Ill. Admin. Code tit. 17 § 4180.650
The State agency and the Director may enter into a written agreement stating that a repetitive undertaking or certain class of undertakings or a large complex undertaking may have an adverse effect on historic resources and may detail the measures to be undertaken to minimize or mitigate the adverse effects programmatically. Such agreements are appropriate when adverse effects to specific resources are anticipated but unknown at the time consultation occurs. Such agreements shall be for a specified period of time and shall be subject to review for amendment or revision. Examples include: major land acquisitions, routine maintenance at State-owned complexes, master management plans or statewide loan programs involving similar work items.
Ill. Admin. Code tit. 17, § 4180.650