EPA initially issued a Notice and Finding of Violation (NOV/FOV) to IPL in 2009, alleging that it had made ?major modifications? under the regulations for the Prevention of Significant Deterioration (PSD) at its Petersburg, Harding Street, and Eagle Valley Stations, without meeting PSD requirements including Best Available Control Technology (BACT) for sulfur dioxide (SO2), nitrogen oxides (NOx) and Particulate Matter (PM).
In 2015 and 2016, EPA issued additional NOVs/FOVs to IPL alleging additional PSD violations and excess emissions of opacity at the Petersburg Generating Station in violation of the applicable New Source Performance Standards, Indiana State Implementation Plan and operating permit issued under Title V of the CAA. Prior to this Decree, IPL retired the Eagle Valley Station and converted the Harding Station units to natural gas.
In settlement of this case, IPL agreed to, among other things, operate a sulfuric acid mist mitigation system on all four Petersburg Units and meet a federally enforceable sulfuric acid emission limitation on each unit (to reduce opacity from the Units). IPL also agreed to install a Selective Non-Catalytic Reduction system on Petersburg Station Unit 4 to reduce NOx, and to continuously operate existing air pollution controls for NOx and SO2. IPL requested and the U.S. agreed that should IPL retire Units 1 and 2 prior to 2023 then it shall be relieved of its obligation to install and operate the SNCR on Unit 4. In addition,