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Caribou Industries <br />Proposed Alternative Seismic Improvements - 888 North Main Street <br />July 25, 2018 <br />Page 2 <br />We previously performed the original geotechnical investigation for the subject building and submitted the <br />results in a report dated March 6, 1964 (our Job No. 64054, submitted under the name of LeRoy Crandall and <br />Associates, a Wood Environment & Infrastructure Solutions, Inc. legacy company). We also provided <br />geotechnical inspection and testing services during the construction of the existing building, the results of which <br />were documented in a report dated February 4, 1966 (our Job No. 64605, also submitted under the name of <br />LeRoy Crandall and Associates). In addition, we recently performed a geotechnical investigation for the NOVA <br />Children's Academy in the vicinity of the subject project site; the results of this investigation, which included a <br />ground motion study and the development of four sets of response spectrum-compatible acceleration-time <br />histories each for both the BSE-lE and the Basic Safety Earthquake 2 (BSE-2E) in accordance with the <br />requirements of ASCE/SEI 41-13, were submitted in a report dated January 28, 2016 (our Job No. 4953-15-1481, <br />submitted under the name of Amec Foster Wheeler Environment & Infrastructure, Inc., a Wood Environment & <br />Infrastructure Solutions, Inc. legacy company). We were also provided a copy of a geotechnical investigation <br />report for the nearby One Broadway Plaza project performed by Leighton Consulting, Inc. (Leighton), dated <br />February 28,2006. <br />Based on our review of the available data, we were to perform the following tasks: <br />• Provide the results of our limited geologic-seismic hazards evaluation for the site, <br />including evaluation of the liquefaction potential. <br />• Provide the site-specific response spectrum for ground motions corresponding to the <br />BSE-lE. <br />• Provide the site-specific response spectrum for ground motions corresponding to an <br />event with a 50% probability of being exceeded in 50 years (average return period of <br />approximately 72 years). <br />• Provide four sets of response spectrum-compatible acceleration time histories each for <br />both of the ground motion levels described above. <br />2.0 Limited Geologic-Seismic Hazards Evaluation <br />2.1 Geologic Setting <br />The project area is located on the Coastal Plain of Orange County, approximately 2 miles east of the Santa Ana <br />River. The Coastal Plain of Orange County is underlain by a deep, structural basin known as the Los Angeles <br />Basin. The site is underlain by approximately 3,600 feet of Quaternary sediments that are underlain by a thick <br />sequence of Tertiary sedimentary rocks (approximately 7,000 feet). Regionally, the site is in the Peninsular Ranges <br />geomorphic province. The province is characterized by elongate northwest-trending mountain ridges separated <br />by straight-sided sediment-filled valleys. The northwest trend is further reflected in the direction of the dominant <br />geologic structural features of the province that are northwest to west-northwest trending folds and faults, such <br />as the nearby Whittier and Newport-Inglewood fault zones. <br />Locally, the site is situated on a Holocene-age alluvial fan attributed to the Santa Ana River floodplain (Morton <br />and Miller, 2006; Sprotte et al., 1980). The elevation at the site is approximately 128 feet above mean sea level <br />(AMSL) (NAVD 88). <br />...