- 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
6.0 Introduction
As with any building system, stormwater management practices (SMPs) require maintenance to ensure long-term function. Post-construction, it is the responsibility of the property owner to maintain all SMPs in perpetuity. This includes notifying PWD if any further site improvements are planned to the property that could affect SMP functionality or regulatory compliance, such as changes in site grading or stormwater drain location/configuration, as well as addition of new impervious areas, such as walkways, patios, decks, driveways, parking lots, sheds, or buildings. As described in Chapter 4, SMPs consist of multiple components (e.g., inflow, conveyance, storage, outflow, and vegetation, etc.). Each of these components must be inspected and maintained regularly to properly function. By conducting routine maintenance, property owners identify and address minor maintenance tasks that ensure the proper functioning of an SMP and reduce the need for larger, more expensive repairs over time. If SMPs begin to fail, the subsequent increase in stormwater loading on the sewer systems may contribute to backups and combined sewer overflows into nearby rivers. This can cause damage to aquatic life, endanger public health and safety, and violate State and Federal water quality laws.
Chapter 6, Post-Construction and Operations and Maintenance Guidance, provides guidance for the property owner on Operations and Maintenance (O&M) requirements in Section 6.1, and on post-construction SMP inspection in Section 6.2. Chapter 6 also provides information on stormwater credits, for which property owners may be eligible following SMP construction. Further information on the Stormwater Credits Program can be found in Section 6.3.
6.1 Operations and Maintenance
6.1.1 Maintenance Requirements for Property Owners
The property owner is responsible for performing long-term maintenance in accordance with the Operations and Maintenance (O&M) Agreement, the Philadelphia Water Department (PWD) Stormwater Regulations (Stormwater Regulations) (or applicable design criteria for Stormwater Retrofit projects that have received Stormwater Grant funding), and Philadelphia Property Maintenance Code. In certain developments, a Homeowner’s Association (HOA) or Condominium Association may assume the responsibility for maintenance. In these instances, PWD recommends that the O&M responsibilities associated with stormwater management practices (SMPs) be incorporated in the declaration for the HOA or Condominium Association. Failure to properly maintain SMPs, or the unauthorized removal of any SMPs installed to achieve compliance with the Stormwater Regulations, will result in enforcement actions by PWD. Any proposed changes to SMPs, drainage configurations, or cover type must be approved by PWD to confirm that the change will not affect the property’s continued compliance with the Stormwater Regulations or approved stormwater management design.
Required routine maintenance is SMP- and site-specific. However, typical routine maintenance tasks include the following:
- Removal of sediment and debris from inlets and outlet control structures, storage areas, and pipes;
- Establishment watering for new plantings (during the first two to three years after the initial planting);
- Emergency watering during prolonged dry periods;
- Removal of invasive plants or weed species;
- Mulching;
- Replacement of worn bolts, latches, and other appurtenances;
- Minor asphalt or concrete patching/repair;
- Minor erosion repairs including slope stabilization;
- Minor replanting, reseeding, and re-grading; and
- Pruning of trees and shrubs, as appropriate, prior to winter months.
These tasks are associated with SMPs that are generally in good condition and properly functioning. If SMPs are not properly functioning, more extensive maintenance or repairs may be needed, which may include full excavation, removal, and replacement of permanently clogged media or porous surfaces.
The designer is referred to Chapter 4 for specific maintenance guidance for individual SMPs. The maintenance guidelines included in Chapter 4 represent typical, basic maintenance tasks and frequencies for the SMPs in each of the sections. The process of choosing appropriate maintenance tasks and frequencies is both SMP-specific and site-specific. An SMP-specific, site-specific SMP Maintenance Guide, prepared by the designer and submitted to, and reviewed by, PWD during the Post-Construction Stormwater Management Plan (PCSMP) Review Phase, should be provided to and implemented by the property owner as a guide for long-term O&M of the SMPs on-site. Proper execution of routine maintenance tasks may require confined space entry and/or the use of specialized equipment. Property owners are responsible for safely conducting maintenance activities in accordance with applicable regulations and using appropriate equipment and properly trained personnel. Some SMPs, such as porous pavement and subsurface basins, require special equipment and/or training to maintain. PWD has a list of local contractors who provide these maintenance services. There may be other qualified contractors who can help, as well.
The SMP Maintenance Guide must be accompanied by a Site Map and a separate Maintenance Schedule Form for each SMP to allow the property owner to track all maintenance activities for their site. SMP Maintenance Guide instructions are available on the first page of the SMP Maintenance Guide to guide the designer through the creation of these items.
Property owners are expected to use the Maintenance Schedule Forms to document inspection and maintenance activity for each SMP. These forms can be used when applying for Stormwater Credits renewals (Section 6.3). The completed forms can also assist PWD at the time of PWD inspections. PWD periodically inspects properties to check the functionality and maintenance of the SMPs. PWD will contact the property owner of record to schedule these inspections. After inspection, PWD will provide the property with a report detailing the results of our visit and identifying any SMPs or features requiring maintenance or corrective action. PWD will work with the property to resolve any issues identified in the report.
SMP Maintenance Guide documents are available for download in Appendix G.
6.1.2 Operations and Maintenance Agreements
An O&M Agreement between the property owner and PWD is a component of PCSMP Approval and required of any project subject to the Stormwater Regulations or receiving Stormwater Grant funding to implement a Stormwater Retrofit. This Agreement requires the property owner to construct SMPs on the listed parcel(s) in strict accordance with the Approved PCSMP and to maintain the SMPs such that they will adequately perform their designed functions. It also requires the property owner to maintain the site in accordance with the Approved PCSMP, which means no conversions of previous pervious areas to impervious cover without authorization from PWD. It does not require the property owner to construct the SMPs if the development project associated with the SMPs does not commence or if no earth disturbance takes place. The Agreement is recorded against the property and runs with the land, if and when the property is sold or otherwise conveyed.
Operations and maintenance tasks should be implemented by the property owner according to the project's SMP Maintenance Guide. SMP Maintenance Guides are SMP- and site-specific, and they must be prepared by the project's designer and submitted to PWD as part of the PCSMP Review Phase (Section 2.3.1) The SMP Maintenance Guide should be provided to, and implemented by, the property owner as a guide for long-term O&M of the SMPs on-site.
The standard O&M Agreement consists of:
- Agreement with signature pages;
- Signatory acknowledgement sections;
- Exhibit A, legal description(s) of the property(ies); and
- Exhibit B, a list of SMPs to be installed on the listed parcel(s).
The signatory(ies) for the property owner(s) must be authorized to bind the property owner(s) to legal agreements. The signatory acknowledgement sections must be notarized and serve to verify the identities of all parties signing the Agreement.
Exhibit A contains a metes-and-bounds description for each parcel, in its entirety, on which earth disturbance is proposed, while Exhibit B contains a listing of all the SMPs to be constructed on the listed parcel(s). Should amendments to the O&M Agreement become necessary after execution, the O&M Amendments will be sequentially numbered and will replace and supersede any and all of the project’s previous O&M Agreements and Amendments.
6.2 Stormwater Management Practice Inspection Guidance
6.2.1 PWD Inspections and Enforcement
As a part of the compliance obligations under agreements with the Pennsylvania Department of Environmental Protection (PA DEP), the Philadelphia Water Department (PWD) is required to periodically inspect all stormwater management practices (SMPs) installed on private properties. Inspections will generally occur during normal business hours. During an inspection, PWD inspectors check to see that SMPs are being maintained in accordance with the Approved Post-Construction Stormwater Management Plan (PCSMP) and Operations and Maintenance (O&M) Agreement (Section 6.1.2) and that all SMPs are functioning as designed. If PWD inspections reveal that an SMP is not functioning properly, PWD will notify the property owner and they will be required to bring the SMP back into compliance. If the property owner is not responsive to such notice, PWD may proceed with elevated enforcement measures, including fines, court action, and/or abatement proceedings. The property owner can avoid enforcement by implementing a robust SMP maintenance program as early as possible.
6.2.2 Property Owner Inspections
Frequent SMP inspections performed by the property owner are critical to identifying and remediating small maintenance issues before they have the potential to become large, costly repairs. Routine inspections should be performed by the property owner at least four times per year, preferably at the end of each season. Property owners, or individuals conducting inspections on the property owner’s behalf, must have a strong working knowledge and understanding of each SMP and its critical design components prior to conducting inspections (Chapter 4). Property owners should perform additional inspections throughout the year, especially during and after large rain events, to ensure that SMPs are functioning as designed.
The primary purpose of an inspection is to make sure an SMP is properly functioning and, if not, to identify corrective actions that are required to restore proper function. A properly functioning SMP allows water to freely enter at each inflow point, collect within the storage areas, infiltrate into the soil or, depending on the design, freely drain through an outlet control structure to a downstream conveyance system. During inspections, owners are to note the following conditions:
- Emergency spillways and overflows are clear of debris;
- Plants within properly functioning SMPs are healthy and thriving;
- Bare soil or areas of active erosion are not present;
- Structures appear to be sound and in good condition, with no signs of settlement; and
- Storage areas are slowly draining after significant rain events (in no more than 72 hours) and are free of significant accumulations of sediment, debris, and trash that would substantially reduce the available storage volume.
If any of these conditions are not true, maintenance is most likely required. More detailed information on conducting inspections for different SMP types is found in Chapter 4 within each SMP section.
Owners should note that proper and thorough inspection may require special certifications for confined space entry and/or special equipment such as closed circuit television systems required to inspect pipes. It is the property owner’s responsibility to make sure that all inspections are conducted in a safe manner, according to applicable regulations, and using appropriate equipment.
6.3 Stormwater Credits Program
All properties within the city of Philadelphia are charged a monthly Stormwater Management Service Charge (Stormwater Charge). Residential customers are charged a flat rate, and non-residential, condominium, and multi-family residential customers (more than four dwelling units per parcel) are charged by the amount of gross and impervious areas on the parcel. To determine a property’s current monthly Stormwater Charge, the Philadelphia Water Department’s (PWD's) Stormwater Parcel Viewer can be used. If a parcel appears to be charged incorrectly, the applicant may contact pwd.stormwaterappeals@phila.gov or refer to the Stormwater Management Service Charge Credits and Appeals Manual (Credits and Appeals Manual) for more information on how to adjust the charge.
To assist non-residential, condominium, and multi-family residential customers (more than four dwelling units per parcel) in reducing their stormwater fees, PWD has implemented the Stormwater Credits Program. This program is administered by PWD Stormwater Billing and Incentives and provides financial incentives to customers who help the City meet its stormwater management goals by mitigating stormwater runoff using stormwater management practices (SMPs) and preserving existing conditions on the parcel that are favorable for stormwater management, such as high quality vegetated area and disconnecting impervious area from the sewer system. Property owners who choose to install and maintain functioning SMPs, retain pervious open space, and/or incorporate stormwater disconnections on their site may be eligible for stormwater credits. The Stormwater Credits Explorer can be used to estimate the stormwater credits savings for implementing SMPs. To apply for stormwater credits, a Stormwater Credits Application (Form B) must be completed after construction has concluded, PWD has approved the submitted Record Drawings, and all water accounts for the property are brought up-to-date.
There is no fee to apply for stormwater credits with a Form B. Credits expire four years from their effective date. It is the property owner’s responsibility to submit a Stormwater Credits Renewal Application (Form C) at least 30 days before the expiration date, along with a Renewal Fee. Records of inspections and maintenance activities are required to support credit renewal applications. Applicants are referred to the Credits and Appeals Manual for more comprehensive guidance.