- Introduction
- Ch. 1 Stormwater Management Requirements
- Ch. 2 Submission, Review, and Approval Procedures
- Ch. 3 Site Design and Stormwater Management Integration
- Ch. 4 Stormwater Management Practice Guidance
- Ch. 5 Construction Guidance
- Ch. 6 Post-Construction and Operations and Maintenance Guidance
- Appendices
- Download
- Back to Chapters
- Manual Organization and Purpose
- Stormwater Regulations
- Private Development Services
- Stormwater Billing and Incentives
- Stormwater Management in Philadelphia
- Applicability and Submission Process
- Preferred Design Approach
- Back to Chapters
- 1.0 Introduction
- 1.1 Applicability Factors
- 1.2 Stormwater Regulations
- 1.3 Stormwater Retrofits
- Back to Chapter 1
- 1.2.1 Post-Construction Stormwater Management Requirements
- 1.2.2 Erosion and Sediment Control Requirement
- Back to Chapter 1
- 1.3.1 Retrofit Project Applicability and Initiation
- 1.3.2 Retrofit Project Requirements and Guidance
- Back to Chapters
- 2.0 Introduction
- 2.1 Existing Resources and Site Analysis
- 2.2 Review Paths
- 2.3 Review Phases
- 2.4 Expedited Post-Construction Stormwater Management Plan Reviews
- 2.5 PWD’s Development Review Process
- 2.6 PWD’s Role in Philadelphia's Development Process
- 2.7 PWD and Pennsylvania Department of Environmental Protection
- Back to Chapter 2
- 2.2.1 Development Compliance Review Path
- 2.2.2 Development Exemption Review Path
- 2.2.3 Demolition Review Path
- 2.2.4 Stormwater Retrofit Review Path
- Back to Chapter 2
- 2.3.1 Development Compliance Review Path
- 2.3.2 Development Exemption Review Path
- 2.3.3 Demolition Review Path
- 2.3.4 Stormwater Retrofit Review Path
- Back to Chapter 2
- 2.4.1 Disconnection Green Review
- 2.4.2 Surface Green Review
- 2.4.3 Expedited PCSMP Review Process
- Back to Chapter 2
- 2.7.1 National Pollutant Discharge Elimination System Permits
- 2.7.2 Other PA DEP Requirements
- Back to Chapters
- 3.0 Introduction
- 3.1 Site Assessment and Stormwater Management Strategies
- 3.2 Stormwater Management Design
- 3.3 Infiltration Testing and Soil Assessment for SMP Design
- 3.4 How To Show Compliance
- 3.5 Integrated Stormwater Management Examples
- Back to Chapter 3
- 3.0.1 How to Use This Chapter
- 3.0.2 Integrated Site and Stormwater Management Assessment and Design Process Overview
- 3.0.3 Interactions between Design Strategies, Stormwater Regulations, and Review Paths
- Back to Chapter 3
- 3.1.1 Background Site Factors and Site Factors Inventory
- 3.1.2 Site Factors Analysis
- 3.1.3 Integrated Design Approach
- 3.1.4 Non-Structural Design
- 3.1.5 Disconnected Impervious Cover
- 3.1.6 SMP Functions
- 3.1.7 Pollutant- Reducing Practices and Roof Runoff Isolation
- 3.1.8 How to Use SMPs to Comply with the Regulations
- Back to Chapter 3
- 3.2.1 Major SMP Types
- 3.2.2 SMP Hierarchy and Selection Process
- 3.2.3 Placing SMPs in Series
- 3.2.4 Stormwater Management Banking and Trading
- 3.2.5 SMP Design Guidance and General Requirements
- 3.2.6 Loading Ratio Requirements
- 3.2.7 Planting and Vegetation Guidance
- 3.2.8 Operations and Maintenance
- Back to Chapter 3
- 3.3.1 Infiltration Testing and Soil Characterization Plan Development
- 3.3.2 Soil Characterization Requirements
- 3.3.3 Infiltration Testing Requirements
- 3.3.4 Soil Characterization Procedures
- 3.3.5 Infiltration Testing Procedures
- 3.3.6 Evaluation of Infiltration Testing Results
- Back to Chapter 3
- 3.4.1 Regulatory Compliance Documentation Requirements
- 3.4.2 Storm Sewer Design Requirements
- 3.4.3 Calculation Methods and Design Tools
- Back to Chapter 3
- 3.5.1 Commercial Office Building Development
- 3.5.2 Residential Multi-Family Development
- 3.5.3 Full Build-Out
- 3.5.4 Trails
- 3.5.5 Athletic Fields
- 3.5.6 Streets
- Back to Chapters
- 4.0 Introduction
- 4.1 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
- 4.1.1 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 Filter Strips
- 4.10.3 Forebays
- 4.10.4 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 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 Chapters
- Appendix Index
- A. Glossary
- B. Abbreviations
- C. PWD Stormwater Regulations
- D. Watershed Maps
- E. Plan and Report Checklists
- F. Design Guidance Checklists
- G. SMP Maintenance Guide Documents
- H. Infiltration Testing Log
- I. Landscape Guidance
- J. Construction Certification Package
- K. Record Drawing Sample
- L. Standard Details
- 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
A. Glossary
Applicant: A property owner, developer, or other person or entity who has filed an application to the Philadelphia Water Department (PWD) for approval to engage in or be exempt from any Regulated Activity at a Development Site in the City of Philadelphia.
Combined Sewer Overflows (CSO): A combined sewer overflow is an intermittent overflow or other untreated discharge from a municipal combined sewer system to the water of the Commonwealth occurring before the sewage treatment plant.
Conceptual Stormwater Management Plan: A preliminary stormwater management plan used by PWD Stormwater Plan Review to understand what is proposed at the project site, to confirm the proposed project limits of disturbance (LOD), and to assess the proposed stormwater management strategy. Conceptual Stormwater Management Plan requirements are described in Chapter 2 of this Manual.
Demolition: 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.
Design Storm: The magnitude and temporal distribution of precipitation from a storm event defined by probability of occurrence (e.g., five-year storm) and duration (e.g., 24 hours), used in the design and evaluation of stormwater management systems.
Developer: Any landowner, agent of such landowner, or tenant with the permission of such landowner, who makes or causes to be made a subdivision of land or land Development project prior to issuance of the Certificate of Occupancy.
Development: Any human-induced change to a tract of land, 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.
Development Site: The land area where any Development activities are planned, conducted, or maintained, regardless of individual parcel ownership. It includes contiguous areas of disturbance across Streets and other rights of way, or private streets and alleys, during any stage of or on any portion of a larger common plan of development or sale.
Diffused Drainage Discharge: Drainage discharge not confined to a single point location or channel, such as sheet flow or shallow concentrated flow.
Directly Connected Impervious Area (DCIA): An Impervious Surface that is directly connected to the drainage system. DCIA generates surface runoff with a direct hydraulic connection to on-site drainage systems (e.g., inlets, curbs and gutters, pipes, etc.), PWD’s drainage systems, or stormwater management practices (SMPs) without flowing over pervious areas.
Disconnected Impervious Cover (DIC): Impervious cover from which runoff is directed toward pervious areas for management within the landscape.
Earth Disturbance: Any construction or other activity that disturbs the surface of land, including but not limited to, excavations, embankments, land development, subdivision development, and the moving, depositing, or storing of soil, rock, or earth. Other examples of earth disturbance in the context of PWD Stormwater Regulations are listed in Section 1.1.3.
Erosion and Sediment (E&S) Control Plan: A site-specific plan consisting of both drawings and a narrative that identifies measures to minimize accelerated erosion and sedimentation before, during, and after Earth Disturbance. E&S Plan requirements are described in Chapter 2 of this Manual.
Evaporation and Transpiration (Evapotranspiration): Evaporation is the process by which water changes from a liquid to gas. Transpiration is the process by which water moves through a plant and evaporates into the atmosphere from its leaves and exterior surfaces. The sum of evaporation and transpiration are commonly referred to as evapotranspiration.
Existing Conditions: Physical conditions on the site including land use, impervious surface, topography, vegetation, soils, and hydrology that exist on the site on the date the owner starts the development process.
Groundwater Recharge: The replenishment of existing natural underground water supplies from precipitation or overland flow without degrading groundwater quality.
Hotspots: Areas where land use or activities have contaminated the soil underlying the site such that infiltration of stormwater would likely cause groundwater contamination through leaching of the soil.
Impervious Liner: A physical barrier to prevent water from crossing a system boundary such as infiltrating through the subgrade beneath a stormwater management practice. Liners may include, but are not limited to, compacted till liners, clay liners, geomembrane liners, and concrete liners.
Impervious Surface: Any building, pavement, or other material that substantially bars the natural infiltration of surface water into the soil.
Infiltration: The process by which water enters the soil from the ground surface and can be measured as a rate.
Management District: Sub-area delineations that determine peak rate attenuation requirements. A Development Site located in more than one Management District shall conform to the requirements of the district into which the site discharges
Manual: The most recent version of the Philadelphia Stormwater Management Guidance Manual.
New Development: Development project on a tract of land where structures or impervious surfaces never existed or were removed before January 1, 1970.
Non-Structural Design: Stormwater management practices that incorporate, preserve, and protect existing natural features while promoting treatment, infiltration, evaporation, and transpiration of precipitation close to where it falls.
Operations & Maintenance (O&M) Agreement: An agreement or declaration which outlines the maintenance requirements associated with the Post-Construction Stormwater Management Plan.
Pavement Disconnection: A type of DIC and a reduction in DCIA when pavement runoff is directed to a vegetated area that allows for infiltration, filtration, and an increased time of concentration.
Post-Construction Stormwater Management Plan (PCSMP): A complete stormwater management plan set as described in the PWD Stormwater Regulations and in this Manual. PCSMP requirements are described in Chapter 2 of this Manual.
Predevelopment Condition: For New Development and Redevelopment, the dominant land use for the previous ten years preceding the planned project.
Record Drawings: Construction drawings revised to represent the as-built conditions.
Redevelopment: Development on a 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.
Registered Professional: A licensed Professional Engineer, Registered Architect, Landscape Architect, Professional Land Surveyor, Professional Geologist, or Licensed Contractor registered in the Commonwealth of Pennsylvania.
Regulated Activity: Development on a Development Site in the City of Philadelphia that results in an area of Earth Disturbance greater than or equal to 15,000 square feet, greater than or equal to 5,000 square feet in the Darby and Cobbs Creeks Watershed, or as otherwise required by local, State, or Federal requirements. The area of Earth Disturbance during the construction phase determines requirements for the erosion and sediment controls and post-construction stormwater management.
Review Path: A linear series of submission, review, and approval/exemption procedures the applicant will navigate to demonstrate a project’s compliance with, or exemption from, the PWD Stormwater Regulations.
Review Phase: A step in a Review Path. Each Review Path has one or more Phases. Each Phase corresponds to one or more submittals of information for PWD's review.
Roof Runoff Isolation: The routing of runoff from non-vehicular roof area that is not commingled with untreated runoff.
Rooftop Disconnection: A type of DIC and a reduction in DCIA when a roof downspout is directed to a vegetated area which allows for infiltration, filtration, and increased time of concentration.
Sewershed: An area of land, or catchment, which drains via storm drain infrastructure to a common outlet point.
Site Assessment: An investigation of the administrative and physical factors that shape the development and stormwater management plan for a proposed site. The assessment consists of three components – collection of background site factors, site factors inventory, and site factors analysis.
Storage Volume: The volume of stormwater runoff that can be held within the above-ground surface area and the pore spaces of any subsurface media or structure of a stormwater management practice.
Stormwater Management Practice (SMP): Any man-made or natural structure, system, landscape feature, channel, or improvement designed, constructed, installed, and/or used to detain, infiltrate, or otherwise control stormwater runoff quality, rate, or quantity.
Stormwater Pretreatment: Techniques employed to remove pollutants before they enter the SMP, including, but not limited to, the techniques listed as pretreatment in this Manual.
Stormwater Retrofit: The voluntary rehabilitation and/or installation of SMPs on a property to better manage stormwater runoff.
Street: Tract of land or part thereof with public access used for vehicular and/or pedestrian traffic, which is maintained by a City Agency, City Related Agency, other Government Agency, or a Non-Profit Organization Created by the City, as determined by the Department.
Street Maintenance Activities: Earth Disturbance activities within an existing Street as determined by the Department and described in the Manual Section 1.1.3.
Tree Disconnection Credit: A type of DIC and a reduction in DCIA when existing or newly proposed tree canopy from an approved species list extends over, or is in close proximity to, impervious area.
Watershed: An area of land that contains a common set of drainage pathways, streams, and rivers that all discharge to a single large body of water, such as a large river, lake, or ocean.