14 ATTACHMENT 6 - Appendix A - E

City of Pleasanton–Spotorno Ranch Reduced Development Project Environmental Checklist Initial Study/Consistency Checklist 100 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 Implementation of the above requirements, including the preparation and implementation of a SWPPP and compliance with Municipal Code requirements, would ensure that potential construction-related erosion impacts are not greater than those analyzed in the 1998 HVSP FEIR. Therefore, the proposed project would not result in any peculiar effects and would not result in new or more severe impacts related to loss of topsoil or soil erosion beyond what was previously analyzed in the 1998 HVSP FEIR. c) Unstable Soils or Geologic Units Would the project: Be located on a geologic unit or soil that is unstable, or that would become unstable as a result of the project, and potentially result in on- or off-site landsliding, lateral spreading, subsidence, liquefaction, or collapse? The 1998 HVSP FEIR determined that moderate to strong ground shaking can result in saturated sediments undergoing a type of failure referred to as liquefaction, where sediments are transformed from a solid to liquid state, resulting in collapse of the ground surface and damage to structures. The alluvial deposits within Happy Valley are recognized in the City's General Plan as having a high susceptibility to seismic shaking and "moderate to high" and "high" potential for liquefaction, as well as associated impacts such as lateral spreading, differential settlement, and lurch cracking, which could result in substantial damage to building foundations or other site improvements. Structures and constructed slopes would be required to implement the most recent UBC and implement additional requirements. The 1998 HVSP FEIR concluded that impacts related to seismic hazards, including unstable geologic units and soils, were significant and unavoidable. A 2015 Geotechnical Feasibility Report prepared for the entire project site concluded that, based on existing subsurface information and experience in the project site and vicinity, the potential for liquefaction for the entire project site is likely to be low with implementation of the proposed improvements to differential settlement. Furthermore, the USGS and the ABAG Resilience Program have mapped the area to have low susceptibility for liquefaction. Therefore, impacts associated with liquefaction and associated impacts such as lateral spreading, differential settlement, and lurch cracking, is likely to be low. Additionally, as discussed previously, the proposed project is in an area where landslides may occur and would implement MM H4 to reduce potential impacts related to landslides. According to the 1998 HVSP FEIR, there is potential for deep fills to result in significant settlement or hydro-compression, resulting in compacted soil losing strength and experiencing consolidation, which can cause damage to structures, utilities, and pavements. According to the 1998 HVSP FEIR, construction that is consistent with the recommendations of the geotechnical report would protect against significant impacts related to fill soils, consistent with MM H7. Additionally, the 2015 Geotechnical Report indicated that development of the project site is feasible from a geotechnical standpoint provided that appropriate mitigation of geologic hazards and design considerations are incorporated into plans and implemented during construction. In addition to implementing MM H4 and MM H7, the proposed project would implement additional measures related to soils, grading, and slope stability, including MM H1, MM H5, and MM H6, as specified in the HVSP MMRP, to reduce potential impacts related to unstable geologic units or unstable soils. Therefore, the proposed project would not result in any peculiar effects and would