The Horntrask open pit mine was originally reclaimed in 1995-1996. However, due tocontinued discharge of metals to nearby Lake Horntrask additional amendments werefound necessary. In 2005-2006 mesa lime, a calcite containing residue from production ofwood pulp, was applied in the saturated zone of the soils within the industry area.Additional measures in 2007-2008 focused on reducing drainage of surface water fromthe local catchment's area and neutralisation of the acidity produced by sulphideoxidation. A saturated solution of mesa lime dissolved in water was infiltrated in theunsaturated zone at a 1:1 volume of solution to soil ratio. The infiltration of the mesalime solution was terminated in September of 2007 and was continued during the snowfree period in 2008. The discharge of water from the springs was reduced to about 50%.While the content of Cu, Zn and Cd in the discharge was reduced by about 85%respectively 50% in one of the springs only a minor increase in pH and varyingconcentrations of heavy metals was observed in another spring. The groundwater closeto the lake showed a significant increase in pH and a decline of the metal concentrations.
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