Remediation in situ of hydrocarbons by combined treatment in a contaminated alluvial soil due to an accidental spill of LNAPL

The soil contamination represents an environmental issue which has become extremely important in the last decades due to the diffusion of industrial activities. Accidents during transport of dangerous materials and fuels may cause severe pollution. The present paper describes the criteria of the actions which were operated to remediate the potential risk and observed negative effects on groundwater and soil originated by an accidental spill of diesel fuel from a tank truck. With the aim to evaluate the quality of the involved environmental matrices in the “emergency” phase and in the following “safety” operation a specific survey on hydrocarbons, light and heavy, was carried out in the sand deposits soil. Elaboration of collected data allows to observe the movement of pollutants in the unsataturated soil. The remediation action was finalized to improve the groundwater and soil quality. The first was treated by a so called “pump & treat” system coupled with air sparging. A train of three different technologies was applied to the unsaturated soil in a sequential process: soil vapour extraction, bioventing and enhanced bioremediation. Results showed that the application of sequential remediation treatments allowed to obtain a state of quality in groundwater and soil as required by Italian law.