KINGSTON—It was the largest ash spill in U.S. history. A dike failed on a storage cell on a cold December night more than four years ago, and roughly 5.4 million cubic yards of coal ash surged out, covering about 300 acres of land and water near the Kingston Fossil Plant.
No one was injured, but 40 homes in the area were affected. The ash filled three embayments north of the coal-fired plant, covered Swan Pond Road, and flowed into the Emory River. Three homes became uninhabitable because of structural damage.
The work to clean up the gray sludge, which had been four to six feet deep, has been under way since the Dec. 22, 2008, spill. On Friday, officials paused to celebrate two milestones in the six-year, $1.2 billion project.
The first milestone: All ash has now been removed from an 80-acre middle embayment north of the coal-fired power plant and the storage cell that failed. The brown river bottom, dry for now because of a dike keeping out water, is visible once again. It’s the end of ash excavation around the storage cell that failed.
“All the ash is out, and we’re starting to close the site,” said Kathryn Nash, general manager of the Kingston Recovery Project for the Tennessee Valley Authority, the public utility that owns the plant.
The second milestone: Workers have used a flexible membrane liner to cover the first 10-12 acres of the failed cell. It’s part of a 240-acre ash disposal area at the north end of the plant. Plans call for closing that ash containment area by November 2014.
A drainage layer will be added over the liner, followed by a 24-inch soil cover, and grass will be planted. It will resemble a closed landfill, TVA said, and it blend in with the surrounding landscape and natural vegetation.
Once the cell is covered, the dike will be removed, and water will flow back into the embayment.
“These are major steps toward our goal of restoring the area to a condition that is as good as or better than it was before the spill,” said Bob Deacy, TVA senior vice president of Generation Construction.
TVA said workers have removed more than three million cubic yards of ash from the middle embayment and areas north of the cell using excavating equipment. The ash will be covered and permanently stored in the disposal area, surrounded by an earthquake-resistant, reinforced wall tied into bedrock up to 70 feet deep. Eleven miles long, it will be one of the largest walls of its type ever constructed in the United States. Work on that structure should be finished this fall, TVA said.
“It really is a light at the end of the tunnel,” said Craig Zeller, project manager for the U.S. Environmental Protection Agency at Kingston. “Now we can focus more on long-term monitoring and other aspects of the project.”
Zeller and Nash led local reporters on a tour of the work on Friday.
The new ash storage area will be 30 feet lower than the old one. Nash said the height of the old cell—it was about 55 feet above ground—was one of the reasons it failed. Other causes included wet ash and a weak foundation.
The Kingston Fossil Plant, which was the world’s largest coal-burning power plant when it opened in 1955, converted to dry ash storage in 2012. Several TVA plants still store wet ash, but they are either closing or converting to dry-ash systems, Nash said.
The dry ash now generated at Kingston is stored at the site, and TVA is getting a permit for a landfill on the southeast side of the nine-unit plant, which can supply power to about 540,000 homes.
While the ash excavated from the embayment and other nearby areas will be stored on site, more than 3.5 million cubic yards of ash dredged from the river was shipped to an EPA-approved landfill in Perry County, Ala., the Tennessee Department of Environment and Conservation said. The dredging was completed in May 2010, and the river was re-opened. The last shipment of river ash went to Perry County in December 2010.
Some ash remains in the river. Zeller said a two-year, $40 million study determined the best course of action was to leave it alone and “let nature run its course.” That option is consistent with other decisions made by the U.S. Department of Energy, which has three sprawling sites in Oak Ridge, when it studied the Lower Clinch River and Watts Bar Reservoir in the mid-1990s, Zeller said.
“The remedy for this river system is very consistent with what other federal agencies have already selected,” he said.
Other options had included capping the ash underwater at a cost of $40 million to $50 million, or dredging up the remaining ash. However, there were concerns about stirring up some legacy sediments on the river bottom if dredging were used, Zeller said.
He said the Emory River could deposit one to five feet of sediment over the underwater ash in the next 30 years, and it will be sufficiently covered in 10-15 years.
TVA said it has implemented a long-term monitoring plan to continue to assess the ecological health of the river system. The Kingston Fossil Plant is located on the Emory River close to where it flows into the Clinch and Tennessee rivers.
Zeller said the project is a federal Superfund site because of concerns about arsenic and selenium contained in coal ash. Arsenic can be harmful to humans, and selenium, in high enough concentrations, can cause reproductive failure in fish.
But Zeller said he was not aware of any damage to the health of humans or fish, although there were low-level risks for bugs that live on the river bottom and the birds that eat them.
During the cleanup, TVA said water, air, and soil samples indicated that contaminants, particulates, toxic metals, and radioactive materials were normal, below levels set by TDEC and the EPA, or significantly below the limits to be classified as hazardous waste.
Besides the ash cleanup project, work also is under way on public recreation areas, including a roughly 40-acre park north of the plant and upriver from it. The public recreation areas will include fishing piers, picnic areas, walking trails, and boat launches around the former Lakeshore Drive area and the middle and north embayments.
The entire Kingston Recovery Project is expected to be completed by early 2015. Nash said it’s on schedule and under budget. The total cost has been estimated at $1.178 billion, and roughly $970 million has been spent so far, she said.
As the project approaches its end, there has been a roughly 50 percent drop in the number of workers. At its peak, the Kingston Recovery Project had more than 800 workers, Nash said. There are now under 400, primarily operators, craftworkers, Teamsters, and laborers. About 130 pieces of heavy equipment remain, including excavators, dozers, dump trucks, and scrapers.
“We still have a lot of work to do, but our employees and contractors can be proud of their efforts so far,” Deacy said. “A tremendous amount of credit goes to the hundreds of skilled trades and labor workers who bring a wealth of experience and skills to the job.”
For more information on the recovery project, visit http://www.tva.gov/kingston.