Level I Investigation Report Eugene Riverfront Development <br />City of Eugene Eugene, Oregon <br />property separates the proposed development from the river. Slopes down to the river are covered with brush <br />and trees. <br />Several structures, asphalt concrete pavement, concrete pavement, and concrete slabs occupy large portions <br />of the proposed development, many of which will demolished as part of future development. <br />2.2Geologic Setting <br /> <br />The site is located within the southern Willamette Valley, a broad alluvial basin within the physiographic <br />province of the Puget-Willamette Lowland that separates the Cascade Range to the east from the Oregon <br />Coast Range to the west, and extends from the Puget Sound to Eugene, Oregon (Yeats, et al., 1996). The <br />Willamette Valley is situated along the Cascadia Subduction Zone (CSZ) where oceanic rocks of the Juan de <br />Fuca Plate subducting beneath the North American Plate have created complex deformation within the Coast <br />Range and Willamette Valley basement rocks (McClaughry, et al., 2010). Extensive valley infilling and <br />catastrophic flooding related to the Missoula Floods during the Quaternary has subsequently buried the <br />Oligocene and Eocene sedimentary and volcanic basement rocks within the valley and concealed many of the <br />structural features throughout the valley (Wiley, 2006). <br />Locally the site is underlain by Holocene age alluvium associated with the nearby active channel of the <br />Willamette River and modern-day flooding. These sediments consist of unconsolidated gravel, sand, silt and <br />clay and may be as much as 50 feet thick (McClaughry, et al., 2010). <br />2.3Subsurface Conditions <br /> <br />Portions of the site have been explored by Squier Associates in 1986 by completing 33 borings to depths of <br />8.1 feet to 41.5 feet bgs and by PBS in 2018 and 2019 by completing 17 borings to depths of 11.5 to 36.5 feet <br />bgs. PBS boring logs are included in Appendix A and Squier boring logs are included in Appendix B. <br />In general, subsurface conditions at the site consist of gravel fill; a layer of clay, silt, silty sand, and sand; and a <br />layer of gravel overlying very stiff silt, interpreted as the Eugene Formation. PBS did not encounter hog fuel in <br />any of the explorations recently completed in the former hog fuel stockpile area identified in the Squier <br />report. <br />2.4Groundwater <br /> <br />Static groundwater was not measured during drilling of the deeper explorations due to the mud-rotary <br />drilling techniques used. Based on the presence of relatively permeable gravel and the proximity to the <br />Willamette River, we estimate these are hydraulically connected and the water levels in the river may reflect <br />the elevation of groundwater on the site. Previous geotechnical explorations at the site generally encountered <br />groundwater at depths of 15 to 20 feet bgs. <br />3GEOLOGIC AND SEISMIC HAZARDS <br /> <br />Geologic and seismic hazards are defined as those conditions associated with the geologic and seismic <br />environment that could influence existing and/or proposed improvements. In general, the geologic and <br />seismic hazards most commonly associated with the physical and chemical characteristics of near-surface soil, <br />rock, and groundwater include those listed below. Those shown in bold are geologic and seismic hazards that <br />could affect the site development and should be considered in the planning process. <br /> <br />April 4, 2019 <br />2 PBS Project 73368.001 <br /> <br />