Document VJNnQXYE9dxxq136pjrnGGV4K

the very types of facilities to which the proposed limits would apply. Agencies "must examine the relevant data and articulate a satisfactory explanation for its action including a `rational connection between the facts found and the choice made." Motor Vehicle Mfrs'. Ass'n v. State Farm Mut. Ins. Co., 463 U.S. 29, 43 (1983) (emphasis added) (quoting Burlington 'ruck Lines v. United ,S'iates, 371 U.S. 156, 168 (1962)); see also EPA, Guidelines Jiff MACT Determinations under Section 112( Requirements (Feb. 2002) ("It is not necessary for the MAT floor to be determined based on emissions information from every existing source in the source category or subcategory if such information is not available. The permitting authority, however, should check with EPA Regional Offices and EPA Headquarters for any available information that could be used in determining the MAC1- floor.") (emphasis added). In addition, the proposed I INR IIRSG main stack emission limits arc expressed purely on a concentration basis (gr/dscf) without normalization to a reference 0, level. Concentration-based emission limits that are not corrected to a reference oxygen level will simply allow dilution of the stack gas with excess air as a means of complying with the emission limits. Similarly, the test data used in the MACT floor analysis to develop the concentration-based emission limits were uncorrected data. -Ile individual data points used in the calculations are associated with varying oxygen levels in the stack. These data points should be corrected to a consistent reference oxygen level before being used in the calculations. EPA must recalculate the HNR HRSG main stack limits using all available stack test data from 2006 through 2022 from SunCokc HNR HRSG main stacks at Haverhill, Middletown, and Granite City, and the Cokencrgy HRSG main stack at Indiana Harbor, corrected to a consistent reference oxygen level. The 45-day comment period did not provide sufficient time for SunCoke to fully evaluate and propose more appropriate and accurate revised limits. Nonetheless, SunCoke's preliminary estimates correcting these two errors i.e., the arbitrarily confined ciataset used and the failure to correct for oxygen levels to enable separately collected ciatapoints to be meaningfully compared demonstrate that the UPL used must be revised significantly. 2. The Proposed Compliance Date is Insufficient and Unreasonable The Proposed Rule specifies that sources must be in compliance with the proposed I INR I IRSG main stack limits within one (1) year of publication of the final rule. 88 Fed Reg. 55858, 55893 (Aug. 16, 2023). Yet the Proposed Rule would, for the first time, impose emission limits for HRSG main stacks (and HRSG bypass/waste heat stacks), among other major changes to Subparts L and CCCCC. One year is not sufficient to establish new controls necessary for compliance with these new limits. Haverhill's P901 HRSG main stack source will likely require SunCoke to install an Activated Carbon Injection (ACI) system to control mercury emissions from the HRSG main stack and meet any proposed or revised mercury limit. SunCoke expects installation of the ACI system to cost approximately $3 million not including annual operating costs or costs for the activated carbon. 'Ile mercury control efficiency will vary widely depending on the inlet mercury loading and the actual control efficiency of the system; however, SunCokc estimates that it would cost at a minimum $6 million per ton of mercury removed. 32 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000109-00033 SC_EVERSPLIT0005707