Approval and Promulgation of Implementation Plans; Oklahoma; Disapproval of Prevention of Significant Deterioration for Particulate Matter Less Than 2.5 Micrometers-Significant Impact Levels and Significant Monitoring Concentration

The Environmental Protection Agency (EPA) is proposing to disapprove severable portions of the February 6, 2012, Oklahoma State Implementation Plan (SIP) submittal that establish certain de minimis thresholds for particulate matter less than 2.5 micrometers in diameter (PM2.5) in the Prevention of Significant Deterioration (PSD) permitting requirements. Specifically, we are proposing to disapprove provisions that adopt and implement the PM2.5 significant impact levels (SILs) and significant monitoring concentration (SMC); both of which were vacated by a federal court and subsequently removed from federal PSD regulations. We are proposing to disapprove the submitted provisions as inconsistent with federal laws and regulations for the permitting of PM2.5. The EPA is proposing this disapproval under section 110 and part C of the Clean Air Act (CAA).