Ill. Admin. Code tit. 35, § 845.720
a) Preliminary Written Closure Plan
1) Content of the Preliminary Closure Plan. The owner or operator of a new CCR surface impoundment or an existing CCR surface impoundment not required to close under Section 845.700 must prepare a preliminary written closure plan that describes the steps necessary to close the CCR surface impoundment at any point during the active life of the CCR surface impoundment consistent with recognized and generally accepted engineering practices. The preliminary written closure plan must include, at a minimum, the following:
3) Amendment of a Preliminary Written Closure Plan
B) The owner or operator must amend the preliminary written closure plan whenever:
b) Final Closure Plan