1001 39TH ST 2016-01-01 MF Import

� . � DAVID L. NEI.SON AND ASSOCIATES, INC. Consulting Engineering Geology November 27, 1991 Project No. 10591 Pag� 5 opinion of the slopes with respect to stability. the envirenmantal sensitive elements discussed pre.viously were evaluated with respect to the steep slopes . Our opinion is `:hat the area is relatively stable, and would be i:nproved through implementation of th� recommendations for development as presei:te ' n our geotechnical evaluation report . CONCLUDI. �PINIONS General � In general, we conclude that the site should be compatible with the proposed residential development. The existing fill placed on the steep slopes is considered marginally stable. Additional fill should not be placed on the slope. Foundations for the � structure should extend khrough the fill an3 loose weathered soils to the medium dense or dense sand, and/or the hard 4�hidbey Fmn silts, that un3erlie the site. Foundations on the s:opes � should have a mir.imum penetration into bearing soils and be founded below established set back line as outlined in the FOUNDATZON section of this report. Foundation excavations on the slopes car, be destabilized by the presence of ground water. Although we did not observe ground water in this area, it could exist during and after the wetter portions os the year. If water is encountered measures should be taken to control it. Excavation Considerations i: Temporary cuts may be necessary if a basement type design is j:: used. Fairly deep excavations will be necessary to reach bearing � � soils if the structure is founded on the steep slope as shown on the site plan. The stability of open excavation cuts rrithin 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 silty sand and weathered zone. -1H to 1V for dewatered medium dense outwash deposits, with cut heights up to 8 feet. -0 . 75 to 1V for stiff Whidbey Formation materials, with cut heights up to 10 feet . Ample slope protection and maintenance should bP used during construction. This would include covering the slopes with plastic sheeting during times of wet weather. Because of the /(o