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1 <br /> - - ' , <br /> AET #20-01080 - Page 10 <br /> ' <br /> Soil conditions can be expected to vary away from the soil boring locations. For this reason, , <br /> excavation depths and excavation bottom elevations should also be expected to fluetuate from those <br /> shown in the above tabulation. The soils in the bottoms of the excavations should be observed and ' <br /> evaluated by AET geotechnical personnel. <br /> , <br /> In areas where fill is reqaired below foundations, the excavations should be oversized laterally at <br /> the bottoms so the new fill system can provide support for the lateral loads exerted by the footings. , <br /> Based on the cond.itions encountered, we recommend the excavation bottoms include 1:1 <br /> oversizing. That is, for each vertical foot of fill required below the foundation, the excavation , <br /> bottom should be oversized laterally beyond each edge of the footing a similar distance. <br /> ' , <br /> If the excavation bottoms have steep slopes, we recommend terracing or benching them to provide <br /> - ' n zone between the naturally deposited soils and the new fill soils to be placed. ' <br /> a good transit�o � <br /> The benching or terracing will provide better stability of the slope of this transition zone, and � <br /> reduce the likelihood of a shear failure or slope failure along this transition zone. Benching is <br /> recommended if the slopes are steeper than 4:1 (Horizontal:Vertical). ' <br /> Fill Placement and Compaction ' <br /> Fill piaced to attain foundation grades should be uniformly compacted in thin lifts to a minimum <br /> of 95% of the Standard Proctor maximum dry density (ASTM:D698). If there are areas where ' <br /> the fill depths wi11 exceed 10' below design bottom-of-footing elevation, the compaction level <br /> should be increased to 98% to maintain tolerable settlement amounts. ' <br /> We recommend using inorganic sands and sil'ry sands. Clayey sands or clays can be used as fill, ' <br /> however, they are more difficult to work with and their ability to compact is greatly affected by <br /> their water content. If these soils are used, they may have to be aerated and dried to a water <br /> i� <br /> content near optimum before placing and compacting them. <br /> ��. <br />