SUPPLEMENTARY INFORMATION:

General Information

The General Provisions of the NSPS in 40 Code of Federal Regulations (CFR) part 60 and the General Provisions of the NESHAP in 40 CFR part 61 provide that a source owner or operator may request a determination of whether certain intended actions constitute the commencement of construction, reconstruction, or modification. 40 CFR 60.5 and 61.06. The General Provisions in part 60 also apply to Federal and EPA-approved state plans for existing sources in 40 CFR part 62. See40 CFR 62.02(b)(2). The EPA's written responses to source or facility-specific inquiries on provisions in parts 60, 61 and 62 are commonly referred to as applicability determinations. Although the NESHAP part 63 regulations [which include Maximum Achievable Control Technology (MACT) standards and/or Generally Available Control Technology (GACT) standards] contain no specific regulatory provision providing that sources may request applicability determinations, the EPA also responds to written inquiries regarding applicability for the 40 CFR part 63 regulations. In addition, the General Provisions in parts 60 and 63 allow sources to seek permission to use monitoring or recordkeeping that is different from the promulgated requirements. See40 CFR 60.13(i), 61.14(g), 63.8(b)(1), 63.8(f), and 63.10(f). The EPA's written responses to these inquiries are commonly referred to as alternative monitoring decisions. Furthermore, the EPA responds to written inquiries about the broad range of regulatory requirements in 40 CFR parts 60 through 63 as they pertain to a whole source category. These inquiries may pertain, for example, to the type of sources to which the regulation applies, or to the testing, monitoring, recordkeeping, or reporting requirements contained in the regulation. The EPA's written responses to these inquiries are commonly referred to as regulatory interpretations.

The EPA previously compiled EPA-issued NSPS and NESHAP applicability determinations, alternative monitoring decisions, and regulatory interpretations, and posted them to the ADI. As of October 2, 2023, the EPA determinations of compliance and applicability under CAA section 111, 112, and 129 will be posted to the CAA section 111, 112, and 129 Dashboard. The CAA section 111, 112, and 129 Dashboard is a data system, accessed via the internet, containing all determinations signed after May 2019.

This document comprises a list of 62 such documents added to the CAA section 111, 112, and 129 Dashboard on June 25, 2025. This document lists the title of each letter and memorandum. Complete copies of these documents may be obtained from the CAA section 111, 112 and 129 Dashboard on the internet through the Resources and Guidance Documents for Compliance Assistance page of the CAA Compliance Monitoring website under “Air” at: https://www.epa.gov/​compliance/​resources-and-guidance-documents-compliance-assistance. ( printed page 51313)

90 FR 51312