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-20- <br />Cut and fill depths are generally anticipated to be minor with the <br />• exception of the cut into the steep sloping hillside separating the <br />lower area and higher plateau. Subgrade soils encountered along the <br />alignment consist of fine sands and silts within the lower area to <br />medium plastic clays within the majority of the upper area. The fine <br />sands and silts are considered a fair subgrade for support of pavement <br />sections, whereas the clays are considered as a relatively poor sub- <br />grade. Properties of the subgrade soils were determined by Atterberg <br />limit determinations, gradation analysis and Hveem stabilometer tests. <br />Results of stabil~neter tests indicate an Rwalue of 8 to 10 on the <br />clays and 28 on the fine sand and silt. Previous testing by <br />International Engineering Company, Inc. (December 1976) indicated an <br />R-value of 7 and 8 for the clays. For design of the pavement section, <br />• we recommend an average Revalue of 8 be utilized in clay subgrade <br />areas and 28 in granular areas. <br />We understand the Ladway :section extending across the landslide <br />area will be partially stabilized by retaining walls placed upslope <br />and d~wnslope of the roadway. We also understand that recommendations <br />for this area are being provided in conjunction with the portal design <br />by Geo Hydro Consulting and will not be discussed further. <br />Within the section of roadway on the steep slope separating the <br />upper and lower portions of the site, wnsiderable cvt into the <br />hillside is•anticipated. Cursory inspection of the slope indicates a <br />shallow soil depth overlying hard sandstone assumed to be similar to <br />that exposed in the overhang near the Bear Mine. No exploratory <br />• drilling was performed in this section due to inaccessibility. The <br />