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File No. 20-3514-01 kn KLEINFELDER September 11, 1991 uniform foundation support and to use a higher bearing value, we recommend that the soils exposed in the bottom of foundations be compacted to a minimum of 90 percent of the maximum dry density as determined by the ASTM D-1557 test method. If the bottom of foundations are entirely within Engineered Fill placed to raise the building pad, this compaction will not be necessary. If any extremely loose soil pockets are encountered, they should be overexcavated and recompacted as described in the "Site Preparation and Grading" section of this report. With these provisions, we recommend a maximum allowable bearing pressure of 2 , 000 pounds per square foot for dead plus live loads be used in design. This value can be increased by 1/3 for the total of all loads, including wind and seismic forces . The recommended minimum width of foundations is 12 inches. The _ anticipated total settlement is less than 1/4-inch. The majority of this settlement should occur during construction as building loads are placed. We recommend that the reinforcing design of the foundations be provided by the structural engineer. We note that the above- stated bearing value is a net value, and the weight of concrete in the portion of the foundations which extends below grade can be neglected in proportioning the foundations. We recommend that all foundation excavations on this project be a observed by a representative of our firm prior to placement of reinforcing steel . The purpose of the observations is to confirm that the bearing soils actually encountered in the foundation excavations are the same as those on which our recommendations are based, and to observe for any extremely loose pockets of soil . C. Lateral Pressures Resistance to lateral forces can be provided either by friction between the base of the foundations and the soil or by passive pressure of the sides of the foundations against the soil . The recommended friction factor is 0. 4 . The recommended passive soil pressure is an equivalent fluid pressure of 350 pounds per square foot per foot of depth. D. Slab-on-Grade Floors We recommend that floor slabs, if used, be underlain by a minimum of 6 inches of recompacted existing soil or by Engineered Fill . The recommended minimum degree of compaction is 90 percent of the maximum dry density as determined by the ASTM D-1557 test procedure, at a moisture content near optimum. In our opinion, due to the near-surface groundwater conditions a capillary moisture break such as provided by a layer of gravel or coarse Copyright 1991 KLeinfelder, Inc. Page 5 of 13