The trouble with tailings

Tailings ponds are big. How big? Stand on the shore of the Mildred Lake pond near Fort McMurray and you'll see how it fills your whole horizon.

On the far shore, you'll see a smoking silver stub that's actually an eight-storey smokestack. Fly up, and you'll see the pond is almost half the size of St. Albert.

And that's just one pond. Tailings ponds now cover about 170 square kilometres of Alberta, or about five St. Alberts, all carved from what once was boreal forest. According to the Pembina Institute, those ponds hold about 840 billion litres of toxic fluid — enough to flood St. Albert 24 metres deep.

Tailings ponds are a big problem. They're a toxic liability that kills animals and keeps people from turning oilsands mines back into boreal forest. The ponds have been around for about 40 years and we've yet to restore any of them.

It's Randy Mikula's job to make these ponds disappear.

Mikula is head of the extraction and tailings group at the CanmetENERGY Technology Centre in Devon, one of the many groups working to reclaim or restore the oilsands to natural conditions.

Companies have already made substantial progress, he says. Suncor used to have a massive tailings pond by the Athabasca River, he notes, calling up a picture on his computer. Using techniques he helped develop, they've now shrunk it to a fraction of its former size. "Now we're creating something that you can reclaim the boreal forest on and we're saving all that water."

Tailings trouble

What are tailings? Mikula pulls four jars out of a box to explain.

The first is full of black sand. This is 500 grams of oilsands, he explains, a combination of sand, bitumen, clay and water. To remove the oil, you add hot water and stir, creating this little 100-gram jar of black, oil-filled froth. You also get a lot of water and two types of tailings: coarse tailings, like wet sand, and fluid fine tailings, a grey mud made of microscopic clay particles. The froth goes to an upgrader; the rest, including any leftover bitumen, goes to the tailings pond.

The pond serves two functions, he explains. First, it gives the tailings time to settle out of the water. Second, it stores that water so it can be used to process more oilsands.

But they also cause problems. The water is toxic, notes Warren Kindzierski, a professor of environmental health at the University of Alberta, as it contains concentrated naphthenic acids and other toxins from the bitumen that could harm people and fish. "At this stage, one could not take tailings [water] and release it into the environment."

The ponds also form huge mats of leftover bitumen on their surface that can kill birds when they land in them, mistaking them for lakes. Scarecrows and propane cannons can repel the birds, but they don't always work. About 1,600 birds died on Syncrude's Aurora pond when its deterrents failed in 2008.

The fluid tailings are the big problem. Mikula cracks open a barrel of them. Coarse tailings settle out of the ponds fast, Mikula says, making them easy to work with — you pile them on the berm around the pond, making a nice beach. But fluid tailings are made of clay particles that form sponge-like, water-holding matrixes when put together, which makes them stay soft and fluid for years. The material in this barrel is 30 years old, and, as he demonstrates, still flows like soup — too soft for machines, animals or trees.

It will take at least 500 years for these fluid tailings to naturally solidify, Mikula says. "My own opinion is 'never,'" he says. "As long as there's water on top of it, it will never develop enough strength to reclaim the boreal."

That's a problem for the oilsands. Directive 074 from the Alberta Energy Resources Conservation Board requires industry to turn at least half of the fluid tailings they produce into stackable, reclaimable chunks by 2013 if they want to stay in business. They can't wait 500 years.

Spin it, spread it, ditch it

Researchers are working on many technologies that could speed up the reclamation process.

The simplest is consolidated tailings, or CT. Adding gypsum and sand to fluid tailings disrupts their ability to hold water, Mikula says, causing them to dry faster. Suncor used this on its oldest pond and saw it go from sopping wet to mostly dry in three years. The company plans to start reclaiming it within a year.

CT was a huge accomplishment when Mikula and his team developed it 1994. "We thought we had invented fire," Mikula says. But it's too slow for today's standards; you can't use CT until you're done using a pond, a process that can take 17 years or more.

Researchers are developing other systems that can solidify tailings as they are produced. Syncrude has built a $10-million centrifuge to spin the water out of tailings. It's expensive and energy-intensive, Mikula says, but you get stackable tailings after about a month.

Syncrude has also invented a process called rim-ditching. Here, you put the tailings in a big bin and dig a ditch around the edge. Gravity squishes the tailings, forcing water into the ditch where it can be drained, creating solid tailings in about nine months. Rim-ditching could handle a lot of material at once, Mikula says, but needs a big, expensive dam to contain the material.

Suncor's thin-lift system uses a similar technique. Here, the tailings are spread in six-inch layers, exposing more of them to the sun to speed evaporation. You get stackable tailings in a few months, but at a cost of a lot of space and labour.

There are plenty of other ideas, too, notes renowned Alberta geologist David Devenny in a 2009 report to the Alberta Energy Research Institute on fluid tailings. You can add thickeners to the tailings and put them in sort of an ice-cream machine that squirts thick tails out the bottom. You could put them on a belt and suck water out the bottom. You could bake them, freeze them, or put water-absorbing plants on them.

Who needs a pond?

Or you could stop using ponds altogether.

Just 20 per cent of the oilsands can be surface-mined, according to the province, and you only need tailings ponds for surface mines. The rest is deep underground, and has to be recovered with in-situ technology. Here, companies use steam to melt the bitumen out of the sand underground. The bitumen flows into a pipe for recovery, leaving the tailings behind.

In-situ mines disturb much less land than surface ones, according to the Pembina Institute — about 1.4 hectares per million barrels of oil compared to 9.4 for surface mines.

They're also easier to reclaim, says Drew Zieglgansberger, spokesperson for Cenovus Energy, one of the oldest in-situ companies in Alberta. They don't have fluid tailings to manage, so rehabilitation should be a matter of removing equipment, capping pipes, spreading stored topsoil and planting trees. No one's actually done this yet, he notes, as most in-situ sites are less than 15 years old.

The oilsands industry has done a poor job of managing tailings ponds, Devenny writes. It's tended to defer reclamation until it's done mining, creating short-term profits and long-term liabilities, including the risk of a catastrophic release.

Nine oilsands operations have submitted plans to the province showing how they will meet Directive 074. Of those, according to the Pembina Institute, just two meet the deadlines set out in the directive.

Even with new technology, it's unlikely that tailings ponds will ever completely disappear, Mikula says. "You need some place to store all that [process] water," he says, and the ponds are a good place for it.

But they could stop the ponds from getting any bigger, he adds. "We're going to be at about the break-even point maybe five years from now."

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What about the birds?

Tailings ponds are a hazard to birds and wildlife. They contain toxic water and bitumen mats, but look like lakes, which draws animals to their deaths.

It's impossible to deter all birds all the time, says Colleen Cassady St. Clair, a professor of biological science at the University of Alberta who testified at the recent Syncrude trial, but you can keep many of them off a pond with scarecrows and propane cannons. But birds can adapt to these deterrents and start ignoring them.

Companies are testing ways to prevent this adaptation. Albian Sands has hooked its scare cannons to radar, for example, so that, instead of firing randomly, they only go off when a bird is approaching the pond.

Companies could also build a decoy pond full of food and shelter to draw birds away from their tailings pond, St. Clair says. No one's tried this yet, but she believes it could work.

Industry could show due diligence and raise public confidence if they simply stepped up their use of deterrents, St. Clair says.

But the most effective way to protect birds is simple, she says: get rid of the ponds.