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66 for site development. This impact is considered less than significant. All grading plans are subject to City review and approval. Also see item (a) above for a summary of the geotechnical report findings regarding proposed foundation types and construction considerations. As the proposed Commercial Component would have a less-than-significant impact with the incorporation of standard conditions and compliance with the regulatory framework, it would be consistent with the EIR/SEIR. It would not create new impacts or increase impacts and there is no new information of substantial importance for CEQA purposes. d. The Downtown Precise Plan program EIR (p. 16-6) determined that development within the DTPP area may be subjected to hazards from expansive soils, representing a potentially significant impact. Mitigation 16-1 requires that the final geotechnical report required by the City Building Official include an analysis of expansive soil hazards and recommended stabilization measures. The DTPP Plan-Wide Amendments program SEIR (pp. 16-12 and 16-13) concurred with the DTPP EIR conclusion and includes Mitigation Measure GEO-4a, which restates Mitigation Measure 16-1 from the DTPP Final EIR with minor text revisions (“clarifying amendments”). Implementation of these measures, combined with conformance with standard CBC and/or CHBC and other applicable State and local regulations (all of which shall be required as conditions of approval for the project component), would reduce the potential effects of expansive soils to a less-than-significant level. According to the Commercial Component-specific geotechnical report, the subject site is underlain by stiff to vary stiff clay with varying sand content (p. 5). The results of laboratory testing conducted on the site’s soil samples indicate soil is highly expansive and is subject to volume changes with changes in moisture content. The geotechnical report recommends moisture-conditioning the expansive soil, providing non-expansive fill below slab-on-grade floors, and either supporting foundations below the zone of severe moisture change or by providing a stiff, shallow foundation that can limit deformation of the superstructure as the underlying soil shrinks and swells (p. 21). The report recommends (1) subdrain systems beneath permeable surfaces, and (2) vertical barriers between permeable surfaces underlain by subdrains and non-permeable surfaces underlain by conventional aggregate base – all to prevent water from collecting adjacent to basement walls and below pavements and concrete flatwork. Additionally, to prevent the subgrade soil from becoming saturated, the geotechnical report recommends that permeable aggregate base courses be underlain by an impermeable liner in zones subject to regular vehicular traffic or in areas adjacent to structural improvements. All geotechnical report recommendations would be subject to City review and approval for feasibility and effectiveness. In addition, the DTPP program EIR (p. 16-8) noted that development occurring under the DTPP would be subject to damage due to the presence of corrosive soils within the DTPP area. DTPP Mitigation Measure 16-2 specifies that buried metal infrastructure should have cathodic protecting using a sacrificial anode system that conforms to Part VII (G) of the City’s water system design criteria and standard specification details Section 02661. Additionally, concrete mixes must conform to Caltrans specifications for Protection of Reinforcement Against Corrosion Due to Chlorides, Acids, and Sulfates as outlined in the Memo to Designers 10-5, January 2002. The DTPP Plan-Wide Amendments program SEIR (pp. 16-12 and 16-13) concurred with the DTPP EIR conclusion and includes Mitigation Measure GEO-4b, which restates Mitigation Measure 16-2 from the DTPP Final EIR with minor text revisions (“clarifying amendments”). These measures, which shall be required as conditions of approval for the Commercial Component, would reduce the potential impacts of corrosive soils on this component to a less-than-significant level. As discussed, the EIR/SEIR determined impacts from expansive soils to be less than significant with mitigation. As the Commercial Component would have a less-than-significant impact with the incorporation of standard conditions and compliance with the regulatory framework, it would be consistent with the EIR/SEIR. It would not create new impacts or increase impacts and there is no new information of substantial importance for CEQA purposes. e. The DTPP EIR did not address the impacts related adequate soils for the use of septic tanks or alternative wastewater disposal systems because septic systems are not appropriate within urbanized areas. The Plan-Wide Amendments program SEIR concurred and found the impact to be less than significant. There would be no use of septic tanks or alternative wastewater disposal systems for the project component. No impact would occur. Because the Commercial Component would connect to the existing sewer system, this project component is consistent with the analysis in the EIR/SEIR. It would not create new impacts or increase impacts and there is no new information of substantial importance for CEQA. f. The DTPP program EIR (p. 7-41) concluded that earthmoving activity associated with DTPP-facilitated development could potentially disrupt, alter, or eliminate as-yet undiscovered paleontological resources, which represented a potentially significant impact. Mitigation Measure 7-5 of the DTPP program EIR requires that, prior to the issuance of grading or demolition permits, the Planning, Housing, and Economic Development Department (now the ATTY/RESO.0031/CC RESO CEQA GUIDELINES (901 EL CAMINO REAL) REV: 04-22-25 VR Page 66 of 148