Abstract
An interpretation approach for analysis of electrical resistivity and chargeability inverse models generated at two upgraded semi-aerobic landfill sites was developed. The inverse models produced from a 2D inversion program (RES2DINV) were used to set up a grid of electrical resistivity and chargeability imaging at the landfill sites. The investigations confirmed a high chargeability unit (>70 ms) depicting waste deposits and a saturated clayey layer, while the leachate plume showed low resistivity (<10 Omega m) and weak chargeability zone (<20 ms). Moreover, the IP responses of a diffused leachate plume downstream of a separate semi-aerobic landfill site in a similar geological setting were evaluated, obtaining an analogous result. The ion-dominated plume that exhibited a weak chargeability promoted membrane polarization rather than electrode polarization in its IP responses. However, the high concentration of ions in the diffused leachate restrained the ionic polarization, diminishing the IP effects in host sediments. The interpretation of the resistivity and chargeability profiles at the characterization sites allowed delineating the different zones of the subsurface strata. In particular, comparison of the leachate zones at the two locations revealed that the active landfill with a lesser proportion of waste deposits contained a greater accumulation of leachate than the closed site. The results in this study support the effectiveness of contaminant plume monitoring through the joint application of resistivity and IP methods. These non-invasive, rapid and cost-effective, geophysical techniques could lead to a promising reconnaissance tool for remediation or reclamation of solid waste disposal sites.