Section 60.28a - Plan revisions by the State(a) Any significant revision to a State plan shall be adopted by such State after reasonable notice, public hearing, and meaningful engagement. For plan revisions required in response to a revised emission guideline, such plan revisions shall be submitted to the Administrator within fifteen months, or as determined by the Administrator, after publication in the FEDERAL REGISTER of a final revised emission guideline under § 60.22a . All plan revisions must be submitted in accordance with the procedures and requirements applicable to development and submission of the original plan.(b) A revision of a plan, or any portion thereof, shall not be considered part of an applicable plan until approved by the Administrator in accordance with this subpart.84 FR 32575, July 8, 2019, as amended at 88 FR 80545, Nov. 17, 2023 84 FR 32575, 9/6/2019; 88 FR 80545, 12/18/2023