Document QgvdQGyGaLbk4YO3yxvjeE2NE

Seward Generation 595 Power Plant Road New Florence, PA 15944 814-446-7162 During the comments period on the proposed MATS Rule, many commenters provided data showing that, by eliminating the LEE provisions which allow once per three-year emissions testing as an incentive to be a low emitter, EPA is forcing massive cost increases by the requirement of continuous emissions monitoring, record keeping, and reporting on the lowest emitting affected EGUs. Seward believes that PM CEMS cannot be used to demonstrate compliance with the new MATS Rule. The fPM standards were lowered by 2/3rds. Starting in 2027, sources will be required to demonstrate compliance with a PM CEMS on the more stringent fPM standards which are 0,010 lbs/MMBtu. Demonstrating compliance with emissions standards this low utilizing a PM CE MS is not a viable option. Some units have used PM CEMS for many years and have encountered problems with operating their PM CEMS with regard to (i) meeting the Quality AssuranceQuality Control (QA-QC) criteria; and (ii) establishing the correlation curve. PM CIW1S also fail to meet the QA/QC criteria. When a PM CEMS fails to meet the QA-QC criteria, the collected data arc considered out-of-control and are no longer considered valid. An owner/operator has no real time indication that its EGU might have failed the required QA-QC criteria until several weeks after the testing has been completed, This could result in hundreds of hours of monitor downtime being created retroactively after the QA-QC criteria failure has been identified and is required to be reported as a deviation under the MATS rule. Most states have minimum data availability requirements that could result in enforcement actions. At the more stringent fPM standard of 0.010 lb/MMBtu, the likelihood of out-of-control periods increases, This downtime is not reflective of poor maintenance or operation but rather the difficulties associated with the quality assurance procedure at such low emission levels and is not accounted for in the EPA analysis. Finally, there currently is no calibration procedure available that can accurately verify continuous measurements of fPM at levels as low as 0.010 lb/MMBtu, Moreover, PM CEMS is not a direct measure of compliance with the applicable emission limitation; rather, emissions are correlated and as such can be in error as much as +/- 25% when having to correlate to standards as low as 0.010 lhs/MMBtu. Sierra Club FOIA 2025-EPA-04883 ED_018388_00000267-00003 SC_EVERSPLIT0006065