Document 1ym3YwL42VdpdL4ddNK7R3wmo

Minnkota Power Cooperative, Inc. Milton R. Young Station Unit 1 and 2 A14559.013 Rev. 2 May 22, 2024 s New feeding equipment, transport piping and injection lances would be required to accommodate a higher injection rate. As the existing PAC storage silo is shared by MRY Units 1 and 2, the higher injection rate required for achieving 3.0 lb/MMacffor both units would reduce the total storage duration to less than seven (7) days of storage. Due to the weather experienced at the site and the remote location, seven (7) days of storage is recommended for each unit. Improved equipment redundancy would also likely be required to accommodate the range of coal Hg expected to be experienced in the future. Therefore,it is likely that the existing equipment would be dedicated to MRY Unit 1, and a separate silo would be required for MRY Unit 2 to ensure adequate supply, turndown flexibility, and reliability is achieved to maintain compliance with a defined Hg emissionlimit. As such, a new MRY Unit 2 system would be required to achieve higher injection rates of PAC. An analogous project to install Hg control equipment at a500 MW coal-fired unit in 2021 costs roughly $5.0 million dollars, based on S&L internal mercury control database, actual project costs from recent relevart projects, and adjusted for MRY specific design Overall, the cost-effectiveness calculated is still a substantial under-estimation for the incremental Hg control on MRY Units 1 and 2. To provide an example, hypothetical MRY Unit 2 costs are summarized in the following table to underscore the magnitude of dollars that EPA failed to include in its calculations and that must be expended by Minnkota. Note the table below does not include or account for any costs associated with MRY Unit 1 system upgrades. Mercury Testing Results for the MATS Residual Risk and Technology Review Sierra Club FOIA 2025-EPA-04883 Sargent S. Lundy 13 ED_018388_00000327-00027 SC_EVERSPLIT0006336