Akamina Parkway Reconstruction and Hazard Mitigation

摘要

Waterton National Park is in southwestern Alberta, it is the southernmost National Park in the Canadian Rocky Mountains. On June 19, 2013, over a 24 hour period, between 60 mm and 125 mm of rain fell (rainfall records provided by Parks Canada for the Akamina and Waterton Warden Office) on the steep mountain sides adjacent to the Akamina Parkway triggering catastrophic flooding, landslides, debris flows and debris floods. The widespread impacts from the various natural hazards resulted in severe impacts to the roadway and severed access to Akamina Lake, Cameron Lake and the associated nearby hiking and camping areas. The flooding and damage as experienced by the city of Calgary, during the same precipitation event, is described by the Government of Alberta as the worst in its recorded history. The Parkway is located in a geomorphically active mountainous area subject to regular flooding and debris flow events. The processes that led to the road damage were primarily related to inadequate control of debris and water passage at eight locations. Tetra Tech EBA was retained by Parks Canada, through their emergency services contractor, Maglio Installations, to provide emergency analyses and design guidance for remediation and mitigation along the Parkway. Tasks included: hydrology assessments, hydraulic analysis, design drawings for culvert replacements, debris storage catchment basins, debris berms, debris racks, rock scaling, retaining walls, specification of riprap prescription and reinforcement of roadway, support for bridge construction, and general field design guidance. The initial design criteria included the 100 year clear water event and the 10 year debris flow event. Gabion and rock walls were designed and constructed at wash-out locations to re-open the vital tourist access. Tetra Tech EBA also provided construction monitoring and materials testing services for this fast-paced project and has adapted designs to suit field conditions. Construction began in July 2013 and was substantially completed by November 30, 2013.