RES 231376 Exhibit A - Addendum and Mitigation Monitoring and Reporting Plan (MMRP)

City of Pleasanton—Stoneridge Mall Residential Project CEQA Checklist Section 15183 Checklist/15164 Addendum 126 FirstCarbon Solutions Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/2148/21480017/Consistency Checklist/21480017 Stoneridge Mall Residential Project Checklist Addendum_Updated.docx Environmental Setting The project site is currently occupied by an asphalt parking lot with 239,773 square feet of impervious surfaces consisting entirely of paved areas and parking. Impervious surfaces on-site are limited to landscaped parking islands. The project site currently drains into various storm drains and catchments on the southern portion of the project site. Remaining stormwater on the project site flows toward Stoneridge Mall Road, where it is collected by existing inlets. Findings a) Water Quality Prior EIR Conclusions The Prior EIR found that projects facilitated by the Housing Element could affect drainage patterns and create new impervious surfaces, causing changes to stormwater flows and water quality. However, it was determined that compliance with the Alameda Countywide Clean Water Program (ACCWP) NPDES Permit, and implementation of the Construction General Permit would require future development at any potential sites that would disturb more than 1 acre to incorporate BMPs to control sedimentation, erosion, and hazardous materials contamination of runoff during construction. Site plans, design, and BMPs for residential projects facilitated by the Housing Element are required to demonstrate proper compliance with applicable water quality regulations during application for development permits and the applicable NPDES permits. It was determined that the City and/or the San Francisco Bay Regional Water Quality Control Board (San Francisco Bay RWQCB) would review and approve applicable permits and would ensure that new development or redevelopment would not substantially worsen existing water quality problems. Therefore, the Prior EIR concluded that buildout of the Housing Element would have a less than significant impact on water quality. Analysis of Proposed Project The proposed project would demolish all the existing impervious surfaces on the project site, totaling 239,773 square feet of impervious pavement and parking surfaces. The proposed project would reduce the amount of impervious surfaces to 220,438 square feet (or approximately 5 acres) of impervious surfaces on the project site post-construction of the proposed project. Therefore, in accordance with Section 2.3.2 of the County’s C.3 Guidebook, set forth in the Municipal Regional Stormwater NPDES Permit (MRP), the proposed project would be required to include water treatment measures, such as the incorporation of multiple bioretention areas throughout the project site.62 The proposed project would also be required to prepare and comply with Pleasanton Municipal Code Chapter 9.14.080, Reduction of Pollutants in Stormwater, which states that all construction activities must follow BMPs outlined in the most current California Stormwater Quality Association (CASQA) construction BMP manual in order to prevent any debris and dirt flowing into the City’s storm sewer system, and all operations following construction must comply with project- 62 Alameda Countywide Clean Water Program. 2021. C.3 Stormwater Technical Guidance – Chapter 2, Background/Regulatory Requirements. February 8.