Stormwater Quality Design Manual (May 2007) - City of Sacramento ...

IntroductionIn July 2003, the permittees published their Stormwater Quality ImprovementPlans, which describe their comprehensive program to comply with their municipalstormwater permit and reduce pollutants in urban runoff to the maximum extentpracticable. The New Development program element of the plans called for anassessment of existing development standards and amendment/adoption of newstandards as needed to better address the permit. (As used here, the term“development standards” collectively refers to the policies, ordinances, codes anddesign standards established and enforced by each of the permitting agencies.)In December 2003, the Partnership submitted a Development Standards Plan (DSP)to the Regional Board; the DSP assessed the existing development standards (as of2003) and proposed actions that would be taken to amend the standards within oneyear of approval of the DSP. The Regional Board officially approved the DSP on May18, 2005, giving the Permittees until May 18, 2006 to complete the process ofamending/adopting new standards. According to the municipal stormwater permit,the Permittees have until May 18, 2007 to publish technical design guidelines to helpthe development community understand and implement the new standards. Thismanual constitutes those required technical design guidelines, completing the workbegun with the DSP.The DSP affected the types of projects subject to this manual. The Sacramentomunicipal stormwater permit specifies eight categories of new development andredevelopment projects that are subject to development standards related tostormwater quality management. Some of the categories and correspondingthresholds specified in the stormwater permit were effectively modified when theRegional Board approved the DSP in May 2005. Those changes are reflected in thismanual (Tables 1-2 and 3-2).City of Roseville Phase II Stormwater Permit RequirementsThe City of Roseville (located in South Placer County) obtained coverage underCalifornia’s Phase II NPDES Municipal General Stormwater Permit in July 2004.Prior to that time, Roseville did not require post-construction stormwater qualitycontrol measures for new development. Under the terms of their Phase II permit,Roseville’s program for controlling runoff pollution from development projects mustcomply with the requirements outlined in Attachment 4 of the permit or with a“functionally equivalent program” approved by the Regional Board.The City of Roseville opted to work collaboratively with the Sacramento areapermittees to create this manual as a functionally equivalent program. Since thePhase I Sacramento and Phase II Roseville municipal stormwater permits haveslightly different requirements regarding development standards, staff conducted ananalysis at the onset of the project to verify that this single design manual wouldsatisfy both permits.Agency Collaboration in Developing this ManualThis manual is the result of a collaborative planning effort by a steering committeecomprised of managers and staff from the following agencies:Stormwater Quality Design Manual for the Sacramento and South Placer RegionsMay 2007 1–3