2400 33RD ST GEOTECHNICAL INVESTIGATION 2018-01-02 MF Import

SC 130 Milbor-Pita &oaa,111.W_ 5.3.2.3 Lateral Resistance for Piles Resistance to lateral loading can be achieved using the pile -soil stiffness analyses method of LPILE, and/or by lateral passive resistance on below -grade pile caps. Lateral passive resistance distributed triangularly on the pile caps can be assumed to be equal to an equivalent fluid weight of 300 pounds per cubic foot (pef). 5.3.3 Spread Footin s Issues The following are spread footing recommendations; • A bearing capacity of 5,000 pounds per square foot (psf) is allowable for properly compacted structural fill that is in direct contact with the underlying dense till or glacial outwash deposits. These materials are approximately 20 feet below the surface across the site, so a major excavation is required. If this type of construction is performed properly, the total settlement of the structure should be less then 0.5 inches, with differential settlement being less then half of that. The settlement will be near instantaneous (elastic). • Shallow and lighter loaded footings may be placed on the upper silt/clay. They should not be loaded over 1500 psf and they should have a minimum of 2 feet of compacted structural fill beneath them. Footings designed to these values should have similar settlement results to that described above. • The large surface water holding basin is a separate issue. These footings will be placed on the silt/clay but at a depth of nearly 15 feet. A recommended footing load of 3000 psf is allowed because of the depth and the pre - consolidation of the material. This loading is within the elastic range of the silt/clay. The structure should have 1-foot minimum layer of structural fill or crushed rock placed beneath it. Settlement in this area will be elastic and instantaneous. The total amount should be less then 3/4-inch and should occur during construction. 5_3.4 Slab on Grade All slab -on -grade construction should have 1-foot minimum layer of structural fill or crushed rock placed beneath it. A vapor barrier for all slabs that are to be kept dry should have a 6-inch minimum of coarse clean sand (ASTM C-33) or WSDOT Gravel Backfill for Drains (WSDOT 9-03.12(4)), overlain by a 10-mil thick layer of plastic. This reduces the potential of moisture rising up through the concrete. 5.4 Temporary Excavations and Shoring Based on the soil conditions observed in our explorations, we anticipate that the on -site soils can be excavated using conventional excavating equipment. Temporary excavations will be required for contaminated soil removal, pile caps or other purposes. Temporary excavations should be performed in accordance with the current requirements of federal, state, and/or local agencies. Exposure of personnel beneath temporary cut slopes should be kept to a minimum. Construction should proceed as rapidly as feasible, to limit the time temporary excavations are open. During wet weather, runoff water should be prevented from entering excavations, and should be collected and disposed of outside of the construction limits. Heavy construction Gcotechnicaal, Tunnel and Environmental rilgineers 3080 1251° Ave NE Phone (425) 869.5779 Belkwc, WA 98005 Page 15 FU (425)861.0677