The Environmental Protection Agency (EPA) is proposing to approve changes to the Alabama State Implementation Plan (SIP) that were provided by the Alabama Department of Environmental Management (ADEM) to EPA in letters dated May 7, 2012 and August 27, 2018 (excluding items that were withdrawn by letter dated May 5, 2017).

The proposed SIP revisions, relating to the State's Prevention of Significant Deterioration (PSD) permitting regulations, add a definition of "replacement unit" and provide that a replacement unit is a type of existing emissions unit under the definition of "emissions unit". This is a follow-up action to a previously published direct final rule and proposal from August 24, 2017, which was withdrawn due to adverse comments. Comments on this proposed rule must be received on or before April 29, 2019.

The March 29, 2019 Federal Register notice is available on the U.S. Government Publishing Office's website.