From The Durango Herald (Peter Marcus):
Part of the dilemma has to do with money. Estimates place national reclamation of inactive mines as high as $54 billion. Mining laws that govern the industry in the United States date back 143 years. The federal government is prohibited from collecting royalties on much of hard-rock mining, thereby leaving the coffers dry for reclamation.
Congress is expected to take up legislation that would allow the government to collect royalties, though the measure faces an uphill battle in a Congress plagued by political gridlock. Even still, there is the underlying issue of inadequate technology to address.
Reclamation work remains a pretty rudimentary process. For cleanup crews to really make a long-lasting impact, they must get beyond the opening of the mine. Back during the mining boom of the late 19th century and early 20th century, there was little engineering. Dams were installed, including a pile of material, and behind it was waste products, residual water and chemicals.
“You’re looking at the potential of these sort of hastily put together dams bursting, and the older they get, the more frequently that’s going to occur,” Cohen said.
For a mine to be properly restored, workers must address the waste rock pile, which includes all the rock that didn’t have enough ore to be worthy of processing. This material likely has a lot of pyrite in it, which can make acid mine drainage after it mixes with oxygen and water. This material is on the land surface.
There’s also tailings storage to address, which is the waste from processing the ore that took place to harvest metals. This fine texture also is on the land surface.
The waste piles – built on top of local soil – contained no liners and can be more than 1,000 acres large and taller than 300 feet.
“The idea was make gravity your friend. If we can dump it down someplace, rather than haul it far and up, we’re in business, and it’s less costly,” Cohen explained. “In the old days, that was their modus operandi.”
These waste piles must be moved to a place that has been properly prepared in a large pit lined with clay or a high-density polyethylene liner. A neutralizing material – like lime – is placed on the bottom of the acid-generating material and then on top of it. It is topped with another clay liner to spur vegetative growth. Some call it the “tailings burrito.”
But these pits will likely fail eventually, and there is usually a body of water running through it, which is problematic for water quality.
Often, a bulkhead, or reinforced concrete plug, is constructed at the mine opening. But this is a temporary solution at best. As Cohen pointed out, “water has this nasty habit of finding the path of least resistance.” The water simply finds its way through other openings, such as fractures in rock.
The bulkhead is really just a way to delay while money is sought for more permanent reclamation work. The ultimate solution is a treatment facility that could cost as much as $20 million to construct and another $1.5 million per year to operate 24 hours a day. The facility usually must be built at high altitudes in remote, difficult terrain.
But with a treatment facility, workers can control pipes in the bulkhead and adjust the flow of water so that it can be treated, offering a more permanent solution.
The EPA said that it is exploring building a treatment facility near Gold King in the wake of the spill. Groups have been calling for a treatment facility in the Upper Animas Mining District for years. Pollution from inactive mines has long contaminated Cement Creek near Silverton, which runs into the Animas. A treatment plant operated in the 1990s. But in 2004, the water-treatment facility was shut down.
In the meantime, EPA officials said water from Gold King is being captured and treated at a system of impoundments before being discharged to Cement Creek. Authorities have constructed four ponds at the mine site, which are treating water to remove as much metal loading as possible.
As Cohen pointed out, the government has few options.
“Even some of these treatment systems, what you see is these very basic systems,” he said. “We’re talking about a hole in the ground that’s lined where you throw some lime in. That’s only going to go so far.”