Former industrial activities of an international automotive company in Venray (the Netherlands) resulted in a significant impact of soil and groundwater with different contaminants: two source areas with cVOC’s and mineral oil were identified, as well as a more homogeneous pollution with heavy metals. The total area of the site is about 8 ha, of which about 5 ha are industrial buildings. The total volume of soil contaminated with cVOC was estimated at 125,000 m³, with concentrations well above 10% solubility for tetrachloroethylene.
For many years, a P&T remediation was carried out on site by means of a hydraulic barrier to prevent further migration of contaminants into the groundwater outside the site. Although this installation had been in operation for a long time, virtually no pollution mass had been removed because the source areas (which were located underneath the buildings) were not actively addressed. In addition, the monitoring results showed that the P&T remediation caused a further horizontal spreading of contaminants within the site boundaries. A combination of complex requirements and restrictions led to years of deadlock: on the one hand, local authorities were concerned about the local and off-site migration of the pollutants. On the other hand, the owner had the desire to redevelop the site and wanted to speed up the process, although there were many uncertainties that entailed a great deal of responsibility. As a result, there were many risks associated with the planned development of the site. In addition, the source of contamination under the building was unknown and the possible remediation had to be combined with demolition work and asbestos removal.
In order to get out of the impasse, GreenSoil offered to take over all liabilities regarding the contaminants and was warded a lump sum contract for demolition and remediation works. The scope of work included asbestos removal within the old buildings, demolition works and a complete remediation of the contaminated soil and groundwater on the site.
The remediation included excavation and off-site cleaning of the source areas up to 4 m-bgl. Subsequently, an in-situ remediation system using recirculation filters (extraction and injection) was installed which took into account the construction of a new building on top of the installation. In order to meet the client's requirements and to enable a quick sale and redevelopment of the site, GreenSoil carried out an underground design. This allowed new construction activities to be carried out on site,such as building new warehouses, without affecting the ongoing in-situ remediation.
The various recirculation filters were connected to the remediation unit via an underground system. In these containers, the extracted contaminated groundwater is mixed with GreenSoil's own carbon source (Dehalo GSTM) before being injected back into the groundwater to stimulate the biological anaerobic degradation of the contaminants, thus creating a large bioreactor in-situ.
The organic substrate Dehalo GSTM together with nutrients, trace-elements and vitamins, ferments in the aquifer to accelerate the anaerobic biodegradation of the contaminants. Careful management of the technique ensures that the electron donor ferments at the correct rate, gradually releasing hydrogen to maintain the biodegradation process, avoiding a strong drop in pH.
Additionally, a biodegradation barrier has been installed to prevent contaminants from spreading beyond the site boundaries.After installation of the in-situ systems, the site was prepared for redevelopment, compacted and finished according to requirements.
GreenSoil offered the project together with BodemBeheer Nederland. Once GreenSoil achieved the remediation objectives for the source remediation, the monitoring on the stability of the remaining contamination will be done by- BodemBeheer Nederland and they will assume the liability for the remaining contamination.
The combination of a pro-active approach, a well thought-out design and an interesting proposal resulted in a fast and cost-effective redevelopment of the site. By using the LEAN planning method, together with good cooperation between all parties involved, all activities went according to plan and without conflict. GreenSoil handed over the site to the client within 5 months after signing the contract to allow for the client to start redevelopment/infrastructure works on the site. The local authorities were enthusiastic about the inventive approach, as the previous technology was no longer efficient. By the end of 2022 the remediation objectives were achieved. In 2023 the active remediation is completed with the approval of the authorities. BodemBeheer Nederland will continue to monitor the site for the foreseeable future and has taken over the liability.
By the end of 2022 the remediation objectives were achieved. In 2023 the active remediation is completed with the approval of the authorities. BodemBeheer Nederland will continue to monitor the site for the foreseeable future and has taken over the liability. This institute is renowned for the aftercare of these specific type of contaminated sites.
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