Heavy rainfall had very little to do with the December 22nd coal ash spill in Kingston, Tennessee. A report commissioned by TVA and released Thursday morning points, instead, to poor drainage and a shaky foundation.
The report’s author, Bill Walton, says the foundation and drainage problems in the 50-year-old ash pile were compounded by its ever-increasing height. As the ash pond gets taller, it reduces the surface area on top for the wet ash to drain. The report indicates TVA didn’t take that into account and kept dumping ash at the same rate.
Walton says, however, there’s no single cause for the collapse.
“Often the final factor is nothing more than the trigger that sets a body in motion that was at the verge of failure.”
Deep inside the settling pond, a layer developed that Walton describes as “unusual and rarely found.” A six-inch slime layer roughly the consistency of yogurt undermined the strength of the ash pond and ultimately led to a more extensive collapse.
The Southern Alliance for Clean Energy, which has become a TVA watchdog, applauded the 1,400 page report. Executive director Stephen Smith says it leads one to conclude that wet storage of ash is an engineering risk and should be phased out.
Read the executive summary of Bill Walton’s report.
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