Management of dredged marine sediments in southern France: main keys to large-scale beneficial re-use

Abstract

Abstract Each year fifty million cubic meters of marine sediments are dredged in France to maintain and develop harbor activities and sustain the economy of littoral territories. Because of anthropogenic activities in and around harbours, bottom sediments can contain more or less significant amounts of chemical and organic pollutants whose behavior during dredging must be addressed in order to avoid releasing and risks for human and environment. French regulations come to govern the management of dredged marine sediments, considering them ‘safe’ and possibly to be dumped at sea or ‘contaminated’ and needed to be treated on land as waste. These last years, new constraints are pushing towards a management on land. This management is however challenging as few channels are proposed to promote or reuse marine sediments, and elimination appears to be economically and environmentally unsustainable. This study provides an overview of the technical and regulatory aspects related to dredged marine sediment management in France and aims to identify and discuss the limits or barriers of their valorization. Dredged sediments are mainly composed of particles with heterogeneous grain size, some being known for many applications such as building materials and growing media. However, several reasons have been put forward to explain why these particles are not reused when extracted from dredged sediments. Several technical, socio-economic and regulatory obstacles explain the low demand for dredged sediments. This demand can be stimulated by government incentives and a good regulatory framework. National regulations could help streamline the reuse of dredged sediments by standardizing sediment composition tests, removing the "waste" status attributed to dredged sediments and creating a regulated market for dredged sediment-based products, thus creating a promising economic sector.