The leaking coal-ash ponds associated with the now retired Colstrip units 1 and 2 will be fully excavated and relocated to new, lined impoundment ponds, according to a ruling released earlier this month by the Montana Department of Environmental Quality.

The ruling means DEQ will fully excavate the 330 acres of ponds and relocate 6.7 million cubic yards of sludge to lined impoundment ponds that will be constructed above the water table near the plant site, DEQ ruled Nov. 17.

DEQ requires a $285 million bond from Talen to cover the work on units 1 and 2, which brings the company's total sitewide financial assurances at Colstrip to $485 million.

"This is exactly what needs to happen," Anne Hedges, deputy director of the Montana Environmental Information Center, told Clearing Up. "You cannot leave waste near the water table and not expect to have problems down the road. The only way to clean it up is to permanently remove the ash from the ground and store it in a place where it will not interact with the groundwater."

DEQ has been reviewing plans for the coal-ash ponds for the past eight years. Talen Energy proposed a plan that would have partially excavated the ponds to about 5 feet above the water table. DEQ studied other options that included draining the ponds, replacing soil caps with plastic ones and removing the ash from one of the unlined impoundments. Clearing Up's calls to Talen Energy were not returned.

Coal ash is a byproduct of burning coal and it includes arsenic, chromium, lead and mercury. The complex of nine unlined ponds associated with units 1 and 2 have been storing ash since the units began operating in the mid-1970s, and have been leaking since the mid-1990s, according to several lawsuits filed over the years. The ponds have leaked an estimated 200 million gallons of contaminated water.

In 2008, the Colstrip ownership group agreed to pay $25 million to settle a lawsuit filed by 55 Colstrip residents claiming the coal-ash ponds had seeped into the local aquifer.

Plaintiffs in the case cited unlined ponds, and alleged plant owners knew about the seepage from the nine ponds, and its potential impact to plaintiffs' property, but did not act to correct the problem or protect their properties from damage. They also argued the owners failed to adequately notify them seepage had gotten onto plaintiffs' properties and threatened their wells.

The lead plaintiff in the case was Montana State Sen. Duane Ankney, an outspoken proponent of saving the Colstrip power plant and critic of environmental groups that have sued the owners over emissions and water-quality issues.

Owners of the coal-fired power plant agreed in 2016 to stop pumping coal ash from the 1,480 MW units 3 and 4 into storage ponds, and convert to a dry-ash disposal method by mid-2022, according to a settlement reached in 2016 with the owners and environmental groups (CU No. 1758 [14]).

Under terms of the 2016 settlement, the "bottom ash" from the ponds associated with units 3 and 4 must be dewatered and disposed of by the end of 2018. By July 1, 2022, all waste from the units' scrubbers must be disposed of as dry waste and covered.

Hedges said removal of the bottom ash ponds is still underway, and there is plenty of work to be done to meet the 2022 deadline.

"This site does not have water pollution discharge permit, so there's an enormous volume of water that must be evaporated, or its goes into the groundwater," she said. "They have to get the technology in place to be able to evaporate the water."

Talen has 60 days to appeal the DEQ ruling, which could be overturned by Republican Gov.-elect Greg Gianforte, who has been a proponent of keeping the Colstrip power plant operating.

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Editor - Clearing Up

Steve began covering energy policy and resource development in the Pacific Northwest in 1999. He’s been editor of Clearing Up since 2003, and has been a fellow at the Institute for Journalism and Natural Resources and University of Texas.