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Mr. Darren Peugh <br />January 19, 2004 <br />Excavations <br />All excavations at the site associated with confined spaces, such as utility trenches and lower building levels, must <br />be completed in accordance with local, state, or federal requirements. Based on current Occupational Safety and <br />Health Administration (OSHA) regulations, soils at the site classified as Group C soils. Accordingly, for <br />excavations more than 4 feet and less than 20 feet deep, the side slopes should be laid back at a minimum slope <br />inclination of 1.5:1 (Horizontal:Vertical). If there is insufficient room to complete the excavations in this manner <br />or if excavations greater than 20 feet deep are planned, you may need to use temporary shoring to support the <br />excavations. <br />This information is provided solely for the benefit of the owner and other design consultants, and should not be <br />construed to imply that Terra Associates, Inc. assumes responsibility for job site safety. Job site safety is the sole <br />responsibility of the project contractor. <br />Foundations <br />The building may be supported on conventional spread foundations bearing on competent native soils or on <br />structural fill placed above competent native soils. Foundation subgrade and structural fill should be prepared as <br />recommended in the Site Preparation and Grading section of this report. Perimeter foundations exposed to the <br />weather should be a minimum depth of 18 inches below final exterior grades. Interior foundations can be <br />constructed at any convenient depth below the floor slab. <br />Foundations bearing on competent native soil or structural fill can be dimensioned for a net allowable bearing <br />capacity of 3,000 pounds per square foot (ps fl. For short-term loads, such as wind and seismic, a one-third <br />increase in this allowable capacity can be used. With structural loading as anticipated and this bearing stress <br />applied, total and differential foundation settlement are estimated to less than one inch and one-half inch, <br />respectively. Building settlement should occur in an immediate nature as building loads are applied. <br />For designing foundations to resist lateral loads, a base friction coefficient of 035 can be used. Passive earth <br />pressures acting on the side of the footing can also be considered. We recommend calculating this lateral <br />resistance using an equivalent fluid weight of 350 pounds per cubic foot (pc fl. We recommend not including the <br />upper 12 inches of soil in this computation because it can be affected by weather or disturbed by future grading <br />activity. This value assumes the foundation will be constructed neat against competent native soil or backfilled <br />with stzuctural fill as described in the Site Preparation and Grading section of this report. The friction and passive <br />values recommended include a safety factar of 1.5. <br />Slab-on-Grade Construction <br />Slabs-on-grade may be supported on subgrade prepared as recommended in the Site Preparation and Grading <br />section of this report. Immediately below the floor slab, we recommend placing a four-inch thick capillary break <br />layer of clean, free-draining coarse sand or fine gravel that has less than five percent passing the No. 200 sieve. <br />This matenal will reduce the potential for upward capillary movement of water through the underlying soil and <br />subsequent wetting of the floor slab. <br />Project No. T-5471 <br />Page No. 6 <br />