Beneficial use of dredged sediments in public works.

With the increase in environmental awareness, in combination with a more restrictive legislation, traditional solutions to the management of dredged sediments, such as dumping at sea or disposal to landfills, become more and more inadequate. In order to improve the management of dredged marine sediments, alternative solutions such as beneficial use in civil engineering, manufacture or agriculture have been proposed. Reuse solutions have to fulfil economical, technical and environmental criteria. At present, the proposed solutions are relatively costly and not adaptable to all types of sediments. In particular, fine sediments are difficult to reuse in comparison to sands because of their high water content, the presence of organic matters, their mechanical behaviour and the presence of pollutants in some cases. In this context, this study aims to design a road material that includes dredged fine sediments from a harbour in the north of France. With an initial water content higher than 100%, the first operation consisted in preparing the dredged sediments by reducing its initial water content and, as a consequence, the content of dissolved salts. Then the sediments were characterized and finally a material with the required properties was designed. This material included fine marine sediments, traditional granular materials and hydraulic binders. This paper focuses on the methodology used to design the road material.

Methodology of management of dredging operations I. Conceptual developments.

This article presents a new methodology for the management of dredging operations. Partly derived from existing methodologies (OECD, UNEP, AIPCN), its aim is to be more complete, by integrating the qualities and complementarities of former methodologies. Moreover, it was carried out in a context of sustainable development. Indeed, it supports, according to a framework of industrial ecology, the development and the implementation of solutions of waste improvement of dredged materials, in order to minimize the environmental impact of dredging. It also uses a tool of MultiCriteria Decision-Making Aid (M.C.D.M.A.), in order to integrate local characteristics. In addition, this tool, called DRAGSED, allows to a dialogue to be established between all the parties concerned with a dredging project (harbour's authorities, industrialists, municipalities, administrations, populations, associations,...). Thus, the implementation of this methodology enables consensus to be reached for the dredging solution retained. It also proposes an environmental follow-up, which will allow an evaluation during its application.

Methodology of management of dredging operations II. Applications.

This paper presents the new methodology of management of dredging operations. Derived partly from existing methodologies (OECD, PNUE, AIPCN), it aims to be more comprehensive, mixing the qualities and the complementarities of previous methodologies. The application of the methodology has been carried out on the site of the Port of Dunkirk (FRANCE). Thus, a characterization of the sediments of this site has allowed a zoning of the Port to be established in to zones of probable homogeneity of sediments. Moreover, sources of pollution have been identified, with an aim of prevention. Ways of waste improvement have also been developed, to answer regional needs, from a point of view of competitive and territorial intelligence. Their development has required a mutualisation of resources between professionals, research centres and local communities, according to principles of industrial ecology. Lastly, a tool of MultiCriteria Decision-Making Aid (M.C.D.M.A.) has been used to determine the most relevant scenario (or alternative, or action) for a dredging operation intended by the Port of Dunkirk. These applications have confirmed the relevance of this methodology for the management of dredging operations.