1901-1919 N Fairview St - Soils Report

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603284-001 According to the State of California Seismic Hazards Zones Map for the Anaheim 7.5 Minute Series Quadrangle, the site ji located within an area of liquefaction hazard (Figure 8, Seismic Hazards Map). As previously reported, groundwater was encountered in most of our borings (Section 2.4) drilled to a maximum depth of 51 M feet bgs. The historic high groundwater level is reported as approximately 15 feet bgs (CGS, 21997). A site-specific liquefaction analysis was performed to evaluate the liquefaction potential at the site. The soil profiles obtained from the hollow-stem auger borings are based on samples taken at five-foot intervals and correlate well with the soil profiles obtained from the six CPT soundings which were logged continuously; the CPT soundings provide a better resolution of data than the hollow-stem auger borings. Therefore, the soil profiles from the CPT soundings were used in our analyses. In addition, the historically high groundwater was assumed in the soil profile. The ground motion parameters used for the analysis were the site-specific design PHGA of 0.38g and the modal magnitude of 6.7 determined from disaggregation of site-specific ground motion. The analyses were performed using the computer program CLiq Version 1.5.1.16 (Geologismiki, 2006). Our analyses are generally based on the procedures outlined in Guidelines for Evaluating and Mitigation Seismic Hazards in California (Special Publication 117)published by the CGS and Recommended Procedures for Implementation of DMG Special Publication 117 Guidelines for Analyzing and Mitigating Liquefaction in California published by the Southern California Earthquake Center (SCEC). The site is generally classified as having low risk pf liquefaction based on the liquefaction potential index (lwasaki et al., 1978). Liquefaction potential index (LPI) combines depth, thickness, and factor of safety of liquefiable material inferred from a cone penetrometer test (CPT) sounding into a single parameter. The LPI ranges from 1 to 2.5. LPI values lower than 5 are deemed low risk. The potential for liquefaction are the site is generally confined within thin layers at depths ranging from about 20 to 50 feet bgs. The results of our liquefaction analyses are included in Appendix E. -13- Leighton