1. a) If closure is to be by removal, the owner or operator must remove all waste, all waste residues, contaminated containment system components (e.g., liners), contaminated subsoils and structures and equipment contaminated with waste and leachate; and, if disposed of in the State of Illinois, dispose of them at a disposal site permitted by the Agency under the Act.

2. b) If closure is not to be by removal, the owner or operator must comply with the requirements of Subpart C and must:

   1. 1) Eliminate free liquids by removing liquid wastes or solidifying the remaining wastes and waste residues.
   2. 2) Stabilize remaining wastes to a bearing capacity sufficient to support final cover.

   3. 3) Cover the surface impoundment unit with a final cover designed and constructed to:

      1. A) Provide long-term minimization of the migration of liquids through the closed impoundment unit;
      2. B) Function with minimum maintenance;
      3. C) Promote drainage and minimize erosion or abrasion of the final cover;
      4. D) Accommodate settling and subsidence so that the cover's integrity is maintained; and
      5. E) Have a permeability less than or equal to the permeability of any bottom liner system.

3. c) If some waste residues or contaminated materials are left in place at final closure, the owner or operator must comply with the requirements of Subpart C for five years after closure and must:

   1. 1) Maintain the integrity and effectiveness of the final cover, including making repairs to the cap as necessary to correct the effects of settling, subsidence, erosion, or other events;
   2. 2) Maintain and monitor the groundwater monitoring system; and
   3. 3) Prevent run-on and run-off from eroding or otherwise damaging the final cover.

(Source: Amended at 47 Ill. Reg. 7631, effective May 16, 2023)