The U.S. Environmental Protection Agency said in a May 6 Federal Register notice that it is finalizing approval of revisions to the Indiana State Implementation Plan (SIP) submitted by the Indiana Department of Environmental Management (IDEM) to EPA in parallel process form on January 27, 2016, and February 5, 2016, and final form on March 21, 2016, and March 31, 2016.
The submittals consist of orders issued by the commissioner of IDEM that require more stringent SO2 emissions limits than those currently contained in the SIP for Vectren‘s A.B. Brown coal plant and Indiana-Kentucky Electric Corp.‘s coal-fired Clifty Creek Generating Station. EPA proposed approval of these revisions to the Indiana SIP on Feb. 25, 2016 and received no adverse comments. EPA’s approval of these revisions makes the commissioner’s orders’ SO2 emissions limits and applicable reporting, recordkeeping, and compliance demonstration requirements federally enforceable.
IDEM established these SO2 emissions limits to enable the areas near A.B. Brown and Clifty Creek to qualify in the future for be designated in “attainment” of the 2010 primary SO2 National Ambient Air Quality Standard (NAAQS). Under a federal consent decree, EPA is required to designate, under the 2010 SO2 NAAQS, certain areas in the United States including the areas near A.B. Brown and Clifty Creek by July 2, 2016.
The purpose of this rulemaking is to take action on IDEM’s request to approve these Commissioner’s orders into the Indiana SIP and thereby make them federally enforceable. It is not, however, to take action on whether the SO2 emissions limits in these Commissioner’s orders are adequate for EPA to designate attainment of the 2010 SO2 NAAQS for the areas near A.B. Brown and Clifty Creek. EPA intends to designate the areas near the sources that meet the criteria for the first phase of the consent decree designations, including the areas near A.B. Brown and Clifty Creek, under a separate future rulemaking, which was the subject of an EPA proposal on March 1, 2016, “EPA Responses to Certain State Designation Recommendations for the 2010 Sulfur Dioxide National Ambient Air Quality Standard: Notice of Availability and Public Comment Period.”
Indiana requested that EPA “parallel process” these SIP revisions to expedite action on the commissioner’s orders.
For A.B. Brown, Indiana issued commissioner’s Order 2016-01 on Jan. 11, 2016, with a compliance date of April 19, 2016. This order established two new limits for A.B. Brown: one limit for Unit 1 when running alone and one limit for Units 1 and 2 when running simultaneously. The emissions limits are 0.855 lbs of SO2 per MMBTU for coal-fired boiler Unit 1 operating alone and 0.426 lbs of SO2 per MMBTU for Units 1 and 2 operating simultaneously. These limits supplement a limit contained in a 1979 Prevention of Significant Deterioration (PSD) permit of 0.69 pounds per MMBTU for coal-fired boiler Unit 2.
For Clifty Creek, Indiana issued commissioner’s Order 2016-02 on Feb. 1, 2016, with a compliance date of April 19, 2016. This order established a combined emission limit for the six coal-fired boilers (Units No. 1 through No. 6) located at Clifty Creek of 2,624.5 lbs of SO2 per hour as a 720 operating hour rolling average when any of Units No.1 through No. 6, or any combination thereof, is operating.