Characterization of a Contaminant Plume Due to a Hydrocarbon Spill Using Geoelectrical Methods

The objective of the research contained in this paper was the characterization of a contaminant plume and the description of the surrounding area, in order to give information for future remediation. The origin of the plume was a hydrocarbon spill produced by fissures in a purge chamber belonging to a gas transmission system. Data from control wells indicated that the soil was composed mainly of clays. The most important result was that, close to the chamber, a 1.5m-thick layer of gasoline was detected at 7m depth, floating over the water table. This is a case in which a resistive contaminant like hydrocarbon is located in a conductive medium; in these circumstances geoelectrical prospecting is particularly good for characterizing the zone. The extent of the area under study was 100×140m2, approximately, and the thicknesses involved were more than 20m of, in many cases, very conductive materials. Thus, a field design was required that would cover the zone with deep penetration and at the same time optimiz...