Preliminary Geotechnical Engineering Report <br />Project No. 18-4986, 177 Day Island Road, Eugene, Oregon <br />NO " <br />Results of laboratory testing conducted on representative samples obtained within soil borings B-1 <br />and B-2 are presented in Table 1. This including sieve analysis, Atterberg limits and soil <br />classification by the USCS and AASHTO standards. <br />Table 1_ Summarv of Laboratorv Testina Results <br />Percent <br />Percent <br />Soil <br />Depth <br />Material <br />USCS <br />AASHTO <br />Passing <br />Liquid <br />Plasticity <br />Moisture <br />Boring <br />(ft.) <br />Description <br />Classification <br />Classification <br />#200 <br />Limit <br />Index <br />Content <br />Sieve <br />Poorly <br />Graded <br />B-1 <br />10 <br />GRAVEL <br />GP-GM <br />A-1-a <br />8.1 <br />NV <br />NP <br />12.2 <br />with Silt and <br />Sand <br />B-1 <br />20 <br />- <br />- <br />- <br />- <br />- <br />- <br />47.7 <br />B-1 <br />25 <br />Elastic SILT <br />MH <br />A-7-5(58) <br />94.6 <br />90.3 <br />49.7 <br />72.3 <br />B-1 <br />30 <br />- <br />- <br />- <br />- <br />- <br />- <br />50.5 <br />Silty SAND <br />B-1 <br />35 <br />SM <br />A-2-2(0) <br />19.6 <br />46.4 <br />17.2 <br />30.8 <br />with Gravel <br />Sandy <br />B-1 <br />40 <br />MH <br />A-7-5(10) <br />52.9 <br />55.4 <br />22.5 <br />41.8 <br />Elastic SILT <br />Groundwater and Soil Moisture <br />Due to the method of exploration, mud rotary drilling, utilized in our soil boring explorations, we <br />were not able to observe static groundwater conditions. However, perched groundwater is <br />assumed to be present at approximately 5 feet below the ground surface based on the saturation <br />of samples retrieved from these depths. The subject site is adjacent to a slough of the Willamette <br />River and static ground water is expected to be closely related to water elevations in the slough. It <br />is anticipated that groundwater conditions will vary depending on the season, local subsurface <br />conditions, changes in site utilization, and other factors. Perched groundwater may be <br />encountered in localized areas. Seeps and springs may exist in areas not explored and may <br />become evident during site grading. <br />PRELIMINARY CONCLUSIONS AND RECOMMENDATIONS <br />Our investigation indicates that the proposed development is geotechnically feasible, provided that <br />the recommendations of this report are incorporated into the design and sufficient geotechnical <br />monitoring is incorporated into the construction phases of the project. In our opinion, the most <br />significant geotechnical issue for development is the presence of loose sand to a depth of 5 feet <br />encountered in borings B-1 and B-2. Since this layer of sand is loose, it may not provide adequate <br />bearing for structural support within settlement tolerances. <br />We recommend that the layer of loose sand be removed from the influence zones of proposed <br />structures or other settlement-sensitive improvements and be replaced with engineered fill. Based <br />on subsurface conditions encountered in borings B-1 and B-2, we anticipate that excavation depths <br />18-4986, 177 Day Island Road GRPT 4 GEOPACIFIC ENGINEERING, INC. <br />Version 1, August 27, 2018 <br />