Application of induced polarization and resistivity to the environmental investigation of an old waste disposal area

Waste disposal in dumpsites, or even in sanitary landfills, can generate contamination plumes in the subsurface. The detection and delineation of the shape of the contaminant plume can be assessed using monitoring systems or different site investigation methods, including geophysical methods. This paper presents the results of a geophysical survey conducted to map the soil contamination produced by a waste disposal site located at a geological vulnerable area, characterized by a trench that resulted from the collapse of sandy soils due to erosion. This paper aims to show the improvement in mapping a waste deposit and the contamination produced in sandy soils by integrating resistivity and induced polarization methods. The results of three survey lines performed to map the site are presented—two across the deposit and one external to it; and resistivity, chargeability and normalized chargeability sections were generated. The geoelectrical sections interpretation was integrated with information from monitoring wells to help the characterization of the waste area and to evaluate soil and groundwater contamination. The results show that resistivity identifies the wastes, the contaminated soil and the contamination plume, but it does not distinguish these zones. Normalized chargeability, on the other hand, is more effective in distinguishing the areas with wastes from the areas impacted by the contamination plume.