Due to the potential extent of industrial setback, Alcan placed a second trans- mission circuit alongside the first in the hazardous areas, and on the same towers in safe areas. In this way, as long as only one side of the parallel lines are lost power still gets to the smelter. As the second circuit is not used by the smelter except in emergencies it now conducts surplass power destined for the BC Hydro power grid. So pres- ently, if either of the lines are lost, significant financial loss will be incurred. In the alpine regions it is normal to have a 5 m snowpack, while the depth of snow at sea level may vary dramati- cally depending on the winter.
Storms are usually very severe with strong winds, fluctuating temperatures, and heavy precipitation.
Each tower exposedto an avalanche hazard hasits own unique avalancheterrain situation, this combined with the full spectrum of mountain weather and snowpacks over the 42 year life of the line, has producednumerable unu- sual, rare, and in some cases unprecedented avalanche events causing tower, work camp or forest destruction. Four reports on the estimated snow avalanche risks to the towers were written during the past 36 years. All towers were given a rating of the hazard based on an unprotected site. In 1973 an avalanchedestroyed tower 105L which was located mid track of a large moderate angled alpine bowl. And in 1985 another tower 124L with the same rating was also destroyed along with several hectares of forest.