Preliminary Geotechnical Engineering Report <br />Project No. 18-4986, 177 Day Island Road, Eugene, Oregon <br />NO " <br />The above recommendations are subject to field verification. GeoPacific should be on-site during <br />construction to verify subgrade strength and to take density tests on the engineered fill, base rock <br />and asphaltic pavement materials. <br />Seismic Design and Soil Liquefaction <br />The Oregon Department of Geology and Mineral Industries (Dogami), Oregon HazVu: 2018 <br />Statewide GeoHazards Viewer indicates that the site is in an area where strong ground shaking is <br />anticipated during an earthquake (Dogami HazVu, 2018). Structures should be designed to resist <br />earthquake loading in accordance with the methodology described in the 2015 International <br />Building Code (IBC) with applicable Oregon Structural Specialty Code (OSSC) revisions (current <br />2014). We recommend Site Class D be used for design per the OSSC, Table 1613.5.2 and as <br />defined in ASCE 7, Chapter 20, Table 20.3-1. Design values determined for the site using the <br />USGS (United States Geological Survey) 2018 Seismic Design Maps Summary Report are <br />summarized in Table 4 and are based upon existing soil conditions. <br />Table 4 - Recommended Earthquake Ground Motion Factors (2018 USGS) <br />Parameter <br />Value <br />Location (Lat, Long), degrees <br />44.057709, -123.080649 <br />Probabilistic Ground Motion Values, <br />2% Probability of Exceedance in 50 yrs <br />Peak Ground Acceleration, PGAM <br />0.419 g <br />Short Period, Ss <br />0.771 g <br />1.0 Sec Period, S1 <br />0.404 g <br />Soil Factors for Site Class D: <br />Fa <br />1.192 <br />Fv <br />1.596 <br />SDs=2/3xFaxSs <br />0.612g <br />SD1 = 2/3 x Fv x S1 <br />0.430 g <br />Seismic Design Category <br />D <br />Soil liquefaction is a phenomenon wherein saturated soil deposits temporarily lose strength and <br />behave as a liquid in response to earthquake shaking. Soil liquefaction typically occurs in loose <br />sands and granular soils located below the water table, and fine-grained soils with a plasticity index <br />less than 15, and SPT N-Values lower than 15. According to the Oregon HazVu: Statewide <br />Geohazards Viewer, the subject site is regionally characterized as having a moderate risk of soil <br />liquefaction (DOGAMI:HazVu, 2018). <br />The subsurface profile observed within our explorations, which extended to a maximum depth of <br />51.5 feet bgs, indicate that the site is underlain by loose SAND (SP) to a depth of 5 feet, medium <br />dense to very dense GRAVEL (GP) from 5 to 15 feet, stiff to very stiff elastic SILT (MH) from 15 to <br />18-4986, 177 Day Island Road GRPT 15 GEOPACIFIC ENGINEERING, INC. <br />Version 1, August 27, 2018 <br />