(January 25, 2017, 10:52 AM EST) -- ST. LOUIS — A federal judge in Missouri on Jan. 23 ruled that Ameren Missouri violated the Clean Air Act (CAA) when making major modifications to two coal-fired burners at its Rush Island facility in Festus, Mo., without first obtaining a prevention of significant deterioration (PSD) permit, ruling that the repairs were not routine maintenance and increased emissions of sulfur dioxide (SO2) (United States of America v. Ameren Missouri, No. 11 CV 77 RWS, E.D. Mo.; 2017 U.S. Dist. LEXIS 8997)....