Air Plan Approval; Indiana; Alcoa BART

The Environmental Protection Agency (EPA) is approving a revision to the Alcoa Best Available Retrofit Technology (BART) averaging time for nitrogen oxides (NOX) in the Indiana State Implementation Plan (SIP). On July 23, 2014, the Indiana Department of Environmental Management (IDEM) submitted to EPA a revision to the daily NOX emissions limits, changing from a rolling 24-hour average to a 24-hour daily average. IDEM provided a statistical analysis showing that no significant increase in emissions will occur as a result of this change. EPA is approving this SIP revision because it will not interfere with attainment or maintenance of the National Ambient Air Quality Standard (NAAQS).