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Preliminary Geotechnical Engineering Report Project No. 18-4986, 177 Day Island Road, Eugene, Oregon NO " We recommend at least 12 inches of 3/4"-0 crushed aggregate base rock underneath structural foundations, extending at least 1 foot beyond the foundation element on all sides. The backfill material should consist of 3/4"-0 crushed rock with less than about 7 percent fines (material passing the U.S. Standard No. 200 sieve). This crushed rock should be compacted to at least 90 percent of its maximum dry density as determined by ASTM D1557 or equivalent. Shallow, isolated or continuous spread footings may be used to support the proposed structures, provided they are founded on 12 inches of crushed rock placed and compacted over competent native soils and/or engineered fill placed and compacted over competent native soils. For footing subgrade soils prepared as recommended above, we recommend maximum allowable bearing pressures of 2,000 pounds per square foot (psf) in design of the below-grade portions of the structure. If desired, higher allowable bearing pressures may be achieved by over-excavating and placing additional compacted crushed rock underneath the footings. GeoPacific may be consulted to provide recommendations for achieving increased allowable bearing capacity. The recommended maximum allowable bearing pressures may be increased by 1/3 the above- recommended value, for short term transient conditions such as wind and seismic loading. All exterior and interior footings should be founded at least 18 inches below the lowest adjacent finished grade or below top of slab. Minimum footing widths should be determined by the project engineer/architect in accordance with applicable design codes. Assuming construction is accomplished as recommended herein, and for the foundation loads anticipated, we estimate total static settlement of spread foundations of less than about 1 inch and differential settlement between two adjacent load-bearing components supported on competent soil of less than about 3/4 inch. We anticipate that the majority of the estimated settlement will occur during construction, as loads are applied. Wind, earthquakes, and unbalanced earth loads will subject the proposed structure to lateral forces. Lateral forces on a structure will be resisted by a combination of sliding resistance of its base or footing on the underlying soil and passive earth pressure against the buried portions of the structure. For use in design, a coefficient of friction of 0.42 may be assumed along the interface between the base of the footing and subgrade soils. Passive earth pressure for buried portions of structures may be calculated using an equivalent fluid weight of 320 pounds per cubic foot (pcf), assuming footings are cast against native soils or engineered fill. The recommended coefficient of friction and passive earth pressure values do not include a safety factor. The upper 12 inches of soil should be neglected in passive pressure computations unless it is protected by pavement or slabs on grade. Footing excavations should be trimmed neat and the bottom of the excavation should be carefully prepared. Loose, wet or otherwise softened soil should be removed from the footing excavation prior to placing reinforcing steel bars. GeoPacific should observe foundation excavations prior to placement of reinforcing steel and formwork, to verify that an appropriate bearing stratum has been reached and that the actual exposed soils are suitable to support the planned foundation loads. 18-4986, 177 Day Island Road GRPT 9 GEOPACIFIC ENGINEERING, INC. Version 1, August 27, 2018