Caracterização geofísica multimétodos de aterros sanitários.

Abstract

This dissertation presents the results of a geophysical investigation in two landfills: the Camaçari Landfill and the Metropolitano Centro Landfill. These two landfills have distinct characteristics regarding the planning, installation, and development of waste disposal activities. In the first, the construction information of the waste pit was lost. In contrast, a historical monitoring and characterization service of the waste and its structure was carried out in the second. The need to use an effective indirect method to delineate the bottom of the pit, as well as the internal volumes, motivated a multiphysical approach for this study, carried out using the geophysical methods of Electroresistivity, Ground Penetrating Radar (GPR) and Very Low Frequency Electromagnetic (VLF). The three methods present different investigation depths and spatial resolutions, acting in a complementary way in the mapping. The resistivity profiles allowed the partial delineation of the impermeable structure of compacted clay installed at the bottom of the pit during its construction. Furthermore, they highlighted resistive volumes possibly associated with biogas and conductive volumes produced by accumulated leachate and/or bioactive zones in deeper portions of the massif. They also allowed the delimitation of the final cover and waterproofing layers, the identification of the characteristics of old cells in the Aterro Metropolitano Centro, and the observation of distinct responses of the electromagnetic method for waste disposed of in different periods. The current density distributions obtained by the VLF allowed a partial extrapolation of the continuity of the bottom waterproofing structure, in addition to indicating increased conductivity in certain areas. The GPR method complemented the investigation by providing shallow information, up to approximately 5 meters deep, allowing the identification of pipes related to the landfill drainage network, zones of conductive soil on the sides of the waste pile, details about the final cover layer, and its waterproofing, as well as information about the most superficial solid waste.