Find out here what we are investigating in NARMENA
The LIFE project NARMENA, co-financed by the European Commission, is a response to the objective of remediating contaminated soils and sediments in rivers, on riverbanks and flood plains. It seeks to develop and implement sustainable, nature-based remediation methods that are both cost-effective and non-invasive. In Europe, these remediation techniques are not yet widely used in watercourses. It seems to be a major challenge to integrate this concept into remediation policy.
Partners
OVAM implements this project together with the Flemish Agency for Nature and Forests (ANB) and Natuurpunt, both owners and managers of nature reserves. The Flemish Environment Agency (VMM), as the watercourse manager of Grote Laak and Winterbeek and implementer of integrated water management, is also a partner in this project. Our experts in the field of soil research and remediation (ABO NV), phytoremediation
(Bio2Clean bvba) and ecotoxicity and eco-modelling (ARCHE Consulting bvba) provide a high-quality partnership for this challenging project.
Demonstration projects
LIFE NARMENA demonstration projects are being established for two types of nature-based remediation methods, which align sediment and soil remediation with nature conservation and water storage - artificial wetlands and phytoremediation. The sediments in almost 50% of Flemish watercourses are contaminated with heavy metals. While the source activities are often no longer present, contamination remains in the sediment and on river banks. The sediment and banks act as secondary source zones. A large number of natural floodplains are therefore currently at risk. This widespread water and sediment pollution poses a serious obstacle to the creation of retention areas, since pollution would spread even further.
The demonstration projects will be rolled out in the valleys of three watercourses polluted by heavy metals. These three streams- the Grote Calie (Turnhout), the Winterbeek (Scherpenheuvel-Zichem) and the Laak (Geel – Laakdal) – flow through Natura 2000 sites. By constructing phytoremediation fields and artificial wetlands, we aim to significantly reduce the bioavailability of the metals, in order to lower or eliminate potential risks to the ecosystem. Monitoring will mainly focus on the reduction of availability of metals such as chromium and cadmium, while changes in nutrient concentrations will also be kept track of, which is an expected, additional benefit of the techniques to be implemented.
In-situ remediation and bioavailability
An important difference between conventional techniques is that nature-based techniques are in-situ. This requires far fewer operations and drastic interventions that affect the environment.
The CO2 emissions are also lower. There is no need, for example, for dozens of trucks to transport excavated soil and sludge.
Unlike organic pollution, metals cannot be broken down. We therefore ensure that the metals are immobilised and can no longer migrate. This is done by means of biochemical processes. For example, by using certain plants that retain metals in their roots or convert metals into a non-harmful form.
In the monitoring strategy, we make a distinction between total and bioavailable concentrations. Metals that are immobilised using nature-based techniques are therefore also no longer bioavailable. They can no longer be absorbed by organisms.
Eco-modelling approaches will also be developed and applied to predict the impact of these remediation techniques. What is the toxicological impact of a concentration change on certain organisms? What is the availability of a particular harmful substance? Answers to important questions like these can help decision-makers to impose threshold values for pollutants in sediments of watercourses.
Results
NARMENA's results and experiences will inspire us to develop a framework for the application of nature-based remediation. These results will then be compared with conventional techniques. Effectiveness and total cost of remediation will be taken into account, as well as CO2 emission and contribution to ecosystem services. The findings will be disseminated in Flanders, Europe and further to encourage competent authorities and relevant economic sectors to apply these techniques more often in vulnerable nature areas.
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LIFE NARMENA demonstration projects are being established for two types of nature-based remediation methods, which align sediment and soil remediation with nature conservation and water storage - artificial wetlands and phytoremediation. The sediments in almost 50% of Flemish watercourses are contaminated with heavy metals. While the source activities are often no longer present, contamination remains in the sediment and on river banks. The sediment and banks act as secondary source zones. A large number of natural floodplains are therefore currently at risk. This widespread water and sediment pollution poses a serious obstacle to the creation of retention areas, since pollution would spread even further. 
