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ARROYO LAGO RESIDENTIAL PROJECT ADDENDUM FCS 141 Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/2148/21480036/Addendum/21480036 Arroyo Lago Residential Project Addendum.docx The proposed project stormwater drainage system, including the bioretention area and detention basin, would have sufficient capacity to serve the proposed project. The stormwater system would be designed in accordance with all applicable standards, including those set out in Pleasanton Municipal Code Chapter 9.14 (“Stormwater Management and Discharge Control”) with adequate capacity to accommodate the project site during storm events and ensure no net increase in off-site flow of stormwater. Consistent with Pleasanton General Plan Public Safety Policy 15, residential development would be located outside of the 100-year flood hazard area, while limited off-site utility infrastructure proposed within Flood Hazard Zone A would be designed to meet applicable FEMA and local flood control standards. In addition, the proposed project includes a controlled overland release in the form of an emergency spillway to safely convey extreme storm flows in accordance with Zone 7 Flood Control standards and historic drainage patterns. Moreover, the proposed project includes residential land uses, which do not represent the type of use that would otherwise degrade water quality (e.g., industrial land uses that utilize hazardous materials that could adversely affect water quality). Anticipated and potential pollutants generated by the proposed project would be limited to household items and normal and expected materials for the proposed land uses and include sediment, nutrients, pesticides, metals, pathogens, oil, and grease. These materials would be limited to personal use quantities. Thus, impacts would be less than significant, consistent with the impact conclusions of the Prior FEIR. Therefore, the proposed project would not introduce new significant impacts or create substantially more severe significant impacts than those previously identified in the Prior FEIR. No additional analysis is required. e) Water Quality Control or Sustainable Groundwater Management Plans Consistency Would the project: Conflict with or obstruct implementation of a water quality control plan or sustainable groundwater management plan? Prior FEIR Conclusions Particularly given the project site’s location and the scope of off-site utility improvements, the Prior FEIR conducted a robust analysis to consider whether the County Project would conflict with or obstruct implementation of a water quality control plan or sustainable groundwater management plan. As detailed more fully therein, the Prior FEIR confirmed that the County Project would comply with the RWQCB Basin Plan and Zone 7’s Alternative GSP. During construction, the County Project would be required to comply with the terms of the Construction General Permit, which requires the preparation and implementation of a SWPPP that includes BMPs to ensure reduction of pollutants from construction activities potentially entering surface waters. During operation, the County Project would be served by Cal Water Livermore District, which derives its water supply from a combination of groundwater and surface water purchased from Zone 7. The County Project complies with the Zone 7 Alternative GSP by demonstrating that its groundwater use would have an insignificant impact on basin conditions and would not interfere with Zone 7’s ability to maintain the Livermore Valley Groundwater Basin within its sustainable yield. The Prior FEIR