In a story I reported recently about how coal ash is handled in Kentucky, I mentioned both the December 2008 coal ash spill at a Tennessee Valley Authority plant in Tennessee and LG&E’s Cane Run plant coal ash pond here in Louisville. While they are both coal ash ponds, there are some pretty important differences between the two, which I thought I’d share.

First, the TVA plant was storing fly ash in the pond, in a kind of slurry, behind a tall dam wall.   At Cane Run, the pond contains bottom ash.  Fly ash is the powdery leftovers from burning coal; bottom ash is the sandy, heavier bits. Whereas fly ash slurry is a kind of goopy mixture, bottom ash settles in a pond. Experts believe it’s generally better to store fly ash in dry landfills as opposed to ponds. In Europe, the push is not to store any of it at all, but to reuse ash in cement and pavement.  Also, the Cane Run pond’s dam walls are quite low, and the pond doesn’t hold nearly as much as the TVA plant.

So, the set-up at TVA spelled disaster.  To get a sense of the size and impact of that spill, see these before and after aerial pictures.

However, it’s true the Cane Run pond is in a residential neighborhood, near a rail line, and on the Ohio River. For that reason, the state ranks it as a “high hazard” pond, requiring regular inspections of the dam walls and surrounding turf.All this means that a disaster like what happened at the TVA plant is highly unlikely at Cane Run, for anyone left wondering. But there are many coal-fired power plants in Kentucky, and that means there’s plenty of coal combustion waste – fly ash, bottom ash – being stored and land-filled at increasing rates.

There are also some innovative projects to try to reuse the ash.  For example, at Western Kentucky Energy’s Coleman station in Hawesville, University of Kentucky researchers helped develop a process for recovering fly ash from ponds to extract the carbon and create a new fuel.