Document zdE65GVgZROqyXYE156n44g13

maintains continuous emission controls to accommodate for the changing lignite quality to assure compliance with existing MATS mercury limitations. The variability of the lignite results in a much broader design range of controls and the equipment operation must account for the maximum mercury ROM and in turn must have a greater performance design standard for removal percentage removal. A compliance margin in the performance design standard for percentage removal is critical to allow for controls to adjust in response to changing lignite content, assuring continuous compliance with the MATS RTR Rule. See Attachment A, at Table 2-4. ELIMINATION OF THE MERCURY SUBCATEGORY FOR LIGNITE CAUSES IMMEDIATE AND IRREPARABLE HARM TO THE NORTH DAKOTA LIGNITE INDUSTRY AND TO MINNKOTA 26. EPA established the lignite subcategory for mercury because lignite units have different characteristics than units designed to combust bituminous and subbituminous coals. 77 Fed. Reg. at 9378. Lignite has a higher mercury content in many instances and presents greater variability than other coals. See E.J. Cichanowicz, "Technical Comments on MATS -1 - Sierra Club FOIA 2025-EPA-04883 ED_018388_00000327-00063 SC_EVERSPLIT0006372