8615 7TH AVE SE Geotech Report 2018-01-02 MF Import

Subsurface Exploration, Geologic Hazard, and St. Mary Magdalen Sport Court Preliminary Georechnieal F.q;tneering Report Everett, Washington _ Geologic Hazards of d Mitigations above -discussed impacts. Structural design of the structure should follow 2003 International Building Code (IBC) standards using Site Class "C" as defined in Table 1615.1.1. The 2003 IBC seismic design parameters for short period (Ss) and I -second period (St) spectral acceleration values were determined by the latitude and longitude of the project site using the United States Geological Survey (USGS) National Seismic Hazard Mapping Project website (http://earthquake.usgs.;,ov/liazmaps/). Based on the more current 2002 data, the USGS website interpolated ground motions at the project site to be 1.21g and 0.43g for building periods of 0.2 and 1.0 seconds, respectively, with a 2 percent chance of exceedence in 50 years. 6.0 EROSION HAZARDS AND MITIGATION IThe sediments underlying the site generally contain silt and fine sand and will be sensitive to erosion, especialiv in the sloping portions of the site. In order to reduce the amount of I sediment transport off the site during construction, the following recommendations should be followed. 1. Silt fencing should be placed around the lower perimeter of all cleared area(s). Silt fencing should be keyed into the existing subgrade a minimum of 6 inches. The fencing should be periodically inspected and maintained, as necessary, to ensure proper function. 2. To the extent possible, earthwork -related construction should proceed during the drier periods of the year, and disturbed areas should be revegetated as soon as possible. Temporary erosion control measures should be maintained until permanent erosion control measures are established. 3. Areas stripped of vegetation during construction should be mulched and hydroseeded, replanted as soon as possible, or otherwise protected. During winter construction, hydroseeded areas should be covered with clear plastic to facilitate grass growth. 4. If excavated soils are to be stockpiled on the site for reuse, measures should be taken to reduce the potential for erosion from the stockpile. These could include, but are not limited to, covering the pile with plastic sheeting, the use of low stockpiles in flat areas, and the use of straw bales/silt fences around pile perimeters. 5. Interceptor swales with rock check dams should be constructed to diver, storm water from construction areas, and to route collected storm water to an appropriate discharge location. April 24, 2006 ASSOCIATED EARTH .SCIENCES, INC. ruPi n - KEM6aet - PwIras12W602601WWP Page 6