PC-2025-16 - Laserfiche WebLink

Hana Japan Steak House 5150.100.001 11991 Dublin Canyon Road November 11, 2024 RESPONSE TO COMMENTS Page 2 Comment 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. ENGEO Response to Comment 2 a. We discuss the previous fault studies in Reference 1, and this includes a discussion that the possible presence of a secondary trace of the Calaveras Fault is based on geomorphic features and not identified by trenching to the north or south. This fault, if present, would constitute a secondary fault splay that diverges from the main trace and is significantly shorter than the main traces of the fault. As such, we opine that a 25-foot setback is appropriate. b. We will add a section as an update to Reference 2 (Reference 2 update). Our recommendation will comprise recommendations to use ties between isolated footings or a mat foundation. c. We opine that secondary displacement, if any, would be less than 4 inches of offset. Comment 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. ENGEO Response to Comment 3 The strike and dip of the apparent bedding at the station identified by BSK is not inconsistent with the variability of strike and dip in localized areas observed in structurally complex areas such as this, as is reflected in the Regional Geologic Map of this area. Furthermore, a fault trace, if present at this location, would have been encountered by the other overlapping trenches performed at the site. Comment 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.