Characterization of the area to be used as a sanitary landfill in southeastern Brazil applying electrical resistivity and induced polarization methods

The increase in municipal solid waste (MSW) generation observed over the years has sparked important discussions regarding its disposal. When MSW is disposed of in sanitary landfills, proper design according to current standards and constant monitoring can prevent environmental impacts. Geophysical methods have been used for subsurface characterization and contaminants monitoring, particularly geoelectrical methods, proving to be efficient and cost-effective. These indirect methods allow for a more comprehensive two-dimensional evaluation of the subsurface, which is impractical through direct surveys. This study aimed to demonstrate the efficiency of electrical resistivity and induced polarization methods in the characterization of MSW disposal areas. The study focused on the current sanitary landfill of São Carlos, Brazil, which was still under geological-geotechnical investigation at the time of the geophysical surveys. Electrical resistivity lines were conducted with a dipole-dipole array to investigate the physical properties of resistivity and chargeability. During the excavation of the first trench of the sanitary landfill in 2013, rock was identified at a shallow depth in a region where SPT results did not indicate the presence of rock at depths less than 17 meters. However, geoelectrical results revealed rocks at shallower depths. These results confirmed the potential of geoelectrical methods in identifying the diabase bedrock. The bedrock was delimited using resistivity profiles for values higher than 350 ohm.m. The chargeability profiles were employed as an auxiliary method to validate the results, showing increasing values with depth and resistivity.