Creating artificial lakes from tailings ponds.
Report explores the challenges of aquatic reclamation plans
Up to 30 large, artificial lakes could be built in the oilsands area if the province approves the idea as a new way to reclaim thousands of hectares boreal forest dug up for the massive open-pit mines.
While the goal is to create lakes clean enough for fish and recreation, it is also possible — given the unproven technology — that some of permanent pools could be left polluted with toxic tailings and solid waste from old mines for decades.
And it will take 100 years to know for sure, says a new report by the industry-funded group in the Fort McMurray area, the Cumulative Effects Management Association, which includes oilsands operators, environmentalists and First Nations.
The association’s report looks at the challenges of building lakes, filled with rain, water from the Athabasca River and “process” water used in mining, and then connecting them to local watersheds.
Up to half the “end pit lakes,” as they are called, could be used for permanent disposal of dry tailings — mining waste made of sand, clay and an array of chemicals — which would be dumped into the lake bottom and “capped” with fresh water. In theory, the fine tailings would stay on the bottom.
In their reclamation plans, oilsands operators have long proposed using lakes as the mines close, though little research was done until now. The last area to be mined — the end pit — would be filled with water, which is easier and more economic to move than soil.
Companies later proposed dumping their tailings into the lakes for permanent storage — a more controversial proposal because the tailings contain hydrocarbons, salt and naphthenic acids that are too toxic to be released into the environment. Currently, the tailings are stored in large ponds on the mine site.
The Cumulative Effects Management Association’s report, submitted to Alberta Environment and the Energy Resources Conservation Board, does not recommend for or against the artificial lake option. Instead, it outlines the gaps in science and provides guidelines for building the lakes, said Glen Semenchuk, the association’s executive director.
It’s up to the province or ERCB to decide whether to include the lakes as an approved technology for reclamation and devise environmental standards for the lakes in the information provided in the report, Semenchuk said.
“If you are even contemplating this, our report tells the regulator what you have to think about and (possible) regulations,” Semenchuk said.
“If we’re going to do it, we wanted everyone to know what the risks are. Unless you can start answering some of those key questions, you have to be cautious.
“It takes a lot of planing and about 40 to 50 years before you start seeing — ‘did we do this right?’ ”
The provincial government will also have to decide whether an artificial lake is a fair replacement for the destroyed trees and landscape that provides habitat for a range of wildlife from moose to caribou, Semenchuk said.
Government policy requires oilsands operators to return the disturbed land to a state “equivalent to” the natural conditions of the boreal forest in northern Alberta.
“The question of equivalency is very big,” Semenchuk said.
End pit lakes have in recent years been approved for abandoned coal mines in Alberta, he said. One of those lakes, East Pit Lake near Wabamun, is used for fishing.
But the lakes planned by oilsands operators are “very different” — a large system of about 30 artificial lakes on seven mining leases that would be linked to the local watersheds. Given that link, there’s a question of whether the water needs to be treated before it flows out of artificial lakes.
While engineers say the tailings will stay at the bottom if the lake is deep enough, the technology is unproven.
“To go from what a mine is today to having a lake in the boreal forest is close to 100 years,” Semenchuk said.
The report recommends an oilsands company be required to design the lake at a mine site before the mining begins — even though it would not likely be used until about 50 years after the first bitumen is removed, given the long life of the mines.
Given the size, the lake would take about 10 years to fill with a combination of fresh water and water used in mining process.
But not all of the 16 stakeholders who belong to CEMA are happy with the report.
Longtime oilsands operator Syncrude, which is preparing to seek approval from the ERCB for the first such lake, Base Mine Lake, rejected the CEMA report as biased against the proposal to dispose of tailings in the lakes.
The report “asserts an unwarranted bias against the inclusion of fluid tails in end pit lakes,” says Syncrude in a letter that accompanies the report. “Syncrude has concerns with the balance, accuracy and functional value of this document ...”
Other oilsands operators supported the report.
But the Alberta Fish and Game Association, a member of the CEMA, was highly critical of the report for not being tough enough, given the unproven science.
“The current information suggests there are significant environmental risks establishing such end uses with tailings ponds contaminated water,” says the association in a letter.
There’s “uncertainty” about water quality in the lakes and “the ability of humans and aquatic life to use the lakes after 100 years.”
As a result, the province could end up with “problem tailings-lakes in 100 years and these will be left to the residents and Albertans who use the area.”
“The Alberta Fish and Games Association does not support the development of end pit lakes as the final end use of reclaimed surface-mined oilsands unless these waters are not contaminated and they meet the principles of healthy aquatic eco-systems that restore lands and the watersheds.”