Laserfiche WebLink
1.0 EXECUTIVE SUMMARY <br />Presented below is a brief summary of the conclusions and recommendations of this <br />investigation. Since this summary is not all inclusive, it should be read in complete context with <br />the entire report. <br />Geotechnical Design Considerations <br />• Our site-specific liquefaction evaluation indicates that some of the on-site soils are subject to <br />liquefaction during the design seismic event. <br />• The liquefaction analysis indicates a total settlement 5.03: inches at Boring No. B-1. The <br />liquefaction-induced differential settlements are conservatively estimated to be 21/2 to 3* <br />inches. Assuming that these settlements occur across a distance of 50* feet, an angular <br />distortion of 0.005 inches per inch would result. <br />• Based on the predicted magnitude of the liquefaction-induced settlements, a conventional <br />shallow foundation system cannot be used to support the proposed structure. Instead, it is <br />recommended that the proposed building be supported on a mat foundation. <br />Site Preparation <br />• The subject site is currently underlain by fill soils, extending to depths of 21/2 to 33: feet. <br />These fill soils possess variable composition and relatively low strengths. They are <br />considered to represent undocumented fill, and are not suitable for support of the new <br />structure. Remedial grading is considered warranted to remove and replace the existing fill <br />soils. <br />• Demolition of the existing convenience store building will be required as part of the proposed <br />development activities. It is also expected that some of the existing pavements will be <br />demolished. Debris resultant from demolition should be disposed of off-site. Concrete and <br />asphalt debris may be pulverized to a maximum 2 inch particle size, well mixed with the on- <br />site soils, and incorporated into new structural fills, if desired. <br />• Existing vegetation and organic materials within any demolished landscape planters should <br />be disposed of offsite. <br />• Remedial grading should be performed within the proposed building area to remove the <br />existing undocumented fill soils in their entirety. The overexcavation should extend to a <br />depth of 3 feet below existing grade and to a depth of 3 feet below proposed pad grade, <br />whichever is greater. Within the foundation influence zone, the overexcavation should <br />extend to a depth of at least 2 feet below proposed foundation bearing grade. <br />• After the recommended overexcavation has been completed, the resulting subgrade soils <br />should be evaluated by the geotechnical engineer to identify any additional soils that should <br />be overexcavated. The resulting subgrade should then be scarified to a depth of 10 to 12 <br />inches and thoroughly moisture conditioned to 2 to 4 percent above optimum moisture <br />content. The resulting subgrade should then be recompacted to at least 90 percent of the <br />ASTM D-1557 maximum dry density. The previously excavated soils may then be replaced <br />as compacted structural fill. <br />• The new parking area subgrade soils are recommended to be scarified to a depth of 123= <br />inches, moisture conditioned to 2 to 4 percent above optimum, and recompacted to at least <br />90 percent of the ASTM D-1557 maximum dry density. <br />> SOUTHERN G&M Convenience Store #72 - Santa Ana, CA <br />CALIFORNIA Project No. 16G123-1R <br />GEOTECHNICAL Page 1