Approval of Arizona Air Plan Revisions, Arizona Department of Environmental Quality and Maricopa County Air Quality Department

The Environmental Protection Agency (EPA) is proposing to approve revisions to the Arizona Department of Environmental Quality (ADEQ) and Maricopa County Air Quality District (MCAQD) portions of the Arizona State Implementation Plan (SIP). These revisions were submitted by ADEQ in response to EPA's May 22, 2015, finding of substantial inadequacy and SIP call for certain provisions in the SIP related to affirmative defenses applicable to excess emissions during startup, shutdown, and malfunction (SSM) events. EPA is proposing approval of the SIP revisions because the Agency has determined that they are in accordance with the requirements for SIP provisions under the Clean Air Act (CAA or the Act).