Foundation Engineering, Me. <br />Professional Geotechnical Services <br />Willard Dixon, AIA October 9, 2013 <br />Willard C. Dixon Architect, LLC <br />300 Blair Boulevard <br />Eugene, Oregon 97402-4150 <br />Oakleigh Meadows Cohousing Project 2131004 <br />Supplemental Consultation <br />Eugene, Oregon <br />Dear Mr. Dixon: <br />Foundation Engineering,. Inc. completed a geotechnical investigation for the <br />above-referenced project. Our findings are summarized in a report dated <br />February 12, 2013. We understand a local resident expressed a concern with <br />ground water levels during a recent public hearing. <br />The site is underlain by fine-grained alluvium (silts and silty sands) followed. by <br />gravels. Ground water along the eastern side of the project was encountered at a <br />depth of ±11 feet at the time of our field exploration (January 2013). This depth <br />corresponds to the surface of the gravels. <br />We anticipate the ground water level in the gravels will respond to fluctuations in <br />the river level due to their relatively high permeability. Flooding typically involves a <br />relatively rapid rise and fall in river levels (i.e., over a period of a few days). The <br />soil above the gravel, however, has a relatively low permeability. Therefore, we <br />expect a significant lag in the rise of ground water in those soils in response to a <br />rise in the river level. We understand the buildings will be built at a finished floor <br />elevation corresponding to the 100-year flood plus 1-foot. Therefore, we do not <br />expect ground water will adversely impact the building floors during such a flood <br />event. <br />We hope this explanation addresses the resident's concern. Please do not hesitate <br />to contact us if you need further assistance. <br />Sincerely, <br />FOUNDATION ENGINEERING, INC. <br />1~_2_ - <br />James K. Maitland, P.E., G.E. <br />Principal Engineer <br />JKM/zc <br />~~~EO I~ROF~ <br />a, R1~00!11 <br />M <br />1=XPIRES: 121311 1ST <br />820 NW Cornell Avenue • Corvallis, Oregon 97330 • Bus. f541) 757-7645 • Fax (5411 757-7650 <br />- 925 <br />