Terri-Jane Yuzda


Climate Change — An Adaptation
Challenge for Northern Engineers


(click on images to view)

Canada’s scientific community continues to preach the climate change message, constantly reinforcing the belief that observed climatic warming trends are greatest in the north. Design engineers who provide services on northern projects may find the array of published predictions from global circulation models confusing, but anyone who assesses the historical records from communities in the north, particularly the Mackenzie Valley, will find the evidence for a climatic warming trend rather compelling.

The air temperature in the valley has, in fact, warmed about 1.7 C° over the past century, according to Environment Canada.

The Canadian Council of Professional Engineers held a workshop last February to examine the role of Canada’s engineers in adapting to climate change. This article is a brief summary of a presentation I made at the workshop. It describes our success at EBA Engineering Consultants Ltd. implementing a procedure into our practice that explicitly recognizes climate change as one more variable to be considered for design of structures on permafrost foundations.

The Intergovernmental Panel on Climate Change concluded in the early 1990s that arctic regions are particularly vulnerable to climate change, partially because of a perceived concern about widespread thinning or disappearance of permafrost.

Environment Canada formed a project group with funding from the Panel on Energy Research and Development to establish guidelines for permafrost engineering design. The objective was to provide a strategy for incorporating climate change into long-term planning in Canada’s North.

The results were presented in an Environment Canada report, Climate Change Impacts on Permafrost Engineering Design (1998). The study team comprised government scientists, academics and practitioners prominent in northern climate and permafrost.

Early skepticism about the outcome turned into acceptance and support for a project screening tool that has been in common use at EBA for the past five years. Implementation and application of the risk-based principles from that process to many projects have proven to be both rational, and to pass the test of peer and regulatory reviews.

Project Screening
For Climate Change Risks

A project is screened to determine its sensitivity to climate change, identified as a probability that climate change will adversely affect permafrost soils or rock that must remain frozen to ensure stability of any structure it supports. Secondly, the consequences of any change, should it actually occur, are examined.

The screening process schematic is shown here. The relationship between sensitivity and consequence define the risk that climate change imposes on the project. A criterium is provided in the study report that establishes the level of analysis that is appropriate for project design, based on the risk of failure.

The analysis complexity can range from no action required or simple qualitative assessment based on judgment to complete quantitative analyses supported by complex ground thermal modeling tools.

These quantitative analyses require cautious attention and documentation of the input parameters that describe the climatic effects over the life of the structure and their annual variability. Specific guidance is provided in the study report on how to assess the sensitivity and the consequence level for any project.

Three projects from EBA files were used in the February workshop to demonstrate how the system has been adopted into our engineering practice. They included a water dam with a permafrost core at Ekati Diamond Mine, a complex building foundation in Inuvik, and upgrading of the primary highway leading to Yellowknife. That highway lies over particularly sensitive, discontinuous permafrost.

The relative positions of these projects on the risk chart are shown in the attached figure.

For this discussion, I will describe only the building in Inuvik as it embodies all of the facets of the project screening system.

Inuvik Regional Health Centre

The new regional health centre, constructed in Inuvik in 2001/02, required an innovative approach to foundation design for permafrost soils prone to substantial settlement if allowed to thaw.

Most previous foundations for large buildings in Inuvik have been elevated and supported on timber or steel piles frozen into the underlying permafrost. Over the years, this type of foundation system has fallen out of favour for architectural, functional, esthetic and cost reasons.

An alternative and somewhat high-tech foundation solution is to intercept heat transferred from the structure to the underlying permafrost with two-phase heat pipes or thermosyphons. These passive cooling devices extract heat from below the structure and dissipate it to the atmosphere during the cold winter months.

The mechanical components are designed, manufactured and installed by Arctic Foundations of Canada Inc. The geotechnical design requires two-dimensional heat flow analyses in order to configure the piping system required to confirm long-term thermal stability of the underlying permafrost.

The principal variable in such analyses is the anticipated variability of outside air temperatures and any climatic trends that could affect future long-term performance.

Application of the screening principles to this project identified that the permafrost sensitivity was high because of the presence of abundant shallow ground ice within the Town of Inuvik. The failure consequence was rated as major or medium to high because the structural design has a low tolerance for differential movements and the economic or social impact of hospital closure could be significant.

This placed the project into a high-risk category, requiring a complete quantitative analysis of climate change effects. Comprehensive geothermal modeling of the foundation system was required, adding considerably to the complexity and cost of the foundation system design.

The foundation design included a probabilistic evaluation of Inuvik air temperature records in order to anticipate long-term trends for a design service length of 30 years starting in 2000. The results were interesting because they show that all five years preceding 2000 were well above the mean, and the 43 years of record and one warm year (1998) had a 1/100 annual exceedance probability For this project the design was tested for all of the following scenarios:

• Five consecutive 1/5 annual exceedance probablity warm years followed by a 1/100 AEP year,
• Ten consecutive 1/5 AEP years,
• Warming trend of 0.47 C° per decade.

The design was judged appropriate for any one of the above climate variability scenarios.

Climate change can be considered one more variable to be considered within a probabilistic framework for the design of northern structures. This is particularly true where stability of underlying permafrost soil or rock is essential to long-term performance.

Application of climate change principles to design still requires considerable judgment because regional climatic trends are poorly defined and the literature contains conflicting information that, if taken at face value, could stifle rational northern development.

Reference: Etkin, D., 1998, Climate Change Impacts on Permafrost Engineering Design. Internal report by Environmental Adaptation Research Group, Environment Canada.

Don Hayley, P.Eng., is principal engineer at EBA Engineering Consultants Ltd. He has been active in northern engineering worldwide for more than 30 years.

Editor’s Note: This article is the second in a series presented by APEGGA's Environment Committee regarding the role of professional members in sustainability, climate change impact and adaptation. These articles will address industry specific initiatives, international initiatives, and regulatory considerations - meant to raise the level of awareness and generate discussion. The opinions expressed by the author are his own and not necessarily those of APEGGA.


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