Because of the shallow relief in Belgium and northern France, the dredging of waterways generates significant quantities of sediments for which few valorization pathways are validated. Waterways operators and public authorities are still waiting for efficient valorization solutions. The VALSE project, funded by the Interreg V FWVl program, aims to validate valorization pathways through large-scale works that promote a good integration in territories and a sustainable use. In this context, landscaping could be an upgrading solution; hence, a mound made with unpolluted sediments is ecologically and ecotoxicologically monitored over time to assess if dredged materials are harmful for the environment. An embankment near the studied site was chosen as a reference. The monitoring consists of, on the one hand, in situ flora and substrate macro-invertebrates surveys. On the other hand, ecotoxicity tests are performed on sediments and soil respectively taken from the mound and the embankment: the activity of nitrifying bacteria in these substrates and the reproduction of an earthworm (Eisenia fetida) are studied. First, results show that the sediments do not seem to impact negatively plant colonization or the settlement of substrate macro-invertebrates. About laboratory testing, sediments do not seem to interfere with natural nitrification process and E. fetida reproduction seems equivalent in sediments and embankment soil. These results do not allow drawing any definite conclusion because they relate to a first year of experimentation only, but they tend towards a good integration of the mound in the surrounding environment for the monitored parameters.
Keywords: Ecology; Ecotoxicity; Landscape development; Sediments; Valorization.