A second phase of coal-ash cleanup at the Tennessee Valley Authority’s Kingston, Tenn., fossil-fuel powerplant could take at least four more years and up to $741 million to complete, says an engineering and cost analysis done for the utility and the U.S. Environmental Protection Agency, which is overseeing the work. Released for comment on Jan. 18, the report covers new remediation options for what remains of more than 5.4 million cu yd of waste that leaked from a collapsed-site dredge cell in late 2008. Cleanup could total $1.2 billion.

Knoxville, Tenn.-based TVA says the first phase of dredging in the nearby Emory River, to be finished in May by Sevenson Corp., Niagara Falls, N.Y., will remove almost half the coal ash released. But before then TVA must choose one of several options for phase two. One calls for removing ash from a pond on adjacent private land and returning it to its pre-spill state. Another calls for rail-shipping all waste from the pond and dredge cell to an Alabama landfill. Other options would remove and ship only pond ash, leaving cell waste in place with appropriate reinforcement, or dispose both pond and cell ash inside the reinforced cell.

Jacobs Engineering Group Inc., Pasadena, Calif., which did the analysis and is managing overall cleanup, cites possible difficulties in building soil-cement columns for a containment dike around the cell if all ash were stored on-site. It would involve building 22,600 linear ft of perimeter dike foundation over 1.24 million sq ft. A TVA spokesman says no decisions about contractors, including whether Jacobs will continue in its role, will be made until a cleanup plan is selected. Also pending is whether EPA will reclassify coal ash as a hazardous waste and how that will impact cleanup options.