About the project
Best practices for sustainable stabilisation and reuse of sulfidic soils with minimised environmental impact (MinImpact)
The MinImpact project is a collaboration between Novia University of Applied Sciences and Vaasa University of Applies Sciences in Finland, and Dåva Deponi och Avfallscenter i Umeå AB, Luleå University of Technology and Linnaeus University in Sweden.
The aim of the project is to build cross-border best practices regarding the handling of sulfidic soils. The best practices will be developed in the projects cross-border network through a mutual transfer of knowledge between the project partners and the target group, i.e. permit-granting and supervisory authorities, consultants, municipal urban planning offices, landfill management companies and national transport authorities involved in land development projects. The project partners will provide the knowledge and support needed and the participants in the reference group will provide a practical orientation to ensure that the best practices will be tailored to the actual situation. This will thereby bridge the gap between knowledge base and practice and help the decision making by the authorities and the implementation of methods of safe soil use and/or disposal by other stakeholders involved in land development projects.
The activities consist of field experiments with complementary laboratory experiments, where management techniques of sulfidic soils under waterlogged and drained conditions and with different amendments are investigated in order to enhance the existing knowledge base. The project results in a report on best practices to support authorities and contractors during the permitting process to allow a local and resource efficient management of the excavated soil.
Why MinImpact?
Sulfide soils are widespread on the coastal plains around the Gulf of Bothnia and occur locally inland along river valleys. These land areas are attractive for human settlements and large urban areas, e.g., Umeå, Skellefteå, Luleå, Vaasa, Kokkola and Oulu are located in sulfidic soil areas. Consequently, the infrastructure between cities (e.g., E4, Norrbotniabanan, Haparandabanan, E8, and Pohjanmaan rata) are also largely built on sulfidic soil and the future northerly development associated to the green transition will be affected by the presence of these soils.
Sulfidic soils are excavated during infrastructure projects and urban expansion due to poor geotechnical properties, as well as dredging to deepen shallow waters. However, when disturbed and drained, the sulfide minerals react with atmospheric oxygen resulting in sulfuric acid and release of toxic metals. This is a threat to streams and groundwater and threatens the water quality goals of the EU Water Framework Directive. To mitigate the risks, disposal at special landfills and under water is a common strategy to manage the excavated soils. While landfilling works, it is an unsustainable management that also includes drawbacks in terms of long transportation with CO2 emission costs and disposal of a potential natural resource.
The microbiology, geochemistry and mechanics of sulfidic soils are interconnected and therefore, a multidisciplinary approach as provided here is needed to assess the best practices in terms of long-term stabilisation, use and minimised environmental effects of sulfidic soil. By building on existing knowledge gained from e.g., the Botnia-Atlantica project STASIS, this project will provide the enhanced knowledge base needed by decision makers and practitioners involved in land-development projects in taking steps towards handling and using sulfidic soils in a way that protects the environment, preserves biodiversity and promotes business plus the economy in the cross-border region.
