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SC 170 MilborTita <br />= DV_ <br />elevation for a pile installed at a given location can be determined by scaling the <br />appropriate embedment depth listed on Table 1. <br />Table I Estimated Allowable Pile Capacities for Deep Foundations <br />rue Type <br />Diameter <br />Embedment In <br />Sand <br />(Feet) <br />Allowable Capacity <br />In Tom <br />Cam <br />Moveable Capacity <br />In Torw <br />erosion <br />Auger -Cut <br />2 feet <br />15 <br />105 <br />85 <br />25 <br />160 <br />150 <br />frilled Shag <br />3 feet <br />15 <br />165 <br />130 <br />25 <br />250 <br />225 <br />4 feet <br />15 <br />230 <br />200 <br />25 <br />340 <br />325 <br />5 feet <br />15 <br />290 <br />240 <br />25 <br />430 <br />400 <br />Driven Concrete <br />(octagonal) <br />16.5 incha <br />5 <br />85 <br />30 <br />Driven Concrete <br />14 inches <br />5 <br />75 <br />25 <br />Driven Steel <br />Pipe <br />16 inches <br />5 <br />75 <br />25 <br />The allowable pile capacities presented in Table 1 hat a been factored from the <br />estimated ultimate capacities. For driven piles, dri,led shafts and auger -cast piles <br />under compressive loading, a factor of safety of 2.0 was used for skin friction. A <br />factor of safety of 1.5 was applied to the sk;n resistance for all pile. under tensile, <br />or pull-out loading. <br />The allowable capacity estimates in Table I are based on the assumption that piles <br />are spaced no closer than three pile diameters center -to -center and that no pile - <br />group -effect reduction is required. If piles are spaced closer than three pile <br />diameters center -to -center, group effects should be considered. <br />5.3.2.2 Design Parameters for Deep Foundations <br />• Settlement: We estimate that piles and drilled piers loaded with the <br />maximum allowable loads shown on Table 1 will settle less than '/4 <br />inch. This estimate assumes that pile tips extend into the competent <br />till or advance outwash deposits that underlie the project sitt. and are <br />not founded in the compressible clay. <br />• Construction Considerations: During drilling, we encountered very <br />few oversize materials, such as cobbles and boulders. Consequently, <br />we do not anticipate oversize materials will significantly affect the <br />installation of driven or drilled piles. There does not appear to be any <br />existing concrete slabs within the footprint of the new structure. <br />Another potential impact to pile installation will be the groundwater <br />level. The perched water table on the upper side of the till will impact <br />drilled shaft installations that extend below that depth, but will not <br />impact drilled shafts above the perched zone, auger -cast piles, or <br />driven piles. The regional groundwater level below the till (38 to 40 <br />Geotechnical, Tunnel and Environmental Engineers <br />3080 125m Avc NE Phone (425) 969-5778 <br />Bellevue, WA98005 Page 11 Fax (425)861-0677 <br />