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NT <br />TS <br />INITIAL STUDY/MITIGATED NEGATIVE DECLARATION FAIRVIEW BPIOGE REVLACEM STREET <br />STREET BEET) PROJECT <br />L S A <br />MAY 2020 (9Tx STPEET To ANTx NA, CA L, OREGT <br />SANTA ANAL CALIFOPHIA <br />3.7 GEOLOGY AND SOILS <br />Less Than <br />Potentially Significant with Less Than <br />Significant Mitigation Significant No <br />Would the project: <br />a. Directly or indirectly cause potential substantial adverse <br />effects, including the risk of loss, injury, or death involving: <br />i. Rupture of a known earthquake fault, as delineated on <br />the most recent Alquist-Priolo Earthquake Fault Zoning <br />Map issued by the State Geologist for the area or based <br />❑ <br />❑ <br />® <br />❑ <br />on other substantial evidence of a known fault? Refer to <br />Division of Mines and Geology Special Publication 42. <br />ii. Strong seismic ground shaking? <br />❑ <br />❑ <br />® <br />❑ <br />iii. Seismic -related ground failure, including liquefaction? <br />❑ <br />❑ <br />® <br />❑ <br />iv. Landslides? <br />❑ <br />❑ <br />❑ <br />b. Result in substantial soil erosion or the loss of topsoil? <br />❑ <br />❑ <br />® <br />❑ <br />c. Be located on a geologic unit or soil that is unstable, or that <br />would become unstable as a result of the project, and <br />❑ <br />❑ <br />® <br />❑ <br />potentially result in on- or off -site landslide, lateral <br />spreading, subsidence, liquefaction or collapse? <br />d. Be located on expansive soil, as defined in Table 18-1-B of <br />the Uniform Building Code (1994), creating substantial direct <br />❑ <br />❑ <br />® <br />❑ <br />or indirect risks to life or property? <br />e. Have soils incapable of adequately supporting the use of <br />septic tanks or alternative waste water disposal systems <br />❑ <br />❑ <br />Elwhere <br />sewers are not available forthe disposal of waste <br />water? <br />f. Directly or indirectly destroy a unique paleontological <br />❑ <br />® <br />El <br />❑ <br />resource or site or unioue eeoloeic feature? <br />3.7.1 Existing Setting <br />This section is based on the Preliminary Geotechnical Information study13 and Paleontological <br />Analysis Memorandum (Appendix A).14 <br />3.7.1.1 Geologic and Soils Information <br />The Project area is located in the Los Angeles physiographic basin, which is a large, relatively flat, <br />low-lying, coastal area surrounded by mountains on the north, east, and southeast. The Project area <br />is located in the southeastern part of the basin known as the Tustin Plain. Regional geologic studies <br />indicate that Holocene -age, flood -plain sediments extend to a depth of a few hundred feet and <br />overlie coarse sand and gravel of the Holocene -age Talbert aquifer. Quaternary -age sediments are <br />about 2,000 ft thick in the region. The Quaternary sediments overlie Tertiary -age sedimentary rocks. <br />The Mesozoic —age crystalline basement rocks are about 14,000 ft below the Project area. <br />13 Earth Mechanics, Inc. 2018. Preliminary Geotechnical Information. March 20. <br />14 LSA Associates, Inc. 2019d. Paleontological Analysis of the Fairview Street Improvements from 9th Street <br />to 16th Street and Bridge Replacement Project Santa Ana, Orange County, California. September 7. <br />R:\WKE1702\ISMND\Final ISMND\Fairview Street Bridge Final ISMND7,658m7 1 3-37 <br />