PWD Stormwater Management Guidance Manual v3.3 F.1 Stormwater Regulation Compliance
Appendices

F.1 Stormwater Regulation Compliance

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F.1.1 Water Quality

  1. Infiltrating Projects
    1. Verify that all DCIA within the project’s limits of earth disturbance is routed to an SMP. [Section 1.2.1; Section 3.4.1]
    2. Verify infiltration of the Water Quality Volume from all DCIA within the limits of earth disturbance. This is achieved by providing static storage of the Water Quality Volume below the lowest outlet elevation of each SMP. [Section 3.4.1]
    3. Verify that the SMP drains within the acceptable 72-hour period after the 24-hour storm event. [Section 1.2.1; Section 3.4.1]
  2. Non-Infiltrating Projects Located in Combined Sewer Areas
    1. Verify that 100% of the Water Quality Volume is routed through an acceptable pollutant-reducing practice. Refer to Table 3.1‑3 of the Manual for reference. [Section 1.2.1; Section 3.4.1]
    2. Verify that the hydrologic calculations include routing of the Water Quality storm event. [Section 1.2.1; Section 3.4.1]
    3. Verify that the release rate for the Water Quality Volume does not exceed 0.05 cfs per acre of DCIA. [Section 1.2.1; Section 3.4.1]
    4. Verify that the SMP drains within the acceptable 72-hour period after the 24-hour storm event. [Section 1.2.1; Section 3.4.1]
  3. Non-Infiltrating Projects Not Located in Combined Sewer Areas
    1. Verify that 100% of the Water Quality Volume is routed through an acceptable pollutant-reducing practice. Refer to Table 3.1‑3 of the Manual for reference. [Section 1.2.1; Section 3.4.1]
    2. Verify that the SMP drains within the acceptable 72-hour period after the 24-hour storm event. [Section 1.2.1; Section 3.4.1]

F.1.2 Channel Protection

  1. Verify if the Channel Protection requirement is applicable.
    1. The project is exempt from Channel Protection if it is a Redevelopment project with less than one acre of earth disturbance. [Section 1.2.1]
    2. The project is exempt from Channel Protection if it is a Redevelopment project which reduces impervious area within the limits of earth disturbance (excluding public right-of-way) by at least 20%, based on a comparison of predevelopment impervious area to post-development DCIA. [Section 1.2.1]
    3. The project is exempt from Channel Protection if it is a Redevelopment project located in the Delaware Direct or Lower Schuylkill Watersheds. [Section 1.2.1]
    4. The project is exempt from Channel Protection if it is the development of new Streets and Street Maintenance Activities. [Section 1.2.1]
  2. Verify that runoff from all DCIA, within the project’s limits of earth disturbance, for the one-year, 24-hour storm event is released at a maximum rate of 0.24 cfs per acre of DCIA in no more than 72 hours. [Section 1.2.1; Section 3.4.1]

F.1.3 Flood Control

  1. Verify if the Flood Control requirement is applicable.
    1. The project is exempt from Flood Control if it is a Redevelopment project that reduces impervious area within the limits of earth disturbance (excluding public right-of-way) by at least 20%, based on a comparison of predevelopment impervious area to post-development DCIA. [Section 1.2.1]
    2. The project is exempt from Flood Control if it is a Redevelopment project located in Flood Management District C that discharges directly to the Delaware Direct or Lower Schuylkill main channels without the use of City infrastructure. [Section 1.2.1]
    3. The project is exempt from Flood Control if it is a Redevelopment project located in District C-1 that discharges directly to the Tookany/Tacony-Frankford main channel or major tributaries without the use of City infrastructure. This exemption applies only to peak rates of runoff for storm events greater than the five-year storm. [Section 1.2.1]
    4. The project is exempt from Flood Control if it is a Redevelopment project located in the Delaware Direct Watershed or Lower Schuylkill Watershed, but situated outside of District C, that can discharge directly to the Delaware Direct or Lower Schuylkill main channels without the use of City infrastructure. [Section 1.2.1]
    5. The project is exempt from Flood Control if it is the development of new Streets and Street Maintenance Activities. [Section 1.2.1]
  2. Verify that the project meets or reduces peak rates of runoff, as determined by its Flood Management District, from predevelopment to post-development conditions during certain storm events. Refer to Table 3.4‑1 of the Manual for reference. [Section 1.2.1; Section 3.4.1]

F.1.4 Public Health and Safety Release Rate

  1. If a Public Health and Safety (PHS) release rate applies to the project, verify that, for all areas within the project’s limit of earth disturbance (pervious and impervious, alike), the post-development peak runoff release rate does not exceed the project-specific PHS Release Rate requirement (cfs per acre of limit of disturbance) when routing the one-year through ten-year, 24-hour storm events. [Section 1.2.1]

F.1.5 Expedited PCSMP Reviews

  1. Disconnection Green Review
    1. Verify that the project is a Redevelopment project that is exempt from the Channel Protection and Flood Control requirements. [Section 2.4.1]
    2. Verify that 95% or more of the post-construction impervious area within the project’s limits of earth disturbance is disconnected in accordance with Section 3.1.5. [Section 2.4.1]
    3. Verify that the project’s intent to qualify for a Disconnection Green Review is indicated on the submitted ERSA Application. [Section 2.4.1]
  2. Surface Green Review
    1. Verify that 100% of post-construction impervious area within the project’s limits of earth disturbance is managed by disconnected impervious cover (DIC) and/or bioinfiltration/bioretention basins. [Section 2.4.2]
    2. Verify that the project’s intent to qualify for a Surface Green Review is indicated on the submitted ERSA Application. [Section 2.4.2]
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