An Investigation of Environmental Contamination at the Silvermines Abandoned Mines Site in Ireland Based on the Preliminary Delimitation of Pollution Hot Spots

Abstract

This paper describes a holistic methodology for the investigation of environmental contamination from abandoned mine sites (AMSs), and is based on a case study of the Silvermines AMS. Groundwater modelling, surface water temperature monitoring, and a geographical information system (GIS) were used to undertake a preliminary delimitation of areas where soil, fluvial sediments, and surface and groundwater were contaminated. Subsequent soil and water sampling and analysis confirmed the accuracy of these predictions. Significant contamination of environmental media in the vicinity of the AMS was largely the product of water-borne pollutants. The concentration of Pb was high in streams receiving direct discharge from the AMS, but decreased rapidly downstream. Concentrations in stream sediments showed the same pattern. Extremely high Pb concentrations were also observed in sediments downslope from the AMS where groundwater discharges into surface drainage. Soil Pb concentrations were highest on floodplains and in areas affected by surface runoff and seasonal groundwater seepage. The methodology described here allows effective and cost-efficient investigation of the environmental impact of AMSs, which in turn provides the basis for site rehabilitation.