Complex environmental risk management at a former mining site
Katalin Gruiz, Emese Vaszita, Zoltán Siki, Viktória Feigl and Ferenc Fekete

Former mining sites pose a particularly high environmental risk. Typically, such sites are highly polluted, and, if not remediated, would remain unusable (Dryden and Beer 1999). Environmental risk management (ERM) may help us to devise adequate and cost-effective strategies to address the hazards posed by these sites (Dryden and Beer 1999). This paper presents an environmental risk management (ERM) approach employed in the Toka catchment, Gyöngyösoroszi, an abandoned Pb- and Zn-sulphide ore-mining area in Hungary. The mine was abandoned in 1985, but mine closure and remediation activities only started in 2005. The main environmental risk in the area is related to the toxic metals (As, Cd, Pb and Zn) derived from point- and diffuse-pollution sources. Acidic leachate (pH 1–3), produced by the bioleaching of mining waste containing pyrite (FeS2), mobilizes toxic metals from the water- and wind-eroded waste material. The ERM approach focuses not only on point sources but also on the diffuse pollution sources originating from mining. The diffuse pollution from mining comprises non-point-source contamination, such as the residual contamination after removal of mining-waste dumps, as well as pollution arising from various dispersed, often individual, minor point sources (mining-waste dumps, soil polluted by acid rock drainage). Diffuse sources are often individually minor, but collectively significant. For this reason, a catchment-scale geographical information system (GIS)-based approach was adopted. The catchment-scale risk-management approach includes: (1) development of a GIS-based pollution-transport model; (2) application of a three-tiered, iterative environmental risk assessment (ERA); (3) calculation of the targeted emission from the diffuse and residual sources, in order to fulfil the environmental criteria for the surface-water system and its ecosystem; (4) planning risk reduction by combined chemical- and phytoremediation, and validation and refinement of the transport model based on the results of the field experiment. The site assessment and scientific work carried out in the area over the years (Gruiz et al. 1993, 2005, 2006a, 2006b, 2007; Feigl et al. 2007) and presented in this paper, substantiated the planning of the ongoing remediation work. The current status of remediation work is also summarized in this paper.

Key words: acid mine/rock drainage, environmental risk assessment, environmental risk management, erosion, former mining site, GIS-based modelling, risk reduction, runoff, toxic metals

Land Contamination & Reclamation, 17 (3-4), 355-367

DOI 10.2462/09670513.949

© EPP Publications Ltd 2009

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Article code 949