The EU-funded CLEANSOIL project has developed a method for the regeneration of contaminated soil in situ. The method was successfully tested on soils in Russia and Ukraine, which have been heavily polluted with petrochemical residues and pesticides, proving particularly effective in removing the latter.

CLEANSOIL brought together eight research and industry partners from inside and outside the EU and received about €750,000 in funding under the Sixth Framework Programme (FP6) with an additional €200,000 contributed by other sources.

The current method of choice for cleaning up these sites is the excavation and removal of the polluted soil. This treatment is highly expensive, ranging from €59 to 109 million per hectare - depending on the technology used and the level of contamination, the CLEANSOIL consortium explains. Also, cleaning the top soil is not always feasible. The CLEANSOIL project tackled both of those problems.

In order to remove the pollutants from the soil, the CLEANSOIL method works on the basis of absorption: a network of sockets inside perforated pipes is laid out along a number of horizontal holes drilled into the ground. According to the project partners, drilling horizontally is particularly effective as underground contamination frequently spreads horizontally rather than vertically.

The sockets contain sorbents that absorb the contaminants with the help of the moisture of the subsoil. Once the process is completed, the sockets and pipes can simply be removed and the sorbents decontaminated, so that they can be re-used.

Different sorbents can be used, depending on which is most appropriate for the pollutant at hand. In addition, the CLEANSOIL method can be applied underneath existing infrastructures such as warehouses, from which contaminants may have leaked.