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i <br /> DAVID L. NELSON AND ASSOCIATES, INC. <br /> Consulting Engineering Geulogy <br /> � <br /> September 19, 1989 <br /> � Project No. 12489 <br /> Page 5 <br /> � and the exposed ground areas stabilized through placement of erosion control . <br /> Landscaping within the setback area could be performed, but should be limited <br /> � to vegetation planting without fill . The residence excavation materials <br /> should not be placed within the setback area, even temporarily. <br /> � Foundations <br /> I Placement of residence foundations should occur within the compact native <br /> � soils. As discussed above, these foundations sho�:ld be placed within the <br /> unfrar,tured dense silty fine sands using the 20 foot setback, or into the <br /> Ifractured medium dense silty fine sands using the 25 foot setback. A net <br /> allowable soil bearing pressure of 2000 pounds per square foot (psf) should be <br /> 7 used for continuous or spread type footings. The suggested soil bearing <br /> 1 capacities use a factor of safety of 2.5 and is based on the following: <br /> � i. All footings should be fourded into the native site soils <br /> as described above. <br /> 2. All footing excavations should be prepared such that a <br /> ) dense, nonyielding, uniform soil condition has been <br /> J established prior to placement of footing concrete. <br /> � 3. All footings shou�d extend through any existing <br /> artificial fills or modified zones and be placed to <br /> bear a minimum of 18 inches below finished adjacent grade. <br /> � 4. Al2 footings should be sized according to the anticipated <br /> wa)1 or column loadings, and the above soil bearing values. <br /> Minimum footing widths of 14 and 20 inches arE recomnended <br /> � for all continuous and isolated footings, respectively. <br /> 5. All footi�gs should be free of ponded water and sloughed <br /> � or water softened soils prior to placement of footing concrete. <br /> Ground settlements due to structural loads should be less than one (1 ) inch <br /> Itotal and o�e-half (1/2) inch differential over the building area. <br /> IBasement walls and slabs-on-grade for basement areas should be performed as <br /> shown on the enclosed Subdrain & Backfill Scheme, sheet S-1. Slab areas <br /> � without basement walls, and crawl space areas, should be performed as shown on <br /> the enclosed Subdrain & Backfill Schemes, sheets S-Z and S-3, respectively. <br /> I <br />