EN 
DE 
WHAT-WE-DO: At the site "Inselpark Gronau", the former premises of the weaving and dyeing mill "M. v. Delden" and later the Landesgartenschau site in Gronau / Losser (NL), a CFC groundwater contamination has been secured and remediated by a pump-and-treat measure since 2003.
After groundwater pumping in the first years 2003 - 2009 had led to a significant decrease in pollutant levels, the pollutant levels have been decreasing only slowly over a longer period of time since then, as is typical for corresponding hydraulic remediation. One of the reasons for this is an HFC source in the marl rock at the base of the pore aquifer. In the years 2011 to 2017, preliminary investigations were carried out to select an additional remediation method to make the pollutant discharge at the site more effective and to minimise it in the long term, and to complete the hydraulic remediation within a foreseeable period of time. These recommendations and innovative investigation measures were fully supported and constructively accompanied by the City of Gronau as the client.
In addition to initial SOD tests in 2012, a push-pull test was carried out in two residual pollution areas in 2015. The PP test showed mobilisable residual phase fractions, anaerobic groundwater conditions (methane, ethene, iron II) and a high prospect of success for surfactant-assisted in-situ chemical oxidation (ISCO) using high-pressure solid injection.
Our Hagen branch was commissioned by the city of Gronau to carry out these services in 2019. The in-situ chemical oxidation was started using the TSE® injection process in January and February 2021. The first six-monthly monitoring phase has now been completed.
The results of the groundwater analysis in both remediation fields show a consistent reduction of the CFC contamination seven months after the input of surfactants and permanganate oxidants. Remediation field 1 shows a reduction of the total content by more than 35 %. In the second remediation field, even higher reductions are recorded with the reduction of 45 % of total content. A continuation of the degradation of pollutants until at least the oxidant is exhausted is to be expected. In this respect, the monitoring measurements already show a good success of the measures. A further injection measure is currently being coordinated in order to be able to generate a further reduction in pollutants and thus successfully complete the hydraulic remediation measure in the foreseeable future.
#EngineeringForABetterTomorrow #mullandpartner #groundwater #contamination #pollutant remediation
