Treatment of a historic spill of chlorinated solvents at an urban (former dry cleaner) site with restricted access. Client: OVAM, Environmental Consultant: ABO NV
Narrator: Bruges, the capital of West Flanders in the north west of Belgium. A UNESCO Heritage site and a famous tourist destination. Just to the south of the picturesque city center is a former industrial site polluted with chlorinated solvents. Now a predominantly residential area next to a busy road, this has been the site of industrial activity as far back as 1912.
Originally a textile, bleaching, and washing company, the site was later used as a dry cleaning facility, active right up until closure in 1976. Spillages and leaks of solvents used in the dry cleaning process have led to a contamination of the soil and groundwater under the site. Site investigation by ABO NV show that a chlorinated solvent plume in the groundwater is migrating across the side boundary in the direction of a local stream.
The contamination is deemed to pose an unacceptable risk to the environment and OVAM, the government body responsible for the cleanup of public sites, is funding and overseeing this remediation project. Remediation of the contamination is complicated by the limited access available on site. Much of the area is made up of residential properties and roads.
The source zone is located beneath one of the original buildings, which is now a busy storage facility and cannot be used for treatment activities. REGENESIS and ABO have designed an appropriate and effective solution to remediate the contamination on site, and stop its migration over the site boundary.
A PlumeStop barrier will be installed down gradient over the source zone, which will allow groundwater to flow freely through it, whilst rapidly absorbing and biodegrading any contamination that migrates into the treatment area. PlumeStop is an innovative remediation technology, which can achieve very low groundwater targets in a short period, and then maintains this treatment for years after a single injection.
Once injected, PlumeStop coats the subsurface with a one-to-two micron layer of activated carbon. This then absorbs the chlorinated solvents and provides a perfect surface on which to grow reductive dechlorinating bacteria, which then degrade the contamination.
This biological degradation frees absorption sites for further contaminant capture. This means that the barrier is self-regenerating and allows it to remain active for years. Before the full-scale installation, we are performing a pilot test to check field conditions. Chris Martin, technical manager for Europe, explains.
Chris: Over there, there is a mixing tank where we prepare the PlumeStop. The PlumeStop is then pumped through this line to the drilling rack, where we inject the PlumeStop in the subsurface.
Narrator: The pilot application is being completed in an accessible area of the site, a narrow, private driveway. The application is completed quickly, with the driveway left neat and tidy. No further surface equipment is now required at the site while active remediation occurs in the groundwater below.
Initial results have shown a more than 99% reduction in contaminant levels in less than two months of application. Full-scale remediation is being planned for later this year.