The Mark at Eugene January 6, 2026 <br />Geotechnical Investigation and Seismic Hazard Study 9 Project No.: 2251077 <br />Eugene, Oregon Landmark Construction, LLC <br />ENGINEERING ANALYSES <br />Foundation Loads <br />A variety of foundation systems were discussed with the design team. We <br />understand that two foundation types are currently being considered: 1) use of a <br />post-tensioned slab-on-grade or 2) conventional shallow spread and continuous <br />footings and floor slab. Therefore, the structure may include a relatively uniform load <br />over the thickened slab with areas of concentrated isolated and continuous footing <br />loads, or a number of concentrated foundation loads with minimal loading of the slab <br />areas. The design team provided preliminary maximum loads for the planned building. <br />The maximum loads are expected to include: <br />• Interior bearing walls: 7.5 kips/ft <br />• Exterior bearing walls: 5.0 kips/ft <br />• Post point loads: 80 kips <br />• Average uniform bearing pressure: 550 lb/ft2 <br />Bearing Capacity <br />We estimated the allowable bearing pressure using a soil cohesion of 1,200 psf and <br />a unit weight of 110 pcf for the upper alluvium. We also assumed that a minimum <br />of 12 inches of imported, compacted crushed rock would be placed beneath all <br />foundations. Our analysis assumed a minimum footing embedment of 1.5 feet and <br />footing widths ranging from 1.5 feet to 5 feet. A minimum footing width of 1.5 feet <br />should be used for continuous footings and a minimum width of 2 feet for isolated <br />spread footings. Based on these conditions, we recommend assuming an allowable <br />bearing pressure of 2,000 lb/ft2 (psf). A one-third increase in the allowable bearing <br />pressure may be used for the evaluation of short-term, extreme event wind and <br />seismic loads. <br />Settlement <br />We anticipate most of the new structure will be underlain by several feet of granular <br />fill due to the presence of previous and current structures on the site. The exception <br />is expected to include the paved parking areas along the south and east sides of the <br />site. Settlement of new foundations overlying granular fill is expected to be relatively <br />minor. Therefore, we focused the settlement analysis on foundations bearing on the <br />native alluvium. We completed settlement analysis using the program Settle3 by <br />Rocscience in combination with the laboratory test data. The subsurface profile <br />encountered in the exploratory borings was used to model the soil conditions beneath <br />the foundations. The consolidation parameters derived from Figures 1C and 2C were <br />used to estimate the compressibility of the deeper fine-grained soil underlying the <br />site. Other soil strata were assigned consolidation index properties based on previous <br />laboratory tests completed for previous local projects and our experience with similar <br />soils. A groundwater level of 6 feet was assumed based on the groundwater <br />measurements in BH-2.