Slide stabilization work has been completed adjacent to US20/WY789 between Shoshoni and Thermopolis at the north edge of the Upper Wind River Campground.
The work was completed December 16th by slide stabilization subcontractor Condon Johnson and Associates, Inc., of Kent, Wash.
“The 179 aggregate shafts are in place and are each six feet in diameter. They were installed 40 feet below the level of the Wind River to catch the toe of the deeper slide, and they will act as shear key to hold the slide in place,” said Wyoming Department of Transportation project engineer Jordan Erz of Worland. “The contractor used 33 working days to stabilize the 700-foot slide area as quickly and safely as possible to prevent further damage to US20/WY789.”
Erz said the slide near the Upper Wind River Campground is unusual because it was moving during the fall and winter “due to the river level dropping and uneven water pore pressures that makes the slide want to move/follow the river level.”
Prime contractor on the $8.78 million project is Oftedal Construction Inc., of Casper.
The Wind River Canyon slide stabilization project includes slide repair, grading, slide stabilization rock (SSR), manual rock scaling, rock fall mitigation and other work on US20/WY789 beginning at milepost 115.9 through 123.12 inside the canyon between Shoshoni and Thermopolis.
After the holidays, the prime contractor will begin excavation silt from the hillside near the campground. “A larger slope will be built with about 40,000 cubic yards of material excavated from other areas in the canyon,” Erz said. “The larger slope will provide resisting force to help hold the deeper slide in place.”
Near the north end of the canyon, the contractor is beginning excavation of two large catch basins to catch future debris flows. Rocks and dirt taken from the areas are being used to rebuild the slide near the Upper Wind River Canyon Campground. The catch basin construction work is between mileposts 122.54 and 123.12, 10 miles south of Thermopolis.
“The catch basins are being built where a large slide covered the highway over Memorial Day weekend in 2014,” Erz said. “Development of these catch basins will allow WYDOT maintenance crews to remove future debris flows, and should prevent future road closures caused by large rainfall events.”
Erz said the contractor’s goal is to complete dirt work on the Wind River Canyon project this winter, weather permitting.