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Subsurface Exploration,Geologic Hazards,and <br /> Former Brien Ford Preliminary Geotechnical Engineering Report <br /> Everett, Washington Project and Site Conditions <br /> glacial ice. The advance outwash sediments encountered in our exploration boring EB-1 <br /> consisted of dense to very dense, fine- to medium-grained sand with trace amounts of silt and <br /> variable amounts of gravel. In the push-probe explorations the encountered advance outwash <br /> generally consisted of silty sands to sands with trace silt and variable amounts of gravels. The <br /> advance outwash contained faint, thin, silt interbeds recognized as lamination. The advance <br /> outwash was observed to a depth of approximately 53i/ feet below existing site grade in <br /> exploration EB-1. <br /> Pre-Fraser Fine-Grained Sediments <br /> Pre-Fraser fine-grained sediments were encountered in exploration EB-1 directly below the <br /> Vashon advance outwash, and extended past total depths explored. These fine-grained <br /> sediments consisted of stiff to very stiff, slightly moist bluish gray to greenish gray, massive, silt. <br /> Trace amounts of coarse sand and fine gravels were observed within the silt, and were <br /> identified as dropstones. These pre-Fraser fine-grained sediments were identified to be that of <br /> a glacial lacustrine deposit. <br /> Review of Selected Available Geologic Data <br /> Review of the regional geologic map of the area titled Geologic Map of the Everett 7.5-Minute <br /> Quadrangle, Snohomish County, Washington, by James P. Minard, 1985 indicates that the area <br /> of the project site is underlain by Vashon lodgement till. Exposures of Vashon advance <br /> outwash, which stratigraphically underlies the lodgement till, are depicted a short distance to <br /> the west. Our on-site exploration and interpretations are not consistent with the conditions <br /> depicted on the referenced published map. We recommend that project planning follow <br /> conclusions in this report and not the published map. <br /> 4.2 Hydrology <br /> A regional ground water aquifer was not encountered in our deep boring location EB-1. An <br /> increase in moisture content was observed in the outwash sediments at a depth of 55 feet, <br /> however no free ground water was observed. Perched ground water was observed within the <br /> encountered existing fill in several of our previously completed push-probe explorations. <br /> Perched ground water occurs when vertical infiltration of surface water is impeded by <br /> less-permeable soil layers, resulting in horizontal flow. The quantity and duration of perched <br /> ground water flow from an excavation will vary, depending on season, soil gradation, and <br /> adjacent topography. The observed ground water was perched on top of the siltier ice-contact <br /> deposits. Fluctuations in the level of ground water and amount of seepage may occur due to <br /> variations in rainfall,time of the year, and changes in site development. <br /> May 16,2017 ASSOCIATED EARTH SCIENCES,INC. <br /> AWR/Id-160594V003-2-Projects120160594\KV\WP Page 5 <br />