Volvo Car Gent is a car manufacturer located in the port district of Gent in the west of Belgium. The plant opened in 1965 and was the first European Volvo plant outside Sweden. Around 5,000 people work at this facility, producing more than 250,000 cars per year. Manufacturing activities at the plant includes: welding, painting, and final assembly, all processes which typically involve the use of lubricating oils and cleaning solvents. The handling and storage of these chemicals has lead to the occasional spill or leakage in the past. This has resulted in soils in groundwater below the plant becoming contaminated with petroleum hydrocarbons and chlorinated solvents.
Site investigation by Artemis Milieu has revealed two plumes relating to these historic spillages. The groundwater contaminant concentrations are low but persistent. Due to the direction of the groundwater flow, the contamination is at risk of migrating across the plant’s site boundary. REGENESIS has been asked to provide a solution to treat the plumes and prevent off-site migration.
On this busy site, access to the contamination is not only limited by manufacturing activities, but also by building structures and underground services. Therefore a barrier approach has been chosen, which has the advantage of needing fewer injection points whilst treating the entire plume as it migrates into the treatment zone. The barrier will be formed from an innovative remediation technology called PlumeStop. PlumeStop is a liquid-activated carbon which firstly absorbs the contamination and then stimulates its biological destruction. In this way, PlumeStop can achieve very low groundwater contamination targets in a short period of time. Enhanced biological degradation on the PlumeStop ensures that treatment is then maintained for years following a single injection.
For this site, we have designed two PlumeStop barriers. The first barrier will be installed in area one, which is located adjacent to the plant’s paint mix area. Here the plume consists of petroleum hydrocarbons associated with the location of a former fuel storage tank. The second barrier will be installed in area two, which is located close to the site boundary. This barrier will treat a mixed plume of BTEX and chlorinated solvents resulting from historic manufacturing activities. For this area, additional source treatment is also being considered.
By injecting PlumeStop in 2 barriers, the plumes will be contained, and any off-site migration will be prevented. The barriers also avoid the need for physical access to the entire plume underneath existing buildings, providing a significant saving in cost and disruption to the busy facility. Prior to the main works going ahead, REGENESIS has completed a pilot test in area one to confirm field conditions. Here, PlumeStop was injected into pre-drilled wells with monitoring completed inside and downgradient of the barrier. This pilot test has been successful and the full-scale barrier installation has been scheduled for next year.
Today, we are performing a second pilot test in area two to verify the local geological conditions, as these are variable across the site. For this area, we’re using a direct push injection technique to test the installation of PlumeStop at intervals between 3 and 5 meters and 8 and 10 meters below ground level. The equipment used is portable and has a small working footprint. None of the equipment is left on site overnight, which means that there is no effect on the ongoing operations of the plant. By firstly carrying out a pilot test, the injection process can be optimized, and any new information used to fine-tune the remedial design if required. This will make the full-scale barrier implementation next year more accurate and cost effective.
REGENESIS and Artemis Milieu have designed an appropriate and effective solution to remediate the contamination on-site and prevent it from spreading and migrating over the site boundary. With all this treatment occurring in situ, Volvo Car Gent operations can continue to proceed without interruption.