R&D highlights edition 2019

Ecosystems and environmental quality 21 R&D Highlights 2019 Gasworks around 1960 (photo: Kees van de Meene) A gasworks operated from 1860 to 1960 on the location of what is now Griftpark (Utrecht, the Netherlands). The operations of the gasworks led to the serious and large-scale contamination of the soil. The city authority of Utrecht is reassessing the current pollution control measures implemented since 1998: groundwater abstraction, water treatment, monitoring and maintenance of the deep wells. As recent observations have shown that there may be extensive biodegradation - the natural ability of the subsurface to break down contaminants - of the pollution in the subsurface, the city wants to know whether it is feasible to change their current pollution control management to an approach based on the natural degradation potential of the subsurface. Biodegradation depends on the presence of micro-organisms, the geochemical and geohydrological properties of the layers in the subsurface and the redox conditions. The aim of the study is to investigate the current biodegradation potential of the subsurface of Griftpark and ways of stimulating the bio­ degradation to accelerate remediation. The project is being carried out by Deltares with its subcontractor Aveco de Bondt, and by Utrecht University (UU) and Wageningen University. Deltares is responsible for assessing the current natural degradation potential by carrying out the necessary fieldwork and laboratory analysis. The UU is developing the groundwater model to simulate different degradation scenarios and the WUR is looking at ways to encourage natural biodegradation. Results are expected in early 2020. If those results confirm the earlier hypothesis that biodegradation plays a major role in cleaning up the contaminants, the city authorities are expected to adjust their current approach in order to reduce the costs associated with groundwater abstraction and groundwater treatment. This will also be a good example to share with municipal authorities elsewhere in the Netherlands who are faced with the same questions. C ontact: Johan van Leeuwen, Johan.vanLeeuwen@deltares.nl , t +31 (0)6 4691 1736 Sophie Vermooten, Sophie.Vermooten@deltares.nl , t +31 (0)6 2293 7435 Further reading : https://www.utrecht.nl/wonen-en-leven/ gezonde-leefomgeving/bodemkwaliteit/ projecten/bodemonderzoek-griftpark/ BIODEGRADATION OF LARGE-SCALE CONTAMINATION IN THE SUBSURFACE: THE CASE OF GRIFTPARK IN UTRECHT The City of Utrecht is reassessing current pollution control measures in Griftpark in the city, where a gasworks operated from 1860 to 1960. The aim of the study conducted by Deltares, Aveco de Bondt, Utrecht University and Wageningen University is to investigate the current biodegradation potential of the subsurface and ways of stimulating the biodegradation to accelerate remediation. Fieldwork in Griftpark, November 2018