Thawing permafrost sinks buildings, hikes costs in North
Northern communities turn to innovative solutions to tackle thawing soil
In the Arctic, the ground is melting beneath northerners’ feet.
This brings a new and costly infrastructure challenge to a region where building is already tricky.
Many buildings need to be renovated because they’re sinking. New buildings struggle to last in an uncertain future.
What is permafrost?
- Permafrost is soil or rock that stays below 0 C throughout the year, and from one year to the next.
- A thinner, 'active' layer of soil sits above the thicker, more solid permafrost. The active layer is increasing in depth as temperatures warm.
- Ian Church, a retired Yukon government senior science adviser, compares permafrost thaw to thawing a turkey. He says if you drop a frozen turkey on your toe, it will probably break your toe. When you let the turkey thaw on the counter, you start to get some parts frozen while some parts are thawed on the surface. The turkey is no longer very stable, so if you drop it on your toe, you will probably only bruise instead of break it. Once the whole turkey is above the freezing point, it’s completely thawed and ready for the oven. Church says the same thing happens with soil; the ground softens and becomes less stable as it approaches the freezing point.
- Some ways to deal with this are to try to keep the permafrost frozen with thermosiphons. Church says these are heat exchangers that draw energy out of the ground. Passive systems take advantage of cold winter air to cool the fluids that circulate in the pipes. Active systems add pumps to speed up the process, just like in a refrigerator. This technology was first used for the Alaska pipeline in the 1970s.
- Another solution builders use is to dig up the soft permafrost completely and put in more solid gravel and rock.
- Permafrost is dependent on ground and air temperatures. Ground temperatures in some parts of the North are warming by one-10th of a degree every 10 years. For the High Arctic, it is warming by 0.5 to one degree every 10 years.
Sara Brown, director of community operational support with the Northwest Territories Association of Communities, says the costs to upgrade and fix buildings in Canada’s North could range from $250 million to $420 million.
"This doesn't just affect community infrastructure. It affects residents’ homes and the amenities they enjoy as well. So the better informed we all are about this, the better we'll be able to deal with it in a proactive way as opposed to reactive way," said Brown.
Building problems throughout the North
The active layer of the ground, which freezes and unfreezes every year, is deepening as ground and air temperatures warm.
The permafrost under it is also warming. As this happens, the ice-rich permafrost thaws and weakens.
Active permafrost can’t freeze as well in warmer temperatures. This means that as that active layer thaws completely, the inactive permafrost underneath is becoming warmer. This makes the ground underfoot less stable, deeper into the ground.
Examples of the havoc this wreaks on buildings are rife throughout the territories.
At Iqaluit’s Arctic Winter Games arena, the floor began sinking soon after the building opened in October 2001. It was closed in 2003 when ice creation became impossible. The repair cost $2.2 million and the arena reopened to ice sports in October 2010.
The school in Ross River, Yukon, had to be rebuilt because it couldn’t withstand the thawing permafrost. Its thermosiphons, or pipes filled with chemicals to keep the permafrost frozen, were not installed correctly.
The pipes were spaced too far apart to provide effective cooling, and faulty plumbing leaked water into the ground, which further thawed the permafrost.
The government replaced the school in 1997, but air temperatures warmed significantly from 1997 to 2007. The thermosiphons at the new school could no longer keep the ground frozen enough to keep up with the pace of thawing permafrost, and corrective measures had to be repeatedly taken to improve the cooling system so that the building wouldn’t continue to sink.
The Canadian Standards Association has come up with guidelines for incorporating climate change into infrastructure design in permafrost regions. The document was released last year.
Inuvik, N.W.T., ‘hot spot’
In Inuvik, N.W.T., Brown says the problem is one of the most serious in the country.
The Arctic town is part of the Mackenzie Valley, which according to the Geographical Society of Canada, has experienced the largest increase in air temperatures in all of Canada in the past century.
Much of the permafrost along the valley is at temperatures close to the melting point of ice, which makes the ground particularly sensitive.
The now-closed Arctic Tern female young offender facility in Inuvik saw some dramatic changes as a result.
Inuvik Mayor Denny Rodgers had a tour of the facility last year.
"It was built on a very ice-rich part of town, almost like a frozen bog."
He could see the building had essentially sunk into the ground.
"It was amazing because of course the floor of the building was all concrete and it was built on grade . . . and it sunk in some places seven to eight inches. You can see the gaps in the walls and the floor there," he said.
Brown estimates the town could be looking at millions of dollars in costs associated with fixing buildings.
"Inuvik is considered a hot spot. Their number is set as high as $121 million for buildings alone, pretty significant when you think of a town of 3,500," she said.
Rodgers acknowledges the fact that temperatures are getting warmer.
"But, like anything, you have to develop technology to keep up with changing conditions and that’s what the contractors have to do and keep monitoring it to ensure that the buildings we are building … are built soundly," said Rodgers.
New Inuvik school leading way in innovation
Next fall, about 1,000 elementary and high school students will pour into 50 classrooms at the new school in Inuvik.
The cost, $92.3 million, is roughly double that of a similar-sized school in southern Canada.
Architect Simon Taylor, of Yellowknife-based Pin/Taylor Architects, designed the school.
"The ground up there is quite tricky to work with. Because you have hills all over the place, you have water draining all over the place, you have a lot of peat in the ground so you have inconsistent soil. And so all of the things you’re trying to do is create scenarios where whatever foundation you’re putting in is permanent and fixed," said Taylor.
Taylor and engineers decided to drill pipes 20 metres into the ground. They filled the pipes with sand and let them freeze into the ground over the winter.
The school site is on a hill, so Taylor designed it taking into account the grade. The gymnasium sits in the middle of the building, flanked on one end by the elementary school and by the high school on the other. The elementary school sits one metre higher than the gym, and the gym sits one metre higher than the high school.
They also did wind and snow studies to see how the elements would affect the school.
Thermometers will monitor the ground temperature for years to come.
Taylor says he’s proud of the facility.
"As it develops, it will be quite a precedent-forming facility…. This is the largest facility the [government of the Northwest Territories] has built and they’ve done it properly. And so one would hope that lessons learned in this facility can be applied whenever they look at other facilities."