Document 3Q1vkNja0LYr1X9Do3wELLv7n

r TALEN ell MONTANA COMMENTS OF TALEN MONTANA, LLC ON THE PROPOSAL ON NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS: COAL- AND OIL-FIRED ELECTRIC UTILITY STEAM GENERATING UNITS REVIEW OF THE RESIDUAL RISK AND TECHNOLOGY REVIEW Docket ID: EPA-HQ-OAR-2018-0794 I. INTRODUCTION On April 24, 2023, EPA published in the Federal Register, at 88 Fed. Reg. 24,854, a Proposal that would amend the National Emission Standards for Hazardous Air Pollutants ("NESIIAP") for coal- and oil-fired electric utility steam generating units ("EGUs") -- i.e., the Mercury and Air Toxics Standards ("MATS") ("Proposal" or "Proposed Rule"). Among other amendments, EPA is proposing to: (i) tighten the surrogate filterable particulate matter ("f-PM") standard for demonstrating compliance with the emissions limits for non-mercury ("non-Hg") metal hazardous air pollutants ("I IAPs") from 0.03 lb/MMBtu to 0.010 lb/MMBtu; and (ii) require continuous emissions monitoring systems ("CEMS") for demonstrating compliance with the fPM standard.' Ialcn Montana, LLC ("Talen Montana") is part-owner and operator of Units 3&4 of the Colstrip Steam Electric Station ("Colstrip") in Rosebud County, Montana. On behalf of itself as an owner and with knowledge gained as the operator of Colstrip, Talen Montana has significant concerns about the Proposed Rule, particularly with the proposed tightening of the f-PM standard. These concerns stem from the unique design and circumstances of Colstrip. Colstrip currently uses venturi wet scrubbers to address both sulfur dioxide ("SO,") and fPM emissions. It would be extremely expensive -- and potentially cost prohibitive -- for Colstrip to comply with the 0.010 lb/MMI3tu fPM limit because the venturi wet scrubbers cannot meet that limit. Colstrip would need to undertake a massive and complex construction project to install new controls either new fabric filters ("FFs") or electrostatic precipitators ("ESPs") -- when Colstrip's remaining life and future generation is likely limited given EPA's other rulemakings targeting older sources like Colstrip. The high costs associated with installing, testing, and implementing new controls, coupled with limited time and electric generation for the recovery of such costs, may cause Colstrip to shut down prematurely if the owners deem that it is not economically feasible to install the necessary controls to comply with the proposed fPM standard. A premature shutdown of. Colstrip would have significant economic impacts on Montana and beyond and raises serious concerns about grid reliability and transmission, factors that were not considered by EPA in setting the proposed fPM standard. Moreover, Colstrip bears a hugely disproportionate burden under the Proposed Rule, especially where EPA has not found any unacceptable risk related to Colstrip's (or any other affected facility's) operation under the current IPM standard. Indeed, by EPA's own calculations, Colstrip is expected to bear almost 50 percent I Sec, 88 Fcii Rcg 24,854 (Apr. 24. 2023). 1 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000307-00002 SC_EVERSPLIT0006098