Environmental assessment: contamination of phreatic aquifer in areas impacted by waste from coal processing activities

The objective of the present work was to evaluate the degree of contaminati on of groundwater in areas under influence of inadequate disposal of residu es from coal-processing activities. Charqueadas and Sao Jeronimo Counties w ere selected for the study. The contamination of groundwater from the phrea tic aquifer was evaluated in a sequence of steps: initially, the target are a was selected; then, the piezometers were installed and groundwater was sa mpled. The location of piezometers was based on the results obtained from t he mapping of pollution sources, geophysical and hydrogeological studies. T he results showed that the groundwater (phreatic aquifer) from the region s tudied is influenced, in variables degrees of intensity, by the type and ch aracteristics of residues, the lithological profile of the site and the dis tance from the pollution sources. Physical and chemical characterization re vealed that coal waste influenced more significantly groundwater contaminat ion, evidenced by acidic pH values, as well as high values of conductivity, total dissolved solids (TDS), sulfates, ferrous iron and metals (Ni, Fe, C o, Cr and Mn). The statistical analysis applied to the variables studied ga ve a General Groundwater Index for each well. By the application of this in dex, it was possible to highlight the kind of residues and variables that a re affecting the groundwater quality. (C) 2000 Elsevier Science Ltd. All ri ghts reserved.