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Subsurface Exploration, Geologic Hazard, and <br /> Krebs Property Preliminary Geotechnical Engineering Report <br /> Everett, Washington Geologic Hazards and Mitigations <br /> 5.4 Ground Motion <br /> Based on the site stratigraphy and visual reconnaissance of the site, it is our opinion that any <br /> earthquake damage to the proposed structures, when founded on suitable bearing strata, would <br /> be caused by the intensity and acceleration associated with the event and not any of the above- <br /> discussed impacts. Structural design of buildings should follow 2003 International Building <br /> Code (IBC) standards using Site Class "C", as defined in Table 1615.1.1. The 2003 IBC <br /> seismic design parameters for short period (Ss) and 1-second period (Si) spectral acceleration <br /> values were determined by the latitude and longitude of the project site using the United States <br /> Geological Survey (USGS) National Seismic Hazard Mapping Project website'. Based on the <br /> more current 2002 data, the USGS website interpolated ground motions at the project site to be <br /> 1.20g and 0.42g for building periods of 0.2 and 1.0 seconds, respectively, with a 2 percent <br /> chance of exceedence in 50 years. <br /> 6.0 EROSION HAZARDS AND MITIGATION <br /> The Vashon lodgement till sediments underlying the site containa high percentage of silt and <br /> fine sand and are highly sensitive to erosion. In order to control erosion and reduce the <br /> amount of sediment transport off the site during construction, the following recommendations <br /> should be followed. <br /> 1. Properly embedded silt fencing should be placed around the lower perimeter of the <br /> cleared area(s). The fencing should be periodically inspected and maintained, as <br /> necessary, to ensure proper function. <br /> 2. Construction entrances should be stabilized with gravel pads to minimize tracking <br /> sediment off-site. <br /> 3. If possible, construction should proceed during the drier periods of the year. <br /> 4. Areas stripped of vegetation during construction should be mulched and hydroseeded, <br /> replanted as soon as possible, or otherwise protected. During winter construction, <br /> hydroseeded areas should be covered with clear plastic to facilitate grass growth. <br /> 1 http://earthquake.usgs.gov/hazmaps/ <br /> February 13, 2007 ASSOCIATED EARTH SCIENCES,INC. <br /> TJP/Id-KE070023A1-Projects120070023IKEIWP Page 6 <br />