Electrical tomographies in the sanitary landfill of the city of Gualeguychú, province of Entre Ríos: Evidences of contamination

Abstract

An important problem associated to sanitary landfills is the leachate production and the risk of groundwater contamination.The leachate electrical conductivity is often much greater than natural groundwater; consequently the contrast found in this property allows the detection of the plume using geoelectrical methods. This paper reports new geophysical data obtained from two landfills of different age located in Gualeguaychúcity. Several tomographies using dipole-dipole electrode configurations were performed and interpreted from bidimensional models. The models obtained on landfills have a first layer with high resistivity values and heterogeneities representing waste disposal. Low resistivity anomalies were detected below the level where the wastes were buried; those were attributed to contamination caused by leachate. The models obtained in areas without solid wastes, but near the landfill boundary present low resistivity at the most superficial layer. These values could be due to the contamination at the border of the waste disposaland also by the presence of clays, considering that the results do not agreewith the value of the specific conductivity determined in the phreatic water. The hydrochemical parameters were estimated in the most conductive zone to evaluate the environmental features of the landfill.