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Between Stations 16+50 and 21+00, the upper 30 inches of road should be overexcavated <br /> and replaced in layers less than 8 inches thick, moisture condition to within 3 percent of <br /> optimum, and be compacted to at least 95 percent relative compaction per ASTM D1557-09. <br /> Between Stations 21+00 and 27+50, the roadway subgrade should be prepared by <br /> scarifying the upper 6 inches, moisture conditioning the scarified soils to within 3 percent of the <br /> optimum moisture content, and compacting to at least 95 percent relative compaction per ASTM <br /> D 1557-09. <br /> The completed roadway should covered with a layer of 2-inch minus crushed rock <br /> approximately 6 inches thick. The crushed rock paving layer should be compacted with <br /> vibratory roller. Four passes with the roller will be sufficient to achieve the desired compaction <br /> of the crushed rock layer. <br /> 5.3 Retaining Walls <br /> Where the minimum allowable roadway width cannot be achieved at the existing fill <br /> slope inclinations, a mechanically stabilized earth (MSE) wall is recommended to construct the <br /> fill slopes. Because MSE walls utilize horizontal reinforcing mats in the fill behind the wall <br /> face, slopes can be increased to 3/a:l or steeper. The wall should bear on bedrock and be <br /> designed in accordance with the manufacturer's recommendations. The manufacturer may <br /> require the use of granular fill which, if not available onsite, may need to be imported or <br /> processed on site. <br /> 5.4 Monitoring <br /> A monitoring program to measure the magnitude and rate of movement of key access <br /> road locations and retaining wall components, if necessary, should be designed and implemented <br /> by the Geotechnical Engineer. At a minimum, monument control points should be established at <br /> 20+20, 20+40, 20+60 and 20+80. The monitoring points should be monitored by a surveyor <br /> licensed in the State of Colorado to within a tolerance of 0.01 feet. Following baseline readings, <br /> the first round of survey measurements should be obtained one week later and quarterly <br /> thereafter while road is in use. <br /> Where movement exceeds 0.1 feet between monthly readings, monitoring frequency <br /> should be reduced to weekly. If movement exceeds 0.1 feet between weekly readings, use of the <br /> access road shall cease until an inspection by the Geotechnical Engineer is performed to assess <br /> the nature of the movement judges the road sufficiently stable or until recommended repairs <br /> implemented under his/her oversight. <br /> Rule 6.5 Geotechnical Stability Technical Revision April 2,2012 <br /> New Access Road Page 6 <br />