Air Plan Approval; Minnesota; Sulfur Dioxide

The Environmental Protection Agency (EPA) is approving a revision to the Minnesota sulfur dioxide (SO2) State Implementation Plan (SIP) for the Flint Hills Resources, LLC Pine Bend Refinery (FHR) as submitted on May 1, 2015. The revision will consolidate existing permanent and enforceable SO2 SIP conditions into the facility's joint Title I/Title V SIP document. This action highlights process modifications necessary to meet EPA's Tier 3 gasoline sulfur standards; a comprehensive monitoring strategy to better quantify SO2 emissions from fuel gas-fired emission units; a new restrictive flaring procedure for refinery process units, and other updates and administrative changes. This revision results in a modeled reduction in SO2 emissions from FHR and modeled SO2 ambient air concentrations less than half of the national ambient air quality standards (NAAQS).