Section 225 ILCS 720/3.04 - Grading(a) Affected land shall be backfilled, compacted (where advisable to insure stability or to prevent leaching of toxic materials), and graded in order to restore the approximate original contour of the land. All highwalls, spoil piles, and depressions shall be eliminated (unless small depressions are needed in order to retain moisture, to assist revegetation, or as otherwise authorized under this Act).(b) In surface mining which is carried out at the same location over a period greater than one year where the operation transects the coal deposit, and the thickness of the coal deposits relative to the volume of the overburden is large and where the operator demonstrates that the overburden and other spoil and waste materials at a particular point in the permit area or otherwise available from the entire permit area are insufficient, giving due consideration to volumetric expansion, to restore the approximate original contour, the operator, at a minimum, shall backfill, grade, and compact (where advisable) using all available overburden and other spoil and mine waste materials to attain the lowest practicable grade, but not more than the angle of repose, to provide adequate drainage and to cover all acid-forming and other toxic materials, in order to achieve an ecologically sound land use compatible with the surrounding region.(c) Where the operator demonstrates that due to volumetric expansion the amount of overburden and other spoil and waste materials removed in the course of the mining operation is more than sufficient to restore the approximate original contour, the operator shall satisfy the requirements set forth in subsection (a) of this Section, and shall backfill, grade and compact (where advisable) the excess overburden and other spoil and waste materials to attain the lowest grade but not more than the angle of repose, and to cover all acid-forming and other toxic materials, in order to achieve an ecologically sound land use compatible with the surrounding region and such overburden and spoil shall be shaped and graded in such a way as to prevent slides, erosion, and water pollution, and shall be revegetated in accordance with the requirements of this Act.(d) Water impoundments which were not part of the original contour may be permitted by the Department under Section 3.08.