Levantamento de resistividade 3-D em uma área contaminada em Bauru – Brasil – resultados preliminares

A contaminated site downstream a landfill in Bauru – Brasil was investigated using a 3-D resistivity imaging technique. The purpose of this investigation was to detect and delineate the contamination plume produced by the wastes and to acquire detailed information about the affected area. The data set was inverted as a complete 3-D survey. The 3-D data set consisted of a series of parallel electrical profile data, acquired with the dipole-dipole array. The profile lines were spaced in 5 meters, the same spacing as the dipoles. This acquisition technique is less troublesome than a complete 3-D survey, and despite of yielding a poorer resistivity model, the resulting model still provide the major resistivity contrasts and enables a tridimensional picture of the main features. In this work we present two depth slices, from the 3-D model obtained using a 3-D least-squares smoothness constrained inversion technique. The results suggest the presence of a contamination plume, which is in good agreement with chemical analysis of waters in the local wells. They also point to a preferential path for the contamination plume that follows the underground flow. The 3-D technique reveals to be efficient in waste disposal sites investigation, and should be taken into account when choosing the investigation technique for complex contaminated sites.