The Mike Horse Mine, MT Wetland Treatment System

An integrated wetland treatment system was designed and constructed at the Upper Blackfoot Mining Complex in west-central Montana to treat metal-enriched, acidic drainage from two inactive mines. Treatment system design considered complexities of site topography and climate, mine drainage chemistry and flow, and engineering stability in order to meet NPDES discharge restrictions. Treatment system flow-through was initiated in the fall of 1996. Functioning of the start-up system demonstrates its capacity for efficient, passive treatment of iron in the pretreatment array and zinc in the wetland cells. Further improvement in metals retention efficiency is expected as the wetlands mature and further optimization is realized as a result of operation and testing.