TVA Ash Spill Cause Revealed

An independent analysis has determined that the December ash spill at TVA's Kingston Fossil Plant happened simply because there was too much ash and silt allowed to fill up the retention pond.

TVA Chief Operating Officer Bill McCollum said today however that, "The combination of conditions and factors identified by AECOM that contributed to the failure at Kingston are unusual, and no other ash pond in the TVA system was built like Kingston."

McCollum said TVA has retained the Stantec Inc. engineering firm to assess all of TVA's other similar facilities to ensure that no failure could occur at any other TVA plant.

According to the just-released findings about the Kingston spill, "A combination of the existence of an unusual bottom layer of ash and silt, the high water content of the wet ash, the increasing height of ash, and the construction of the sloping dikes over the wet ash were among the long-evolving conditions that caused a 50-year-old coal ash storage pond breach and subsequent ash spill..."

The findings and analysis were part of a six-month report made public today by AECOM, an independent geo-technical engineering firms. The AECOM study, officially known as the Root Cause Analysis of TVA Kingston Dredge Pond Failure, was commissioned by TVA in January 2009.

AECOM shared information with independent consulting engineers retained by the Tennessee Department of Environment and Conservation and TVA's Office of Inspector General. These groups met several times to conduct workshops and review data as it was being collected and processed.

"TVA accepts the detailed findings and associated analysis put forth by AECOM," said TVA Chief Operating Officer Bill McCollum. "We are confident that AECOM conducted an in-depth study that identified what caused our storage pond to fail. TVA deeply regrets the spill of coal ash from our Kingston plant and is fully committed to restoring the community near the site and to seeing to the needs of our Roane County neighbors."

In forming its conclusions, AECOM took hundreds of soil borings and numerous core samples, and performed extensive laboratory testing on the samples. The engineering firm also performed exploratory excavations; installed instrumentation; studied maps, photographs and surveys; analyzed relics from the coal ash release; reviewed design records and drawings; and interviewed TVA engineers and site operations personnel.

AECOM's complete report on the cause of the Kingston coal ash storage pond breach and subsequent ash spill is available via TVA website (www.tva.com).

"TVA will carefully consider the findings in the AECOM reports as we evaluate options for closing the failed dredge cell at Kingston," McCollum said.