11229 19TH AVE SE SILVER LAKE TOWNHOMES WHOLE SITE Geotech Report 2022-10-25

Geotechnical Report Proposed Development: 11229 - 19th Avenue SE, Everett, WA September 16, 2016 UNIT 2: Undifferentiated Glacial Drift—From surface in PG-2 and below the fill at other boring locations, the borings encountered medium dense to very dense, slightly silty gravelly sand and sandy gravel extending to the bottom of the borings at about 11.3 to 21 feet below the surface. We interpret this unit as undifferentiated Glacial Drift deposits. Glacial drift typically comprises both glacial till and outwash. Our subsurface descriptions are based on the conditions encountered at the time of our exploration. Soil conditions between our exploration locations may vary from those encountered. The nature and extent of variations between our exploratory locations may not become evident until construction. If variations do appear, PanGEO should be requested to reevaluate the recommendations in this report and to modify or verify them in writing prior to proceeding with earthwork and construction. 4.3 GROUNDWATER Groundwater was encountered at about 61/2 feet,6 feet,and 9 feet depth below grade during drilling in Borings PG-1, PG-3,and PG-4,respectively. Groundwater was not observed within the drilling depth in Boring PG-2 during drilling. It should be noted that groundwater levels will fluctuate depending on the season, precipitation, the water level in Silver Lake, and other factors. In general, groundwater levels are higher during the wet season (October through May). 5.0 GEOTECHNICAL RECOMMENDATIONS 5.1 SEISMIC DESIGN PARAMETERS The Table 1 on page 5 provides seismic design parameters for the subject site that are in conformance with the 2012 edition of the International Building Code (IBC), which specifies a design earthquake having a 2% probability of occurrence in 50 years (return interval of 2,475 years). The spectral response accelerations were obtained from the USGS Earthquake Hazards Program Interpolated Probabilistic Ground Motion website(2008 data)for the project latitude and longitude. 16-210 11229 19th Ave SE Rpt Page 4 PanGEO, Inc.