Local leaders, neighbors, and environmentalists learned about an elevated level of cobalt in groundwater outside of an ash pond at Coffeen Power Plant, and what the company that owns the plant intends to do about it during an open house at Coffeen School on Monday evening, Oct. 7.
One of 12 monitoring wells around Ash Pond 2, a coal combustion residuals surface impoundment that has not been used since 1982, tested for cobalt levels that were .006 milligrams per liter over federal standards.
"Cobalt at that level has not migrated off Coffeen Power Plant Property," Phil Morris, one of the company officials, said at the open house. "There is no risk to ground water or drinking water, no threat to Coffeen Lake, and no threat to public health."
According to information on file in the public record at www.luminant.ccr, Ash Pond 2, located northwest of the physical power plant, is an unlined 60-acre surface impoundment surrounded by 47-foot berms that was removed from service and capped in the mid-1980s.
It contains about 2.2 million cubic yards of coal combustion residuals covered by vegetated soil.
Power plant officials believe a "cap-in-place" option–one that already has the approval of the state EPA–is the best remedy due in large part to the speed in which the job can be accomplished.
Morris said the cap-in-place option could be completed as early as next year, whereas if the impoundment were completely removed from the site, that would take as much as ten years, "during which time groundwater would continue to be impacted," according to the "Corrective Measures Assessment" on the company website.
That assessment also asserts that with the cap-in-place option, "concentrations will begin to decline and the extent of groundwater impacts will begin to reduce approximately one year after cover construction."
The cap-in-place option already approved by the Illinois EPA includes construction of a geomembrane cover, removal of free water, grading and reshaping the existing closure, constructing a stormwater management system, and 30 years of monitoring. An option includes a potential groundwater extraction system within the uppermost aquifer.
Ash Pond 1, the one in which coal combustion residuals are currently being impounded, will also be closed after the power plant ceases operation before the end of the year.
Texas-based Vistra Energy announced in August that Coffeen and three other Illinois power plants would be shut down before the end of the year.