Disaster at Chavenay (France). The great decontamination steps

On December 3rd 1990, the derailment of a train carrying gasoline resulted in soil contamination in the Luzin, district of Chavanay (Loire). The infiltration of an estimated 200 to 250 m3 of unleaded gasoline posed many risks relating to: - the presence of inhabitants nearby, - the existence of domestic and agricultural water supplies, - the proximity of national highway RN 86, - and the railway track. After the intervention of several engineering and contracting soil remediation companies, a positive balance of the remediation operation has been obtained: 120 m3 of hydrocarbons have been recovered from the vadose zone and 50 m3 of floating products removed from the groundwater table by skimming operations. The clean-up objective determined through a risk assessment pilot was fixed at 10 ppm TPH in the vadose area. The groundwater clean-up objective was fixed at 2 mg/l TPH to enable its future use. At the end of the operation, the remediation proved to be more efficient than expected, the TPH concentration in the vadose zone has decreased to a level of 1 ppm and of 0.5 mg/l in the groundwater. (author). 12 figs