The U.S. Environmental Protection Agency sued Ameren Missouri, alleging the utility made major upgrades to its two-unit, 1,242 MW Rush Island coal-fired power plant without installing modern pollution control equipment.

In the complaint filed Jan. 12 in federal court in St. Louis, the EPA asks the court to order Ameren to install and operate air pollution control technology to reduce sulfur dioxide emissions at its Rush Island plant. The United States also seeks civil penalties.

Ameren said the EPA requires that electric utilities undergo pre-construction review for environmental controls if the utilities propose to build new generating units or make modifications to existing units that result in a significant increase in emissions.

Ameren said, however, that such requirements do not apply to projects that constitute routine maintenance.

“Many of the cited projects were actually undertaken by Ameren Missouri to expand our efforts to reduce emissions,” Ameren Missouri President and Chief Executive Warner Baxter said in a statement. “We have cut emissions at every plant, significantly improving air quality in the region.”

Ameren said all the Ameren Missouri projects cited by EPA fall into the classification of routine maintenance, including project repair and replacement activities; projects that did not cause an emissions increase; projects that were necessary to respond to demand growth on a utility system; and modification projects to switch plants to low-sulfur coal, which provided environmental benefits.

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