Narrator: We’re here at an active manufacturing site in the west of Sweden, located close to a major river. The site is presently owned by a multinational chemical company and has a long industrial history. Since the 1920s, it has been a fuel depot, a lubricant blending facility, and a distribution center for chlorinated solvent products supplying the dry-cleaning industry. These historic activities have resulted in a number of spills and leaks of predominately tetrachloroethene, PCE, contaminating the soil and groundwater below the site.
Regenesis’s involvement in the remediation process started in 2012 when AECOM commissioned a pilot study and subsequent full-scale application of our 3DME and HRC technologies to biologically degrade the contamination on the site and prevent further migration towards the river. Two years of validation monitoring has shown sustained reduction of PCE concentrations in the groundwater with full reductive dechlorination occurring.
In another part of this site, PCE contamination, including DNAPL, has been found underneath an active storage warehouse, called the J Building, which has a footprint of around 500 square meters. Groundwater flow is towards the river, where low concentrations of PCE have been detected.
Tim Mulliner, AECOM’s project manager, explains.
Tim: The J Building here has been on site for many decades and it’s been used, historically, for the storage of chlorinated solvents, as well as other products. Our task has been to keep this building intact with minimal interference but also to intercept that pathway from the contamination below the building to the river.
Narrator: With access to the inside of the building not possible due to commercial activities, Regenesis and AECOM designed a solution to cut the pathway to the river. This is to be completed through the installation of a Plumestop barrier, which will absorb and then degrade dissolved contaminants migrating towards the river. Because the Plumestop barrier will be injected in between the building and the river, no access is needed to the building itself, apart from monitoring, allowing for commercial activity to continue uninterrupted. The barrier will be 25 meters long, cutting across the plume identified by AECOM. Plumestop will be injected in combination with HRC and BDI Plus to provide initial biostimulation and bioaugmentation of the treatment. By using Plumestop in a barrier formation, the chlorinated solvents migrating towards the river will be immediately captured and degraded as they pass through the treatment zone. Due to its fast-acting absorption and biological degradation mechanism, the barrier is essentially self-cleaning and will be active for years.
The installation will be completed in one week. Following this, AECOM will take groundwater samples to monitor the barrier’s performance. Regenesis and AECOM have worked together to create an intelligent, staged approach to the remediation of this site. Appropriate technologies have been deployed across the site and throughout the remediation program, reducing source contamination where possible and preventing contaminant migration across the site boundary.
And the good news for the client is that all of this remediation has been achieved with no disruption to their commercial activities.