ERT and TDIP survey for mapping of leachate plumes: application to a MSW landfill in Italy

Uncontrolled accumulation of leachate in municipal solid waste (MSW) landfills represents a potential risk for the environment since it is a liquid with a high pollutant content that can contaminate aquifers. Geoelectrical methods (ERT/TDIP) can be highly effective for detecting areas with the presence of leachate, given its electrical properties (highly conductive and chargeable). In the present study, we present an application in a real-case scenario of ERT/TDIP data for imaging leachate levels in a MSW landfill located in Central Italy. The integrated interpretation of resistivity and chargeability revealed distinct zones characterized by variations in resistivity and chargeability values, suggesting variations in waste composition, moisture content, and leachate accumulation, as well as highlighting the geometry of the landfill. This approach can be effective for mapping leachate accumulation zones, as confirmed by the good match between the geophysical models and the leachate levels logged in wells. More specifically, the resistivity model agrees with the leachate levels logged in wells, while the chargeability in these zones does not similarly increase as expected. Future work will be focused on performing a full decay inversion of the acquired data to reduce the residual ambiguities and the depth resolution issue arising from integral chargeability.