In July 2011, the Wyoming Department of Transportation (WYDOT) desired to stabilize a recurring landslide located on Highway 28 between Farson and Lander, Wyoming in Fremont County. The landslide referred to as "Double Nickel" is located at Milepost 55.5 and had affected approximately 1,500 lineal feet of roadway section. The slope had experienced repeated events of movement with the most recent occurring in the spring of 2010 following a heavy snowfall and rapid melt. Several repairs and various roadway alignments had been tried in the past dating back to 1992 in an attempt to mitigate the slide. Using a consultant design and an accelerated design schedule, WYDOT completed their subsurface investigation and landslide stabilization design documents within five months. After evaluation of several landslide mitigation alternatives, over 500 large diameter (12") micropile "shear piles" were selected as the most technically and economically feasible design and construction solution. Bid documents were then finalized for a January 2012 bid letting with construction anticipated in the spring of 2012. This paper will present and discuss descriptions of the historical landslide movements and repairs, environmental and geotechnical assessments for design and construction, slope stability analysis, landslide mitigation alternatives, micropile shear pile design features, site challenges, micropile installation, and monitoring and performance (to date) of the landslide stabilization system.
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