Remediation of groundwater in an industrial area, removing chlorinated solvents using anaerobic dechlorination
Location: Zurich-Seebach (ZH)
Customer: Stierli Real Estate AG
Phases: Preliminary investigation of legal requirements for contaminated site, detailed investigation, remediation project, pilot remediation, remediation of the groundwater
Duration: 2010-2015 Investigation of the site / 2016-2019 Pilot remediation and full-scale remediation
Building costs: --
The subsoil under this industrial area has been damaged with highly chlorinated hydrocarbons (tetrachloroethylene). The pollutants extend into the groundwater-saturated area (8-17 m below ground). Due to the deep location of the contamination, the implementation of an in-situ remediation variant was preferred.
Considering the site characteristics, anaerobic dechlorination was decided upon. A cosubstrate (in this case molasses) was injected via injection wells, as a source of carbon. This makes the anaerobic dechlorination of the tetrachloroethylene possible.
The procedure was continuously monitored by taking groundwater samples. The groundwater-saturated area was successfully remediated. The unsaturated soil, 0-8 m below ground, will be remediated via excavation, as part of a construction project.
Ecosens AG developed the remediation project and carried out a pilot study following the preliminary and detailed investigations required by contaminated sites regulations. During the remediation phase, Ecosens AG coordinated all third-party services (remediation company, drilling company, laboratory, etc.), and was responsible for the evaluation of the data, ongoing adjustments to the remediation process, and the presentation of the data to the customer and the authorities (AWEL).
- Preliminary investigation according to legal requirements for contaminated sites and detailed investigation of the site (2010-2015)
- Pilot study for the in-situ remediation and accompanying laboratory tests (2016)
- Conducting an in-situ remediation of the groundwater via anaerobic dechlorination, in collaboration with a specialist company (systems technology), observing the procedure, organisation and evaluation of laboratory results, ongoing adjustments to the remediation procedure, compiling various interim reports (2017-2020)
- Contamination of highly chlorinated hydrocarbons in the groundwater 8-17 m below ground, that can thus only be reached via in-situ procedures
- Former industrial site, built over and very large with various tenants
- Incident due to unforeseen groundwater reduction in the vicinity of the site as a result of construction water management