Approval and Promulgation of Air Quality Implementation Plans; 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 proposing to approve a state implementation plan (SIP) revision, submitted by the Commonwealth of Pennsylvania through the Pennsylvania Department of Environmental Protection (PADEP), to EPA on October 11, 2017, for the purpose of providing for attainment of the 2010 sulfur dioxide (SO2) primary national ambient air quality standard (NAAQS) in the Indiana, Pennsylvania SO2 nonattainment area (hereafter referred to as the ``Indiana Area'' or ``Area''). The Indiana Area is comprised of Indiana County and a portion of Armstrong County (Plumcreek Township, South Bend Township, and Elderton Borough) in Pennsylvania. The major sources of SO2 in the Indiana Area emitting over 2,000 tpy of SO2 include several large electric generating units (EGUs): Keystone Plant, Conemaugh Plant, Homer City Generation, and Seward Generation Station (hereafter referred to as ``Keystone,'' ``Conemaugh,'' ``Homer City,'' and ``Seward''). The SIP submission is an attainment plan which includes the 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 SO2 attainment, and contingency measures for the Indiana Area. As part of approving the attainment plan, EPA is also proposing to approve into the Pennsylvania SIP SO2 emission limits and associated compliance parameters for Keystone, Conemaugh, Homer City and Seward and proposes to find Pennsylvania has measures in place to address nonattainment new source review. EPA proposes to approve Pennsylvania's attainment plan and concludes that the Indiana Area will attain the 2010 1-hour primary SO2 NAAQS by the applicable attainment date and that the plan meets all applicable requirements under the Clean Air Act (CAA).