Part of the problem is that modern mining with its open pits, massive waste rock dumps and toxic processing chemicals has outstripped environmental and mining regulations. They simply weren’t written to deal with massive open pits over a mile wide, mountains of waste rock and water pollution that can last 1000 years. And where regulations prohibited some actions, such as dumping tailings in stream drainages, industry has successfully gained exemptions to the law.

Another part of the problem is perception. Greenwashing by the mining industry portrays mines as strictly regulated facilities that temporarily use the land with minimal lasting effects. Public relations campaigns by industry trade groups, such as the Gold Institute, imply that with modern technology, mining nowadays poses little risk to the environment or public health. This article looks at two major mining components – cyanide leaching and “zero discharge” tailings impoundments – in an effort to explode these myths.

Ft. Knox tailings impoundment -- the green color is a result of ore processing chemicals.

Cyanide - Mining’s Poison Pill

Used to process both base and precious metals, cyanide is the reagent of choice at modern mines. 85% of the world’s gold is produced through the cyanide leach process.(1) Although acknowledging cyanide’s acute toxicity (1 teaspoon of 2% cyanide solution will kill an adult) the mining industry maintains that accidental releases of cyanide are rare, but that when they do occur, impacts “are transient and the recovery of the environment occurs in a short period.”(2)

However, that claim is not born out on the ground; lots of mines leak lots of cyanide into ground and surface waters. In Idaho, the Grouse Creek mine had numerous violations discharging cyanide at levels two to five times higher than allowed. Even after mining ceased in 1997, cyanide continued to leak into nearby Jordan Creek at levels harmful to aquatic life. At the Beal Mountain, Kendall, Golden Sunlight and Zortman-Landusky mines – all in Montana – numerous cyanide spills and leaks contaminated drinking water aquifers and killed streams. These weren’t transient effects. Because of persistent cyanide contamination, Pegasus Gold had to provide an alternative drinking water source to the town of Zortman, and Placer Dome bought out landowners downstream of the Golden Sunlight mine.(3) In fact, Montana has so many streams and aquifers contaminated with cyanide from mining operations that, in 1999, a citizen’s initiative to ban new cyanide leach operations passed by a healthy margin. Clearly Montana taxpayers, after watching their streams die and faced with a clean-up bill of close to $60 million, didn’t buy industry’s argument that cyanide doesn’t cause long-term problems.

“Zero Discharge” – Fact or Fiction?

Most mines process millions of tons of ore a year. The consistency of wet cement, tailings are what’s left over after the ore has been processed. Current practice for permanent tailings storage is to construct a dam across the mouth of stream, divert the stream, and dump the tailings in the drainage. At Ft. Knox, outside of Fairbanks, for example, over 1,000 acres of the upper Fish Creek drainage will be consumed by tailings.

The Clean Water Act, Section 402, prohibits polluting streams or wetlands with millions of tons of sediment laced with heavy metals and chemicals. Modern mining has circumvented this by arguing that through the construction of a dam, the stream is converted to a waste treatment facility, and thus is no longer subjected to Section 402 regulations, unless there is discharge from the facility. In general, mines do not apply for such discharge permits because they assert the facility is designed for “zero discharge”. In theory this means the dam is high enough and the impoundment large enough to hold all tailings, entrained water, normal precipitation and major storm events so that no fluid escapes from the impoundment. In practice, however, zero discharge is mostly fiction.

First, although the dams are lined, the drainage impoundments aren’t – mining companies rely on underlying bedrock characteristics to keep tailings fluid contained. But all too often, bedrock has fractures and cracks not adequately modeled in the design phase. These become conduits for contaminated fluid to leach into ground water outside of the impoundment. Roughly two years after mining began, the Ft. Knox tailings impoundment started leaking. Now, pumps below the dam keep contamination from reaching groundwater and lower Fish Creek, mechanically maintaining the operation’s compliance as a zero discharge facility. Second, a dam/pumpback containment system can fail. In 1983, at the Golden Sunlight, an open pit cyanide vat leach mine like Ft. Knox, the containment system failed, polluting groundwater with 19 millions gallons of cyanide solution.

The only true zero discharge facilities are those that are designed with redundant liners and require no pumpback wells to contain fluids. Impoundments created out of sacrificed stream drainages, like the one at Ft. Knox and proposed at Pogo, aren’t lined. Such facilities eventually leak, making the term “zero discharge” a paper fiction.

Thus, as a result of weak enforcement of the Clean Water Act, drinking water, streams, wetlands and aquatic life can be seriously impaired by tailings impoundments masquerading as waste treatment facilities. And as the pollution problems in the western mining states demonstrates, cyanide really is a poison pill for the industry. Left with a legacy of dead streams, poisoned aquifers and huge clean-up bills, Montana – long a stalwart mining state – looked beyond industry mythology and banned cyanide leach operations. It may be time to take a similar hard look at drainage tailings impoundments. It is definitely time to look beyond the mining myths and hold mining companies accountable to their corporate environmental policies, which, without exception, promote their commitment to environmental excellence and protection.(4)

1. Global Mining Snapshot, Mineral Policy Center
2. Making Sense of Cyanide, The Gold Institute, August 1999
3. Reasons to Vote Against SB 436, Montana Environmental Information Center
4. See, for example, Kinross Gold Corporation (Ft. Knox), Hecla Mining Company (Grouse Creek), and Placer Dome (Golden Sunlight).