PC-2026-15 - Laserfiche WebLink

330 Land Company, LLC 9785.004.001 Arroyo Lago October 31, 2025 RESPONSE TO CITY REVIEW COMMENTS Page 6 BSK Comment 17 – Geotechnical Report, Section 6.1, Foundation Subgrade Moisture Vapor Reduction a. Consideration should be given to recommending a capillary break section consisting of several inches of crushed rock under PT mat foundations. b. Consideration should be given to eliminating the option to use clean sand or pea gravel above the vapor retarder membrane. 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. ENGEO Response to Comment 17 a. In our experience, the moisture vapor reduction recommendations provided in Section 6.1 are sufficient to adequately reduce the potential for detrimental moisture migration through the slab. However, we take no exception to others recommending a capillary break section in addition to our recommendations. b. As presented in Section 6.2, we defer to the structural engineer for the use of pea gravel or clean sand above the PT mat. BSK Comment 18 – Geotechnical Report, Section 6.3, 2022 Seismic Design Parameters The 2025 California Building Code (CBC) becomes effective on January 1, 2026. Is this project being designed based on the 2022 or 2025 CBC? If the latter, then revised seismic design parameters should be presented. This could also require rerunning the liquefaction analysis if the PGAm value changes significantly ENGEO Response to Comment 18 The geotechnical report has been revised to include 2025 California Building Code (CBC) seismic parameters. The liquefaction analysis has also been revised based on the updates to the 2025 CBC. BSK Comment 19 – Geotechnical Report, Section 8.1, Flexible Pavement Consideration should be given to recommending a deepened curb or “cutoff” extending several inches below the aggregate base layer at the edge of paving where it is adjacent to landscaping. ENGEO Response to Comment 19 A deepened curb is typically constructed to mitigate expansive soil potential within pavement or landscaping areas. We anticipate the majority of pavement subgrade areas will be underlain by imported low-expansive engineered fill or on-site low-expansive material. We believe placement of the low-expansive engineered fill will be sufficient to mitigate expansive soil potential; however, we take no exception to others recommending a deepened curb in addition to our recommendations.