Electro-bioreclamation: A combination of in situ remediation techniques proves successful at a site in Zeist, the Netherlands

The site of a former silver factory that has been severely polluted with chlorinated solvents was treated by excavating the polluted soil and installing a pump and treat system. After an initial fall in contaminant concentrations, no further progress was observed over a number of years. The Province of Utrecht tried to solve the problem by requesting remediation contractors to propose a solution at a fixed price. The winning solution was electro-bioreclamation, a combination of in situ techniques: heating soil and groundwater in the source areas, combined with soil vapour extraction and low-yield groundwater pumping, and enhancing biodegradation in the groundwater plume area. Two years of heating and 2.5 years of biodegradation has been resulted in near-complete removal of the contaminants.