Appendix A Water Quality Memo - Laserfiche WebLink

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7 Orange County National Pollutant Discharge Elimination System Permit The proposed Project is subject to the requirements of the Waste Discharge Requirements for the County of Orange, Orange County Flood Control District and the Incorporated Cities of Orange County within the Santa Ana Region Areawide Urban Storm Water Runoff Orange County (North Orange County MS4 Permit), Order R8-2009-0030, NPDES No. CAS618030, as amended by Order No. R8-2010-0062. The North Orange County MS4 Permit regulates discharges into the MS4 system in the cities and county areas within Orange County in the Santa Ana Region. As discussed further below, the North Orange County MS4 Permit requires preparation of a Water Quality Management Plan (WQMP) and implementation of postconstruction BMPs for new development and significant redevelopment projects that qualify as Priority Projects. Drainage Area Management Program The Drainage Area Management Plan (DAMP) was implemented and created by the County of Orange, the Orange County Flood Control District, and incorporated cities (permittees) and includes specific water pollutant requirements of the North Orange County Stormwater Program. The DAMP is the principle policy and guidance document for the NPDES program. It is the foundation for model programs, local implementation plans, and watershed implementation plans. Section 7 of the DAMP discusses issues relating to new developments and significant redevelopments. Model Water Quality Management Plan The Model Water Quality Management Plan (May 2011) was developed to aid Orange County, the Orange County Flood Control District, the cities in Orange County (permittees) and developers within Orange County to address postconstruction urban runoff and stormwater pollution from new development and significant redevelopment projects that qualify as Priority Projects. The proposed Project is categorized as street, road, highway, and freeway of 5,000 square feet or more of paved surface and, thus, is considered a Priority Project. The proposed Project will be required to comply with the North Orange County MS4 Permit Priority Project requirements. Priority Projects are required to develop a Project WQMP to minimize adverse impacts of development to on-site hydrology, volume and rate of runoff, and pollutants of concern. The Project WQMP includes project-specific BMPs to minimize these effects (e.g., Low Impact Development [LID], site design measures, source control BMPs). The requirements identified in the Project WQMP are subject to DAMP Section 7. According to the North Orange County MS4 Permit, all street and road construction project of 10,000 or more of street, road, highway, and freeway of 5,000 square feet or more of paved surface must also comply with the EPA guidance Managing Wet Weather with Green Infrastructure Municipal Handbook: Green Streets (December 2008 EPA-833-F-08-009) to the maximum extent practicable. Technical Guidance Document The County of Orange developed the Technical Guidance Document for the Preparation of Conceptual/Preliminary and/or Project Water Quality Management Plans (WQMPs) (TGD) (County of Orange 2013) in cooperation with the incorporated cities of Orange County to aid agency staff and project proponents with addressing postconstruction urban runoff and stormwater pollution from new development and significant redevelopment projects in the county. The TGD serves as a technical guidance to complete the Project WQMP.