RSK helps acquire EU LIFE+ funding for novel bioremediation
A chemical facility produces, stores and distributes monovinylchloride, a raw material for producing polyvinylchloride. On-site soil and groundwater investigations have revealed contamination by aromatic, aliphatic and chlorinated volatile organic hydrocarbons. An intermediate in the production of polyvinyl chloride, 1,2-dichloroethane, accounts for 80% of this.
Anaerobic dechlorination by soil organisms is a promising remediation technique for chlorinated aliphatic hydrocarbon contamination under suitable conditions. The University of Ghent in Belgium has isolated Desulfitobacterium dichloroelimans strain DCA-1, which can biodegrade 1,2-dichloroethane to ethene without the formation of toxic intermediates, as bacteria for the degradation of chloroethanes are not commonly available.
To be successful, in situ remediation techniques always require adequate groundwater velocities. The University of Ghent has developed hydrogeobiocells (HGBcells) that increases the groundwater flow velocity by applying a specific pumping and injection programme, after which treatment of the contaminated groundwater is unnecessary.
In anticipation of the site remediation required, laboratory tests showed substrate injection to be a valid remediation option. Enhanced groundwater modelling techniques were used to develop a tailored treatment that uses HGBcells for the in situ treatment. EU LIFE+ funding was requested and granted for that part of the remediation involving HGBcells. This funding required RSK to prepare an extensive submittal file.
In parallel with the LIFE+ funding file, RSK prepared the remedial action plan (RAP), which was approved by the authorities in June 2010. The estimated cost of the remediation is €6.5 million spread over 30 years. The RAP offers a phased approach in view of the planning required and to spread the investment costs.
The following actions are planned:
- off-site groundwater remediation by stimulating biological degradation in groundwater cells consisting of extraction and injection filters (HGBcells)
- on-site pump and treat in source zones for lowering groundwater concentrations
- on-site remediation of unsaturated soil by dual-phase vacuum extraction in source zone areas
- on-site groundwater remediation by stimulating biological degradation in groundwater cells consisting of extraction and injection filters (HGBcells). Where necessary because of high contaminant concentrations, bacteria will be added to enhance the biodegradation.
RSK’s goal was to translate theory into reality and apply the innovative HGBcell technique in the field. To do this following approval of the RAP in 2010, RSK drafted the technical specifications for the installation of the extraction and injection wells of the first HGBcell off-site. In January 2011, a pumping test was performed and then the HGBcell was installed. Start-up of the HGBcell showed that the normal development of the extraction and injection filters was inadequate to prevent pressure build-up in the injection well. Subsequent modification of the well made it possible to extract and inject 16 m³/h without pressure build-up in the injection well.
After several tests, the first operational phase of the HGBcell started in October 2011 with sodium lactate dosing. In the following months, RSK showed that the HGBcell was becoming active and that 1,2-dichloroethane biodegradation was occurring.
The European Commission has recognised this innovative technology and will fund 50% of the costs of the remedial works for five years through the LIFE+ programme. Funding began in 2010 and will continue until December 2014.