Air Plan Partial Disapproval and Partial Approval; Pennsylvania; Attainment Plan for the Indiana, Pennsylvania Nonattainment Area for the 2010 Sulfur Dioxide Primary National Ambient Air Quality Standard

The Environmental Protection Agency (EPA) is revising its prior action that erroneously fully approved a state implementation plan (SIP) revision submitted by the Commonwealth of Pennsylvania (PA), through the Pennsylvania Department of Environmental Protection (PADEP), to EPA on October 11, 2017, and supplemented on February 5, 2020. The SIP revision provided a plan for attainment of the 2010 sulfur dioxide (SO<INF>2</INF>) primary national ambient air quality standard (NAAQS) in the Indiana, Pennsylvania SO<INF>2</INF> nonattainment area (hereafter referred to as the "Indiana, PA NAA" or "Indiana Area"). The attainment plan submission included a base year emissions inventory, an analysis of the reasonably available control technology (RACT) and reasonably available control measure (RACM) requirements, enforceable emission limitations and control measures, a reasonable further progress (RFP) plan, a modeling demonstration of SO<INF>2</INF> attainment, and contingency measures for the Indiana Area. EPA is revising its prior action and is partially approving and partially disapproving the SIP. This action is being taken under the Clean Air Act (CAA).