68th Canadian Geotechnical Conference and 7th Canadian Permafrost Conference

CATHEDRAL MOUNTAIN 2014 ICE FALL AND DEBRIS FLOW

Session: Landslides and Slope Stability III / Mouvements de terrain et stabilité des pentes III

Lukas Arenson, BGC (Canada)
Chris Bunce, CP (Canada)
Dave Gauthier, Queens University (Canada)
Richard Guthrie, SNC-Lavalin (Canada)
Jean Hutchinson, Queens University (Canada)
Matthias Jakob, BGC (Canada)
Cory McGregor, SNC-Lavalin (Canada)

Cathedral Mountain is located in the southern Rocky Mountains of British Columbia along the Continental Divide. High elevations of the mountain are occupied by the Cathedral Glacier and a supra-glacial lake that drains north towards the Kicking Horse River through Cathedral Gulch. Since 1925, 16 debris flows have been recorded in Cathedral Gulch impacting both Canadian Pacific railway and the TransCanada Highway. At 06:30 on July 10, 2014, approximately 100,000 m3 of ice collapsed from Cathedral Glacier followed by the drainage of the supra-glacial lake. Ice and water descended Cathedral Gulch, transformed into a debris flow and buried the uppermost CP tracks. Analysis of the event included: a rapid assessment and safety plan for workers who had the track functional by 14:20 on the day of the incident, a qualitative assessment using detailed 3D surface models from oblique aerial photos, an analysis of the stability of the remaining glacier and supra-glacial lake, and a magnitude frequency analysis of Glacial Lake Outburst Floods (GLOF) and debris flows that have occurred down Cathedral Gulch. This case study highlights the key results of the analyses and reports on some of the innovative techniques available for rapid Geohazard assessments in similar terrain.