Abstract: The production of acid rock drainage (ARD) from mine tailings is a significant environmental concern at various abandoned mine sites in Yukon. Leachate with low pH and high dissolved metals concentrations deriving from mine tailings impoundment areas can negatively impact various groundwater and surface water resources.

The presence of both oxygen and water is required for ARD to develop. Therefore, the reduction of the oxygen and water sources from the mine tailings will limit ARD production. This is the basis of reclamation of the Arctic Gold and Silver (AGS) Tailings Site near Carcross, Yukon using a lowpermeability tailings cover which acts as an oxygen and water infiltration barrier. ARD processes have resulted in a significant contamination of the groundwater beneath the tailings impoundment at the AGS site with multiple dissolved metals showing elevated concentrations.

The use of a low permeability cover to reduce ARD such as that used at the AGS site is one of the first such reclamation applications in Yukon. EBA Engineering Consultants Ltd. and partners initiated a performance assessment of the low permeability cover system in the fall of 2000 and continued the monitoring in 2001 as part of Mining Environment Research Group (MERG) funded studies. The results of these assessments suggested that the low-permeability cover functions as an oxygen and infiltration barrier; however, the limited data and short period of monitoring precluded any prediction of the long-term performance of the tailings cover. Further monitoring was recommended.

Authors: EBA Engineering Consultants Ltd.

Citation: EBA Engineering Consultants Ltd., 2010. Assessment of low permeability cover as infiltration and oxygen barrier to reduce acid generation in mine tailing at the Arctic Gold and Silver Mine Site, Carcross, Yukon. Mining and Petroleum Environment Research Group, MPERG2010-1.

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