Changing Permafrost Landscapes

From science to decision-making: The roles of science, hazard and risk assessment, and mitigative measures in the management of geohazards along the Dempster Highway corridor

Tuesday, November 19, 2019 - 11:20am to 11:40am Theatre Three


R.J. McKillop (Presenting)
Palmer Environmental Consulting Group Inc.
L.U. Arenson
BGC Engineering Inc.
S. Kokelj
Northwest Territories Geological Survey
S. Gibson
Government of the Northwest Territories

Effective management of geohazard risks within and outside the right-of-way of the Dempster Highway, in Yukon and Northwest Territories, requires an appreciation for the sequential and synergetic roles of foundational science, hazard and risk assessment, and mitigative measures.

Foundational science and engineering embody the primary phase of data collection and analyses by which knowledge fundamental to understanding geohazards is developed. This geoscience information may be collected at regional, local or site scales and is often spearheaded by federal (Geological Survey of Canada) or territorial (Yukon or Northwest Territories Geological Surveys) geological surveys and academic institutions. Hazard assessment then involves the application of knowledge to estimate the probability and magnitude of particular geohazard processes, in turn, supporting qualitative or quantitative evaluation of the risk posed to public safety and/or highway infrastructure. Hazard and risk assessments in northern Canada are typically conducted by geoscience or engineering consultants specialized in geohazard processes in permafrost terrain. Typically, the datasets and theoretical understanding of processes generated by foundational science are applied to guide professional assessments and justify recommended follow-up actions. Mitigative measures are techniques used to manage the risk posed by geohazards within and/or outside the highway right-of-way. Surveillance monitoring is a tool that can be implemented to inform maintenance requirements and public safety. This may precede development of engineered solutions for risk mitigation, typically devised by consultants and suppliers based on the results of the prior risk assessment.

Application of this risk management framework is demonstrated in association with a retrogressive thaw slump about 500 m upslope of the Dempster Highway on the Peel Plateau at km 28.5 in the Northwest Territories. Scientific studies examining landscape changes in slope stability and monitoring of off right-of-way phenomena informed highway infrastructure managers of potential risks and provided context to support the design of a proposed surveillance system to alert infrastructure staff of imminent impacts to the road embankment. An ongoing investigation of the risk posed by rapidly degrading ice-rich permafrost underlying the Dempster Highway, near Chapman Lake, Yukon, also showcases the application of the risk management framework. As climate stresses on highway, airport and community infrastructure in permafrost regions grow, conducting fundamental science and integrating this knowledge base in risk assessment and the design of engineering solutions becomes increasingly important.