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HomeMy WebLinkAboutItem 3.4 NPDES PresentationCTTY CLERK AGENDA STATEMENT CITY COUNCZL MEETTNG DATE: August 19, 2003 SUBJECT: Presentation by Public Works Staffon the NPDES Program Report Prepared by: Melissa Morton, City Engineer ATTACHMENTS: Comparison of Current and Anticipated New and Re-Development Requirements for Controlling Stormwater Quality and Quantity by EOA, Inc. RECOMMENDATION:F~('-~M~eceive and accept Public Works Staff presentation FINANCIAL STATEMENT: The new NPDES permit requirements will add costs to the City for City sponsored projects. Development projects will also realize an increase in total project costs that will be passed on to the buyers of development real estate. DESCRIPTION: The National Pollutant Discharge Elimination System (NPDES) established by the Clean Water Act was modified in 1987 to include municipal stormwater dischargers. These amendments required individual municipalities to effectively prohibit non-stormwater discharges from entering storm drainage systems and to implement controls to reduce pollutants in stormwater to the maximum extent practicable. The Alameda Countywide Clean Water Program (ACCWP) is a consortium that was formed in 1991 by a Memorandum of Agreement and Joint NPDES permit, and is comprised of Alameda County, its 14 Cities, the Alameda County Flood Control and Water Conservation District (ACFCWCD), and Zone 7 of the ACFCWCD. The NPDES Permit is granted to the ACCWP and is administered locally by the San Francisco Bay Regional Water Quality Control Board. The permit is renewed every five years and was recently renewed to include more stringent requirements for new development and pollutants of concern. These changes have been colloquially referred to as the "C.3 Modifications." City projects like street widening and trail projects will require that stormwater runoff from the new impervious surface created by the project be "treated'' by incorporating treatment measures like stormceptor inlets and bioretention swales. For new City buildings, landscape areas will have to incorporate bioretention swales and some parking areas may have to utilize pervious pavements. Private development projects will have to incorporate the same measures and for larger projects, hydromodification may require the construction of one or more detention basins. Projects will have to COPIES TO: G:~GENMISChgst_Public Works NPDES Presentation.doc ITEM NO. incorporate stormwater source control and treatment measures up front to insure adequate land area is set aside to incorporate the necessary improvements to reduce the potential for stormwater pollution. The presentation by Public Works is intended to illustrate the important details and deadlines incorporated into the new permit as part of the C.3 Modifications and their impact on the City of Dublin's new development and capital improvement programs. Staff recommends that the City Council receive and accept the presentation and provide any comments. Page 2 d~2.- Comparison of Current and Anticipated Additional New and Re-Development Requirements for Controlling Stormwater Quality and Quantity Current NPDES Permit Anticipated Additional Requirements Requirements (SCVURPP Permit reference is shown in (based on ACCWP's existing parentheses) performance standards) Stormwater . No minimum size of project is specified · Defines size of projects that must have stormwater Treatment as requiring stormwater treatment, treatment BMPs and phases in requirements based on project size. (C.3.c.) o Group 1 projects - any development, street/highway, or significant redevelopment that creates or replaces 1 acre or more of impervious surface. Starts 24 months after NPDES permit adoption. (Deadline: February 15, 2005) o Group 2 projects - any development, street/highway, or significant redevelopment that creates or replaces 5,000 sq. ft. or more of imperviousness. Starts 42 months following permit adoption. (Deadline: August 15, 2006) o Projects that do not fall within definition of Groups 1 or 2 are specifically described as exempted. · Municipalities will require development · Unless a project fits into a waiver program, all Group 1 projects to include stormwater and Group 2 projects must have stormwater treatment treatment BMPs, if insufficient site BMPs. (C.3.c and C.3.g) planning measures are not implemented or feasible. · Amount of stormwater requiring · There are specific numeric sizing requirements for the treatment is unspecified, volume of stormwater that must be treated. (C.3.d.) o Treatment systems based on volume must be sized to capture and treat about 85th percentile, 24-hour storm event or 80 percent of the annual runoff. o Treatment systems based on flow rates must capture and treat 10% of 50-year peak flow rate; flow from two times the 85 percentile hourly rainfall intensity; or flow from rain event of at least 0.2 inches/hour , · · Type of stormwater treatment (e.g., · Unchanged from current requirements. detention basins, sand filters, storm drain filter inserts) is not specified, but RWQCB staff has been advocating the use of grassy and vegetated swales. Operation and · Requires documentation of"operation · Requires that each municipality implement an operation Maintenance and maintenance of structural controls and maintenance verification program. (C.3.e.) of Stormwater in conditions of approval for both public o Need to maintain a list of properties and Treatment and private projects." responsible operators for all treatment BMPs. o Need to inspect annually a subset of prioritized treatment measures for operation and maintenance. F:\NPDES\thumbnail overview.doc Current NPDES Permit Anticipated Additional Requirements Requirements (SCVURPP Permit reference is shown in (based on ACCWP's existing parentheses) performance standards) Limitations on · No requirements specified. · Requires that each municipality manage increases in Increase of peak runoff flow and increased runoff volume where Peak these can cause downstream erosion of creek beds Stormwater and banks and other adverse impacts to beneficial Discharge uses through implementation of a Hydrograph Rates Modification Management Plan (HMP). (C.3.f) o Requires General Program to develop the HMP within 24 months of NPDES permit adoption. HMP proposal must describe how municipalities will incorporate HMP requirements into their local approval processes. o This requirement does not apply to new development and redevelopment projects where the potential for erosion or other impacts to beneficial uses is minimal. (HMP is to include guidelines for situations where it does not apply). o This requirement does apply unless there is information demonstrating that increases in runoff will not increase potential for erosion or other adverse impacts to beneficial uses. o HMP must describe a rainfall event below which the standards apply. (equivalent · Municipalities may develop "an equivalent limitation protocol) protocol, as part of the HMP, to address impacts from changes in the volumes, velocities, and/or durations of peak flows through measures other than control of those volumes and/or durations." (C.3.f.vii) Waiver · None · Optional program that the municipalities may choose to Program for establish that would allow waiver from the requirement treatment to install treatment BMPs for a given project provided BMPs there is treatment of an equivalent pollutant loading or quantity of stormwater runoff or other equivalent water quality benefit. (C.3.g.i). o "The waiver program may allow a project to participate in a regional or watershed stormwater treatment facility, without a showing of impracticability on the individual project site, if the regional or watershed stormwater treatment facility discharges into the same receiving water, where feasible." o The General Program is encouraged to propose a model waiver program for approval by the Regional Board for potential adoption and implementation by the municipalities. o There is a list of specific reporting requirements for each project granted a waiver. · Municipalities may grant an interim waiver ifa waiver program has not been established. Project proponent must (1) demonstrate impracticability due to extreme limitations of space for treatment and lack of subsurface treatment options and (2) assure equivalent F:\NPDES\thumbnail overview, doc 2 EOA, Inc. Current NPDES Permit Anticipated Additional Requirements Requirements (SCVURPP Permit reference is shown in (based on ACCWP's existing parentheses) performance standards) Waiver stormwater pollutant and/or volume treatment at (continued) another location within the drainage basin. (C.3.g.vi) Site Design · Currently the performance standards · Municipalities will review their local design standards Requirements require that site planning and design and guidance for ways to make revisions that would techniques be used to prevent and improve water quality and beneficial uses. Examples minimize impacts on water quality, include many of the existing examples plus: (C.3.j) Examples include: o Minimum-impact street design standards for new o Minimize land disturbance and redevelopment. o Minimize impervious surfaces o Minimum-impact parking lot design. o Use clustering o Lot-level design with disconnected roof o Preserve quality open space downspouts; alternate driveway standards; and o Maintain and, if possible, restore microdetention, including landscape detention riparian and wetland areas as and use of cisterns project amenities, o Landscape-based measures to reduce velocity of, detain, and/or infiltrate stormwater runoff. · Municipalities will submit a draft review and analysis of local standards and guidance, opportunities for revision, and proposed revised standards 23 months following NPDES permit adoption. (C.3j.ii.2) · Municipalities shall incorporate any revised standards and guidance into their approval processes 35 months following NPDES permit adoption (C.3.j.ii.3) Source · Each municipality was required to · Municipalities will enhance performance standards to Control incorporate the New Development limit pollutant generation, discharge and runOff from Requirements Subcommittee's conditions of approval new and redevelopment projects. List of examples is into its standards of development, offered (C.3.k.) Many of the examples listed in the · Municipalities will submit enhanced performance SCVUP, PPP permit (indoor standards and proposed work plans for their mat/equipment washing for implementation 16.5 months following NPDES permit restaurants, covered trash enclosures, adoption. etc.) are already being implemented. · Implementation shall begin no later than 20.5 months' following NPDES permit adoption Update · Each agency will incorporate policies · Each municipality must update its General Plan to General Plans into General Plans to help preserve incorporate water quality and watershed protection and enhance water quality. This principles and policies at the next scheduled requirement is to be met when General update/revision of its General Plan occurring after Plans are amended. October 15, 2004. (C.3.1) Water Quality · Each agency will incorporate New · When municipalities are conducting environmental Review Development Subcommittee's reviews of projects, they shall evaluate water quality ProceSSes conditions of approval into its effects and mitigation measures. (C.3.m) standards for development, as · Summarize any revisions to the Environmental Review appropriate. Processes in 2003 and 2004 annual reports (C.3, Attachment Table 1) Pesticide · None · Municipalities must summarize pesticide reduction Reduction measures required for new development and significant Measures redevelopment projects. (C.3.n.) F:\NPDES\thumbnail overview.doc 3 EOA, Inc.