35 Ill. Adm. Code 724.675
Closure
Section 724
Section 724.675Â Closure
a)Â Â Â Â Â Â Â Â At closure, the owner or operator must remove or decontaminate
all waste residues, contaminated containment system components (pad, liners,
etc.), contaminated subsoils, and structures and equipment contaminated with
waste and leakage, and manage them as hazardous waste.
b)Â Â Â Â Â Â Â Â If, after removing or decontaminating all residues and making
all reasonable efforts to effect removal or decontamination of contaminated
components, subsoils, structures, and equipment, as required in subsection (a),
the owner or operator finds that not all contaminated subsoils can be
practically removed or decontaminated, the operator must close the unit and
perform post-closure care in accordance with closure and post-closure  care
requirements that apply to landfills (Section 724.410). For permitted units,
the requirement to have a permit continues throughout the post-closure period.
In addition, for the purposes of closure, post-closure , and financial
responsibility, such a drip pad is then considered to be a landfill, and the
owner or operator must meet all of the requirements for landfills specified in
Subparts G and H.
c)Â Â Â Â Â Â Â Â Existing Drip Pads without Liners
1)Â Â Â Â Â Â Â Â The owner or operator of an existing drip pad that does not
comply with the liner requirements of Section 724.673(b)(1) must do the
following:
A)Â Â Â Â Â Â Â Include in the closure plan for the drip pad under Section
724.212 both a plan for complying with subsection (a) and a contingent plan for
complying with subsection (b) in case not all contaminated subsoils can be
practicably removed at closure; and
B)Â Â Â Â Â Â Â Prepare a contingent post-closure plan under Section 724.218
for complying with subsection (b) in case not all contaminated subsoils can be
practicably removed at closure.
2)Â Â Â Â Â Â Â Â The cost estimates calculated under Sections 724.212 and
724.244 for closure and post closure care of a drip pad subject to this
subsection (c) must include the cost of complying with the contingent closure
plan and the contingent post-closure  plan, but are not required to include the
cost of expected closure under subsection (a).