2024-27635. Air Plan Approval; Michigan and Minnesota; Revision to Taconite Federal Implementation Plan

Table 1—NO _X Limits and Limit Modification Ranges Established in the 2016 FIP

Furnace	Emission limit (lbs NO X /MMBtu)	Emission limit modification range (lbs NO X /MMBtu)
Tilden Line 1:
Natural Gas	2.8	2.8-3.0
Co-fire	1.5	1.5-2.5
Hibbing Line 1	1.2	1.2-1.8
Hibbing Line 2	1.2	1.2-1.8
Hibbing Line 3	1.2	1.2-1.8
Minorca	1.2	1.2-1.8
UTAC Line 1:
Natural Gas	2.8	2.8-3.0
Co-fire	1.5	1.5-2.5
UTAC Line 2:
Natural Gas	2.8	2.8-3.0
Co-fire	1.5	1.5-2.5

For Tilden, Hibbing, Minorca, and UTAC, the process specified in the 2016 FIP to either confirm or modify the NO_X emission limits within the established ranges included the installation of a CEMS, submission of an engineering report to EPA, installation of NO_X reduction control technology, submission of pellet quality analyses to EPA, and submission to EPA of a report to either confirm or modify the limit. For any furnace without CEMS already installed, CEMS installation was required for each furnace by 6 months after May 12, 2016, and the owner or operator was required to submit quarterly CEMS data to EPA after May 12, 2016, for the time periods specified ( print page 96156) below in Table 2. Engineering reports containing detailed engineering analyses and modeling of the selected NO_X reduction technology for each furnace demonstrating that the technology was designed to meet an emission limit equal to the lower bound of the established range were required to be submitted to EPA by the deadlines specified in Table 2. NO_X reduction technology was required to be installed two months after the engineering report submission deadline. Beginning on the earlier of six months after the installation of NO_X reduction technology or the deadline for installation of the NO_X reduction technology, the owner or operator was required to submit quarterly pellet quality analyses to EPA, including an explanation of causes for pellet samples that failed to meet the acceptable range for any pellet quality analysis factor, for the time periods specified in Table 2. At the end of the CEMS and pellet quality data collection periods, the owner or operator of each furnace may submit a report to EPA to either confirm or modify the NO_X limits within the bounds described in the 2016 FIP (and above in this section). The 2016 FIP also allows the owner or operator to submit a report proposing a single NO_X limit for all fuels. The process for confirming or modifying limits detailed in the 2016 FIP specifies that EPA's determinations shall be based on the appropriate UPL equation, using CEMS data that meet pellet quality specifications and proper furnace/burner operation. For a more detailed description of the process set forth in the 2016 FIP to confirm or modify the emission limits, see40 CFR 52.1183 and 40 CFR 52.1235.

Table 2—Timelines of Processes To Confirm or Modify Limits

Furnace	Period of CEMS data required for submission to EPA	Engineering report deadline	NO X reduction technology installation deadline	Period of pellet quality data required for submission to EPA *	Report to confirm or modify limit deadline
	Months after May 12, 2016
Tilden Line 1	0-57	48	50	50-57	57
Hibbing Line 1	6-34	24	26	26-34	34
Hibbing Line 2	6-52	42	44	44-52	52
Hibbing Line 3	6-57	48	50	50-57	57
Minorca's Indurating Furnace	6-52	42	44	44-52	52
UTAC Line 1	0-34	24	26	26-34	34
UTAC Line 2	0-52	42	44	44-52	52
* If the owner or operator installed NO X reduction technology more than six months before the required date, pellet quality analyses were required to be submitted to EPA beginning six months after installation.