Soil and groundwater of a multinational electronic manufacturer is impacted with chlorinated volatile organic compounds (cVOC) due to site activities. Three main contaminated areas have been identified: A, B and C. Zones A and C are mostly outside the buildings, whereas zone B is located underneath a building in which a production area is present.
The remediation strategy selected by the client was the “source driven concept”. To address this concept, GreenSoil proposed a phased and zone specific approach:
In-situ remediation system to stimulate the anaerobic biological degradation of chlorinated compounds (ERD) using a combination of direct push and groundwater circulation with dosing of the electron donor Dehalo-GSTM .
Based on the outcome of these investigations, a full-scale remedial strategy was designed (Q3 2019):
GreenSoil installed the entire in-situ remediation system underneath the building complying with the requirements of the client (dust and vibration free environment).
Additional investigation (unknown source) with respect to the migration of the contamination which included camera inspection of the sewer system to identify further leaks. Based on the results collected, excavation of the contaminated soil and in-situ ERD were carried out. A grid network of injection wells between 2 and 10 m-bgl is installed to supply the shallow aquifer of necessary nutrients. The concentration levels of the contaminants were reduced to tens of µg/l in about 2 years.
To enhance the anaerobic biodegradation of the different cVOCs, a groundwater circulation system is implemented which consists of extracting contaminated groundwater, supply GreenSoil’s electron donor (Dehalo-GSTM) and re-infiltrate the groundwater into the soil again.
During remediation, groundwater quality is being closely monitored by sampling monitoring wells on site. By March 2020, the remediation zones A and C reached the target values.
The first stage multiphaseextraction (MPE) until 4 m-gl succesfully removed the bulk of the containment in Area B.
The biobarrier at the site boundary was operated with a high efficiency (> 95%). Evidence of on-going anaerobic degradation is given by the increasing concentrations of the final degradation products, e.g. VC, and the rapid decrease in the concentrations of PCE, TCE and 1,2 Cis.
Besides the short term installation works (largely conducted in holiday period) the remediation did not generate interference with site activities.
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