Air Plan Approval; Michigan; Partial Approval and Partial Disapproval of the Detroit SO2 Nonattainment Area Plan

The Environmental Protection Agency (EPA) is partially approving and partially disapproving a revision to the Michigan State Implementation Plan (SIP) for attaining the 2010 1-hour primary sulfur dioxide (SO<INF>2</INF>) national ambient air quality standard (NAAQS or "standard") for the Detroit SO<INF>2</INF> nonattainment area (NAA). This SIP revision (hereinafter called the "Detroit SO<INF>2</INF> plan" or "plan") includes Michigan's attainment demonstration and other elements required under the Clean Air Act (CAA). EPA is approving the base year emissions inventory and affirming that the nonattainment new source review (NNSR) requirements for the area have been met. EPA is disapproving the attainment demonstration, as well as the requirements for meeting reasonable further progress (RFP) toward attainment of the NAAQS, reasonably available control measures and reasonably available control technology (RACM/RACT), and contingency measures. Finally, EPA is disapproving the plan's control measures for two facilities as not demonstrating attainment and is approving the enforceable control measures for two facilities as SIP strengthening.