Document 7OYBBexZ7adwQoRgZ7wayxbO8

Hugo Generating Station MATS Presidential Exemption Request WFEC Page 3 of 6 years. It may be difficult to maintain optimal operation of the ESP during peak conditions unless there are additional outages scheduled for such maintenance, which may not always be feasible. Coal characteristics. The availability of coal is limited to certain regions and, as a result, the characteristics of coal vary depending on location. Ash content of the coal being fired may impact the ability of HU-UNIT1 to comply with the PM limit, regardless of the effectiveness of the control technologies in place.' EPA did not consider operational variability in establishing the revised limitation as will likely become apparent during EPA's reconsideration process. EPA purposely and selectively picked stack test data (representing only the maximum achievable load operation during discreet time periods) and established a revised limitation that applies during all operational periods outside of a prescriptive startup definition. EPA set a revised standard and an associated continuous compliance demonstration (via PM CEMS) that does not reflect operational variability of EGUs. There is no data or other basis to conclude that continuous compliance is achievable for affected units based on currently available technology during all operational periods. By enforcing the current compliance deadline, EPA runs the risk of significantly restricting HU-UNIT1's operational flexibility and decreasing reliability of the unit. Operational flexibility is critical for HU-UN71, which will likely be called on to operate by SPP based on fluctuations in demand, unexpected downtime of other units in the region, extreme weather, and other scenarios that are outside of WFEC's control. HU-UNIT1 might need to derate for a significant period of time or adjust HU-UNIT1's coal supply to comply with the proposed fPM limit on a continuous basis, creating additional reliability risks. These operational challenges support the finding that technology is not currently available to continuously meet the Final Rule's fPM limit. 2. The Necessary Monitoring Technology Is Not Available EPA failed to consider the practical accuracy limitations of the measurement techniques used as the basis of the revised standard. EPA relied upon a combination of stack test data (as discussed above) as well as existing PM CEMS data. Existing PM CEMS were subject to an allowable measurement error tolerance of 25% of the current fPM emission standard of 0.030 lb/rnmBtu. In other words, EPA relied on monitoring systems with an allowable measurement error of approximately 0.0075 lb/MMBtu to establish the revised limitation of 0.010 lb/MMBtu. In short, WFEC has no data upon which to conclude that a commercially available PM CEMS can reliably measure emissions at HU-UNIT1 at the level of the revised standard. EPA has recognized that PM CEMS presents technical challenges that may impact the feasibility of compliance by 2027. EPA agrees that "measuring very low and non-normal high fPM emissions can be See EPA AP-42, Fifth Edition, Vo. 1, Ch. 1.1, Table 1.1-6 "Cumulative Particle Size Distribution and SizeSpecific Emission Factors for Dry Bottom Boilers Burning Pulverized Bituminous and Subhituminous Coal," at 1.126, https]/www.cpa.govlsites/defaultitiles/202009/documents/1.I hituminous_and_subbituminons_coal_combustion.pdf (reflecting direct and linear relationship between ash content and controlled fPM emission). Sierra Club FOIA 2025-EPA-04883 ED_018388_00000260-00003 SC_EVERSPLIT0006059