Eugene Planning Commission <br />May 2, 2018 <br />Page 4 <br />2.EC 9.8320(6) The PUD will not be a significant risk to public health and safety, including but <br />not limited to soil erosion, slope failure, stormwater or flood hazard, or an impediment to <br />emergency response. <br />Finding: <br />Slope Failure: The applicant's evaluation of risk due to `slope failure' is included in the applicant's <br />geotechnical investigation. That investigation concludes that the proposed development is feasible <br />from a geologic and geotechnical perspective, and that the proposed development will not adversely <br />impact the proposed site or adjacent properties. As it relates specifically to slope failure, the <br />applicant's investigation states: No indications of significant active or recent slope instability (such <br />as tension cracks, sunken grades, springs, bare soil head scarps or incised erosional channels) were <br />observed during reconnaissance. Soil creep indicated by fir trees with curved trunks is common, and <br />quite extreme in places. Slopes below the proposed loop road are slightly hummocky due in part to <br />logging activities, but there were no indications of recent or extensive slope failures observed. The <br />Ribbon Trail is buttressed by low wooden cribbing in places, but no culverts or indications of high <br />runoff were observed. The steeper slopes are generally vegetated with middle-age to relatively <br />mature trees up to 3 feet or more in diameter and in our opinion appear to be relatively stable. Ferns <br />are common on the steeper slopes, but other wetland type species are not. <br />Branch Engineering Geotechnical Investigation, February 6, 2017. <br />By its terms, the applicant's geotechnical report is a preliminary investigation and also includes <br />numerous specific recommendations to minimize any potential for slope failure. <br />As noted above, the Response Committee presented its own Geotechnical assessment, which <br />disputes nearly every finding of the applicant's report. As it relates to slope stability, the <br />GeoSciences analysis relies on Dr. Schlieder's interpretation of LIDAR data and extensive <br />discussion to suggest that the subject property may be geologically unstable. Following his initial <br />investigation, Dr. Schlieder provided an addendum to support his interpretation, based on the <br />presence of `lobes' in the pavement of Floral Hill Drive, located "at or near the toe of the eastfacing <br />slope below the proposed PUD." (Addendum to Geotechnical Review of Capital Hill PUD, March <br />21, 2018.) <br />The Response Committee's forester, James Mehrwein, also disagrees with the applicant's analysis <br />regarding the potential for slope failure. He concludes that "there is current evidence in the project <br />area of slope instability. After viewing the site and reviewing published studies regarding tree <br />removal and slope instability, it is my opinion that the proposed plan to harvest the trees designated <br />for removal would increase the likelihood of slope failure in the future." He further explains that type <br />of slope instability he observed would be considered "soil creep." The applicant's geotechnical <br />engineer responded to Mr. Mehrwein's assertion that the property may be subject to soil creep as <br />follows: <br />