Abstract: For the treatment of contaminated mine waters reliable treatment methods with low investment and operational costs are essential. Therefore, passive treatment systems recently have been installed in Great Britain and in Germany (e.g. anoxic limestone drains, constructed wetlands, reactive barriers, roughing filters) and during the last eight years such systems successfully treated mine waters, using up to 6 ha of space. In some cases with highly contaminated mine water, a combination of active and passive systems should be applied, as in any case the water quality has to reach the limits. Because not all the processes of passive treatment systems are understood in detail, current research projects (e.g. EU-project PIRAMID) were established to clarify open questions.

Abstract: Steel slag from the Waylite steel-making plant in Bethlehem, Pennsylvania was leached with acidic mine drainage (AMD) of a known quality using an established laboratory procedure. Leaching continued for 60 cycles and leachates were collected after each cycle. Results indicated that the slag was very effective at neutralizing acidity. The AMD/slag leachates contained higher average concentrations of Ba, V, Mn, Cr, As, Ag, and Se and lower average concentrations of Sb, Fe, Zn, Be, Cd, Tl, Ni, Al, Cu, and Pb than the untreated AMD. Based on these tests, slag leach beds were constructed at the abandoned McCarty mine site in Preston County, West Virginia. The leach beds were constructed as slag check dams below limestone-lined settling basins. Acid water was captured in limestone channels and directed into basins to leach through the slag dams and discharge into a tributary of Beaver Creek. Since installation in October 2000, the system has been consistently producing net alkaline, pH 9 water. The treated water is still net alkaline and has a neutral pH after it encounters several other acidic seeps downstream.