YELLOWKNIFE (CP) -- The Canadian federal and Northwest Territories governments have announced a joint cleanup plan for one of the North's most notorious environmental problems - 237,000 tonnes of arsenic, stored in underground stockpiles under the shores of Great Slave Lake.
The agreement, signed Tuesday in Yellowknife, will commit the governments to at least another $53 million towards cleaning up the Giant Mine, one of the longest and most expensive environmental cleanups ever undertaken in Canada, all at public expense.
The Giant Mine poured its first gold brick in 1948 and the millions of ounces that followed have long since gone _ as has the last owner to fully operate the mine, Royal Oak Mines.
But its toxic legacy remains.
Under the agreement, the territory will spend $3 million over three years on care and maintenance of the mine and another $20 million at some point in the future on the actual cleanup.
Ottawa expects to spend another $30 million over three years toward care and maintenance, as well as finalizing the remediation plan and shepherding it through the regulatory process. The federal government has already spent $30 million over the last five years on the cleanup.
After 10 years of engineering studies and public hearings, engineers, politicians and community groups agreed on a solution: freeze the entire mine like an enormous, inverted Popsicle and let the arctic permafrost hold it all in place.
The federal government assumed control of the mine after Royal Oak's 1999 bankruptcy. Although it was later bought by Miramar Mining, which continued for a while to haul ore from the Giant, the environmental liability remained with the government.
The arsenic is a byproduct of Giant's refining process. The mine has 15 underground chambers filled with arsenic dust, some large enough to swallow an 11-storey office building with plenty of room left for a few walk-ups.
The solution involves devices called thermal siphons, commonly used in the North to keep permafrost solid under a building's foundations. Office buildings, homes, even a dam at the Diavik diamond mine depend on the technology.
At the Giant, refrigerating pylons would be sunk to the level of the lowest arsenic chamber to restore the permafrost destroyed by decades of mining. The siphons, which require no outside power to operate, would then keep the ground frozen.
Water would slowly be flooded back into the mine, freezing and immobilizing the entire area.
The entire process will take 20 years. Estimates suggest it will cost the taxpayer somewhere between $90 and $120 million.
Even that figure doesn't include Giant's surface cleanup, which includes several tailings ponds, numerous garbage dumps, and a handful of large, dilapidated mine buildings, many with exposed asbestos waving in the breeze.