Geotechnical Investigation <br />Capital Hill PUD <br />Eugene, Oregon <br />DOGAMI's HazVu website classifies landslide hazard as low on the relatively flat upper slopes, moderate on the gentle <br />slopes near the hilltop (landsliding possible), to high on the steeper eastern slopes (landsliding likely). <br />Refer to Figure-1 for a site plan with reconnaissance notes. No indications of significant active or recent slope instability <br />(such as tension cracks, sunken grades, springs, bare soil head scarps or incised erosional channels) were observed <br />during the reconnaissance. Soil creep indicated by fir trees with curved trunks is common, and quite extreme in places. <br />Slopes below the proposed loop road are slightly hummocky due in part to logging activities, but there were no <br />indications of recent or extensive slope failures observed. The Ribbon Trail is buttressed by low wooden cribbing in <br />places, but no culverts or indications of high runoff were observed. The steeper slopes are generally vegetated with <br />middle-age to relatively mature trees up to 3 feet or more in diameter and in our opinion appear to be relatively stable. <br />Ferns are common on the steeper slopes, but other wetland-type species are not. <br />The DOGAMI HAZVU website rates the site vicinity likely to feel strong shaking in the event of an earthquake, but at <br />no risk of flooding. The landslide terrains mapped nearby and onsite have a moderate liquefaction risk in the event of <br />a large earthquake but the majority of the subject site is not deemed at risk based on subsurface material composition. <br />The nearest active fault mapped by DOGAMI is approximately 24 miles southeast of the subject site. <br />Site slopes estimated from the survey range from generally flat-lying at lot 24 (presently occupied) to approximately <br />15-20% (9-12 degrees) adjacent to Capital Drive on the west, 13-22% above the eastern loop of Capital Drive (lots 28- <br />33) and generally 35-40% below the proposed eastern loop of Capital Drive (lots 12-18), ranging up to 50% or more in <br />places (lots 8, 9, 10, 19 and 20). <br />Strong soil shaking is expected at the site during a significant seismic event such as a subduction zone earthquake, <br />which is expected to produce acceleration of 0.23g and magnitude of 8.3 with an occurrence interval of 1/1000 years. <br />4.0 CONCLUSIONS <br />Our conclusions are based on the September 2016 Preliminary Site Plan by Schirmer Satre Group (Figure-2) and follows <br />our initial site reconnaissance and subsequent revision to the preliminary layout originally provided to BEI in March <br />2016 as shown on our Site Exploration Map (Figure-1). <br />The project site is generally underlain by Eugene Formation sandstone that weathers to clay near the surface with <br />moderate shrink-swell potential. Moderate-size landslides are mapped adjacent to the northeast and southeast site <br />corners and two small slides are mapped above the Ribbon Trail as mentioned above. Over-steepened slopes and debris <br />were observed in the vicinity of the proposed road extension near the southern margin of the site, but aside from <br />common soil creep evidenced by fir trees with curved trunks, no indications of significant recent or ongoing instability <br />were observed. Shallow slide debris can be expected to be encountered within the top 2.5-feet of material for steep lots <br />south of the loop. The slide debris is generally associated with the over-steepened slope conditions and are underlain <br />by stable decomposed bedrock. No flowing water was observed on site and none is mapped in the geologic literature, <br />but minor seeps would not be unexpected in the rainy season. There was no evidence of significant active landslide <br />activity within the project limits. <br />In our opinion there are no significant geologic hazards that would impede or otherwise restrict the planned development <br />as proposed. The proposed development will not adversely impact the proposed site or adjacent properties. The primary <br />challenge will be establishing and maintaining stable slope conditions for access roads and building pads constructed <br />outside of the Capital Drive/loop area (steeper lots) through proper construction practices and drainage considerations. <br />Branch Engineering, Inc. <br />7 <br />