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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 5 17. Geotechnical Report, Section 6.8.1 (Surface Drainage) Note 2: Per Section 1804.4 of the 2019 and 2022 CBC, consideration should be given to recommending that the ground adjacent to foundations have minimum gradients of 5% and 2% for a lateral distance of 10 feet for exposed ground and impervious surfaces (such as concrete flatwork), respectively. 18. Geotechnical Report, Section 6.8.2 (Subsurface Drain): The minimum lateral spacing between consecutive parallel rows of subdrain lines/trenches under the building pad should be provided. 19. Geotechnical report, Section 7.1 (Conventional Footings with Slab-on-Grade): This section of the Geotechnical Report should discuss how the footings should be designed in order to mitigate the potential for secondary ground deformations discussed in the Fault Exploration. 20. Geotechnical Report, Section 7.2 (Footing Dimensions and Allowable Bearing Capacity): BSK takes no exception to the minimum footing embedment depths shown in Table 4 of the Geotechnical Report provided that the upper 3 feet of the building pads consist of low expansion potential soil having a plasticity index of less than 12. Otherwise, consideration should be given to extending the minimum footing depth to 24+ inches similar to Section 9.4 (Foundations) of the Geotechnical Report. 21. Geotechnical Report, Section 7.4 (Reinforcement): What is the purpose of recommending that the continuous footings be designed to structurally span (unsupported?) over a clear (lateral?) distance of 5 feet? Perhaps the purpose of this is to address the potential for secondary ground deformations? If so, this should be stated in this section of the Geotechnical Report. 22. Geotechnical Report, Section 7.5 (Foundation Lateral Resistance): Consideration should be given to neglecting the upper 1 foot of subgrade for passive resistance where the subgrade is not protected by asphalt/paving or concrete flatwork. 23. Geotechnical Report, Section 8.1 (Exterior Flatwork): Consideration should be given to recommending placement of a layer of low expansion potential soil having a plasticity index of less than 12 under the exterior flatwork (such layers are typically 6+ inches thick). Previous sections of the Geotechnical Report recommend removing clay soil (expansive soil) from under building pads, but do not mention exterior flatwork. Consideration should also be given to recommending that thickened edges extend at least 2 inches below the low expansion potential soils where adjacent to landscaping in order to reduce the potential for migration of landscaping water into the subgrade for exterior flatwork. 24. Geotechnical Report, Section Slab 8.2.2 (Slab Moisture Vapor Reduction): a. Consideration should be given to specifying the minimum thickness of the vapor retarder membrane. Using a membrane with a minimum thickness of 15 mil is considered current industry standard. b. Consideration should be given to eliminating the last paragraph of this section of the Geotechnical Report. Placing a layer of sand or gravel over the vapor retarder membrane is no longer considered industry standard as it could result in the entrapment of water between the vapor retarder membrane and the slab leading to long-term vapor moisture issues. 25. Geotechnical Report, Section 10.1 (Flexible Pavements): This section of the Geotechnical Report recommends that the upper 18 inches below finished subgrade within flexible pavement areas of the Site have an R-Value of at least 25. Caltrans typically requires that the upper 24 inches of the