Hearings Official Decision - Laserfiche WebLink

Slopes of 20 percent to 30 percent 3. Eugene Formation Soil depth of 40 inches and above Slopes of 20 percent to 30 percent 4. Basalt flows Soil depth of 20 to 40 inches Slopes of 30 percent and above 5. Eugene Formation Soil depth of 20 inches to 40 inches Slopes of 30 percent and above Finding: This South Hills Development Standard requires an `adequate review of both on-site and off-site impacts' by a qualified engineering geologist when the subject property includes specific listed conditions. As recognized through the applicant's geotechnical analysis, the site contains Eugene Formation sandstone and siltstone formation with soil depths exceeding 40 inches and slopes exceeding 30 percent. Accordingly, because the property contains soils consistent with conditions 41 and 45 listed above, this criterion requires that the applicant's geotechnical analysis required both on-site and off-site review of impact. In compliance with this requirement, the applicant's geotechnical engineer's inspection included surrounding area to map geological surface features. Offsite landslide forms were mapped in the existing residential areas. The results of the applicant's on- and off-site analyses are documented in the applicant's preliminary geotechnical/geologic investigation. As the staff report summarizes, the applicant's geotechnical/geologic investigation found no significant geologic hazards that would impede or restrict the construction on the site. As discussed below regarding compliance with EC 9.8320(6) and EC 9.6710 Geological and Geotechnical Analysis, the applicant's investigation acknowledges that shallow slide debris in the top 2.5 feet of ground material can be expected in the steeper lots. The map included with the May 30, 2017 Geotechnical Addendum identifies the steepest areas along the eastern portion of the site as "High - Landsliding Likely," affecting Lot 5, Lots 8 through 20, and Lot 33. The geotechnical/geologic investigation also found that the site is geologically and geotechnically suitable for the proposed development, provided that specific recommendations described in the investigation are incorporated into the design and construction of the project. In response, the Response Committee critiqued the applicant's assessment through its own geotechnical/geologic review conducted by Dr. Gunnar Schlieder of GeoSciences. In that review, Dr. Schlieder disputes nearly all of the applicant's analysis and concludes that the site is not suitable for the proposed development. For purposes of compliance with the South Hills Study, the applicant has recognized the existence of conditions 41 and 45 listed above and, accordingly, has provided an in-depth, detailed analysis that includes an "adequate review of both on-site and off-site impact" of the proposed PUD as required by the South Hills Study. While critical of the applicant's methods and analysis, Dr. Gunnar does not dispute the scope of the study or provide evidence that it does not adequately consider both on-and off-site impacts. As relevant to required compliance with Hearings Official Decision (PDT 17-1) 21