The activities of a metallurgic company that had operated in Brussels, had led to substantial site contamination due to storing and discharging chlorinated solvents.
Two main areas of contamination (mainly by trichloroethene, 1.2-cis-dichloroethene and vinyl chloride) were found in the soil and groundwater. Additional contaminations of PAHs, mineral oil and heavy metals were also found. The soil remediation project involved the excavation of both contaminated areas.
In order to avoid complex stabilising and drainage works and the construction of a groundwater purification plant, DEC proposed the cased excavation and filling technique. This involves placing a steel cylinder and - by means of orange peel grabs - the soil in the cylinder is excavated. Gradually, the cylinder is excavated and pushed further into the ground until the desired depth is reached. The steel cylinder absorbs all strain from the surrounding subsoil to prevent subsidence.