Document mBoD2zayjr3gbz73NoQn1xQ8Q

r TALEN ell MONTANA ciataset pursuant to the proposed 0.010 lb/MMBtu f-PM limit PS-11 correlation will still be valid at such low levels. EPA needs to establish that the 2. Colstrip's Challenges with PM CEMS Colstrip has utilized PM CEMS as a particulate control performance indicator in its PM CAM Plan since 2014. 'Ile initial PM CEMS were a light scattering technology that encountered times when they did not accurately indicate particulate emissions from the wet venturi scrubber at Colstrip Units 3&4. In September 2020, the PM CEMS were changed to the MSI BetaGuard 3.0 PM CEMS. the BetaGuarci PM CEMS has performed better than the light scattering technology at Colstrip; however, it still exhibits variability that would not be acceptable to be used as a continuous compliance monitor. When compared to the quarterly MATS PM compliance test results, the BetaGuard PM CEMS has provided mg/m3 values that varied from the RMS m2/m3 value by -24% to --31%. Palen Montana believes this range of variability with the PM CEMS is not acceptable for use as a compliance monitor, but its use as part of a PM CAM Plan like Colstrip utilizes, is reasonable. The PM CAM Plan is a requirement under Colstrip's Title V Operating Permit to help ensure compliance to the particulate standard utilizing performance indicators and an operational parameter. 'Ile performance indicators include opacity monitoring and PM CEMS, and the operational parameter is scrubber plumb bob delta P. PM CEMS requirements under Colstrip's PM CAM Plan arc robust and include: Installation per manufacturer's standards. Daily zero and span checks using manufacturer's standards. Initial correlation based on three levels (zero, normal operations, and at scrubber operations that increase PM but not at a level that puts Colstrip's Title V requirements at risk). This initial correlation used three RMS runs at normal operations and two RMS runs at the higher PM level. This correlation relates PM CEMS m2/m3 to RMS mg/m3. A PM CEMS CAM Plan excursion limit in terms of mg/m3 is established. A PM CEMS CAM Plan excursion requires a prompt investigation to identify and correct the condition, followed by a RMS test to confirm compliance with the particulate standard. On a quarterly basis, one RMS test (comprised of three runs) will be conducted to update the initial correlation. if the result from the average of the three runs differs 25 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000307-00026 SC_EVERSPLIT0006122