1. a) Except as otherwise provided in subsection (b), the owner or operator must at all times maintain financial assurance in an amount equal to or greater than the current approved removal cost estimate calculated pursuant to Section 848.404.

2. b) Within 60 days after the occurrence of any event listed in this subsection (b), the owner or operator must increase the total amount of financial assurance to an amount that is equal to or greater than the current approved removal cost estimate calculated pursuant to Section 848.404:

   1. 1) the current approved removal cost estimate increases; or
   2. 2) the value of a trust fund established pursuant to Section 848.410 decreases.

(Source: Amended at 39 Ill. Reg. 12934, effective September 8, 2015)