4107 OLIVE ST 2018-01-02 MF Import

J A tJ - 2 2- 9 3 FRI 1 4 -,1 9 R.04 DAVID L. NELSON AND ASSOCIATES, INC. Consulting Enginctring Geology October 10, 1990 Project No. 9490 Page 2 findings of the subsurface conditions, including soils and hydrologic csnditiom, and our conclusions and rooasealdations for development and construction within the site area. In general, we concluded that the evaluated site area should be carpatable with the proposed residential devalckimb. He then presented our recasmardations for development and construction of the proposed residences within the lot areas. 7be information presented in this letter should be considered as additional and supplement,l information to our original geotechnical evaluation report on the site area. SENSITIVE 11NFA EVAUWION The subject site area was evaluated for sensitive area evaluation, as recaknauded in the now ordinance. Of the potential reasons for classification as ouvircemastally sensitive (ennvironmmntally sensitive characteristics), the following could occur on site; unstable soils hazard areas, landslide hazard areas, seismic hazard areas, springs, ground water seepage, and steep slopes associated or in conjunction with are or more of the environmentally sensitive area elemanta. He will discuss these potential oleeants below. Seismic Hazard The Puget Sound region in classified as a zone 3 by the uniform Building Cade. Seismic considerations for this type of site include liquefaction potential and attenuation of ground motions by soft soil deposits. Typically, seismic hazards are highest for thick alluvial (organic and/or normally Consolidated) soils. The liquefaction potential is highest for loose sand and silty sand deposits with a high ground water table. The thickness of the sand deposit should be considered, as liquefaction is dependent on the ability of excess pore pressured to dissipate. That is, if the deposit is relatively thin with a short drainage path, the pore pressures can dissipate fairly rapidly. He did not encounter any alluvial type soils on site which are typically liquefaction sensitive. we did not find a significant thickness of fill or