Okla. Stat. tit. 45, § 45-755

Exemptions.

The following performance standards shall be applicable to steep

slope surface coal mining and shall be in addition to those general

performance standards required by this act. These provisions shall

not apply to those situations in which an operator is mining on flat

or gently rolling terrain, on which an occasional steep slope is

encountered through which the mining operation is to proceed,

leaving a plain or predominantly flat area.

Oklahoma Statutes - Title 45. Mines and Mining Page 96

1. The operator shall insure that when performing surface coal

mining on steep slopes, no debris, abandoned or disabled equipment,

spoil material, or waste mineral matter be placed on the downslope

below the bench or mining cut;

2. Complete backfilling with spoil material shall be required

to cover completely the highwall and return the site to the

appropriate original contour, which material will maintain stability

following mining and reclamation;

3. The operator may not disturb land above the top of the

highwall unless the Department finds that such disturbance will

facilitate compliance with the environmental protection standards of

this act. The land disturbed above the highwall shall be limited to

that amount necessary to facilitate said compliance; and

4. For the purposes of this section, the term steep slope is

any slope above twenty (20) degrees or such lesser slope as may be

defined by the Department after consideration of soil, climate and

other characteristics of a region or state.