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File No. 20-3821-Ol.G01 k'q K L E I N F E L D E R January 6, 1995 �I support to the foundations. With these provisions, the maximum bearing value can be increased to 4,000 psf for dead plus live loads. The bearing values may 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 with the foundations bearing in the native soils is approximately 1/2 inch. With foundations founded on Engineered Fill, settlement is expected to be negligible. Differential settlement can be assumed to be approximately 1/2 this value. Most of the settlement is expected to occur during the construction period shortly after loads are applied, provided the foundations are not exposed to sustained standing water or flooding. We recommend that the actual foundation and reinforcement design be provided by the structural engineer. We note that the above stated bearing pressures are net values, and the weight of concrete in the portion of the foundations which extend below grade can be neglected in proportioning the foundations. It is further recommended that all foundations on this project be observed by a representative r of our firm, preferably prior to placing reinforcing steel. The purpose of this recommendation u is to confirm that the bearing soils encountered in the foundation excavations are the same as those in which our recommendations are based and to observe for any loose pockets of soil or debris. 2. Lateral Pressures Resistance to lateral forces can be provided either by friction between the base of the 4 foundations and the soil or by passive pressure of the sides of the foundations against the soil. The recommended friction factor is .35. The recommended passive soil pressure is an 4 equivalent fluid pressure of 350 psf per foot of depth. 4 3. Floor Slabs We recommend that floor slabs be underlain by a minimum of 6 inches of recompacted existing soil or 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, a capillary moisture break, such as provided by a layer of gravel or coarse sand beneath floor slabs, can be omitted because of the sandy nature of the near-surface soils. However, if clay or silty soils are encountered during the grading operations, the capillary moisture break should be added to the floor slab area. In areas to receive moisture sensitive floor coverings, such as offices, we recommend that the subgrade C soils be covered by a moisture-proof membrane, such as "Moiststop," or equivalent, to act as vapor barrier. Care should be exercised to avoid tearing, ripping, or displacing the membrane during construction. If the membrane becomes torn or disturbed, it should be removed and C patched, or completely replaced. The membrane should be covered with approximately 1 inch of moist sand to protect it during construction and aid in curing the concrete. L Copyright 1995 Klcinfelder, Inc. page 4 of 9