Partial Approval and Partial Disapproval of Air Quality State Implementation Plans; Arizona; Infrastructure Requirements To Address Interstate Transport for the 2008 Ozone NAAQS

The Environmental Protection Agency (EPA) is proposing to partially approve and partially disapprove a State Implementation Plan (SIP) revision submitted by the Arizona Department of Environmental Quality on December 27, 2012, and supplemented on December 3, 2015, to address the interstate transport requirements of Clean Air Act (CAA or Act) section 110(a)(2)(D) with respect to the 2008 ozone (O3) national ambient air quality standard (NAAQS). We are proposing to approve the portion of the Arizona SIP pertaining to significant contribution to nonattainment or interference with maintenance in another state and proposing to disapprove the portion of Arizona's SIP pertaining to interstate transport visibility requirements. EPA's rationale for proposing to partially approve and partially disapprove Arizona's December 27, 2012 SIP revision and December 3, 2015 supplement is described in this notice. EPA previously took two separate actions on Arizona's December 27, 2012 submittal, on July 14, 2015 and August 10, 2015. We are taking comments on this proposal and plan to follow with a final action no later than June 7, 2016.