A multi-method approach to groundwater risk assessment: a case study of a landfill in southern Poland

Estimating groundwater vulnerability to pollution is based on the quantitative and qualitative assessment of the degree of exposure to the pollution. This article attempts to assess groundwater vulnerability to pollution in the area of a complex of landfill sites located in the supply area of one of the important groundwater reservoirs in southern Poland. Two dynamic leaching tests and two static tests were carried out on two different samples of slag from one of the metallurgical landfills during various periods of storage (15 year old waste and freshly deposited waste). Transport equations were based on the data from a column experiment. The advection-dispersion equation for column leaching was employed, which confirmed the simulation parameters through experimentation. The results of the leaching tests on chlorides showed that they are leached from the landfill over a period of -60-90 years from the moment of depositing the waste. The seepage time for the Quaternary aquifer is 1-7 years and, for the Triassic aquifer, 5-40 years. The Backman's contamination index (1998) values exceeded 25, while a high threat to groundwater is observed when the contamination index value equals 3. The use of all the aforementioned methods determined the most vulnerable area.