Monday, August 31, 2015

The Colorado Mine Waste Spill: The Fix That Broke

On Wednesday, Aug. 5, heavy-equipment operators employed by the U. S. Environmental Protection Agency (EPA) were working at the site of the abandoned Gold King mine near Silverton, which is about a hundred miles northeast of the Four Corners area in southwestern Colorado.  The mine had not operated since 1923, and the workers weren't trying to get gold out of the mine.  Instead, they were trying to make sure that thousands of gallons of toxic-mineral-laden water that had filled large parts of the mine would stay there.  Their efforts were part of a larger project to clean up some nearby mines, an effort that would be spoiled if toxic water were to leak out of the Gold King mine and run downhill to the other mines. 

So, the workers had good intentions.  But good intentions don't always stop bad things from happening. 

It turned out that there was a lot more water backed up behind the "adit" (the horizontal mine opening) than the workers realized.  Apparently, if they had bored a test hole beforehand, they might have determined from the high pressure that it was dangerous to do what they were doing.  But bore holes cost money and time, the geology of the site made such a project tricky, and so they went ahead with some shoring-up operations.

Exactly what happened has not yet come to light, but somehow, the actions of the construction machinery disturbed the delicate balance of whatever loose rock was keeping the water in the mine, and here it came.  Some veiled references about prompt action preventing fatalities imply that things must have gotten pretty exciting for a while, as a flood of yellow acid water poured from the mine's opening down the hill to find its way to Cement Creek, where it spread to watersheds that cover parts of three states.  Some of these now-polluted streams pass through Indian reservations, and the Navajo Nation's president Russell Begaye has declared that his tribe is going to sue the EPA.

Clearly, the EPA has a mess on its hands.  But what about those good intentions?  Doesn't that count for anything?

The Gold King spill has drawn attention to an ongoing problem shared by many regions where mining was carried out with more enthusiasm than wisdom by operators who did only what they had to do to get the gold out.  As anyone knows who as a child played in sand on the beach with a toy shovel, holes in the ground dug below the water table eventually fill up with water.  Abandoned mines often contain soluble compounds such as iron sulfide (pyrite, or fool's gold) and minerals containing toxic elements such as lead, cadmium, and arsenic.  When water gets into these mines, the water acquires significant concentrations of these undesirable chemicals, and oxidized pyrite makes it highly acidic.  Sooner or later, water usually finds its way out of an old mine, either through natural fissures in the rock or more violently as water pressure builds up and breaches blockages, which is what happened at the Gold King mine, with a little accidental help from the EPA.

What one generation messed up, a succeeding generation is trying to clean up, but the task is Herculean—or maybe even Sisyphean.  Sisyphus was a mythological Greek king who played tricks on the gods.  The gods, in particular Zeus, didn't appreciate this, and so when Sisyphus died, Zeus condemned him in Hades to try to roll a boulder up a hill.  Just as he'd get nearly to the top, the enchanted boulder would elude his grasp and roll back downhill, and Sisyphus had to lather, rinse, and repeat, so to speak—forever.

The EPA won't have to clean up mines forever, but with 22,000 abandoned mines in Colorado alone, they have enough to keep them busy for quite a while.  The fact that the EPA has resources to prevent mine-water spills at all is due to the passage of laws such as the Superfund act, which helps pay to clean up environmental messes that the owners (or former owners) can't afford to fix.  The agreement under which the EPA was working on the Gold King mine wasn't a full-fledged Superfund situation (such a label was feared to discourage tourism), but millions of government dollars were committed to the cleanup anyway.  And it was in pursuit of this type of cleanup that the site workers inadvertently caused exactly the kind of problem that they were there to prevent.

There is an opportunity here, even in this crisis, for engineers and engineering educators.  It's hard enough to dig a mine without having it fall on your head, but as numerous accidents have shown, digging a mine is a piece of cake compared to trying to do anything with an old abandoned mine for which few records exist and maintenance ceased decades ago.  But doing the kind of thing that the EPA is doing is engineering too—pure-D environmental engineering, but probably not of a kind that too many environmental engineering departments consider. 

With so many abandoned mines to fix and federal money to fix them, one can imagine a new engineering subdiscipline of abandoned-mine remediation.  Typically, new engineering disciplines are practiced under other guises for some time before anyone recognizes them as distinct from previous disciplines.  For all I know, there may be a division of some civil engineering department somewhere that already teaches these things, but I doubt it.  If there isn't, though, there ought to be.

Maybe all the education in the world might not have prevented the breach that caused the Gold King spill.  Sometimes a bad thing is bound to happen no matter what you do.  But now that we've had a bad example of how not to handle abandoned mines, maybe the academics and engineers can get together to develop best practices and procedures to prevent things like this from happening in the future. 

Sources:  I referred to articles on the spill carried in the online editions of the Washington Post on Aug. 10 at and the Denver Post on Aug. 26 at, as well as an article about the Navaho lawsuit at  The Wikipedia article on Sisyphus has some great details about exactly what it takes to tick off Greek gods, by the way.

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