Detection of chlorinated contaminants coming from the manufacture of lindane in a surface detritic aquifer by electrical resistivity tomography

Abstract This work presents a case study using electrical resistivity tomography at a site mainly affected by the presence of residual lindane coming from a close landfill constructed by an old pesticide manufacturer. In addition, the landfill also collected chlorinated contaminants derived from the same industry. Lindane itself is a highly toxic contaminant that in small concentrations constitutes a high risk to health, which together with the other compounds, makes it a site with very hazardous characteristics. The geological distribution, formed by a complex detrital deposited over a marls substrate, is known from the existing network of monitoring wells. A geophysical prospecting survey consisting of seven electrical tomography profiles was carried out in the site. The lateral and vertical geometry of the contaminant plume was established, and the preferential flow directions were inferred by means of the resistivity sections obtained. Combining this information with analytical data from water samples, an empirical relationship between the conductivity value and the dissolved chloride content was developed, and the distribution of the concentration of chlorinated contaminants in the surface aquifer by isochloride sections was obtained. The results obtained are a very useful tool as a preliminary stage to remediation trials.