Groundwater remediation of an industrial site in Seebach
In-situ remediation of chlorinated solvents in groundwater using anaerobic dechlorination
The project
Location: Zurich-Seebach
Client: Stierli Real Estate AG
Phases: Preliminary investigation under contaminated site law, detailed investigation, remediation project, pilot remediation, remediation of groundwater
Duration: 2010-2015 site investigation / 2016-2019 pilot refurbishment and full-scale refurbishment
In the subsoil of this industrial site there is damage with highly chlorinated hydrocarbons (tetrachloroethene). The contaminants extend into the groundwater-saturated zone (8-17 m a.s.l.). Due to the deep location of the contamination, the implementation of an in-situ remediation variant was in the foreground.
Considering the site characteristics, anaerobic dechlorination was chosen. A cosubstrate (in this case molasses) was injected as a carbon source via injection wells. This enabled anaerobic dechlorination of the tetrachloroethene.
The measure was continuously monitored by groundwater sampling. The groundwater-saturated area was successfully remediated. The unsaturated subsoil between 0-8 m a.s.l. will be remediated by excavation as part of a construction project.
Ecosens AG developed the remediation project and carried out a pilot test following the preliminary and detailed investigation required by the law on contaminated sites. During the remediation phase, Ecosens AG coordinated all third-party services (remediation company, drilling company, laboratory, etc.) and is responsible for the evaluation of the data, ongoing adjustments to the remediation process and the presentation of the data to the client and the authorities (AWEL).
Preliminary investigation and detailed investigation of the site (2010-2015)
Pilot test for in-situ remediation, accompanying laboratory tests (2016)
Carrying out in-situ remediation of groundwater using anaerobic dechlorination in collaboration with a specialist company (plant technology), monitoring the measure, organizing and evaluating laboratory results, making ongoing adjustments to remediation operations, writing various interim reports (2017-2020)
Challenges
Contamination of highly chlorinated hydrocarbons in groundwater between 8-17 m below sea level and can therefore only be achieved using in-situ methods
Former industrial site, overbuilt and very large with various tenants
Incident due to unforeseen groundwater lowering in the vicinity of the site as a result of construction dewatering
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