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Peer Review of Geotechnical and Geologic Hazard Investigations BSK Project G2300051 11991 Dublin Canyon Road (Hana Japan) September 6, 2024 Pleasanton, California Page 3 During our review of the subject documents, we have identified items that require additional information or clarification. Items requiring additional information or clarification are listed below. 1. CBC Update Letter: The letter characterizes the Site as Site Class D whereas the Geotechnical Report characterizes the Site as Site Class C. Some of the values provided in Table 1 appear to be consistent with a Site Class C, while others are consistent with Site Class D. The discrepancy between Site Class characterizations and their associated seismic design values should be clarified. In addition, consideration should be given to providing an appropriate justification for the Site Class selected. 2. Fault Exploration Report, Conclusions and Recommendations: a. Based on the mapped fault location by Hart (1981) and others, and the lack of existing subsurface information in this area of the Site within the Alquist-Priolo Earthquake Fault Zone (AP Zone) for the Calaveras Fault, we do not consider a setback distance of 25 feet for structures intended for human occupancy to be adequate based on the amount of subsurface uncertainty at the southwest edge of the Site. The consultant should provide reasoning why a smaller setback distance was recommended from a potential fault trace in an area with limited subsurface information. b. Clearer recommendations should be provided for addressing the potential for secondary ground deformations. c. Please define the term “a few inches” when discussing secondary ground deformations. Perhaps provide a range of possible values. 3. Fault Exploration Report, Figure A1 (Trench Logs T-1 through T-3): At approximately Station 0+52 in exploratory trench ET-1, apparent bedding with a strike of N15°W and dip of 65°W was encountered between sandstone, siltstone, and conglomerate. This apparent bedding attitude is not consistent with the apparent bedding documented within the exploratory trenches at the site (majority are striking further west and dipping to the east). Given the strike of the Calaveras Fault at the Site and the inconsistency with local bedding noted in the other exploratory trenches, the consultant should provide a discussion and reasoning as to why this potentially anomalous bedding attitude is not considered potentially fault-related. 4. Geotechnical Report, Section 1 (Introduction): This section of the Geotechnical Report states that finished floor elevations are anticipated to be 385.5 feet above mean sea level (MSL). However, according to Sheets C3 through C5 of the project plans, the finished floor is shown as 382 feet MSL. ENGEO should evaluate whether this is a concern or not given that perched groundwater was encountered as shallow as 379.5 feet MSL according to the Geotechnical Report. 5. Geotechnical Report, Section 3 (Project Description): This section of the Geotechnical Report states that site improvement will include cuts up to 16 feet. However, Sheet C4 of the Project Plans shows greater than 20 feet of cuts along the east edge of the planned building footprint. ENGEO should evaluate whether this is a concern or not. 6. Geotechnical Report, Section 4.3 (Subsurface Conditions): Consideration should be given to presenting the previous boring logs by Hydro-Geo Consulting and Harding Lawson Associates in an Appendix of the Geotechnical Report. The locations of these boring logs are shown on Figure 2 of the Geotechnical Report.