Ill. Admin. Code tit. 35 § 201.535
For eligible emission units under Section 201.505, the owner or operator of a proposed emission unit must submit a complete application to the Agency for a minor modification to the CAAPP permit for the source to address the emission unit, pursuant to Section 39.5(14) of the Act, before the emission unit begins operation. The application for minor permit modification must address all applicable requirements contained in this Subpart M, the applicable PBR Subpart, and Section 39.5(14) of the Act. Pursuant to Section 39.5(14)(a)(vi) of the Act, the owner or operator may begin operating the emission unit immediately after it files the application. Until the Agency takes any of the actions specified in Section 39.5(14)(a)(v)(A) through (C) of the Act, the owner or operator must comply with both the applicable requirements governing the emission unit and the proposed terms and conditions of the suggested draft of the modified CAAPP permit in the application, pursuant to Section 39.5(14)(a)(iii)(B) of the Act.
Ill. Admin. Code tit. 35, § 201.535