The task of the project was to treat soil and groundwater impacted by PCE, TCE and other chlorinated hydrocarbons at former industrial facility in the northern part of Stockholm. The site had been industrially active since the late 18th century with production of cables and telephone parts. The contamination was caused by the extensive use of chlorinated solvents applied for cleaning the manufactured parts.
The objective was to remove all risk for the future use of the property, including indoor climate in the existing buildings, which were transformed into offices, apartments and a library.
A preliminary site characterization was done by using dynamic approach MIP-screening of the chlorinated solvents combined with 3D modelling. The model showed a CVOC-plume covering a total area of approximately 1,500 square meters. In the source area concentrations, up to 150 ppm of TCE was detected. The characterization of the bedrock surface was important for designing the injection program as it turned out the bedrock contour indicated a narrow but deep depression directly under the building. Based on gathered information the injection programme was designed as a grid of more than 600 injection points for installation of 30 tons of BOS 100®.
BOS 100® is a proprietary technology, which utilizes an injectate consisting of activated carbon impregnated with zero valent iron, which is applied to a chlorinated VOC plume or source area. The carbon-based injectate treats dissolved chlorinated solvents in-situ. The injectate consists of an activated carbon catalyst impregnated with nano scale reactive iron. Contaminants are trapped by the carbon and thus co-located
in concentrated form with the reactive iron. The CVOC´s are effectively treated by reductive dechlorination as a result of direct contact with the iron. The adsorptive carbon carrier captures and retains the initial contaminant and retains the degradation daughter products until complete reductive dechlorination by the reactive iron occurs, thus protecting groundwater quality throughout the clean-up cycle.
After completion of a full scale composed injection programme the local environmental authorities were able to approve the clean-up level at the site and to issue a NFA letter to the client.