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What lies beneath

The bills come due for hardrock mining's toxic past

November 1, 2002


Douglas Clement Senior Writer

When he died in 1925, Montana "copper king" and U.S. Sen. William Andrews Clark—the eighth richest American of his time—left behind an ostentatious legacy: impressive mansions in Butte and New York City, a major railroad in Nevada, an important collection of European art donated to the Corcoran Gallery in Washington, D.C. But his most significant bequest remained deeply hidden for decades. And it was revealed only because of a small wooden dam he had ordered built in 1905 near the tiny Montana community of Milltown.

The Milltown dam—made of timber cribs filled with rocks—was built to generate electricity for sawmills and for the young city of Missoula, a few miles downstream. The power surged through wires made of copper from Clark's own mines 120 miles upriver. "This is an important day for Missoula," trumpeted the Daily Missoulian when the dam was completed in 1908 and its reservoir began to fill. "The city will have a supply of electric power second to no municipality in the state."

Nearly a century later, the aging dam still provides a few megawatts of electricity. What it generates best, though, is anxiety.

In 1981, a routine check of drinking water in homes near the dam revealed arsenic levels as high as 500 parts per billion (ppb), 12.5 times the existing federal limit (and 50 times the standard set in 2002). Vegetables in backyard gardens were also laden with the carcinogen. One spinach sample had 2,660 ppb of arsenic; a head of lettuce registered 1,410 ppb. Normal levels are 1 ppb.

After months of research, investigators found that the source of contamination lay beneath the placid waters of the Milltown dam. In deep sediment that had collected over decades in the dam's reservoir, scientists discovered thousands of tons of arsenic, lead, cadmium, copper, iron, zinc and manganese—waste products sent downriver from the copper mines of Butte and Anaconda, the source of William Clark's wealth.

In the years since the sediment was discovered, the people of Missoula have grown increasingly worried that the dam is a disaster waiting to befall them. If an ice floe hits, as nearly occurred in 1996, or if an earthquake trembles, as some geologists predict, the dam would breech. The trickle of toxins that now seeps through the dam could become a poisonous flood, polluting the aquifers of Montana's second largest city and contaminating the river for miles.

The fate of the Milltown dam will soon be decided by the Environmental Protection Agency (EPA), with a recommendation issued this fall and a final decision early next year. Many have called for dredging the sediment and removing the dam—a permanent but expensive solution. Others (including Atlantic Richfield Co., which inherited the liability and must pay the bill) prefer the cheaper option of reinforcing the dam and monitoring the sediment.

But the dam sediment has turned out to be just an indicator of a far larger disaster, the proverbial canary in the mineshaft. Milltown's arsenic plume led investigators to far worse problems upstream, at the smelters of Anaconda, the enormous metal ore waste piles of Opportunity Ponds and the mine shafts of Butte. And then there's the infamous Berkeley Pit, the milewide strip mine in Butte that became an international rallying cry for environmentalists when an ill-fated flock of geese landed on its acid waters in 1995 and never took flight again.

The little dam that Clark built thus revealed the most enduring legacy of Montana's copper mines: an environmental nightmare that will take at least a billion dollars to remedy and decades—if not centuries—to heal.

Hazards of hardrock

Hardrock mines have generated countless tons of valuable metals and vast quantities of durable toxins, and these benefits and costs of mining tend to fall upon very different parties. Within the Ninth District, Montana, South Dakota and Wisconsin are the states most affected by the promises and problems of hardrock mines, so the questions that confront the citizens of Missoula are being faced by others as well: How did the problems become so extreme? What is to be done with the toxic legacy left by decades of hardrock mining? And who will pay?

Fingers point, understandably, at the hardrock mining industry, the companies that extract metal from hardrock ores (as opposed to coal, gas and oil, where mining practices differ considerably). It is an industry already facing hard times—tough global competition, declining ore quality and historically low prices [see the July 2002 fedgazette]. It is also an industry whose products we need or desire: Copper carries our electricity; zinc coats our auto parts; gold is our quintessential, if somewhat archaic, symbol of wealth.

The industry itself reminds us that it also creates jobs and economic multipliers. Click on the National Mining Association's Web site and you'll learn that the "mining industry is vital to the state's economy" in every state of the Union, including Delaware where it employs 100 people and mines $14 worth of metal per resident. But despite its undeniable contributions, the hardrock mining industry is facing profound skepticism about the benefit/risk ratio it presents and growing doubt about whether the economic privileges and protections it long has enjoyed should be preserved.

Burden of gilt

Dead are the days when a lucky gold miner could dig a nugget from the wall of a mine shaft or pan a few flakes from a stream. With the richest deposits played out long ago, gold mining in the United States now involves crushing tons of rock, piling it in huge heaps and spraying those heaps with cyanide to dissolve microscopic gold deposits from its ore. The technique, called "cyanide heap leaching," is tremendously cost-efficient. But cyanide carries obvious risks, and over the last two decades mining-related cyanide spills have occurred with disturbing regularity. According to industry data supplied to the EPA, 1.6 million pounds of cyanide were released into the environment by hardrock miners in 2000 alone.

Large-scale cyanide heap leach mines have been around since 1979, when Pegasus Gold, incorporated in Canada, opened the Zortman-Landusky mines near Hays, Mont. State permitting authorities allowed the mining complex to expand nine times over the next decade despite numerous cyanide spills. But not until the EPA pressured the state after discovering cyanide, arsenic and lead leaking from each of the mine's seven drainages in 1993 did Montana file suit against Pegasus for violating state water laws. The EPA filed its own suit in 1995 and the company settled out of court, admitting no guilt but paying a fine, establishing a reclamation bond to cover future damage and agreeing to implement a detailed pollution control plan.

The Gilt Edge Mine, near Deadwood, S.D., was another Ninth District mine with repeated cyanide spills during its 11-year history. Run by Brohm Mining, a subsidiary of Canadian-owned Dakota Mining Co., Gilt Edge had its first spill within the first year of production, was fined by the state's Department of Environment and Natural Resources (DENR) and told to improve its cyanide capture process. But spills continued.

Numerous other mines in the district have had similar cyanide problems, and spills recurred at many of these sites even after state authorities caught and fined the mine operators. To prevent future problems, Montana voters approved a 1998 ballot initiative banning cyanide heap leaching. A bill prohibiting cyanide use at mines died in committee at the Wisconsin Legislature in 2002. But as it turned out, while government authorities and environmental groups were focusing on cyanide spills, a far more serious problem was developing.

Acid waste

Most metals we mine are located in hardrock that also holds sulfur compounds. Deep within the earth those compounds pose no problems. But when the rock is crushed and exposed to air and water, it begins to generate sulfuric acid. The acid dissolves other heavy metals—selenium, lead, cadmium—and as it flows into nearby rivers, lakes and underground aquifers, the acidic solution kills aquatic life and renders water supplies poisonous. Cyanide spills are harmful, but acid mine drainage is an environmental and economic catastrophe.

"Zortman-Landusky is generating a large amount of acid that we currently can control," said Jim Kuipers, a Boulder, Mont., mineral engineer who managed hardrock mines in the United States and overseas for a dozen years and now consults with state and tribal governments, and citizen groups. "It'll be generating 10 times that amount in 20 years. A lot of these things are just maturing. It takes time to cook. As you expose the sulfides longer to oxygen and water, and the bacteria have a chance to go to work, it just continually generates."

When acid mine drainage (AMD) was discovered at the Gilt Edge Mine in the mid-1990s, state officials pushed Brohm Mining to address the problem and bump up reclamation bonding from $1.2 million to $6 million to ensure that cleanup costs would be covered. But Brohm's parent, Dakota Mining, went bankrupt in July 1999. "It's one of those sad stories where about the time that we recognized the problem with the acid mine drainage, that was the time the company was in financial problems," said Mike Cepak, the DENR engineer in charge of site reclamation.

Now the state of South Dakota is left with massive piles of acid-generating rock and three pits filled with millions of gallons of acidic water. Two of the pits are "a burgundy red," said Cepak, because of metals dissolved in the acid. The third pit is being treated with an experimental mix of lime, ethanol and molasses in the hope of generating a biochemical brew sufficient to buffer the acid. The experiment has failed so far, but the side effects are interesting. "It's kind of Prestone green," said Cepak, and the alcohol levels are high-proof. "If it wasn't denatured, it would be quite a party out here."

"Forever, almost"

What will it cost to reclaim the Gilt Edge mine? "That's a big question right now," Cepak answered as he listed the steps that will be taken to clean up the mine site: Capping waste piles with a plastic geomembrane so rain doesn't penetrate; regrading land to encourage water runoff; revegetating the denuded landscapes. "The work that we're looking at right now is going to cost around $30 million, and then we still have to do the water treatment and take care of the pits," he said. "I have no idea how much that will add to the cost. It could easily double to $60 million. That's just a guess. It could be even more. With this type of acid mine drainage, the main problem is it's a reaction that could last for centuries, so you have to plan for forever, almost."

Unfortunately, Gilt Edge isn't the Ninth District's only AMD problem. Virtually every gold mine in the area, as well as copper mines in Butte and elsewhere, will require water treatment for years. And while the biochemistry and geology are still too unclear to permit accurate guesses about the time it will take to mitigate damage at any given site, nobody thinks it can be done quickly. "The predictions the best in the industry have been able to come up with" for acid drainage at Zortman-Landusky, said Kuipers, "suggest that we're going to be treating for at least 1,000 to 10,000 years there. And at Golden Sunlight [near Whitehall], I think 7,000 years is what they're predicting for a period of water treatment."

While acid mine drainage is the most daunting of mine cleanup chores, other hazards must also be addressed. In fish taken from streams near the closed Beal Mountain mine site in Montana, for example, the U.S. Forest Service has found abnormally high selenium levels. "Not every mine has an acid drainage issue," noted Kuipers, "but may have a thallium issue or a selenium issue or a nitrates issue. It just seems like every one has something."

Indeed, hardrock mining has such a widespread environmental impact that it has topped the EPA's Toxic Release Inventory every year since 1998, when the industry was first included in the list. In 2000, the most recent year available, hardrock mining companies were responsible for over 47 percent of all toxic waste released into the nation's air and water. The National Mining Association responds that the industry's 2000 releases were "generally lower" than in 1999 and that the data aren't necessarily indicative of health risks because they don't report on levels of human exposure or on the toxicity of specific pollutants.

Still, the Western Governors' Association has been concerned enough to compile a list of streams polluted by hardrock mines; it concluded that mine wastes have contaminated 3,346 miles of rivers in six Western states, including 1,118 miles in Montana alone. And the scale of the cleanup task is immense. According to South Dakota's DENR, there are 900 inactive and abandoned mines in four of that state's western counties in the Black Hills. Not all pose serious environmental risks, but cleanup costs will be substantial nonetheless. In the United States as a whole, according to the Mineral Policy Center, an environmental group in Washington, D.C, there are approximately 550,000 abandoned mines, with cleanup costs ranging as high as $70 billion.

Related stories:
Digging in or digging out? [July 2002 fedgazette]
Despite new exploration, mining's future in a deep hole.