Document k9ekZRm3OvL4RKmknjx4VZyby

allow for a reasonable compliance margin. See I'et'rs' Brief at 18; Luminant Comments at 26. EPA also does not appreciate that mercury in lignite is harder to control compared to other types of coal and that the effectiveness of activated carbon in controlling mercury is inhibited by selective catalytic reduction ("SCR") systems. Luminant Comments at 24-25 (Iuminant's Oak Grove units utilize SCR). These limitations arc analyzed in detail in ,S7te Specific Analysis of Oak Grove Power Plant by J. Edward Cichanowicz (June 22, 2023) attached to Luminant's comments. Finally, even setting aside the technological and operational limitations which would make compliance with the revised mercury standard impossible, the MATS RTR would impose significant costs that would jeopardize the future use of lignite-fired units and imperil grid reliability. Even if existing controls for mercury could be "dialed up," EPA failed to account for the considerable costs associated with the ACI equipment additions and modifications necessary for increased sorbent injection and the necessary enhancements to other control equipment. Pet'rs' Brief at 80. Inevitably, operators would also thee costs associated with noncompliance when they cannot meet the stringent mercury standard. These costs should be taken into account when considering the unavailability of the technology required for compliance with the Rule. Furthermore, to avoid noncompliance with the Rule's impossible standard, operators would choose to run their units less but this comes at a cost to grid stability and reliability. To avoid these problems. President Frump should determine that the technology to implement the revised mercury standard in the MATS RTR at Oak Grove is not available. II. Particulate Control Technology and CENTS Technology is Not Available As an initial matter, EPA has been very clear that the revised fPM standard and CEMS requirement are completely integrated, such that any exemption must cover both requirements in the Rule. Specifically, EPA explained "that a fPM standard of 0.010 lb/MMBtu ... is the lowest fPM emission limit possible at this time with use of PM CEMS." 89 Fed. Reg. at 38,534. And EPA identified the revised IPM standard and the PM CEMS requirement as a combined "twopronged approach," stating that "requiring PM CEMS in addition to a lower IPM limit . . . is the most stringent option that balances the benefits of using PM CEMS with the emission reductions associated with the tightened fPM emission standard." Id. at 38,530. In other words, EPA's effort "to implement" its revised standard depends equally on both the more stringent numeric standard for fPM and on the obligation to install new monitoring equipment. Part A explains that the technology required to implement the Rule's revised fPM standard is "not available" on a continuous basis, and Part B explains that changes to the CEMS are likewise unavailable. Given the interdependence of these requirements, however, the unavailability of technology as to either component makes "implementation" of the standard likewise unavailable for the other. a. The Particulate Control Technology Required to Implement the Rule's fPNI Standard is Not Available There are operational limits at Oak Grove that make it difficult and expensive to meet the revised fi'M standard. EPA based its decision to lower the IPM standard on data from only a select few units, see Pet'rs' Brief at 65-68, AOrth Dakota r. EPA, No. 24-1119, Doc. 2077742 (Oct. 1, 2024), but not all units meet the new limit under all conditions. Oak Grove currently utilizes a baghouse for particulate control. Even though Oak Grove's baghouse runs efficiently, the new standard is challenging to meet because not all baghouscs were originally designed to meet a limit 3 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000159-00003 SC_EVERSPLIT0005927