Document 7R3RRvk2jQ7Jr54y57xBw72Ya

used as a primary fuel. In addition, an SNCR system injecting urea is used on ST3 for the control of NOx. Apache respectfully requests explains the basis for its request in accordance with the instructions provided by the EPA. Emissions Standards or Limitations Subject of Request NESIIAP Subpart UUUUU, particulate matter limits, 40 C.F.R. 63.9991, Table 1, Row 2.a Facility and/or Affected Source AEPCO Apache Generating Station, Air Quality Control Permit No. 69734, EPA Registry Id: 110043804390 Apache Steam Unit 43 Length of Compliance Period Being Requested Two years Explanation of Why Technology to Implement the Standard Is Not Available Apache Station Steam Units #3 is a 1979 vintage steam generating unit. Steam Unit #3 is a coal unit. Steam Unit #3 is outfitted with electrostatic precipitators and wet scrubbers. Steam Unit #3 struggles to meet the emissions standards in 40 C.F.R. 63.9991, Table 1, Row 2.a on a consistent basis with its installed technologies. It is not feasible for Apache to improve the particulate capture at Steam Unit #3 because there is not space available to install a baghouse, which is what would be required to try to achieve the more stringent limit. AEPCO believes that where the baghousc cannot be accommodated without substantially tearing down large sections of the existing facility, that such technology is not 'available' to the facility in the common-sense meaning of the term intended by Congress. Additionally. AEPCO currently maintains a particulate matter continuous emission monitoring system on Steam Unit #3, these systems arc very costly to maintain including being labor intensive. The technology for these instruments is not made to continuously measure particulate limits that would provide valid data. Explanation of Why National Security Interests of the United States Requires Variance Apache Station Steam Unit #3 is an important generating unit for the bulk electric grid in Southeastern Arizona, including portions of the grid serving the United States/Mexico border, ports of entry, and other U.S. border security assets. If Steam Unit #3 were to be forced off-line, it is unclear whether AEPCO could maintain bulk electric grid stability for an extended period. Benefits to National Security and Limited Environmental Cost of Requested Variance Grant of the requested variance benefits national security by removing the uncertainty about the reliability of the bulk electric grid in Southeastern Arizona. The environmental impact of the grant of the proposed variance is very limited because Apache Steam Unit #3 would continue to operate its existing controls, which achieve similar levels of control except during periods of operational instability. Requester Michelle R. Freeark, Executive Director of Regulatory Affairs & Corporate Services Michelle Freeark, Executive Director of Regulatory Affairs and Corporate Services mfreeark@anit.coop Mobile: 520-237-1825 Office 520-586-5122 Arizona G2T Cooperatives Sierra Club FOIA 2025-EPA-04883 ED_018388_00005754-00002 SC_EVERSPLIT0006423