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collapse characteristics. Finally, significant disturbance of the upper 2 to 3 feet of soils is <br />expected to occur during demolition of the existing building and surrounding improvements. <br />Based on these conditions, it is recommended that remedial grading be performed within the <br />area of the proposed building. <br />As discussed in a previous section of this report, potentially liquefiable soils were identified at <br />this site. The presence of the recommended layer of newly placed compacted structural fill <br />above these liquefiable soils will help to reduce any surface manifestations that could occur as a <br />result of liquefaction. The foundation and floor slab design recommendations presented in the <br />subsequent sections of this report also contain recommendations to provide additional rigidity in <br />order to reduce the potential effects of differential settlement that could occur as a result of <br />liquefaction. <br />Settlement <br />The proposed remedial grading will remove the existing undocumented fill soils and a portion of <br />the underlying native alluvium from within the proposed building area. The native soils that will <br />remain in place beneath the recommended depth of overexcavation possess favorable <br />consolidation and collapse characteristics, and will not be subject to significant stress increases <br />from the foundations of the new structure. Therefore, following completion of the recommended <br />remedial grading, post-construction static settlements are expected to be within tolerable limits. <br />Sulfates <br />The results of the soluble sulfate testing, as discussed in Section 5.0 of this report, indicate <br />soluble sulfate concentrations of 0.169 percent. These concentrations are considered to be <br />moderate with respect to the American Concrete Institute (ACI) Publication 318-05 Building <br />Code Requirements for Structural Concrete and Commentary, Section 4.3.Based on these <br />concentrations, the ACI requires that all concrete which will come into contact with the on-site <br />soils incorporate the following characteristics: <br />• Cement Type:II (Two) <br />• Minimum Compressive Strength (f'c) =4,000 lbs/inz <br />• Maximum Water/Cement Ratio:0.50 <br />It is recommended that additional sulfate testing be performed at the completion of rough <br />grading to verify the concentrations which are present in the actual building pad subgrade soils. <br />Expansion <br />Laboratory testing performed on a representative sample of the near surface soils indicates that <br />these materials are medium to non-expansive (EI = 0 to 70). Based on the presence of <br />expansive soils at this site, special design and construction considerations are warranted. All <br />building pad and flatwork subgrade soils should be properly moisture conditioned and <br />maintained at adequate moisture content throughout the construction process. Further <br />recommendations concerning the expansive soils are presented in subsequent sections of this <br />report. It is recommended that additional expansion index testing be conducted at the <br />completion of rough grading to verify the expansion potential of the as-graded building pad. <br />> SOUTHERN G&M Convenience Store #72 - Santa Ana, CA <br />CALIFORNIA Project No. 16G123-1R <br />GEOTECHNICAL Page 14