The leak was discovered Monday at a Suncor (TSX:SU) base plant north of Fort McMurray.
Company spokeswoman Sneh Seetal said a pipe about four metres long and 10 centimetres wide froze and burst, sending "process-affected water" into a partially frozen outfall pond containing treated water.
Some of the fluid then entered an approved discharge area containing clean water, and was released into the Athabasca River.
Seetal said it's not yet known what exactly was in the waste water or how much of it was discharged.
The leak lasted for at least a few hours. Seetal said the company notified government officials about 1 p.m. and the pipe was shut down three hours later. The move has not affected the plant's operations.
Seetal said because the waste water was diluted with clean water, the company isn't too concerned it will affect the environment.
"We don't anticipate any impact on the river, but we are going to continue to monitor river samples."
Seetal said tests are also being done to reveal the contents of the waste water. It would be premature to speculate whether oil is in the water, she added.
"It is water that has been used in our extraction and upgrading process and has not yet been treated," she said.
The company also posted on its website that water quality is an important issue to its stakeholders. "This incident is unacceptable to us. Our focus is on investigating how this occurred and ensuring this doesn’t happen again."
Greenpeace Canada reacted as soon as the leak was reported. Spokesman Mike Hudema said processed water often contains bitumen and dangerous chemicals.
He said Suncor should be keeping a closer eye on its pipes during cold weather. "For a pipeline to freeze on their watch is quite troubling."
He's further frustrated about the lack of information the company is giving out. It should know what is in its waste water and easily be able to calculate the volume that went through the pipe, he suggested.
"The public has a right to know. I believe Suncor has that information. They're just not giving it out."
Alberta Environment spokesman Wayne Wood said the department is relying on Suncor to supply numbers about the spill. Government staff were on the site Tuesday overseeing containment and cleanup, he said.
Wood said the government is also conducting water tests. They should be completed in a couple of days.
Suncor initially said it didn't know if any waste water had spilled into the river and didn't confirm the news until late Tuesday. But the chief of the Athabasca Chipewyan First Nation said company officials earlier informed the reserve that it had.
"It got into the river, guaranteed," said Allan Adam.
He expects it will take about six days for any spilled fluid to flow north and reach the community. The reserve sits on the shore of Lake Athabasca, where residents get their drinking water.
Adam recently returned from a trip to Ottawa where he and other First Nations leaders met to underline their opposition to the Northern Gateway and Keystone XL pipelines.
A pipeline breach so soon after he got home just makes it more clear that the industry needs to be more responsible, he said.
"There has to be another means, or mechanism, put in place to make sure community well-being is looked after in regards to how these lines are put in place."
— By Chris Purdy in Edmonton
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