved The storage area for a bioretention SMP must provide adequate storage to control release rates to meet all applicable Stormwater Regulations Void space in the soil and or stone layers beneath the bioretention area surface may be considered part of the available volume of the SMP Bioretention basins may also be sized per the Bioinfiltration Bioretention Basin Sizing Table Table 4 1 4 to ensure that storage and Water Quality release rate requirements are achieved The maximum allowable static storage volume without supporting documentation defined below is the runoff volume from the one year 24 hour storm The maximum allowable static storage volume with supporting documentation is the runoff volume from the ten year 24 hour storm Requirements for supporting documentation include a letter signed and sealed by both the geotechnical and design engineer indicating that the proposed design is recommended with the following components acknowledged and considered The designer is encouraged to contact PWD for further guidance when pursuing this design A summary of the long term impacts to the neighboring properties including but not limited to subsidence change in basement moisture water and structural damage The location of the groundwater table References to other projects that have successfully infiltrated more than the one year 24 hour storm event and Rigorous pre treatment to promote longevity of the infiltration SMP When SMPs are used in series the storage areas for all SMPs must provide cumulative static storage for the WQv but there is no minimum storage requirement for each individual SMP used in series Bioinfiltration bioretention SMPs can be designed with additional storage beyond the WQv and with outlet controls that allow all remaining applicable

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