Abstract:
This presentation will discuss the challenges we encountered in design and construction of micropiles and tiebacks to be installed at 11,160 feet on the summit of Lone Peak Mountain in Big Sky, MT to support a new tram. Condon-Johnson and Associates, Inc. (CJA) was hired to design and build the foundation system of the new ski tram structure - soon to become the flagship of the most technologically advanced lift system in North America.
At this elevation, the ground is permanently frozen year round and is covered in snow during 10 months of the year. Storms roll in with little to no warning, and the oxygen levels are less than 14% (versus 21% at sea-level). There are no roads to top of the mountain, and all access is provided via helicopters. CJA was responsible for not only the installation of the micropiles and tiebacks for the project but also all the concrete work, rebar, and embeds for the new tram top station and tower location.
CJA had to come up with innovative solutions to excavate and blast over 2000 yards of rock from the side of the mountain, remove massive amount of snow, and tackle logistical issues of transporting drill rigs, equipment and material to top of the mountain via helicopter only. CJA was able to install over 40 heavy duty micropiles and tiebacks - embedded into the frozen ground - that will support the future structures against over-turning, rotation and sliding off the mountain. The project ended up spanning over two summers which meant that when work started again in the Spring of 2023 there was over 30-feet of snow CJA had to remove by hand in certain parts of the project to access our work.
This project recently won the Micropile World Cup award for best micropile project in the world during the 2023 International Society of Micropiles Workshop in Vail, Colorado. Voting was conducted by all active participants at the event in a head to head competition with each continent presenting a project