Our Site Solutions experts are using an innovative approach to remediating chlorinated solvents at a brownfield development site in Belgium. The former metal processing site is heavily contaminated with tetrachloroethene and trichloroethene to a depth of 16m and over a surface area of more than 5,000m².
Following the removal of asbestos-containing buildings and excavation of three source areas of contamination, an in-situ remediation system, designed to treat residual contamination in groundwater, has been installed entirely below ground level. It was important to our client that the redevelopment of the site for industrial use could continue alongside the groundwater remediation programme, rather than wait for the remediation phase to be completed.
The enhanced bioremediation technique involves the use of an organic substrate, or electron donor (in this case, Dehalo-GS), together with nutrients, trace elements and vitamins, which ferments to stimulate anaerobic biodegradation of the solvents. Careful management of the technique ensures that the electron donor ferments at the right speed, steadily releasing hydrogen to maintain the biodegradation process, while only marginally decreasing the pH of the soil and water.
The remediation system includes 180 extraction and infiltration wells, with the well heads installed at 2m below the ground surface, enabling the development works above-ground to continue.
The active remediation phase will continue for three years with post-remediation groundwater monitoring continuing until 2024.