Abstract: Permeable reactive barriers are an emerging alternative to traditional pump and treat systems for groundwater remediation. This technique has progressed rapidly over the past decade from laboratory bench-scale studies to full-scale implementation. Laboratory studies indicate the potential for treatment of a large number of inorganic contaminants, including As, Cd, Cr, Cu, Hg, Fe, Mn, Mo, Ni, Pb, Se, Tc, U, V, NO3, PO4 and SO4. Small-scale field studies have demonstrated treatment of Cd, Cr, Cu, Fe, Ni, Pb, NO3, PO4 and SO4. Permeable reactive barriers composed of zero-valent iron have been used in full-scale installations for the treatment of Cr, U, and Tc. Solid-phase organic carbon in the form of municipal compost has been used to remove dissolved constituents associated with acid-mine drainage, including SO4, Fe, Ni, Co and Zn. Dissolved nutrients, including NO3 and PO4, have been removed from domestic septic-system effluent and agricultural drainage.

Abstract: Previous mining history in Norway has resulted in ongoing release of acid mine drainage. Preservation of the historical sites in mining areas does not allow for remediation technologies that result in significant alteration of the historical landscape. Therefore, alternative remediation techniques such as passive mine water treatment have been tested. The climate in Norway varies from mild coastal climates to artic climates, and one of the challenges with passive treatment systems is the cold winter conditions. Anaerobic treatment systems have been built at Kongens Mine near Røros, at Folldal mines, and at Titania's tailings impoundment near Storgangen Mine. These systems utilize sulfate-reducing bacteria that result in the precipitation of metal sulfides. A full- and pilot-scale system at Kongens Mine and Folldal were built in 2006 to remove copper and zinc from typical ARD in an alpine climate. Previous testing with pilot scale systems at Kongens Mine showed that up to 85% copper and 48% zinc could be removed. At Titania A/S the anaerobic system is designed to remove nickel from neutral waters. At this system over 90% nickel is removed when water flow is regulated at a constant flow. Testing shows that the system can function in cold winter conditions, however, optimal metal removal is achieved under warmer temperatures. Temperatures changes by global climatic warming will not adversely affect these anaerobic systems. However, extreme precipitation events and the resulting rapid fluctuations of ARD runoff will provide a challenge for the effectiveness of these systems.

Abstract: Remediation of the Eagle Mine Superfund Site began in 1988. Remedial action included: bulk-heading adits, flooding mine workings; constructing diversion ditches around waste rock; consolidating mine wastes in an on-site tailings pile; capping the tailings pile with a multi-layer, engineered cap; and revegetating disturbed areas with native plants. Flooding the mine workings resulted in unacceptable seepage into the Eagle River in late 1989. A water treatment plant was constructed to collect mine seepage and groundwater at the main tailings pile. In October 2001, construction of the remedy was declared “complete” and the site is now in the operation, maintenance and monitoring phase. A strong downward trend in zinc and cadmium concentrations in the Eagle River has occurred and, trout and macroinvertebrate populations have increased. Biological data are being used to establish water quality standards for the Eagle River.