What is that yellow goop in the water? Acid rock drainage–metal leaching, or just “acid drainage”, is usually associated with mining but also happens during large building projects, like the Site C dam — basically any time a large amount of rock has been crushed, blasted, or otherwise made to have a lot of new surface area open to the air. It’s a result of sulphur-containing compounds in the rock reacting with air and water, causing the formation of sulphuric acid.

It gets worse: That acid can then leach heavy metals out of the rock, which can get into nearby watercourses. This process can go on for hundreds or even thousands of years after the mine is shut down.

So, sulphuric acid and heavy metals in the water. Got it. Why is that bad?

I shouldn’t have to explain this, let alone to myself, but here we are. With the lower pH and heavy metals such as cadmium, nickel, chromium, and arsenic, watercourses can be made unsafe for humans and animals. It can also kill the fish living in the water, as well as their eggs, insect larvae, and other organisms. It’s sulfuric acid and heavy metals… in the water.

Wait, you didn’t answer my question re: the Goop.

Fine, geez. That’s what’s known as Yellow boy; it’s when iron is leached out of rock by strong acids. When the pH comes back up, the iron comes back out of the solution as that yellow goop. Yellow boy can coat stream beds, blocking plant photosynthesis and suffocating wildlife.

Thank you.

You’re welcome. Let’s move on.

Who knew piles of rock could be so dangerous?

The mining industry does. It’s a major concern for them; a publication by the Canadian Mining Innovation Council called it “the largest environmental risk facing the mining industry.” There are even entire annual conferences on the subject.

A Canadian government program called Mine Environmental Neutral Drainage (MEND) has been working on reducing the risk and liability from acid rock drainage for nearly three decades. That liability was estimated in 1994 to be between $2 and $5 billion.

One example of an ongoing problem with acid rock drainage is the Tulsequah Chief mine in northwestern B.C. That mine shut down 60 years ago, but continues to pollute the Tulsequah River, a tributary to the salmon-bearing Taku River. Two companies have gone bankrupt while looking to restart that mine, and the lack of cleanup continues to be a sore spot for Alaskans living downstream.

What is the mining industry doing about it?

There are a number of approaches to this problem, some more technologically advanced than others. The simplest method is to just dump the tailings in water — remember, the problem comes from air reacting with the sulphides — in order to prevent contact between the air and the rock. That’s not a perfect solution, as the Mount Polley disaster showed, because if the dam holding that tailings pond fails, the problem is essentially spread throughout an entire river system.

Other methods follow a similar tack, covering the rock in various materials to keep it from reacting with the air.

There are also more complicated methods of preventing acid rock drainage, involving adding chemicals, bacteria, or bacteria-like organisms to the rock to remove the sulphates before they can react with the air and produce the acid. Mines can also add buffers, chemicals that offset the acid.

To treat ongoing problems, usually from abandoned mines, companies can add lime (a very basic chemical that lowers the acidity), divert the runoff through limestone channels for the same effect, or even use constructed wetlands to treat the water before it reenters existing watercourses.

TL;DR

Mines crush a lot of rock. Often, because of where valuable metals are found, those rocks contain sulphides, which react with air to make acid. That acid can then leach metals out of the rock and contaminate water, making it unsafe for consumption. It’s responsible for billions of dollars in environmental liabilities in Canada alone. It’s a whole thing.

Companies and governments around the world are working on solving the problem, but it’s a tough one. It can be prevented to some degree, and it can be remediated. But it takes time and money, and the problem can go on for generations. Countries like the UK are still dealing with Industrial Revolution-era acid rock drainage problems.

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The Tulsequah Chief mine, a zinc and copper mine close to the Alaska border, has been leaking acid mine drainage into the Tulsequah River since it was first shut down in 1957 and attempts to re-open the mine have failed, along with a multitude of promises to clean up the site.

Two companies have gone bankrupt during their ownership of the Tulsequah Chief, with the current owner, Chieftain Metals, declaring bankruptcy last September and there are now reports that Black Loon Metals has backed away from a potential deal to take over the site.

Black Loon chairman, Gordon Bogden, would not say whether the company remains interested in buying the Tulsequah Chief.

“As a private company we do not comment on our investment opportunities,” Bogden said in an email.

The NDP have indicated cleanup of the Tulsequah will be a priority for the new government. In early July, Jen Holmwood, caucus spokeswoman for the NDP, said cleanup of mine “is a serious issue we’ll be looking into and have to say more on in the weeks ahead.”

Green Party leader Andrew Weaver has previously stated the abandoned mine gives B.C. “an environmental black eye.”

Mine Closure, Water Treatment, Priority for Alaskans Living Downstream

Chieftain still holds a permit to build the initial phase of the mine, but receiver Grant Thornton LLP wants to sell assets and the water treatment plant — which operated only briefly because of operating costs — to help repay creditors.

Decades of pollution, running into the Tulsequah River, have infuriated Southeast Alaskans as the Tulsequah is a tributary to the salmon-rich Taku River and there are fears that the acidic drainage could affect salmon runs.

In 2015 then mines minister Bill Bennett appeared shocked by the mess when he visited the site and promised that the mine would be cleaned up, but he later backtracked, claiming the runoff poses no environmental threat.

But a study by SLR Consulting (Canada) Ltd. — which was commissioned after a risk assessment by Chieftain Metals was found to be flawed — documents details of damage to fish habitat from the acid mine drainage.

The report, released last month, looks at four zones within the river and tests showed hazards are highest in the zone closest to the discharge.

“This is likely because multiple undiluted and untreated sources of historic mine waste are discharging into the Tulsequah mainstem and side channels from surface water and groundwater inputs,” says the report.

“Metal concentrations pose unacceptable risks to fish, fish eggs and pelagic invertebrates.”

The waste includes cadmium, copper, zinc, aluminum, iron, lead, cobalt and sulphate, says the study, which recommends reducing the overland flow and doing follow-up assessments.

In some zones the contamination could be worse than documented as the study may not have captured the “worst case scenario,” according to the SLR assessment.

The new study should put an end to claims that the mine runoff is not harming fish and water quality, said Chris Zimmer, Rivers Without Borders Alaska campaign director.

“After two bankruptcies and failed attempts to sell the mine out of receivership, it is clear that the Tulsequah Chief is not a viable mine, financially, environmentally or politically,” he said.

“The only way to stop the illegal and clearly harmful acid mine drainage from the abandoned mine into the salmon-rich Taku watershed is for B.C. to honour its promises and take responsibility for mine cleanup and closure.”

New BC Gov Inherits Toxic Legacy as #Tulsequah Buyer Backs Away from Abandoned, Leaky #Mine https://t.co/BsPYWQfMxK #bcpoli @BCNDPCaucus

— DeSmog Canada (@DeSmogCanada) August 4, 2017

Trying to reopen the mine is a recipe for another bankruptcy, more pollution and exposing the Taku watershed to mining and road building, said Zimmer, who is urging the new NDP government to take a more responsible approach to the cleanup than the former BC Liberal government.

“We urge the new Minister of Energy and Mines, Michelle Mungall, to honour the promise made by her predecessor and accept responsibility for cleaning up the mess at Tulsequah Chief,” Zimmer said.

Mungall could not be contacted in time for publication.

Image: Tulsequah Mine in 2010 by Chris Miller

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