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Geotechnical Engineering Report 3 May 25,2017 <br /> Central Everett CHC,Everett,Washington RGI Project No.2017-094 <br /> 4.4 GROUNDWATER <br /> Groundwater seepage was encountered in boring B-2 at depths ranging from 10 feet to <br /> 22 feet below grade during drilling. It should be recognized that fluctuations of the <br /> groundwater table will occur due to seasonal variations in the amount of rainfall, runoff, <br /> and other factors not evident at the time the explorations were performed. In addition, <br /> perched water can develop within seams and layers contained in fill soils or higher <br /> permeability soils overlying less permeable soils following periods of heavy or prolonged <br /> precipitation. <br /> 4.5 SEISMIC CONSIDERATIONS <br /> Based on the 2012/2015 International Building Code (IBC), RGI recommends the following <br /> seismic parameters provided in Table 1 be used for design. <br /> Table 1 IBC Seismic Parameters <br /> 2012/2015 IBC Parameter Value <br /> Site Soil Class'. D2 <br /> Site Latitude 47.96171 N <br /> Site Longitude 122.21027 W <br /> Maximum considered earthquake spectral response <br /> acceleration parameters(g) S.=1.353, S1=0.514 <br /> Spectral response acceleration parameters adjusted for site <br /> Class (g) Sms=1.353,Smi=0.770 <br /> Design spectral response acceleration parameters(g) Sds=0.902,Sd1=0.514 <br /> 1 Note: In general accordance with the USGS 2012/2015 International Building Code. IBC Site Class is based on the average <br /> characteristics of the upper 100 feet of the subsurface profile. <br /> 2 Note:The 2012/2015 International Building Code requires a site soil profile determination extending to a depth of 100 feet for <br /> seismic site classification.The current scope of our services does not include the required 100 foot soil profile determination.Borings <br /> extended to a maximum depth of 31.5 feet, and this seismic site class definition considers that similar soil continues below the <br /> maximum depth of the subsurface exploration. <br /> Liquefaction is a phenomenon where there is a reduction or complete loss of soil strength <br /> due to an increase in water pressure induced by vibrations from a seismic event. <br /> Liquefaction mainly affects geologically recent deposits of fine-grained sands that are <br /> below the groundwater table. Soils of this nature derive their strength from intergranular <br /> friction. The generated water pressure or pore pressure essentially separates the soil <br /> grains and eliminates this intergranular friction, thus reducing or eliminating the soil's <br /> strength. <br /> II I <br /> I <br /> RILEYGROUP <br />