Two additional air monitors will help to determine if Missouri's large coal-fired power plant complies with federal safety thresholds for an airborne pollutant.
The Environmental Protection Agency announced new safety standards for sulfur dioxide emissions more than six years ago. Ameren Missouri said its preliminary tests show the air near its coal-fired Labadie Energy Center meets the standard, but questions have been raised about the placement of existing sulfur dioxide monitors.
After the EPA said more information was needed, the utility agreed to install two additional monitors near the Labadie site in January and will use them, along with two already in operation, to gather three years of data to determine if Franklin and St. Charles counties exceed limits for sulfur dioxide. The pollutant is linked to respiratory ailments and other health problems.
The plan is open to public comment until Thursday, which leaves little time for the Department of Natural Resources and regional EPA officials to process comments.
The compliance process has been drawn out, in part, by debate around the use and placement of air monitors. The EPA allows states to rely on either air quality modeling or actual monitoring to assess local sulfur dioxide levels. State modeling showed the Labadie site exceeds the standard, but Ameren argues the models overstate emissions and has pushed to conduct monitoring in the area. In 2015, the utility began operating two sulfur dioxide monitors near the plant.
"We felt the need to fill the gap in data collections," Steve Whitworth, Ameren's senior director of environmental policy and analysis, said in June.
Critics question the adequacy of Ameren's locations for the two existing monitors. The EPA said neither of the current monitoring site locations is "in areas representative of maximum concentrations."
Maxine Lipeles, co-director of the Interdisciplinary Environmental Clinic at Washington University School of Law, also said the monitors at Labadie, which is the largest U.S. coal plant that does not have any sulfur dioxide controls in place, "were not in good locations" to catch higher concentrations.
Ameren said in a statement it has been cooperative in determining the locations of the additional equipment and that the monitors currently in place "show no air quality issues."