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COBALT <br /> GEOTECHNICAL INVESTIGATION GEOSCIENCES <br /> EVERETT, WASHINGTON <br /> November 16,2018 <br /> 5.1.2 Groundwater <br /> Groundwater was not encountered in any of the hand borings. We anticipate that light volumes of <br /> perched groundwater could develop during winter and spring months below about 6 feet below existing <br /> site elevations. <br /> Water table elevations often fluctuate over time. The groundwater level will depend on a variety of factors <br /> that may include seasonal precipitation, irrigation, land use, climatic conditions and soil permeability. <br /> Water levels at the time of the field investigation may be different from those encountered during the <br /> construction phase of the project. <br /> 6.o Geologic Hazards <br /> 6.1 Erosion Hazard <br /> The Natural Resources Conservation Services(NRCS)maps for Snohomish County indicate that the site is <br /> underlain by Alderwood-Urban land complex (8 to 15 percent slopes). These soils have a slight to <br /> moderate erosion potential in a disturbed state. <br /> It is our opinion that soil erosion potential at this project site can be reduced through landscaping and <br /> surface water runoff control. Typically erosion of exposed soils will be most noticeable during periods of <br /> rainfall and may be controlled by the use of normal temporary erosion control measures, such as silt <br /> fences,hay bales,mulching,control ditches and diversion trenches. The typical wet weather season,with <br /> regard to site grading,is from October 31sr to April 1st. Erosion control measures should be in place before <br /> the onset of wet weather. <br /> 6.2 Seismic Hazard <br /> The overall subsurface profile corresponds to a Site Class D as defined by Table 1613.5.2 of the 2015 <br /> International Building Code(2015 IBC). A Site Class D applies to an overall profile consisting of dense to <br /> very dense soils within the upper too feet. <br /> We referenced the U.S.Geological Survey(USGS)Earthquake Hazards Program Website to obtain values <br /> for Ss,S,,F,,,and F,,. The USGS website includes the most updated published data on seismic conditions. <br /> The site specific seismic design parameters and adjusted maximum spectral response acceleration <br /> parameters are as follows: <br /> PGA (Peak Ground Acceleration,in percent of g) <br /> Ss 142.20%of g <br /> S, 54.00%of g <br /> FA 1.00 <br /> Fv 1.50 <br /> 3 <br /> PO Box 82243 <br /> Kenmore,WA 98028 <br /> cobaltgeoogmail.com <br /> 2o6-331-1097 <br />