The U.S. Environmental Protection Agency filed suit against Michigan’s largest energy company, DTE Energy, for alleged violations of the federal Clean Air Act at that company’s  coal-fired Monroe Power Plant in Michigan.

In a July 24 Notice and Finding of Violation issued by the EPA to DTE Energy, the federal agency said DTE violated the Prevention of Significant Deterioration requirements, Non-attainment New Source Review, New Source Performance Standards, and operating permit requirements under Title V of the Clean Air Act for its Monroe, Saint Clair, River Rouge, Belle River, and Trenton Channel power plants. The agency said the company also violated the Michigan State Implementation Plan.

The suit, filed against the company in the U.S. District Court for the Eastern District of Michigan on Thursday, asks the company to shut down the 1973-built Monroe plant’s 832-MW Unit 2 until the company complies with federal air rules. The suit also asks for civil penalties of up to $37,500 per day.

The EPA alleges that DTE made major modifications in March to the Monroe plant unit in March without getting necessary approvals. The $30 million upgrade was made without the installation of best available technology to minimize sulfur-dioxide and nitrogen-oxide emissions, as required under the Clean Air Act, and boiler replacements that cost about $65 million were “unpredicted” in the life of the plant.

The EPA’s action was “an absurd and overly aggressive interpretation of environmental regulation,” DTE spokesman John Austerberry told the Detroit Free Press. “The work at Monroe Unit 2 is very common at Detroit Edison and the entire industry. It is the type of work every utility must do periodically to maintain reliability, efficiency and safety of the equipment, in compliance with its duty to serve and its obligations to the ratepayers,” he was quoted as saying.

Austerberry added that closure of the unit would cost customers nearly $250,000 a day because the utility would have to buy power elsewhere.

In a related story, Edison International is under an agreement with Illinois State to cut mercury, nitrogen oxide, sulfur dioxide, and particulate emissions at six coal-fired power plants. The equipment required could cost the company $1.2 billion, Edison CEO Ted Craver told Dow Jones newswires. The company will reportedly seek construction permits for the projects later this year.

Sources: EPA, Detroit Free Press, POWERnews, Dow Jones