Air Plan Approval; MS; Section 128 Board Requirements for Infrastructure SIPs

The Environmental Protection Agency (EPA) is proposing to approve the draft State Implementation Plan (SIP) submissions, submitted by the State of Mississippi, through the Mississippi Department of Environmental Quality (MDEQ) for parallel processing, on June 23, 2017, and February 2, 2018. Together these draft submittals address specific Clean Air Act (CAA or Act) requirements applicable to Mississippi state boards or bodies that approve CAA permits and enforcement orders. These submissions also request that EPA convert the previous partial disapproval of Mississippi's infrastructure SIPs related to the CAA state board significant portion of income requirements for the 2008 8-hour Ozone, 2008 Lead, 2010 Nitrogen Dioxide (NO2), 2010 Sulfur Dioxide (SO2), and 1997, 2006 and 2012 fine particulate matter (PM2.5) national ambient air quality standards (NAAQS) to full approvals. Whenever EPA promulgates a new or revised NAAQS, the CAA requires the state to make a new SIP submission establishing that the existing SIP meets the various applicable requirements, or revising the SIP to meet those requirements. This type of SIP submission is commonly referred to as an ``infrastructure'' SIP. In this proposed action, EPA is proposing to approve the June 23, 2017, and February 2, 2018 submissions with respect to the CAA requirements applicable to state boards; and the related state board infrastructure SIP requirements for the 2008 8-hour Ozone, 2008 Lead, 2010 NO2, 2010 SO2 and 1997, 2006 and 2012 PM2.5, NAAQS. If this proposed approval action is finalized, EPA will no longer be required to promulgate a Federal Implementation Plan (FIP) to address the CAA state board requirements for Mississippi, as described in more detail below.