A Chlorinated hydrocarbon contamination in an industrial area

A chlorinated hydrocarbons pollution was discovered, near the city of Turin, at a site which was used in the past as an industrial landfill. In order to characterize the contamination, a detailed site and contamination investigations were performed: 678 samples of gas, soil and groundwater were collected with the Geoprobe System. Several horizontal and vertical cross section reconstructions revealed two contaminated plumes, which contained chlorinated solvents in the groundwater. The sampling investigation did not show the presence of a free DNAPL phase: probably the source of pollution is contaminant at the residual saturation both in the vadose zone and in the saturated medium. The investigation revealed an old deep contamination in the groundwater and a more recent one in the upper part of the aquifer. The latter was probably caused by the dissolution of the soluble fraction of the residual solvent in the vadose zone after heavy rains. A remediation project of the site consisting in a permeable reactive barrier using zero valent iron is planned. This will result in a reductive dechlorination of solvents in the first plume. A capping and monitoring of natural attenuation is to be applied to the second plume.