20A - AA FIRST ST BRIDGE REPLACEMENT PROJECT

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LSA ASSOCIATES, INC. INITIAL STUDY/MITIGATED NEGATIVE DECLARATION JULY 2010 FIRST STREET BRIDGE REPLACEMENT PROJECT CITY OF SANTA ANA No impact. The site has been previously graded and paved. As discussed in the V a) and V b) the site has been disturbed for many years and no human remains are known or likely to exist on site. However, if any unknown human remains are encountered the work will be halted and County Coroner will be informed about the finding. As a result, no impact is anticipated, and no mitigation is required. VI. Geology and Soils Would the project: A. Expose people or structures to potential substantial adverse effects, including the risk of loss, injury, or death involving: 1. Rupture of a known earthquake fault, as delineated on the most recent Alquist-Priolo Earthquake Fault Zoning map issued by the State Geologist for the area or based on other substantial evidence of a known fault? Less than significant impact. As with all of Southern California, the proposed project site will be subject to strong ground motion resulting from earthquakes. According to the Federal Emergency Management Agency (FEMA) earthquake database (HAZUS) and the 1999 Index to Fault Zone Maps (State Conservation Service Web site: http://ftp.consrv.ca.gov/pub/dmg/pubs/sp/sp42.pdf), there are no major faults in the City of Santa Ana and no fault or fault Zone crosses the project site. Therefore the proposed project would not result in a significant impact related to rupture of a known earthquake fault as delineated on the most Alquist-Priolo Earthquake Fault Zone Map, and no mitigation is required. 2. Strong seismic ground shaking? Less than significant impact. The project site, like all of Southern California, is located in an active seismic region. Ground shaking resulting from earthquakes associated with both nearby and more distant faults is likely to occur. Several earthquake fault zones are located in Orange County, including the Newport-Inglewood Fault Zone which trends northwards and is located along the coast line, the Whittier fault zone which trends north east along the Puente Hills, and the Norwalk Fault which trends eastward along the southern edge of the Coyote Hills. Earthquakes on faults located within the 50 miles from the City can cause damage within the City. Depending on their magnitude, earthquakes generated within a 50-mile radius of a given point are considered noteworthy and could cause minor to moderate damage.' The project site will experience effects of the regional seismic activity; the risk of strong seismic events would remain the same on site with the new bridge and street widening. The project does not propose any additional structures and the potential risk is considered the same or less than the existing risk due to the fact that the new bridge and First Street will conform to current building and seismic 1 Orange County General Plan, Safety Element, p. IX-80. 07/25/10 «P:\DMJ070l\MND\4.0 Environmental Analysis.doa> 4-15 20A-66