40 CFR §60.5375c

1. (a)Your state or Tribal plan must address designated facilities that meet all three criteria described in paragraphs (a)(1) through (3) of this section.
   1. (1)Designated facilities in your state that commenced construction, modification, or reconstruction on or before December 6, 2022.
   2. (2)Designated facilities that are listed in table 1 to this subpart.
   3. (3)Designated facilities not exempt under § 60.14(e).
2. (b)If the owner or operator of a designated facility makes changes that meet the definition of modification after December 6, 2022, the designated facility becomes subject to subpart OOOOb of this part, and the state or Tribal plan no longer applies to that facility.
3. (c)If the owner or operator of a designated facility makes physical or operational changes to a designated facility for which construction commenced on or before September 9, 2024, primarily to comply with your state or Tribal plan, subpart OOOOb of this part, does not apply to that designated facility. Such changes do not qualify as modifications under subpart OOOOb of this part.