Document q7Qy6gmx58YRVE2V0J2jnmEn

Hon. Lee M. Zeldin March 31, 2025 Page 5 of the domestic steel industry and the critical supply chain; and is appropriate while EPA reconsiders the Taconite RTR Rule. In addition, these concerns are subject to petitions for judicial review with the United States Court of Appeals or the District of Columbia Circuit. TECHNOLOGY IS UNAVAILABLE A. Technology is unavailable to meet the new mercury limits (See amendments to 40 (TR 63 Subpart RRRRR including hut not limited to 40 CH? 63.9583(1), (1)(1)-(7); 63.9590(a), (h), (h)(1)-(h)(8); 63.9600(h), (h)(1)-(4) as applied to mercury; 63.9610(d), (d)(1)-(d)(6) as applied to mercury; 63.9620(k), (k)(1), (k)(2); 63.9621(a) as applied to mercury; 63.9621(d),(d)(1)-(d)(9) as applied to mercury; 63.9621(e); 63.9622(h), (h)(1)(2); 63.9622(i), (i)(1)-(2); 63.9623(a)(5)-(7);63.9623(d), (d)(1)-(4); 63.9623(e); 63.9623(1); 63.9630(a)-(e) as applied to mercury; 63.9631(g)-(k); 63.9632(h), (h)(1)(4); 63.9632(i), (i)(1)-(4); 63.9634(; 9634(k); 9634(1); 63.9634(m); 63.9634(n); 63.9637 as applied to mercury; 63.9640 as applied mercury and, in particular; 63.9640(J) and (g): 63.9641 as applied to mercury and, in particylat; 63.9641(i); 63.9642 as applied to mercury and in particylat; 63.9642((h)(5), (c), (d), (e), and (J); 63.9650 as applied to mercury; and ,S'uhpart RRRRR Tables 1 through 4.) Based on the best information currently available, both Minntac and Keetac will be required to install post-induration pollution control technology to meet the existing source emission standard for mercury in the Taconite RTR Rule. However, there is no post-induration pollution control technology for mercury in use in the taconite industry and no pollution control technology has been demonstrated to he able to meet the Taconite RTR Rule's emission standard. U. S. Steel has invested significant effort and money into researching mercury control strategies. These efforts include research and pilot testing of activated carbon injection ("AC1"). That testing indicated a potential for modest mercury reductions not achieving the levels of reduction necessary to meet the Taconite RTR's new mercury limits. In addition, the testing results raised concerns both with the technical feasibility of installing and operating ACI at Minntac and Kectac. There are also significant concerns that employing such controls may result in unintended, but significant, adverse environmental impacts. Based on these results. C. S. Steel does not consider ACI as an available or feasible control technology to meet the Taconite RTR Rule's new mercury limits. Significant additional research and pilot testing will be required to establish whether AC1 or any other post-induration mercury control technology will be able to reliably meet the Taconite MR Rule's mercury standard at Minntac and Keetac without causing significant adverse environmental impacts. Since no technology is currently available, U. S. Steel has raised concerns with EPA that the compliance deadlines in the Taconite RTR Rule do not allow sufficient time for this research or to achieve compliance with the standard. Research alone could take the three years provided for compliance without identifying a viable control technology. Permitting will likely be required in Minnesota which could also result in delays beyond U. S. Steel's control that exceed the Taconite RJR Rule's current three-year compliance period. Sierra Club FOIA 2025-EPA-04883 ED_018388_00000151-00005 SC_EVERSPLIT0005885