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Colstrip Ash Pond Cleanup Plan Announced

Coal stacks at Colstrip Power plant
Kayla Deroches
Yellowstone Public Radio
The Montana Department of Environmental Quality released a cleanup plan for waste ponds at two of the Colstrip power plant’s four units on Feb. 11 2020..";


A Montana agency on Feb. 11 released a cleanup plan for waste ponds at two of the Colstrip power plant’s four units.

The Montana Department of Environmental Quality agreed to plant operator Talen Energy’s preferred plan for cleaning up contaminated groundwater from leaking coal ash storage ponds at Colstrip Units 3 and 4.

Coal ash is the residue from burning coal and it contains toxins.

DEQ Project Manager Sara Edinberg says the plan calls for flushing out contaminants from the ash ponds using injection and capture wells.

“Talen does have an existing capture well system out there, so they are actively pumping water to essentially keep the plume from spreading currently. But we want kind of a more active remediation to address the existing groundwater contamination, so that’s impacts from historical seepage,” Edinberg says. 

DEQ took enforcement action against the Colstrip coal-fired power plant for its leaking ash ponds in 2012. Power plant operator Talen Energy faces the task of remediating decades of contamination at all four of its units.

Edinberg says the Units 3 and 4 ash ponds, which span more than 400 acres, were found with elevated levels of toxins like lithium, cobalt, manganese and selenium, with boron and sulfate at especially high concentrations.

“I do know high sulfate levels are concerning to some of the ranchers around there. They can cause weight loss in cattle. And there’s some other effects on livestock. That’s kinda the big thing with sulfate,” Edinberg says.

Edinberg says Talen will also close some of those ponds and switch to dry-stack storage by 2022, which means it’ll stop disposing of wet ash in the ponds by that time.

She says remediation for Units 3 and 4 should cost around $107 million. While Talen has promised to pay that as the operator, it’s actually being split between all the owners based on their percent share of the respective units.

DEQ is asking for additional sampling and treatment studies before finalizing the plan. 

Kayla writes about energy policy, the oil and gas industry and new electricity developments.