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ARROYO LAGO RESIDENTIAL PROJECT ADDENDUM 114 FCS Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/2148/21480036/Addendum/21480036 Arroyo Lago Residential Project Addendum.docx f) Destruction of Paleontological Resource or Unique Geologic Feature Would the project: Directly or indirectly destroy a unique paleontological resource or site or unique geologic feature? Prior FEIR Conclusions The Prior FEIR found that the project site is underlain by Holocene- and Pleistocene-age deposits. While Holocene deposits have low potential for paleontological resources, deeper Pleistocene layers have high potential. The University of California Museum of Paleontology (UCMP) database identified five vertebrate fossil localities within 3 miles of the project site. Therefore, given the foregoing, and the possibility of inadvertent discovery during construction, the Prior FEIR concluded there would be a potentially significant impact and identified MM GEO-6, which requires a qualified Paleontologist to conduct WEAP training, monitor excavations deeper than 6 feet, and implement fossil salvage procedures if resources are encountered. The Prior FEIR concluded that impacts would be less than significant with mitigation incorporated. (Draft EIR, pp. 3.6-22, 6-14). Proposed Project Analysis and Conclusion Consistent with the impact conclusions set forth in the Prior FEIR for the County Project, the proposed project would have a potentially significant impact in this regard due to potential inadvertent discovery and, thus, would be required to implement MM GEO-6, which would ensure that potential impacts related to any unique paleontological resources and unique geologic features would be less than significant. 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. Zone 7 Stormwater Option The Zone 7 Stormwater Option would not result in any new or more severe impacts related to geology, seismicity, or soils because it was described and considered in the Prior FEIR. By eliminating construction of the detention basin, pump facilities, and storm drain force main (as contemplated in the City Stormwater Option), this option would incrementally reduce grading and soil disturbance and would not increase exposure to seismic hazards, erosion, liquefaction, expansive soils, or other geologic risks. In addition, reduced subsurface disturbance would lessen the potential to encounter paleontological resources, and all previously adopted inadvertent discovery procedures would continue to apply; therefore, impacts would remain less than significant and consistent with the Prior FEIR. Mitigation Measures MM GEO-1 Design-Level Geotechnical Study Prior to issuance of building and grading permits, an updated design-level geotechnical exploration and assessment shall be performed by a qualified