4107 OLIVE ST 2018-01-02 MF Import

DAVID L. NELSON AND ASSOCIATES, INC. Consulting Engineering Geology July 13, 1990 Project No. 9490 Page g of about 3.5 to 7 feet from the existing ground surface using the data from test pits 2, 3, 6 A 7. TI,e fill area shown on the Location Map has potential fill depths of 10 feet or more. This should be considered in structure design: Potentially, a daylight basement could require the removal of most of this material having a minimal amount for overexcavation in the slab areas. The excavation depths necessary for the rest of the site should be much less. The deeper excavations on the slopes can be destabilized by the presence of ground water. Although we did not observe significant ground water in this area, this should be understood and if water is encountered measures should be taken to control it. Excavation Considerations Temporary cuts may be necessary if basement type designs are used. Stepped - type excavations may be necessary to reach bearing soils if the structure is founded partially on the sloping portion of the site area. The stability of open excavation cuts within the sloping portions of the site during construction will depend on the nature and consistency of the naturally occurring soils, as well as the presence of ground water seepage and runoff. The following temporary cut slopes assume no emerging ground water and are expected to be appropriate for their respective soil types: -2H to 1V for loose surficial soils and fill. -1.5H to 1V for loose -medium dense/stiff silty sand/silt and the upper weathered zone materials. -1H tc 1V for medium dense-dense/hard silty sand/silt deposits. -0.75 to 1V for stiff Whidbey Formation materials, or glacial till, with cut heights up to 8 feet. Ample slope protection and maintenance should be u3ed during construction. This would include covering the slopes with plastic sheeting during times of wet weather. Because of the many variables involved, the above values should be considered general guidelines. Unsupported permanent cut slopes in medium dense native or compacted structural fill soils shculd be no steeper than 2H to 1V. Once specific plans are developed, more definitive information can be provided.