Snow sails are a form of passive avalanche starting zone defense. A deployment of snow sails will disrupt the snowpack in an avalanche starting zone and inhibit the formation of coherent, continuous avalanche “wind-slabs.” Snow sails where first constructed from on-hand materials and deployed in the European alps in the late 1940’s through the 1950’s. They were known in German as kolktalfen - which translates literally as (airflow) eddy (generating) tables. Snow sails are only applicable to certain specific avalanche environments, including sites where the dominant avalanche mechanism is through the formation of wind slabs. The objective the milepost 151 avalanche project was to assess, test, and install an operational deployment of ˜50 snow sail in the avalanche starting zone as a means of cost effectively reducing the avalanche hazard, due primarily to wind-slab avalanching, for motorists and WYDOT maintainers on USR 89/191. The 151 avalanche is located adjacent a populated residential area of Jackson, Wyoming and is also critical, managed big game winter habitat. After 4 years of pilot phase trials and technology demostrations, a compliment of 60 snow sails were fabricated, transported and installed during the autumn of 2002. The final sail design was similar to the initial trial design. Helicopter supported logistic were used to transport 50 of the preassembled snow sails, earth pin anchors and cabling from the Jackson valley floor to the 151 avalanche site. Unlike other forms of constructed, passive avalanche starting zone defense facilities, snow sails may be removed annually in the spring and re-installed in the autumn. This minimizes their year-round visual impact. The 151 avalanche snow sail deployment has undergone a requisite USDA Forest Service/National Environmental Policy Act (NEPA) Environmental Assessment (EA). The Finding was one of No Significant Impact (FONSI).
|Original language||English (US)|
|Title of host publication||Snow Engineering V|
|Number of pages||7|
|State||Published - Jan 1 2004|
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)