Permafrost cost: Long-term fix at Ross River school could require constant power
As school shifts in Yukon, company pitches 'a giant air conditioner' to freeze ground during summer
A Yukon school could soon require constant electricity for months of the year to ensure it's sitting on solid permafrost.
The 'active refrigeration system' would chill the ground under the 2,840-square metre Ross River school.
The device would be the first of its kind in Yukon. Last week, Yukon Public Works minister Richard Mostyn said the government would assess whether the system was "technically viable and financially responsible."
It's not clear how much electricity the device would require or how much it would cost to install — but one Alaska company working in the field suggests it wouldn't be cheap.
'It's basically a giant air conditioner'
Electrically-powered permafrost freezers are already being used under some buildings in Alaska, with the technology dating back about 30 years, according to Keith Mobely, who works with Northern Geotechnical Engineering Ltd. in Anchorage.
Some models cycle liquid refrigerant through coils underground, while others blow cold air directly onto the surface.
"It's basically a giant air conditioner," Mobely says.
Mobely says the system is usually installed as a last resort. The company's website notes active systems "can be expensive to operate," and therefore says it tries to pair them with non-powered systems, like thermosyphons.
One such system is already installed under the Ross River school, though it has not performed to expectations. The school has needed many rounds of renovations to repair damage caused by shifting.
Company pitching idea installed thermosyphon system in 2001
The company pitching the idea has worked in Ross River before. Arctic Foundations Canada installed the current thermosyphon system underneath the school in 2001.
The system was criticized in a report by Associated Engineering in 2015, which noted that the thermosyphons were placed above the building's concrete footing pads and inside the building, rather than in the subgrade below them.
Bill Watt is vice-president of the Manitoba-based company.
"I think that would be successful," he says of an electric system. "During the summer months [under the Ross River school] the ground thaws out. If you can cool it artificially during the summer months, you can cut off that heat degradation," he said.
Watt said the company has approached the Yukon government with an estimate. He wouldn't discuss the projected cost.
"I'm not sure whether I should be divulging that," Watt said. "We have given the Yukon government an estimate but I prefer you got that information from them."
The Yukon government has not disclosed details of the company's pitch.
Solution seems 'awkward', says permafrost researcher
Dr. Fabrice Calmels studies permafrost at the Yukon Research Centre at Yukon College.
He thinks the solution proposed for Ross River is an odd one that raises bigger questions about adaptation to climate change.
"I'm not an expert in this kind of system, but what seems a bit awkward is that if the climate change trend continues, it will mean the last place where permafrost will remain is under these buildings," he said.
"It will only preserve permafrost on the disturbed site while permafrost is thawing all around."
Calmels notes that Yukon will require plenty of solutions in the long-term, as permafrost shifts under buildings and roads.
A report from David Nairne and Associates Ltd., an engineering firm tasked with evaluating the Ross River school, says the school "is currently structurally safe to occupy, but requires a long-term strategy to monitor and mitigate permafrost degredation."