b) Notwithstanding subsection (a), an owner or operator may demonstrate compliance with 35 Ill. Adm. Code 215 pursuant to an Agency approved alternative compliance plan contained in a permit utilizing an ACS which is applied for prior to December 31, 1982. The Agency shall approve such an alternative compliance plan if, and only if, the applicant demonstrates that:

1. 1) The alternative compliance plan extends the compliance date for each emission source subject to the ACS no longer than necessary to enable that emission source to utilize the ACS, but in no case later than December 31, 1987;
2. 2) The emission source belongs to a category of emission sources having a compliance date of December 31, 1982 or later under 35 Ill. Adm. Code 215;
3. 3) The use of an ACS will result in either greater or faster overall emission reductions than would otherwise be achieved; and
4. 4) Such extension is consistent with the requirements of the Clean Air Act.