6130.2400 STANDARDS FOR ROCK, LEAN ORE, AND COARSE TAILINGS STOCKPILES.
Rock, lean ore, and coarse tailings stockpiles, unless they are an integral part of a tailings impoundment, shall be designed and constructed according to either of the following standards:
The final exterior slopes shall consist of benches and lifts as follows:
no lift shall exceed 30 feet in height;
no bench width shall be less than 30 feet wide, measured from the crest of the lower lift to the toe of the next lift;
the sloped area between benches shall be no steeper than the angle of repose;
benches shall be designed and constructed to control runoff;
when vegetation is required pursuant to part 6130.3600, subpart 2, item D, the sloped areas between benches shall be prepared to support vegetation; and
when the sloped area between benches is covered with surface overburden and vegetated, lifts may be raised to a maximum of 40 feet.
Based upon acceptable research the commissioner shall approve other measures which satisfy part 6130.2000.