Proposed Changes to the Reclassification of Major Sources of HAP Emissions as Area Sources (Previously Once-In-Always-In)
As part of the issuance of Executive Order 13990, President Biden required EPA to review the final rule entitled “Reclassification of Major Sources as Area Sources under section 112 of the Clean Air Act” (MM2A final rule) and propose a rulemaking either suspending, revising, or rescinding the rule. The MM2A final rule withdrew the long-standing EPA interpretation that a major source of hazardous air pollutant (HAP) emissions subject to a maximum achievable control technology standard (MACT) would always be classified as a major source and subject to MACT standards even if the source later reduced emissions to below major source thresholds, commonly referred to as the “Once-In-Always-In Policy” (OIAI Policy). The MM2A final rule permitted major sources to reclassify as area sources by reducing their potential to emit to below major source thresholds. See 40 C.F.R. § 63.1(b)(6).
On September 27, 2023, EPA issued a notice of proposed rulemaking reconsidering the withdrawal of the OIAI Policy and the MM2A final rule. EPA’s proposed rule would allow sources to continue to reclassify from major source status to area source status so long as three criteria are met: (1) any permit limitations taken to reclassify from a major source to an area source must be federally enforceable; (2) any such permit limitations must contain safeguards to prevent emission increases after reclassification beyond the applicable major source MACT standard at time of reclassification; and (3) reclassification will only become effective once a permit has been issued containing enforceable conditions and electronic notification has been submitted to the EPA within 15 days after reclassification. Once finalized, sources that reclassified since January 25, 2018 under the MM2A final rule would be required to comply with the additional requirements in order to remain an area source.
The proposed rule would only apply to synthetic minor sources, i.e., sources that have a potential to emit above major source thresholds, are or would be subject to MACT standards, and are taking a restriction to limit the facility’s potential to emit to below major source thresholds. The proposed rule would not apply to (1) a synthetic minor source that has taken restrictions to limit its potential to emit before the source’s first compliance date of the applicable MACT standard, (2) to minor sources that have modified operations such that they are no longer capable of emitting above major source thresholds, or (3) sources that were never a major source.
The public comment period on the proposed rulemaking ended on November 13, 2023 and the rule is expected to be finalized in May 2024.