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Naugle, W. K. (2003). Remediation of the Eagle Mine superfund site: a biological success story. Tailings and Mine Waste '03, , 481–485.
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.
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Younger, P. L. (2003). Passive in situ remediation of acidic mine waste leachates: progress and prospects. Land Reclamation: Extending the Boundaries, , 253–264.
Abstract: The reclamation of former mining sites is a major challenge in many parts of the world. In relation to the restoration of spoil heaps (mine waste rock piles) and similar bodies of opencast backfill, key challenges include (i) the establishment of stable slopes and minimization of other geotechnical hazards (ii) developing and maintaining a healthy vegetative cover (iii) managing the hydrological behaviour of the restored ground. Significant advances have been made over the past four decades in relation to all four of these objectives. One of the most recalcitrant problems is the ongoing generation and release of acidic leachates, which typically emerge at the toes of (otherwise restored) spoil heaps in the form of springs and seepage areas. Such features are testament to the presence of a “perched” groundwater circulation system within the spoil, and their acidity reflects the continued penetration of oxygen to zones within the heaps which contain reactive pyrite (and other iron sulphide minerals). Two obvious strategies for dealing with this problem are disruption of the perched groundwater system and/or exclusion of oxygen entry. These strategies are now being pursued with considerable success where spoil is being reclaimed for the first time, by the installation of two types of physical barrier (dry covers and water covers). However, where a spoil heap has already been revegetated some decades ago, the destruction of an established sward or woodland in order to retro-fit a dry cover or water cover is rarely an attractive option for dealing with the “secondary dereliction” represented by ongoing toe seepages of acidic leachates. More attractive by far are passive treatment techniques, in which the polluted water is forced to flow through reactive media which serve to neutralize its acidity and remove toxic metals from solution. A brief historical review of the development of such systems reveals a general progression from using limestone as the key neutralizing agent, through a combined use of limestone and compost, to systems in which almost all of the neutralization is achieved by means of bacterial sulphate reduction in the saturated compost media of subsurface-flow bioreactors. In almost all cases, these passive treatment systems include an aerobic, surface flow wetland as the final “polishing” step in the treatment process. Such wetlands combine treatment functions (efficient removal of metals from the now-neutralized waters down to low residual concentrations, and re-oxygenating the water prior to discharge to receiving watercourses) with amenity value (attractive areas for recreational walking, bird-watching etc) and ecological value.
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Blowes, D. W., Bain, J. G., Smyth, D. J., Ptacek, C. J., Jambor, J. L., Blowes, D. W., et al. (2003). Treatment of mine drainage using permeable reactive materials. Environmental Aspects of Mine Wastes, 31, 361–376.
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Wiseman, I. M., Rutt, G. P., & Edwards, P. J. (2004). Constructed wetlands for minewater treatment: Environmental benefits and ecological recovery. Water and Environment Journal, 18(3), 133–138.
Abstract: The ecology of the River Pelenna (in South Wales) was impoverished by polluted discharges from abandoned coal mines. A series of passive constructed wetlands was created in order to treat these discharges and to improve the ecology of the river. A three-year Environment Agency R&D project investigated the performance, environmental benefits and sustainability of the constructed wetlands. It showed that the treatment systems were removing most of the iron contamination. In the reaches downstream from the minewaters, the dissolved-iron concentration quickly dropped below the target level. Invertebrate abundance, trout and riverine bird populations increased in following years. However, occasional overflows from the systems have significantly affected the ecology of one stretch of river The research work has provided an insight into the potential for ecological recovery associated with future minewater treatment.
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Zhuang, J. M. (2004). Lignor(TM) process for acidic rock drainage treatment. Environ. Technol., 25(9), 1031–1040.
Abstract: The process using lignosulfonates for acidic rock drainage (ARD) treatment is referred to as the Lignor(TM) process. Lignosulfonates are waste by-products produced in the sulfite pulping process. The present study has shown lignosulfonates are able to protect lime from developing an external surface coating, and hence to favor its dissociation. Further, the addition of lignosulfonates to ARD solutions increased the clotting and settling rate of the formed sludge. The capability of lignosulfonates to form stable metal-lignin complexes makes them very useful in retaining metal ions and thus improving the long-term stability of the sludge against leaching. The Lignor(TM) process involves metal sorption with lignosulfonates, ARD neutralization by lime to about pH 7, pH adjustment with caustic soda to 9.4 – 9.6, air oxidation to lower the pH to a desired level, and addition of a minimum amount of FeCl3 for further removal of dissolved metals. The Lignor(TM) process removes all concerned metals (especially Al and Mn) from the ARD of the Britannia Mine (located at Britannia Beach, British Columbia, Canada) to a level lower than the limits of the B.C. Regulations. Compared with the high-density sludge (HDS) process, the Lignor(TM) process has many advantages, such as considerable savings in lime consumption, greatly reduced sludge volume, and improved sludge stability.
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