A mine plans its death before its birth. The leftover waste from mines is so hazardous that mining companies must figure out what to do with it decades in advance, even before they start digging.
That’s how it works today, at least. But in 1981, when the United States government began requiring mines to have rehabilitation plans, many operators simply up and left instead. The government has identified about 46,000 abandoned mines on public lands alone. Some of them are top-priority Superfund sites.
But most haven’t even been mapped. By some estimates, there are as many as half a million abandoned mines in the U.S. These sites have the potential to contaminate water, pollute soil, kill wildlife and sicken humans, to say nothing of the risks of falling down a hidden mine shaft. (This is a legitimate concern in some areas – in California, the state employs teams that scour the state looking for abandoned mines and plugging them up. There was even a “Dirty Jobs” episode about these folks.)
Last month, heavy rains from Hurricane Odile caused two abandoned mines in Arizona to leak orange and brown sludge, threatening a waterway that runs into Patagonia Lake State Park. With thousands of abandoned mines dotting the American landscape, particularly in the West and Southwest, just how worried should we be?
The problem with tailings
Minerals have to be separated from the rocks once they’re taken out of the ground. That process of separation creates a waste called tailings, a combination of ground-up rock, chemicals and heavy metals. This waste is often stored as a liquid in a pond, though sometimes it is dried and kept in a special building.
Today, a mine’s storage facilities for tailings are one of the most scrutinized parts of its construction plan. If a wall breaks, massive amounts of toxins would be released into the water and soil, causing what is considered an environmental catastrophe. This summer, a tailings pond spill at a mine in British Columbia was compared to an “avalanche” of toxic waste.
Abandoned mines don’t necessarily have the same level of protection around their tailings. Tailings can leach toxins up to 100 years after the mine is abandoned, and older abandoned mines weren’t necessarily as careful with their tailings as mines are today. There are several things about tailings that make them toxic:
Acid: Sulfides in the tailings turn into acid that drains into surface water, along with chemicals used during processing, like cyanide. Acid drainage makes the water more corrosive. Marine habitats become unable to support fish and plant life.
For the rest of this article, click here: https://beta.cironline.org/reports/the-problem-with-americas-abandoned-mines/