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W-6984 <br /> SUBSURFACE E"PLORATION AND <br /> GEOTECHNICAL ENGINEERING REPORT <br /> 75th Street and Hardeson Road: Parcel Number 1 <br /> Everett, Washington <br /> 1.0 SUMMARY conitins <br /> The proposed project construction is feasible with respect to the subsurfaceeote chnocal <br /> encountered at the subject site. A brief summary of the project <br /> g <br /> considerations is presented below: <br /> o Our test pit explorations disclosed the site to be underlain by a native medium <br /> dense silty sand at a depth of 1 to 2 feet below existing grades. Dense <br /> glacially consolidated silty sand with some gravel (Glacial Till) was observed <br /> below the medium dense sand in all of the test pits. Surficial deposits of top <br /> soil, and loose silty sand with some roots were found above the medium <br /> dense sands. <br /> 0 Shallow spread footing support for the proposed office buildings is feasible. <br /> We anticipate .that an allowable soil bearing pressure of 2500 pounds per <br /> square foot (psf) can be used for footings bearing in the medium dense <br /> natural soils or properly compacted structural rill placed above suitable native <br /> soils. Footings extended to bear on the deeper dense glacial till, may be <br /> designed for a higher allowable bearing pressure of 4000 psf. These bearing <br /> pressures should be re-evaluated during final design of the structures on the <br /> site. <br /> The site soils are silty and highly susceptible to disturbance in the presence of <br /> water. Construction should be scheduled during warm, summer months, if at <br /> all possible. Wet weather construction will make reuse of the on-site silty soils <br /> for fill difficult or impossible, and therefore will require strict attention to <br /> construction procedures to minimize additional earthwork cost and reduce <br /> site disturbance. <br />