Okla. Stat. tit. 45, § 45-730: Lateral support

In the case of strip mining operations which remove and do not

replace lateral support, unless pursuant to written agreement

between the operator and the adjacent property owner, the top of the

consolidated material of the open cut adjacent to the property line

of other property not owned or leased by the operator shall, at the

time mining is completed, not be closer to such other property line

than a distance of twenty-five (25) feet plus one and one-half (1

1/2) times the depth of such cut as measured from original ground

surface to the top of consolidated material.