October 2, 2008

Melting permafrost gives Canadian North that sinking feeling

Construction Corner

Korky Koroluk

The Canadian North is becoming a bit of a mess.

For a few years now, we’ve seen an increasing number of newspaper and magazine articles about the effects global warming is having on northern wildlife (especially polar bears) and, occasionally, the effects of warming on aboriginal populations and their traditional lifestyles.

But what about the built environment?

There are always a few tales of buildings that have begun to “float” because the permafrost beneath them has thawed, but it is only lately that scientists and public officials have begun to realize the enormity of the mess.

Across the Arctic, melting permafrost has damaged housing, airport runways, roads, water mains and treatment plants. There has been some talk of the need to relocate communities — always an unpopular notion. And, increasingly, there is talk of different building design and materials.

And until global warming is checked — if it ever is — the problems will only get worse. There’s going to be a lot of engineering and construction work to be done wherever communities exist in the permafrost region, which consists of most of the Yukon and Northwest Territories, Nunavut, and at least parts of every province except the three Maritime provinces. Quebec, Ontario and Manitoba all have substantial areas of permafrost.

Melting permafrost has been with us for a long time, of course, simply because any heated structure will, given enough time, leak heat through the floor or foundation and warm the permafrost beneath it. But the advent of gradually warming weather has speeded the process.

Truckers who rely on the so-called “ice roads” across lakes to make deliveries during the winter, have found their season is anywhere from two to four weeks shorter than it was just a decade ago.

In one community the fire station had to be moved because its concrete slab floor had collapsed. Predictably perhaps, given the amount of permafrost in the state, the University of Alaska has done quite a bit of research on the subject. More than 30 years ago, one of its scientists wrote a paper on the subject, and, over the years, it became such a respected summary of the problem that another scientist, Richard Seifert, updated it a few years ago for republication. It’s called Permafrost: A Building Problem in Alaska, and it’s a free download from the website of the school’s extension service. Point your browser to www.uaf.edu/ces/publications/freepubs/HCM-00754.pdf

Although it is not highly technical, engineers should also find it useful. What they are sure to find useful is a link at the end of the paper leading to the Permafrost Technology Foundation, a group formed in 1989 when a small group met to discuss the plight facing more than 350 families in the Alaska interior whose homes were being damaged because of subsidence due to melting permafrost.

The homeowners needed to find professional help to stabilize the foundations beneath their homes, but at the time, there was no accepted, standardized procedure for stabilizing the foundation of a building in trouble because of melting permafrost.

Now, thanks to the foundation, there is, along with a number of highly detailed case studies of methods of stabilizing foundations.

All this stuff is available on the foundation’s website at www.permafrost.org

There you will find links to design manuals aimed directly at engineers. One deals with stabilizing foundations on permafrost; the other is for new foundations on permafrost.

Both are free downloads, although you can, for a price, order hard copies.

The case studies are also free downloads, and everything, free or not, is worthwhile reading for an engineer or builder thinking of working in the North.

Korky Koroluk is an Ottawa-based freelance writer. Send comments to editor@dailycommercialnews.com

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