14 ATTACHMENT 6 - Appendix A - E

City of Pleasanton–Spotorno Ranch Reduced Development Project Environmental Checklist Initial Study/Consistency Checklist 120 FirstCarbon Solutions https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/2148/21480021/Consistency Checklist/21480021 Spotorno Ranch Consistency Checklist ScreenCheck.docx As discussed previously, consistent with the 1998 HVSP FEIR, the proposed project would comply with the NPDES permit issued by the RWQCB. Under the NPDES permitting program, the proposed project would be required to prepare and implement a SWPPP because it is more than 1 acre in size. The SWPPP would identify potential sources of erosion or sedimentation that may be reasonably expected to affect the quality of stormwater discharges as well as identify BMPs that ensure the reduction of these pollutants during stormwater discharges. Therefore, the proposed project would not result in any peculiar effects and would not result in new or more severe impacts related to erosion or siltation beyond what was previously analyzed in the 1998 HVSP FEIR. (ii) substantially increase the rate or amount of surface runoff in a manner which would result in flooding on- or off-site; The 1998 HVSP FEIR determined that the project site is not located within the mapped 100-year flood hazard area or dam failure inundation area that limited flooding has been known to occur during winter storms along Alisal Street and Happy Valley Road. The 1998 HVSP FEIR’s planning, and development actions included storm drainage facilities such as detention basins, wet ponds, and grass swales to be integrated into specific projects to reduce the frequency and severity of flooding; in addition, minor improvements will be made to reduce flooding along Alisal Street near the Faith Chapel Assembly of God. Impacts were determined to be less than significant. Development of the proposed residential lots would result in a net increase of impervious surfaces. Increased runoff volume could exceed the capacity of downstream drainage components, causing localized flooding. As discussed above, the HVSP noted there were areas in the project vicinity where flooding has been known to occur. However, the City of Pleasanton’s Department of Engineering determined that there does not appear to be flooding issues within the Spotorno property, and the proposed detention area could accommodate any anticipated runoff from the project. The proposed bioretention areas and self-retaining areas would control the volume and flow of runoff on-site. Therefore, the proposed project would not result in any peculiar effects and would not result in new or more severe impacts related to flooding from runoff beyond what was previously analyzed in the 1998 HVSP FEIR. (iii) create or contribute runoff water which would exceed the capacity of existing or planned stormwater drainage systems or provide substantial additional sources of polluted runoff; The 1998 HVSP FEIR determined that stormwater runoff would increase as a result of more intensive development in the planning area. Residential development would introduce urban pollutants to surface runoff typical of that found in other similar residential areas, but hazardous substances are not expected. Drainage system improvements will be subject to current City standards. The Federal Emergency Management Agency (FEMA) flood hazard maps indicate that the project site is not located within a flood-prone area; however, portions of the Happy Valley Creek are known to experience occasional localized flooding. The 1998 HVSP FEIR concluded that this impact may be significant. Additionally, the 1998 HVSP FEIR required MM G4, which would require practices to improve drainage conditions along Alisal Street, and MM G5, which would require replacement of