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Avalanche Mitigation Protects Vital Power Line

WHITTIER, AK — On March 26, 2009 an avalanche fell 2,480 vertical feet, crossed the Alaska Railroad tracks, the Portage River and destroyed a 5 span section of Chugach Electric’s 25,000 volt power line that serves the community of Whittier, the Whittier Railroad and Auto Tunnel, Portage Visitor’s Center and Portage Lodge. The avalanche left a snow and debris run-out 15’ to 30’ deep and several hundred feet wide. Despite a massive effort, the power to this community and these facilities was not restored for 7 days.

A week with no electrical power can cause a severe impact in an Alaskan community. A permanent mitigation solution was desperately needed to avoid a repetition of this event. The decision was made to invest in burying the lines to keep them safe from the avalanche path, known locally as Whittier the “Door Four Path.”

After careful planning and the commitment of $250,000 in Federal and State of Alaska funding, work could begin:

Equipment was brought to the site and set up. Next came clearing and grubbing of a 1,350’ by 20’ right-of-way, followed by digging 1,260 feet of trenches through fractured rock and glacial till.

Dead-end poles and risers were needed at the beginning of the underground section, and the 3- pole dead-end structure that provides for a span of Portage Creek a terminal at the railroad tunnel door was removed and relocated.

Old lines and distribution poles were also removed, followed by installation of new conductors throughout the system.

Last updated Jun 3, 2020