Surface overburden stockpiles 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 40 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 2.5:1.
Benches shall be sloped toward the interior to control runoff. They shall be large enough to handle runoff water until it can be infiltrated into the stockpile, or a drainage control system shall be constructed to remove water consistent with part 6130.2100, items B and C.
Rock, lean ore, or coarse tailings shall not be used to cover surface overburden stockpiles in order to avoid compliance with sloping and vegetation requirements. This shall not preclude the abutting of rock, lean ore, or coarse tailings stockpiles with surface overburden stockpiles, or the placement of rock, lean ore, or coarse tailing lifts atop surface overburden pads or lifts.
MS s 93.47
June 11, 2008
Official Publication of the State of Minnesota
Revisor of Statutes