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11 <br /> can be flattened,regraded to add intermediate slope benches,or additional dewatering can be provided if <br /> the poor slope performance is related to groundwater seepage. <br /> 11 <br /> Soldier Pile and Timber Lagging in Walls <br /> 11 A soldier pile and timber lagging wall system combines wide flange steel sections embedded in concrete <br /> filled below-grade shafts, and timber lagging spanning between adjacent soldier piles in the <br /> belowground portion of the wall. The concrete and steel section solider piles are typically positioned at <br /> Icenter-to-center spacings of 8 feet or less. <br /> 1 The wall system is typically designed to resist lateral soil loads by cantilever action through the lateral <br /> restraint provided by the embedded portions of soldier piles. Additional lateral restraint can be provided <br /> by tie-backs or dead-man anchors. <br /> The advantage of this wall system is that no mass excavation is necessary to install the wall. This is a <br /> key consideration in areas where a temporary excavation could undermine the support of existing <br /> adjacent improvements or trees. The solider piles are first drilled into the existing ground, and the <br /> remainder of the wall is subsequently constructed below ground with the solider piles providing active <br /> 11 restraint during construction. <br /> If shoring is needed to accomplish the building excavation, GeoEngineers can develop appropriate <br /> lateral earth pressure diagrams. Traffic or equipment surcharge pressures should be included in <br /> developing the earth pressure. <br /> SHALLOW FOUNDATIONS <br /> 11 <br /> We recommend that the proposed apartment building be supported on shallow spread footings founded <br /> 11 on the undisturbed dense to very dense glacial soils encountered in our explorations or on properly <br /> compacted structural fill extending down to the dense to very dense glacial soils. If structural fill is used <br /> to support foundations then the zone of structural fill should extend beyond the faces of the footing a <br /> distance at least equal to the thickness of the structural fill. <br /> 11 <br /> Foundation Design <br /> 9 <br /> 11 For shallow foundation support, we recommend widths of at least 18 and 36 inches, respectively, for <br /> continuous wall and isolated column footings supporting the proposed building. Provided that footings <br /> are supported as recommended above,an allowable bearing value of 8,000 psf may be used for footings <br /> 11 supported on the dense to very dense glacial soils. In order to use 8,000 psf on the east side of the <br /> building,the footings will have to extend at least 3.5 to 4 feet below the ground surface to bear on dense <br /> native glacial soils. Otherwise, the old fill should be removed from below the footings and be replaced <br /> "'°° with structural fill. Footings supported on structural fill compacted to at least 95 percent MDD may also <br /> be proportioned for an allowable bearing capacity of 3,000 psf. These allowable bearing pressures <br /> apply to the total dead and long-term live loads and may be increased up to one-third for short-term live <br /> '°` loads such as wind or seismic forces. <br /> II Exterior footings for the gshould be founded at least 18 inches below lowest adjacent finished <br /> g building J <br /> grade. Interior footings should be founded at least 12 inches below bottom of slab or adjacent finished <br /> Igrade. <br /> 7 <br /> III <br /> File No.12547-001-00 Page 10 GEOENGINEERS_a <br /> February 3,2006 <br />