Northern communities turn to innovative solutions to tackle thawing soil
Layers of permafrost can be seen on the side of this cliff near Tuktoyaktuk, N.W.T. Pingos, or mounds of earth-covered ice, can be seen in the background. (CBC) 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.
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.
A Gold Rush-era building in Dawson City, Yukon, suffers some damage because of shifting permafrost underneath. Kim Howson
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.
'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.'—Sara Brown, Northwest Territories Association of Communities
“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 architects who designed the new, not-yet-finished, school in Inuvik, N.W.T., used pipes frozen 20 metres into the ground as part of the building’s foundation. The pipes are meant to keep the school’s foundation stable. CBCThe 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.
A worker continues building at the school in Inuvik, N.W.T. It is scheduled to open in September 2012. Philippe Morin/CBCThe 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.
No comments:
Post a Comment