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1 MEETING DATE: January 27, 201 PREPARED BY: Erik Steenblock, Environmental Programs Manager DEPT. DIRECTOR: Glenn Pruim DEPARTMENT: Public Works CITY MANAGER: Karen P. Brust SUBJECT: STORMWATER BEST MANAGEMENT PRACTICE DESIGN MANUAL RECOMMENDATION: Adopt City Council Resolution , approving the City of Encinitas Stormwater Best Management Practice (BMP) Design Manual and its inclusion as Chapter 7 of the Engineering Design Manual. STRATEGIC PLAN: Environment Protect and preserve our natural resources. Organizational Effectiveness & Efficiency Agency collaboration. FISCAL CONSIDERATIONS: There are no direct fiscal impacts associated with the staff recommendation. BACKGROUND: On May 8, 2013, the San Diego Regional Water Quality Control Board (RWQCB) adopted Water Quality Order No. R , National Pollutant Discharge Elimination System (NPDES) Permit and Waste Discharge Requirements for Discharges from the Municipal Separate Storm Sewer Systems (MS4s) Draining the Watersheds within the San Diego Region (2013 Municipal Stormwater Permit). Provision E.3.d of the 2013 Municipal Stormwater Permit requires the City to update its existing Stormwater BMP Design Manual to incorporate the new permit requirements. The new requirements will become effective on February 16, The current Encinitas Stormwater Manual was adopted by City Council on March 17, 2010 and incorporated as Chapter 7 of the Engineering Design Manual. It defines the policies and procedures by which stormwater BMP facilities are implemented and maintained on new and significant redevelopment projects. These requirements are enforced through the Stormwater Management and Discharge Control Ordinance (EMC 20.08), recently updated through City Council adoption on May 13, Item 10E 1 of

2 Over the past 18 months, the City collaborated with the other 20 San Diego Region stormwater Copermittees to develop a regional Model BMP Design Manual, which the RWQCB approved on May 29, 201. This Model BMP Design Manual was supplemented with local City requirements, culminating in the proposed City of Encinitas Stormwater BMP Design Manual. ANALYSIS: The proposed City of Encinitas Stormwater (BMP) Design Manual (Attachment 2) provides procedures for new and redevelopment projects (defined in the proposed BMP Design Manual as construction, rehabilitation, redevelopment, or reconstruction projects) to implement source control, low impact development, stormwater treatment, and hydromodification management facilities consistent with the requirements of the 2013 Municipal Stormwater Permit. The intended users of the BMP Design Manual include private development project applicants, City personnel designing public projects, applicant representatives responsible for preparation of newly required Stormwater Quality Management Plans (SWQMPs), and City personnel responsible for review of SWQMPs. As defined by Provision E.3 of the 2013 Municipal Stormwater Permit, and consistent with the Model BMP Manual approved by the RWQCB, a variety of updates have been incorporated into the proposed City of Encinitas Stormwater BMP Design Manual. The following section describes these updates and their potential impact on future development projects in the City: 1. Priority Development Project (PDP) Categories: PDPs must meet specific stormwater pollutant control standards and hydromodification management requirements, and they typically require a higher level of engineering design and project review. To determine whether a project is a PDP, developments that propose creating and/or replacing impervious area on the project site are first classified into residential, commercial, industrial, or one of the other categories specified in the 2013 Municipal Stormwater Permit. The square footage of impervious area proposed is then compared against the threshold for that particular PDP category to determine whether the project meets the permit definition for a PDP. The new permit approach and reduced thresholds will result in an increase in development and redevelopment projects meeting the PDP definition. For example, under existing standards (adopted in 2010), a residential development or redevelopment project may fall under the PDP category of Housing subdivisions of 10 or more dwelling units. By comparison, the proposed City of Encinitas Stormwater BMP Design Manual defines a PDP more broadly as New development or redevelopment projects that create 10,000 square feet or more of impervious surfaces (collectively over the entire project site). Each PDP definition would apply to a residential development and redevelopment project, however the newly proposed standard, based solely on the amount of impervious surface, will yield more PDP s overall. 2. Low Impact Development (LID) Requirements Applicability: All development and redevelopment projects will be required to implement LID BMPs where applicable and feasible, not just PDPs as was required under the 2007 Municipal Stormwater Permit. 3. Stormwater Retention Requirements: The new standard for stormwater pollutant control requires retention of the first flush of stormwater on the project site. Retention BMPs are designed to filter stormwater through onsite soil, resulting in 100 percent removal of pollutants, but they are necessarily larger in area and take up more space on a project site than previous stormwater treatment control BMPs. For situations where onsite retention is technically not feasible, supplemental biofiltration must be incorporated into the project design Item 10E 2 of

3 4. Hydromodification Management (Flow Control): Hydromodification refers to changes in magnitude and frequency of stormwater flows as a result of land development. Hydromodification causes impacts to channels and streams such as increased erosion, sedimentation and habitat degradation. Under the previous permit, PDPs in Encinitas were commonly exempt from meeting hydromodification management requirements. However, under the 2013 Municipal Stormwater Permit, most of the exemptions from hydromodification management have been removed. Most PDPs will now be required to comply with hydromodification management requirements, and the hydromodification performance standards require a larger volume of water to be controlled in many cases. The BMPs sized to meet these hydromodification standards are typically two to three times larger than BMPs sized to pollution control standards only. For example, under the previous permit, a project may have been required to install a bioretention facility taking up 4% of the project area. Whereas, under the proposed manual, the project would have to install a bioretention facility occupying approximately 10% of the project area.. Coarse Sediment Yield: To protect local natural water resources, in addition to controlling the volume and velocity of stormwater from developed areas, it is equally important to ensure that downstream systems receive coarse sediment discharges each time it rains. When parcels are developed, impervious surfaces cover up much of the available coarse sediment that local creeks need to remain stable. Therefore, the 2013 Municipal Stormwater Permit introduced a new provision requiring PDPs to protect areas on the project site known to contain coarse soil material. A map of potential critical coarse sediment areas is included in the BMP Design Manual and available for project site specific viewing through the City s myencinitas mapping application ( by turning on the Potential Coarse Sediment Yield Areas layer in the legend. Guidance for addressing potential critical coarse sediment yield areas on a project site is provided in the BMP Design Manual. 6. Alternative Compliance: Lastly, the 2013 Municipal Stormwater Permit introduced a new, optional provision called Alternative Compliance. This provision provides an avenue by which PDPs may satisfy stormwater requirements at an offsite location. The Copermittees are currently in the process of developing the required program elements that would enable jurisdictions to optionally allow offsite stormwater BMPs. The proposed BMP Design Manual allows the City of Encinitas to implement an Alternative Compliance Program in the future if so desired. ENVIRONMENTAL CONSIDERATIONS: The action being considered by the City Council is exempt from the California Environmental Quality Act (CEQA) because it is not a project per Section 1378(b)() of the CEQA Guidelines. The action involves an organizational or administrative activity of government that will not result in the direct or indirect physical change in the environment. ATTACHMENTS: 1. City Council Resolution titled A Resolution of the City Council of the City of Encinitas approving the City of Encinitas Best Management Practices Design Manual as Chapter 7 of the Engineering Design Manual. 2. City of Encinitas Best Management Practices Design Manual Final Draft ( 3. Map - City of Encinitas Potential Coarse Sediment Yield Areas Item 10E 3 of

4 RESOLUTION A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF ENCINITAS, CALIFORNIA, APPROVING THE BEST MANAGEMENT PRACTICES (BMP) DESIGN MANUAL FOR PERMANENT SITE DESIGN, STORMWATER TREATMENT AND HYDROMODIFICATION MANAGEMENT WHEREAS, on May 8, 2013, the San Diego Regional Water Quality Control Board (RWQCB) issued NPDES Order No. R (2013 Municipal Stormwater Permit), which includes requirements in addition to those that were imposed on the Copermittees, including the City of Encinitas, in NPDES Permit No. R ; WHEREAS, Provision E.3.d of the 2013 Municipal Stormwater Permit requires the City of Encinitas to update its BMP Design Manual; WHEREAS, per Resolution , the City of Encinitas approved the City of Encinitas Stormwater Manual as required by NPDES Order No and is the City s current BMP Design Manual; WHEREAS, The Model BMP Design Manual - San Diego Region was approved by the RWQCB on May 29, 201; WHEREAS, the approved City of Encinitas BMP Design Manual will replace the existing Encinitas Stormwater Manual in Chapter 7 of the Engineering Design Manual, satisfying the Provision E.3.d of the 2013 Municipal Stormwater Permit; NOW, THEREFORE, BE IT RESOLVED, that the City Council of the City of Encinitas does hereby approve the City of Encinitas Best Management Practices Design Manual as Chapter 7 of the Engineering Design Manual effective February 16, 2016; PASSED AND ADOPTED by the City Council of the City of Encinitas at a regular meeting thereof, held on the 27 th day of January, 2016, by the following vote to wit: AYES: NAYS: ABSENT: ABSTAIN: Kristin Gaspar, Mayor ATTEST: Kathy Hollywood, City Clerk Item 10E 4 of

5 Saxony South Ponto SB San Marcos Carlsbad 101 Beacons Leucadia Moonlight El Camino Real Encinitas Encinitas Rancho Santa Fe Santa Fe P a c i f i c O c e a n Swamis San Elijo 101 Manchester Birmingham Manchester County San Diego San Elijo SB San Elijo Lagoon City of Encinitas Potential Critical Coarse Sediment Yield Areas Solana Beach Potential Critical Coarse Sediment Yield Areas 1 in = 1 miles Miles This map includes locally known potential critical coarse sediment yield areas as determined by the San Diego County Regional Watershed Management Area Analysis, 201. For a more detailed, site-specific view, refer to the myencinitas interactive mapping application located on the City s website home page. Data Source: San Diego County Regional Watershed Management Area Analysis, 201 DISCLAIMER: This map should not be used for Engineering, Survey, or Site-Specific Analysis. Every reasonable effort has been made to assure the accuracy of the data provided; nevertheless, some information may not be accurate. The City of Encinitas assumes no liability or responsibility arising from the use of or reliance upon this information. Map Coordinates: Stateplane NAD83 Feet, CA Zone 6. Photo date: 7/ in pixel resolution. Digital true color. Ortho and Topo positional accuracy meets precision adequate to support NMAS, 1"=100' mapping Item 10E of