Rescue package for Europe's polluted soils
Contamination of soils with pollutants, such as non-aqueous phase liquids (NAPLs), that include many petroleum products is a serious problem throughout Europe. Most of the continent has soil of glacial origin that can fracture therefore allowing contaminants to move down to underground reservoirs. As part of soil treatment, hydraulic fracturing increases the zone of influence of the remedial process. Combined with various clean-up measures, hydraulic fracturing is the most common method in use. However, the actual knowledge base on technologies for treatment of NAPLs has, up until now, been very patchy. For optimum effectiveness, the 'In situ stimulation and remediation of contaminated fractured soils' (Stresoil) project aimed to gather scientific information to be able to select the most appropriate means of rehabilitation of NAPL-polluted soils. A fractured test site was selected, geologically analysed and its permeability estimated. After the extent of pollution had been determined, several soil rehabilitation techniques were applied after hydraulic fracturing. These included biodegradation, bioventilation and steam injection. For every test simulation scenario, information was stored in specially designed databases for cost-benefit analysis. A multi-criteria data set was also designed to help decision making during the remediation process. Data from Stresoil indicates that cost-effective technologies combining stimulation and remediation are a realistic alternative to conventional treatments. Other methods aimed at tackling the pollutant itself, including vacuum extraction and thermal treatment, also looked very promising. Effective treatment of polluted soil is crucial to protect Europe's underground water supplies. Stresoil results have provided a firm basis for the best ways to achieve this.
