Environmental groups filed a federal lawsuit Wednesday against the owners of Montana's massive Colstrip coal-fired power plant, seeking to force the installation of more pollution controls at the decades-old facility.
The Montana Environmental Information Center and Sierra Club also asked the U.S. District Court in Billings to issue penalties for alleged emissions violations.
The center's Anne Hedges said the penalties could total many millions of dollars for violations over 20 years.
Colstrip is the second-largest power plant west of the Mississippi River. At issue is whether changes made to the plant amount to major modifications that require pollution upgrades under the Clean Air Act.
According to the lawsuit, those changes include several turbine replacements, plant overhauls and other work that dates to 1993.
David Hoffman with PPL Montana, which operates the plant on behalf of its six owners, said the changes generally were needed to maintain the 2,000-megawatt plant or meet government mandates, and as such do not qualify as modifications.
"Part of this might be a lack of understanding on their part about what it takes to maintain a coal plant of that size," Hoffman said. "We closely examine that every time we have an overhaul."
The first two units of Colstrip began operating in the mid-1970s, and two more units came online in 1984 and 1986.
The plant was grandfathered in under the Clean Air Act and was not required to comply with the tougher pollution control standards unless the plant's operator made upgrades modernizing it.
The industry had argued at the time that plants such as Colstrip would eventually be retired. But instead, Colstrip has been upgraded and expanded without the same pollution controls as newer plants, according to Hedges.
"They've been getting an unfair economic advantage over the competition for a very, very long time," she said.
If the suit is successful, it would require Colstrip to apply for a new emissions permit and potentially install new pollution equipment to come into compliance.
The penalties for the period in which it was in violation of pollution limits would be in excess of $30,000 a day under federal law, according to the lawsuit.
The plant's owners are PPL Montana, Avista Corp., Puget Sound Energy, Portland General Electric Co., Northwestern Corp. and PacifiCorp. They were all named as defendants in the lawsuit.
The Montana Environmental Information Center and the Sierra Club have a separate lawsuit pending to learn whether the coal-fired plant has been in compliance with environmental laws.
PPL has argued the information can't be released by the U.S. Environmental Protection Agency, because it includes data that contains trade secrets that are exempt from the federal Freedom of Information Act.