Laserfiche WebLink
rock cuts. The cutslopes and outslope were conservatively modeled at a 0.5:1 slope and a 1:1 <br />slope, respectively. <br />3.4.2 Stability Analysis Results <br />The stability analysis results are presented in Figures 4 and 5. They indicate safety <br />factors of about 1.4 for the rock cuts, and over 2 for existing cuts in terrace deposits /colluvium. <br />4.0 Conclusions <br />Based on the findings of the geotechnical investigation and stability analyses conducted, <br />the following is concluded: <br />• The cut -fill road section appears to be in cut, with fill placed over bedrock on the <br />resulting bench and on the outslope. <br />• The results of the stability analyses indicate a factor of about 1.4 for the rock cuts and <br />over 2 for cuts in terrace deposits /colluvium. <br />• The cuts in rock are steep but the rock is relatively strong, and the rock bedding is <br />dipping favorably from a stability standpoint. <br />• Occasional raveling of the cutslopes and minor rock falls will occur, especially during <br />the spring snow melt, requiring road maintenance. <br />• The new access road can be used for the purposes intended, provided the <br />recommendations summarized in this report are incorporated during construction. <br />5.0 Recommendations <br />5.1 Cutslopes <br />As described above, occasional raveling of the cutslope could occur. Accordingly, <br />measures to protect vehicles and workers from potential rock falls should be considered. A <br />formal annual inspection of the cutslopes should be performed by an experienced geotechnical <br />engineer or engineering geologist, to check that the slopes are performing as anticipated. <br />5.2 Roadway Grading <br />The road should be constructed in a manner that results in road grades of less than 18 <br />percent. Fill slopes should be no steeper than 1.5:1. Between Stations 15 +00 and 16 +50, the <br />roadway subgrade should be prepared by scarifying the upper 6 inches, moisture conditioning the <br />scarified soils to within 3 percent of the optimum moisture content, and compacting to at least 95 <br />percent relative compaction per ASTM D1557-09. Materials used as fill should be free of <br />organic material, have a liquid limit and plasticity index less than 30 and 15, respectively, with <br />the largest particle sizes less than six inches. Most onsite materials will be suitable for use as fill. <br />Rule 6.5 Geotechnical Stability Technical Revision <br />New Access Road <br />April 2, 2012 <br />Page 5 <br />