Siracusa – Italy
The area covered by the reclamation has an extension of 14 hectares characterised by a geology consisting of a consistent horizon of sandy-limestone sediments with an underground water circulation of the phreatic type. The use of the area as a land for petrochemical plants for over thirty years has led to the presence of large quantities of organic (total, aromatic, polycyclic hydrocarbons) and inorganic (sulphate and metal) contaminants besides PCB and Dioxins. The compounds are adsorbed in the unsaturated horizon of lands as well as dissolved in the soil due to the de-watering effects.
The implemented system, part of a complex barrier system apt to allow groundwater de-watering of the phreatic strip and the simultaneous stripping of the persistent contaminants, consists of 60 MPE extraction wells connected to 9 modules apt to generate the necessary depression with a total capacity equal to 2,250 Nmc/h. The subsequent treatment involves the catalytic combustion for the extracted gaseous phases, and a disoleation, for the liquid phase, resulting in the physical-chemical treatment of the residual mixture.
Important reductions in the VOC contractions (Volatile Organic Compounds) extracted from the subsoil and the disappearance of the separate hydrocarbon phase floating in the aquifer (LNAPL) have been observed already in the first months from the start up and operation of the plants. The plants are still active in reducing the volatile phase of the adsorption contamination in the desaturated horizon.