Dredged Materials in Dike Construction - Implementation in the SBR using Geosynthetics and Soil Improvement

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Due to the expected sea level rise the authorities of the Baltic Sea region are intensively planning the improvement of coastal protection structures. In Mecklenburg-West Pomerania (M-V), a total of 220 km of coastal dikes and another 530 km of primary and secondary river dikes exist, protecting 53,500 ha of land. An investment of Euro 50 Mio is estimated for the improvement or reconstruction of coastal dikes in M-V until 2014, followed by 15 Mio per year for coastal protection measures in the next two decades. In the Pomeranian region in Poland a total of 655 km of primary dikes protect over 141,000 ha of coast and lowlands. Within the next two decades investments of Euro 160 Mio are planned for dike construction, improvement, and reconstruction. Approximately 4 Mio people are directly or indirectly protected by these structures in Poland and Germany. Because of a major shortage of dike construction material along the Baltic Sea coast, the regional authorities of M-V and Gdański region are looking for technologies to use dredged and other waste materials for dike construction. In the project, a German and a Polish approach are investigated to get dredged materials implemented in dike construction (Comp. 3). (1) The very fine grained, organic dredged sludges of M-V region (similar materials can be found in Szczecin region) will be used directly in the top layers of dikes. To level possible inhomogeneities of different materials and to allow steeper slopes the integration with geosynthetic solutions, such as permanent erosion control or reinforcement systems, will be used to convert the dredged materials into valuable resources for coastal protection. (2) Fine grained sandy dredged materials from Gdański region are usually not well suited for dike construction. They will be improved by mixing technologies using ashes to produce a reliable construction material. To show the reliability of the best practice solutions found in the field tests, a pilot dike construction will be realised within an actual flood-protection project, actually protecting arable land and settlements. It will be shown to the target groups and monitored after the project (Comp. 4). To guarantee the use of dredged materials after the project, a multilingual best practice guideline will be developed and distributed to responsible decision makers, such as environmental and coastal authorities (Comp. 5). The knowledge will be disseminated in the South Baltic region by means of a website, newsletters, meetings, technical visits, and a final conference (Comp. 2). Extensive savings and a major social and environmental improvement are expected if these materials are sustainably used for dike construction. As results, two environmentally efficient approaches to get rid of unwanted dredged spoil together with cost efficient methods to sustainably secure the coastal population from storm surges are at hand and the recent problems of dredged material storage are solved (see 2.1).

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