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Appendix B - Soils Report - Geological ReviewSeptember 11, 2017 ECI Project No. 3712 Engineering Geology Review 8449 Garvey Avenue and 3014 Earle Avenue, Rosemead Page 1 of 3 City of Rosemead Geological Report Review Project Name: Mixed Commercial and Residential Project Location: 8449 Garvey Avenue and 3014 Earle Avenue Lat: 34.06230, Long: -118.0848 Proposed Development: Mixed-use (commercial and residential) development consisting of a four- story building with one level of subterranean parking. The lowest subterranean level will be approximately 9 to 11 feet below existing ground surface. The subterranean garage will occupy the entire building site. Report Reviewed: Cal Land Engineering, Inc. dba Quartech Consultants, (QCI), 2017, Report of Geotechnical Engineering Investigation, Proposed 4-Story Mixed-Use Building with one Level of Subterraneous Garage, 8449 Garvey Avenue, APN: 5288-004-057 and 3014 Earle Avenue APN: 5288-004-041, Rosemead, California: QCI Project No. 16-087-001GE, dated April 4, 2017; signed by Jack C. Lee, GE 2153, Principal, Keith Au, Project Engineer, and Abe Kazemzadeh. Type of Report: Geotechnical Engineering Investigation; in liquefaction-susceptible area Previous Reviews: None FINDINGS ! Report is Acceptable as Presented ! Report is Acceptable with the Following Conditions " Response is Required (see Remarks) The site is located within a Liquefaction Hazard Zone as defined by the Seismic Hazards Mapping Act (California PRC Div. 2, Chapter 7.8, sec. 2690-2699.6). Within 30 days of approval of this study, the City must forward the report and the review letters to the State Geologist. The site is not located within an Alquist-Priolo Earthquake Fault Zone (per California PRC Div. 2, Chapter 7.5, sec. 2621-2630), and it is not located within or near a fault hazard management zone identified in the City of Rosemead (2008) Safety Element of the General Plan. As a result, a fault investigation is not required for this site. The study completed by QCI included the drilling of two 8-inch-diameter, hollow stem auger borings; one of these extended to a depth of 51.5 feet, the second to 21.5 feet. Thus, neither of these borings extended to at least 50 feet below the proposed maximum depth of the subterranean structure. According to the boring logs presented in the report, the site is underlain by fine- to medium-grained silty sand to a depth of about 40 feet, and sandy silt to clayey silt below, to the September 11, 2017 ECI Project No. 3712 Engineering Geology Review 8449 Garvey Avenue and 3014 Earle Avenue, Rosemead Page 2 of 3 maximum depth explored of 51.5 feet. Groundwater was not encountered in the borings, although the samples below 40 feet in boring B-1 were reported to be very moist. The historical high groundwater level, based on California Division of Mines and Geology (CDMG) Seismic Hazard Zone Report 024, is approximately 8 feet below the ground surface. The consultant used a peak ground acceleration of 0.867g and a 7.0 magnitude earthquake for the liquefaction analysis, and concluded that the layer of silty sand at a depth of 37 to 42 feet has a factor of safety of less than 1.3. The consultant calculated a total seismic-induced settlement at the site of 0.42 inches, with differential settlement estimated at 0.21 inches. The geotechnical engineering reviewer will evaluate these statements further. The consultant reported that the ground motions with a 2% and 10% probability of being exceeded in 50 years are 0.867g and 0.519g, respectively. We calculate similar but slightly higher values of 0.9941 and 0.5289g, respectively (https://earthquake.usgs.gov/hazards/interactive/). These strong ground motions are reflective of the site’s location relative to several near seismic sources, including the Upper Elysian Park and Puente Hills thrust faults, and the northward extension of the Whittier fault. The seismic design parameters provided are in agreement with the values that we calculated independently for the site using the 2015 NEHRP Provisions (https://earthquake.usgs.gov/designmaps/beta/us/), but significantly lower than the values calculated using the 2015 International Building Code as the building code reference document (https://earthquake.usgs.gov/designmaps/us/application.php). The 2015 NEHRP Recommended Seismic Provisions seismic design parameter values are being adopted into the 2018 International Building Code, and are thus not yet official. REMARKS Earth Consultants International, Inc. (ECI) reviewed the above-referenced report for compliance with applicable codes, guidelines and standards of practice. Please note that the City of Rosemead has adopted the Los Angeles County Department of Public Works Manual for Preparation of Geotechnical Reports, the 2016 California Building Code and the 2017 County of Los Angeles Building Code. The following item needs to be addressed before the project can be approved: 1. Given that the City and Los Angeles County are currently using the 2016 California Building Code, which is based on the 2015 International Building Code, the seismic design values provided in the report should use the 2015 International Building Code as the code reference document. Although not required to address in their report, the consultant should take note of the following for future reference: 1. The Upper Elysian Park thrust fault is not a zone but rather a single, low-dipping buried thrust fault that extends below the entire western half of the City of Rosemead. The site is located approximately 1 mile from the eastern termination of the fault plane, in the area where the fault is approximately 2 km (1.2 miles) below the ground surface. September 11, 2017 ECI Project No. 3712 Engineering Geology Review 8449 Garvey Avenue and 3014 Earle Avenue, Rosemead Page 3 of 3 2. If the consultant makes statements about the similarity of the sediments exposed in the borings to indicate that there are no fault-related discontinuities under the site, the report needs to be signed by a California-registered geologist or certified engineering geologist. The engineer making these determinations is essentially practicing geology without a license. Furthermore, geotechnical borings sampled every 5 feet should not be used to correlate geological materials and confirm the lack of faulting. If the City, the consultants or the owners have any questions regarding the comments presented above, please contact Earth Consultants International, Inc. Respectfully submitted for EARTH CONSULTANTS INTERNATIONAL, INC. Tania Gonzalez, CEG 1859 Engineering Geologic Reviewer for the City of Rosemead Earth Consultants International, Inc. 1642 E. Fourth Street, Santa Ana, California 92701 (714) 412-2654 (direct), (714) 544-5321 (general office) References and Sources: California Division of Mines and Geology, 1991 (revised Official Map), Alquist-Priolo Earthquake Fault Zone Map for El Monte 7-1/2 minute Quadrangle, California; Scale: 1:24,000. California Division of Mines and Geology, 1998, Seismic Hazard Zone Report for the El Monte 7.5-Minute Quadrangle, Los Angeles County, California: Seismic Hazard Zone Report 024. City of Rosemead General Plan Update, 2008, Chapter 5: Public Safety, adopted October 14, 2008. California Building Standards Commission, 2016 California Building Code, Title 24, Part 2, Volume 2 of 2 – Effective January 1, 2017 (available from https://ia801200.us.archive.org/25/items/gov.ca.bsc.title24.2016.02.2/gov.ca.bsc.2016.02. 2.pdf). Treiman, J.A., 1991, Whittier fault zone, Los Angeles and Orange Counties, California: California Division of Mines and Geology Fault Evaluation Report FER 222, 17p. U.S. Geological Survey (USGS), 2017, U.S. Seismic Design Maps and Tools, web pages accessed on September 10 and 11, 2017 at http://earthquake.usgs.gov/designmaps/us/ application.php and https://earthquake.usgs.gov/designmaps/beta/us/).