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). H. KLEINFELDER & ASSOCIATES File No. S-2568-4 October 11, 1983 Page 5 obtained during the site preparation and street utility excavating. We recommend that native soils placed as Engineered Fill be spread in thin horizontal layers a maximum of 8 inches in loose thickness and compacted to between 85 and 95 percent of the above referenced dry density at a moisture content of 5 percent in excess of optimum. If construction is to be delayed, moisture conditioning need not be performed during initial site preparation. However, it is important that the recommended ' moisture content be achieved and maintained just prior to actual construction. Without proper conditioning, there is a greater risk that the predominately dark-brown clay subgrade soils may swell and cause heaving of foundations and floor slabs. With this in mind, we stress the importance that the native soils beneath the floor slabs be AM moisture-conditioned as described. In areas to receive asphaltic concrete, we recommend that the native soils be scarified to a minimum depth of 12 inches and recompacted at near-optimum moisture content to a minimum of 95 percent of the maximum dry density as determined by the above referenced test. In our opinion, structural or trench backfill can be mechanically compacted in the same manner as Engineered Fill, or jetted. If jetting is performed, sufficient time should be set aside to allow consolidation to occur. In addition, density tests should be taken to verify compaction. Pavement Section According to our laboratory tests, the surface silty and clayey fill soils encountered at this site have an R-Value of 7. This value is comparable to other tests for adjacent projects. We have used this value as the minimum design R-Value. Based on this design R-Value and on assumed Traffic Indices, we recommend the following pavement sections. 1