Document qqKkqkeZv89ej6d3zmZwnRkK

and demonstrations of compliance with numeric emissions limits. The Copper Rules' "waiver" of isokinetic calculations, at 40 C.F.R. 63.1450(e)(1)(v) and 63.1450(g)(1)(v), reflects EPA's recognition that such sampling cannot occur across and within the large vent-openings of the smelter roofline, given the "low flow rates and high variability" of flow. But the "waiver" leaves entirely unaddressed the problem that sampling and calculations that are not isokinetic are incapable of yielding accurate emissions measurements for purposes of demonstrating compliance with numeric emissions limits. Without the "isokinetic" requirement, there would be no assurance that the velocity of flow entering the sampling probe's nozzle is representative of actual flow, making the corresponding calculations of the emission rates in pounds per hour meaningless for purposes of demonstrating compliance with the PM and Pb emissions-rate limits specified in 40 C.F.R. 63.1444(h) and 63.1444(p)(1). Based on the information provided above, Asarco recommends that owners and operators of primary copper smelters be exempted, under Clean Air Act 112(i)(4), from having to comply with 40 C.F.R. 63.1444(h), 63.1450(e), 63.1444(p)(1), and 63.1450(g). Thank you for the opportunity to provide this information. Please do not hesitate to let me know if you have any questions regarding the information; or would like to convene a virtual meeting to discuss the information further--including, perhaps, Freeport McMoRan, which operates the primary copper smelter in Miami, Arizona. Sincerely, James M. Stewart Director of Environmental, Governmental and Community Affairs ASARCO LLC From: Dunkins, Robin <Dunkins.f flov> Sent: Monday, March 24, 2025 2:35 PM Subject: Presidential Exemption under CAA Section 112(i)(4) Hello -- EPA wanted to share with you information about submitting a request for an exemption from nine different NESHAPS using Clean Air Act section 112 (i)(4). Requests can be emailed to iractioriepa sp', by March 31, 2025. The link below provides more information: httpS. ::0 t;ilia informailon ronarv-sourcesaipipoirutionfclean-aii--af ection112-presiciential-exemption- Robin Dunkins, Senior Advisor Office of Air Quality Planning and Standards U.S. Environmental Protection Agency 109 T.W. Alexander Drive Research Triangle Park, NC 27711 O: 919-541-5335 M: 919-605-1178 dunkins.robineepa.qov Sierra Club FOIA 2025-EPA-04883 ED_018388_00000318-00003 SC_EVERSPLIT0006296