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( <br />OWR CONSULTANTS, Inc., Geotechnical lnvesfiga(ion <br />Proposed Saleway Gasoline Slalion, June 8, 2000 <br />The allowabl� bearing pressure uses both the bearing capacity and the predicied <br />setilements under load. I(ound no settlements over 1/4 in. for any postulated loading. <br />Therefore, the allowable bearing pressure is controlled by the bearing capacity. Tabie <br />18-1-A, Allowable Foundation and Lateral Pressure, in the 1997 Uniform Building Code <br />allows a maximum bearing pressure of 2,200 psf for this soil while considering 2 ft. of <br />burial for the footings. While this prescriptive standard is extremely conservative, it <br />does help °bracket" a range for consideration. A minimum burial depth of 18 inches <br />with an allowable bearing capacity of 4,500 psf is appropriate for this project. This <br />accounts for some loosening of ihe soil during the excavation process and limits ihe <br />amount of fiil activity. <br />5.3 Excavation of On-Site Soils <br />On Reference Site No. 1, we found that a John Deere 490E excavator easily <br />constructed the test pits. <br />5.4 Storm Water Management <br />We found the soil to be essentially free draining with a percolaiion rate of at least <br />8 ft. per hour. <br />5.5 Use of Native !�Aaterials for Structural Fill <br />The native gravel or gravel mixed with less than 20 % by weight of the silt layer <br />will provide a suitable fill for material for up to 2 ft. below grade. In general, rock sizes <br />of more than 6 inches in diameter will require screening and discard. <br />Page 6 of 11 <br />