WILSON, Wyo. — The Wyoming Department of Transportation (WYDOT) has adjusted the timeline for a permanent rebuilding of the Teton Pass at milepost 12.8, where the Big Fill landslide took out the road in June. WYDOT Resident Engineer Bob Hammond spoke with Buckrail about the new building schedule and explained the agency’s strategy for fortifying the road.
Originally, WYDOT estimated that the road work would be complete by November. Now, Hammond estimates an end date of July 31. He said crews will be working around the clock throughout the fall until freezing temperatures halt construction. Once favorable conditions return, crews will get back to work.
“The timeline that we originally sent out three months ago was a really aggressive time schedule,” Hammond said. “It was too aggressive for getting the logistics of everything we need to make a permanent solution that will last 75 years.”
According to Hammond, rebuilding the portion of Teton Pass that collapsed in a landslide will take many phases of completion. Crews have recently finished excavation work and the removal of slide debris to ensure a safe working space.
Work crews have now moved on to constructing a permanent fix, which will focus on three elements to prevent landslides: a resisting force, a driving force and soil stability. Hammond said installation of micropiles will serve as the resisting force, which will counteract above-ground movement. The driving force, which pushes the weight of the road downward, will be constructed with lighter material. Lastly, the installation of water drainage will increase the stability of the soil.
Over 100 micropiles, which are nine and three-quarter inch diameter steel rods with a grouted bottom, will be installed to provide greater stability. The rods will be drilled throughout the fill area, approximately 50 feet deep, to create a reinforced foundation. This work is estimated to take three to four weeks.
Next, approximately about 50,000 cubic yards of a recycled glass material, called foamed glass will arrive. The substance will be mixed with native material to create a light weight fill. According to Hammond, foamed glass has not been used in Wyoming, so it will be imported from Florida. Hammond said that local fill material usually weighs 110 pounds per cubic foot and the foamed glass weighs much less at 27 pounds per cubic foot.
“We are putting something in that will weigh a lot less than what was there before,” Hammond said.
Approximately eight water drains or perforated pipes will be drilled horizontally and slightly uphill to allow gravity to move water outside of the fill area. Additionally, the entire fill will have a five-foot-layer of drain rock underneath it to filter out water.
“If you have the lubrication of water, that allows for the ground to slip and slide,” Hammond said. “So our horizontal drains will remove water from the situation.”
The two-lane temporary detour, which has been recently chip-sealed with a friction surface for better traction, will allow drivers to commute all winter long. The concrete barriers along the detour will be replaced with normal guard rails to keep plow trucks from catching on the barriers.
“The detour is very safe,” Hammond said. “It will still be 20 miles per hour around the sharp curves. We are making sure that driving on Teton Pass is safe for the public.”
