MT SB365

Siltation structures at strip or underground mines must be constructed with design capacity specified in administrative rule to detain water inflow from an anticipated precipitation event plus average inflow from underground mines

Mine operators remain in compliance even if pond capacity is exceeded due to multistorm events consisting of consecutive small storms that cumulatively exceed the anticipated precipitation event

Operators must actively restore pond capacity as soon as weather and ground conditions permit when capacity is exceeded

Any provision disapproved by the U.S. Secretary of the Interior under 30 CFR 732 becomes void, with the Department of Environmental Quality required to notify the code commissioner within 15 days of disapproval

Effective immediately upon passage and approval