“Talen Montana is an environmentally responsible company,” said Todd Martin of Pennsylvania-based Talen Energy, Talen Montana’s parent company. “We and the other owners of the Colstrip plant have invested millions of dollars to minimize the plant’s impact on the environment.”

In the next 30 months, the power plant owners will have to come up with a way to dry the bottom ash for storage. The same methods will have to be used by mid-2022 for ash collected by the power plant’s air pollution scrubbers.

The change in coal ash treatment comes as Talen exits its role as plant operator. In May, Talen gave the other owners of Units 3 and 4 two years notice of its exit as operator.

The company has said it is losing millions operating the power plant. Talen has been frank about its intention to leave Colstrip altogether in coming years.

“We believe we have identified the proper technology, but are continuing the process of researching the design and engineering” to dewater the coal ash, Martin said. “Our departure, in approximately two years, as operator in no way effects our responsibility for, and commitment to, environmental compliance and remediation.”