Current through Register Vol. 48, No. 51, June 17, 2024
Part 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:
A. The final exterior slopes shall consist of benches and lifts as follows: (1) no lift shall exceed 30 feet in height;(2) 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;(3) the sloped area between benches shall be no steeper than the angle of repose;(4) benches shall be designed and constructed to control runoff;(5) 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(6) when the sloped area between benches is covered with surface overburden and vegetated, lifts may be raised to a maximum of 40 feet.B. Based upon acceptable research the commissioner shall approve other measures which satisfy part 6130.2000.Statutory Authority: MS s 93.47