Document NEZq22g1yEaY7Rpzb5LZXo12Q

1I. CENIS Technology is Not Available The MATS RTR requires coal-fired units to implement the revised fPM standard using, CEMS, rather than periodic stack testing. As explained above, this requirement is an integral part of the numeric limit itself. Unit 1 does not have a PM CEMS, and while Unit 2 is equipped with a PM CEMS it has not been calibrated and certified for measuring, the revised. much lower limit. Historically. Unit 1 has conducted PM stack testing to meet the PM limit for Low Emitting EGU (I.F.F) status and demonstrate compliance with the standard for non-hg, metals. Due to technological limitations, as well as cost and market limitations. installing a new CEMS on Unit 1 and upgrading the existing PM CEMS on Unit 2 is "not available" by July 2027. PM CFMS does not provide direct measurements; it uses correlation curves to calculate emissions levels. However, the low fP1V1 standard in the Rule makes developing this correlation curve "virtually impossible." PGEA' Comments on EPA 's Proposed Rule: NESHAP Coal- and Oil-Fired Electric UlditY Steam Generating I Inits Review of Residual. Risk and Technology Review, Docket No. EPA-HQ-OAR- 2018-0794-5994, at 22 (June 28. 2023) [hereinafter "PEEN Comments"] (citing and attaching Ralph I.. Roberson, 'Technical Comments on EPA 's Proposed Rule: Mercury and Air l'aVICS .9illidardS Risk and Technology Review, at 3 (2023) [hereinafter "PM CEMS Technical Memo"]). Similarly. the QA/QC criterion for CEMS are extremely difficult to meet at such low levels. See <'omments qt. the Class of '85 Regulatory Response Group On the PropOS11 (ili LMISSUM SkindUIYIS .Jour HclAirdMIS Air Pollutants: Coal- and Oil-Firecalectric .9eam Generating ((nits Review of the Residual Risk and Technology Review, Docket No. EPA-HQ-OAR-2018-0794-5989. at 16 (June 28. 2024) [hereinafter "Class of '85 Comments"]. In fact, at the time of the proposed MATS R FR. no commercially ayailable PM CEMS would have been able to meet the tight confidence and tolerance intervals associated with the low proposed fPM standard. PGFN Comments at 23 (citing PM CEMS Technical Memo at 5). EPA was, thus, forced to address these issues in the final MATS R FR by loosening the QA criterion and correlation procedures. Sec 89 Fed. Reg. at 38,528-29. However, it has not yet been shown that these changes are enough to address the fundamental issue that PM CEMS has difficulty reliably measuring such low fPM levels due to the error rates of the instrument. See PGFN Comments at 23 (finding insurmountable the "uncertainties inherent the in the measurement device" and the "problems associated with relative size of the uncertainty to the limited data range of fi'M concentrations and the confidence levels and tolerances"); see also Class of '85 Comments at 18. And, in reality, units would need to target emissions below 0.010 lb/MMbtu in order to ensure continuous compliance. See Pet'rs' Brief at 72. Therefore, the CEMS technology to demonstrate compliance with the revised !PM standard is unavailable. Second, there arc significant costs and market limitations associated with PM CEMS, which make it "not available." Installing and operating CFMS is more costly than stack testing. See PGFN Comments at 25-26. Costs include purchasing and installation of CFMS, as well as potential modifications to the units to accommodate CEMS, extended correlation testing., and annual operational costs. See id. at 26; see also Class of '85 Comments at 18 (estimating $180,000 to 5400,000 for "site preparation and engineering analysis, analyzer equipment and installation costs, and initial PS-11 correlation testing"). This does not include the costs of maintaining a full-time employee to operate PM CEMS and the costs of lost generation during testing events For CEMS. Luminant Comments at 16-17. There are also market factors which limit the availability of installing and operating CEMS by the compliance deadline. hhcre arc a limited number of vendors for CFMS, as well as a limited number of professionals certified to install and test CEMS. Currently, two-thirds of facilities utilize stack testing and would need to install CFMS by July 2027, which would overwhelm the current supply of CEMS and the availability of professionals certified to inspect and test the newly installed systems. See Class of '85 Comments at 16. 3 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000174-00003 SC_EVERSPLIT0005954