EDMONTON – Alberta Environment approved new guidelines for constructing large artificial lakes in the northeast to store toxic tailings and close off old oilsands mine sites, though the technology remains “contentious.”
The department’s endorsement of so-far unproven technology was welcomed by Syncrude, the first oilsands operator trying out the technology to transform a 20-year-old tailings pond into a clean lake.
About 30 artificial lakes are planned as an alternative to reforesting some of thousands of hectares of boreal forest dug up to get at the oilsands – as well as to store tailings or waste from the open-pit mines. Called “end pit lakes,” they are constructed in the last pit of a mine.
The technology for cleaning tailings from the water hasn’t yet been proven on a commercial scale in the oilsands, Alberta Environment and Sustainable Resource Development notes in a letter to the region’s major environmental group, the Cumulative Effects Management Association. But that will happen in the future, said the letter.
“When we approve mine applications and closure plans, we accept in principle that the end pit lakes can be successfully reclaimed. Over time, we expect mine operators to demonstrate this,” said deputy minister Dana Wood in the Feb. 26 letter.
“Although many aspects of oilsands end pit lakes development remain contentious,” the CEMA report on how best to construct these lakes, released last fall, is “authoritative,” says the letter.
“As such, the government would anticipate oilsand mine operators demonstrate their consideration of the guidance document …” when they submit mining plans for approval by the Energy Resources Conservation Board.
Syncrude last fall disagreed with the CEMA report which called for caution when dealing with tailings in the proposed lakes, as it could take decades to find out if artificial lakes will actually clean the water. If they don’t, the landscape would be dotted with polluted lakes.
But the government’s endorsement of the lakes is encouraging, say company spokesperson Cheryl Robb.
“We are pleased the government recognizes end pit lakes as a common feature in reclaimed landscapes,” said Robb.
CEMA is also “pleased” the government has endorsed its scientific report which outlines the most up-to-date science on how best to construct such lakes, said Kyle Harrietha, CEMA communications manager.
Filling an old mine pit with water at the end of the mine’s life is common in the metals mining industry, but the technique has not yet been tried in the oilsands mining in the boreal forest.
Nikki Booth, AESRD spokesperson, noted that several coal mines in Alberta closed with an end pit lake, and at least one is now used for fishing. It has received a provincial reclamation certificate, which relieves the company of liability for the site.
“We do recognize the successful reclamation of an oilsands mine end pit lake has yet to be demonstrated on a commercial scale,” said Booth, adding that will happen in time.
CEMA did not make a recommendation in favour or against the use of end pit lakes to reclaim old mine sites. That issue was left to government and the ERCB.
The report focuses on dozens of techniques the oilsands companies should follow in planning the lakes, how to connect them to the local watershed and raises questions on whether the water needs to be treated before entering local streams to avoid polluting the watershed.
Syncrude’s effort is the first commercial-scale use of the technology on the its 20-year-old tailings pond into a lake – the same pond where 1,500 birds died in the sticky sludge a few years ago.
In January, the company stopped pouring the mine waste, a sludge of water, sand, acids and leftover bitumen particles into its Base Mine Lake.
In the spring, a freshwater cap of five metres will be put on top of the sludge. The particles will drop to the bottom of the lake, and naturally occurring bacteria at the bottom of the lake will eat the sludge that makes the ponds lethal to birds, says the company,
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