Toxic Mining Waste: Just Moments from a Disaster for Wildlife
When I saw footage last week of a tailing dam collapse at Mount Polley Mine, my immediate thought was of the Chino Mine near my hometown of Silver City, New Mexico. There’s a tailing dam 4 miles long and a mile wide about 20 minutes from where I grew up, where wastewater and other toxic materials are pumped and stored from the mine.
But I also thought about our work at National Wildlife Federation to protect Alaska’s Bristol Bay from the Pebble Mine—a tailing dam breach in that magnificent place would be nothing short of devastating.
What exactly is a tailing dam?
There are several ways of extracting valuable mineral ores (copper, silver and gold, etc) from the ground. Most ores are far from pure and are found as mineral compounds, so separating the valuable ore from the worthless rock can be difficult. Smelting is one way: you pulverize the ore and earth and use a high temperature furnace to separate the valuable minerals (a process called concentration). The process itself is dirty, resulting in a lot of byproducts like sulphuric acid. The larger problem is one of waste: of all the rock crushed and smelted and refined, only about 2 percent is worth something. For every $1,300 ounce of gold extracted, 49 other ounces of worthless rock were mined. For every $3.17 pound of copper, 50 pounds of rock has piled up.
Regardless of the specific mining methods, one thing is common for all tailings: they contain minerals and compounds from before the mining process (like fluorite, arsenic and mercury), and additives that were used during the mining process, (such as sulphuric acid and cyanide). In the early days of mining, tailings were discharged down a river or piled up in giant heaps, and water or wind could carry them away. These days, the tailing slurry is transported to special storage areas called tailing impoundments/dams. Usually constructed of whatever happens to be lying around (including the tailing themselves), the structures are huge and often filled with a dangerous mixture. The latest pond (No. 7) for the tailing dam near my hometown will be 230 feet tall when it’s completed, and have a storage capacity of 450 million tons (PDF).
Right now, there is no law or regulation requiring tailings impoundments to be lined with any material to prevent leaks. So it’s not a matter of if they leak, it’s when they leak. In fact, the No. 7 Chino Mine pond is designed for seepage, because any kind of liner would be clogged by the slurry, causing structural problems for the dam.
Pebble Mine and the 700-foot dams
The Chino Mine is a copper porphyry (read: low grade) mine. The proposed Pebble Mine would be one too. The only way to profitably obtain the precious metals from the earth is to conduct mining on a massive scale. Here’s a photo of the Chino Mine:That’s one big hole in the ground, but it’s not even large by worldwide comparison—and the Pebble Mine would be larger. How big? Some 3 miles wide and 4,000 feet deep. It would generate an estimated 10.2 billion tons of waste material. And a lot of that would be contained in tailing dams 700 feet tall.
Protecting Bristol Bay
Watch this video (skip to the 11-minute mark) of the broken tailing dam for Mount Polley Mine spilling into Hazeltine Creek, which is itself part of a larger system of rivers and lakes in British Columbia. Now imagine a dam 700 feet tall doing the same thing in Bristol Bay.
Tailing dam failures are actually pretty common: there have been at least sixty in the past 30 years. And the tailing impoundment isn’t the only problem: since 1986 there have been 13 separate tailing spills from pipes and other infrastructure at Chino Mine. Groundwater at the site is so bad that long after the mine closes the water won’t be safe for use without treatment.
Speak Out to Protect Bristol Bay and Habitat for Brown Bears and Wild Salmon
The untouched streams and waterways of Bristol Bay, where brown bears make their home and wild salmon spawn, are considered exceptionally pure by biologists. Even the deepest parts of these waters are so pristine that you can see clearly to the bottom. Right now is our best chance to make sure Bristol Bay’s watershed is protected from toxic, polluting mining waste that inevitably would leak from Pebble Mine into this pristine habitat.
The area is also incredible habitat for brown bears, who rely on the summer salmon runs every year. The proposed mine would immediately disrupt this summer ritual, and a toxic waste disaster would cause irreparable harm to the bears’ habitat.