Minnesota Administrative Rules

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

Published Electronically:

June 11, 2008