Coal Ash

Advocates, TVA spar over safety of compaction as a coal ash solution

Photo by Tennessee Valley Authority

Photo by Tennessee Valley Authority

KINGSTON, TN — “How to dispose of coal ash? It’s a particularly pressing question for the Tennessee Valley Authority (TVA), whose 2008 dam breach at their Kingston, Tennessee plant spilled 5.4 million cubic yards of coal ash into the Clinch and Emory rivers, and led to congressional hearings and new 2015 regulations on depositing ash.

Companies are now turning to multiple solutions for both current and retired coal plants: cap-in-place, closure-by-removal, and hybrid closure methods that blend re-use with stabilization strategies, such as adding concrete, lime, or water-repellant hydrosilanes.

TVA is taking a new approach by experimenting with ‘intelligent compaction technology,’ which is primarily used to create roads and airfields. By 2024 TVA will close all but six of its coal plants and will use the technology at all of them, at a cost of around $1 million for each location.

Advocates warn, however, that the area’s geology still poses risks.

…That’s because at least two of the TVA’s ash sites—the Kingston plant, and Gallatin, both in Tennessee—are built on vulnerable karst bedrock, which is characterized by dissolved fractures, sinkholes, caves and cavities. Chemicals from coal ash can be carried by water through karst into vulnerable rivers.”

— Gillian Neimark, Southeast Energy News

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