If I’ve said it once I’ve said it, oh, around eleven kazillion times now: "coal is cheap" because the coal industry externalizes costs.

Take, for instance, coal ash. It contains several substances that are classified as toxics individually, but the ash itself isn’t thus classified. That means it can be stored in enormous pools with no liners, behind earthen dams that, as the disaster in Tennessee illustrates again, periodically fail.

What would happen if ash were classified as toxic? The answer can be found in this stellar piece from Bloomberg.

Increased regulation would bring costs to upgrade or close more than 600 landfills and waste ponds at 440 plants nationwide. While the Environmental Protection Agency put the price tag at $1 billion a year in 2000, power generators predict the cost would be as high as $5 billion, said Jim Roewer, executive director of the industry-funded Utility Solid Waste Activities Group, in a telephone interview.

Why so costly?

An EPA report in 2000 found a quarter of retention ponds and 57 percent of landfills lacked liners to prevent pollution from leaking into nearby water supplies, though the 2007 follow-up study found such controls more common at newer sites.

So much for cheap.

Also note this macabre/hilarious bit:

AEP, the biggest producer of coal-fired energy in the U.S., stores ash both in wet slurry ponds like the one in Tennessee and in dry landfills, said Melissa McHenry, a spokeswoman for the Columbus, Ohio-based utility, in a phone interview.

"Some of these ponds have been operating for decades without a spill," she said. "We have a regular inspection schedule for each site and the largest ones have instruments to tell us when there’s a problem."

Oh, well, as long as some of your waste facilities haven’t disgorged hundreds of millions of gallons of toxic sludge on poor surrounding communities, I guess we’re good!