Document x154pwJvkyEka4G0yqYVkjOp0

r TALEN ell MONTANA of the costs of the Proposed Rule. For these reasons, as well as other legal and technical reasons discussed below, 1-alen Montana asks that EPA not finalize the proposed 0.010 lb/MM13tu fPM limit. However, should EPA ultimately finalize the proposed 0.010 lb/MMBtu fPM limit, Talon strongly urges EPA to establish a subcategory for coal-fired units that use wet scrubbers to address both SO, and PM emissions and that do not presently have an ESP or IT, where the fPM limit for those units is no lower than 0.025 lb/MM13tu [PM. Given that EPA's rationale for the Proposed Rule is that existing control technology is more effective and cost effective than was known at the time of the original MATS rule, a targeted limit that is specific to the existing wet scrubber technology is consistent and appropriate with that approach. As an additional alternative, 'Ialen Montana requests that EPA establish a subcategory for near-term existing coal units electing to retire where the fPM limit remains at 0.030 lb/MMBtu until ceasing operations. This would be consistent with the approach EPA has taken in other rulemakings. Under such an approach, units could opt-in to the subcategory by making an enforceable retirement commitment within a specified timeline after the Proposed Rule is finalized and with retirement planned by a specified date. For this subcategory, Talon Montana proposes that units opt-in within 18 months after the effective date of the final rule with a retirement date no later than December 31, 2035 (with a "safety valve" that would allow longer operation depending on circumstances in the future, as described below). II. BACKGROUND Colstrip is one of the largest coal-tired electric generating facilities west of the Mississippi River, supplying electricity throughout Montana and the Pacific Northwest. 1-alen Montana has a 15% ownership stake in Colstrip, which currently consists of two active coal-fired generating units capable of producing up to 1,480 MW of electricity that have been operating for approximately 37 years. Each of the units has approximately 740 MW of generating capacity, and the adjacent Rosebud coal mine supplies Colstrip's low-sulfur subbituminous coal. A. Colstrip's Unique Design Colstrip's design sets it apart from other coal-fired units in the country that arc currently operating. Colstrip began construction in the 1970s and Units 3 and 4 began operations in the 1980s. Colstrip was designed to utilize low-sulfur coal and with then state-of-the-art venturi wet scrubbers to reduce its SO, emissions below the applicable limits. Colstrip also relies on the venturi wet scrubbers to mitigate fPM. Colstrip has eight wet venturi scrubbers on each of unit. Seven scrubbers are used during normal full load operation and one scrubber is a "backup," used only when one of the other seven scrubbers in operation needs to be removed from service or is undergoing routine cleaning and maintenance. Below is a diagram of the wet venturi scrubber used at Colstrip Units 3&4: 2 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000307-00003 SC_EVERSPLIT0006099