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Page Five <br />After the excavation is deemed acceptable, the excavated area <br />should be filled to grade with controlled, compacted fill. The fill <br />'hould consist of a suitable inorganic soil, free of debris and <br />rubble. The borings indicate that the excavated soils would not be <br />suitable for reuse as engineered fill. The fill should be placed <br />and compacted in thin lifts to a minimum of 95% of the maximum <br />density as determined by the Standard Proctor method (ASTM:D698). <br />If surface water infiltration or precipitation result in localized <br />pondine of water during earthwork. then standing water in the <br />excavation should he directed to sumps outside the building area <br />where portable pumps can then he used to convey the collected water <br />away from the building pad. <br />Foundation Recommendations - <br />Hy following the above recommended earthwork procedures. it is our <br />opinion that the proposed structure can be supported on <br />conventional spread footings supported by the new fill or natural <br />soils. where the foundations will be constructed adjacent to <br />free /ing temperatures. they should be placed at minimum frost depth <br />(42 "). In unheated building areas, such as garages. we recommend <br />the foundations be placed with a minimum soil cover of 60 ". <br />Rased .on the recommended grading program and our interpretation of <br />the standard penetration resistance data. it, is our opinion the <br />foundations could be designed for allowable soil bearing <br />pressures of up to 2000 psf. In our judgment. this would allow for <br />a minimum factor of safety of at least three with respect to <br />';hearing or base failure of spread footing foundations. Also. it <br />is our judgment that total settlement would be limited to less than <br />I" and differential settlement from opposite diagonal corners of <br />the structure would be limited to less than 3/4 ". <br />Floor Slab Support - <br />In our opinion, the above recommended earthwork program should <br />provide satisfactory support for the floor slab. However, we do <br />suggest that a 6" laver of free- draining sand he placed directly <br />below the floor slab. This material should have less than 10% <br />passing the #200 sieve by weight. This soil type should serve as <br />a capillary moisture break between the slab and the subgrade soils <br />below. Any backfill placed below the floor and against the below - <br />srnde foundation wall should be placed in thin lifts and compacted <br />to q5—.. of the Standard Proctor density. <br />Page 52 <br />