Geophysical Detection of Soil and Underground Water Contamination in the Vicinity of Oil Refineries

More than fifty years of industrial activities in the refineries located at the outskirts of Ploiesti city, Romania, determined a high level of contamination of the environment, affecting mainly the topsoil and the phreatic aquifers. Geoelectrical resistivity methods (VES and ERT) performed on profiles located in the vicinity of Petrobrazi and Astra refineries proved to be effective in locating the underground contamination by high resistivity anomalies. The pollution of the environment is due in all cases to the past contamination. In some areas, a supplementary contamination is associated with actual leakages from storage tanks located inside the refinery and/or from the network of underground pipes. High resistivity anomalies associated with the oil-contaminated plumes situated at the level of topsoil and the phreatic aquifers are locally interrupted and characterized by variations in intensity. Such aspects are interpreted to be associated with inhomogeneities in the permeability of the clayey soil and of the geological formations that host the aquifer and the floating oil contaminant.