Pilot application of the TreeWell phytoremediation technology to manage benzene-contaminated groundwater and reduce spreading risks at Stockholm’s Kolkajen

Research Project, 2026 – 2029

A commercial phytoremediation solution for hydraulic control of contaminated groundwater using plants, called TreeWell1 (described in detail below), will be tested and evaluated. The technology has been successfully applied in North America and Europe under complex geological conditions and high contamination levels but has never been tested in Sweden. In general, access to practical knowledge and full-scale pilot studies of phytoremediation with scientific evaluation of results remains limited, especially under Swedish conditions, and has been a barrier to wider application of these methods2,5. Phytoremediation has the potential to provide additional benefits if the trees can be left in place: both educational and experiential through demonstrating the capabilities of nature to a broader public and ecological by providing ecosystem services. This pilot is a good opportunity not only to investigate how to ensure plant development and groundwater management during the project, but also to discuss and examine what is required if the trees are to be preserved after the remediation in an urban park area. However, there is an inherent challenge in that the trees in this and any future projects are planted at a very early stage, before detailed development plans and other design work are established. This makes it difficult to coordinate the placement of the trees with future land use. In addition, parks require more qualities than just trees, such as playgrounds, grass areas, and more. Trees in a dense city must also withstand more, and sometimes entirely different, demands than just managing groundwater. Despite the challenges, there is great added value in using and preserving trees, so it is important to know more about the suitable conditions and opportunities for applying this technique.