Increase of sea level and land subsidence necessitate heightening and strengthening of dikes and embankments, creating large material demands. On the other hand, maintenance of fairways, harbor basins, sluices, barrages and water reservoirs generate large volumes of dredged sediment. Physical and biogeochemical properties of freshly dredged, saturated sediment differ significantly from those of ripened, unsaturated soil. Beneficial use of sediment as earthen construction material therefore requires dewatering and further biogeochemical and physical ripening. If repurposed for dike construction, particularly the shrinkage potential of the material and hence its susceptibility to crack formation is of interest. Further, compactibility of the material determines key mechanical properties such as shear and tensile strength. Here, we investigate the effect of field ripening of partially dewatered dredged sediment (METHA material) on these parameters.

Dredging produces large sediment volumes with organic matter (OM) from natural and industrial sources, which even in small amounts, can significantly affect sediment properties [1]. For beneficial use of dredged sediment, OM stability is paramount. Sediment ripening aims to reducing and stabilizing the organic fractions [2], [3]. This study examines OM degradation in mechanically dewatered dredged sediment (METHA plant, Hamburg, Germany) during ripening, analyzing sediment respiration and the Tea Bag Index [4]. Together, these methods provide a comprehensive understanding of the dynamics of organic matter transformation during biological ripening of dredged sediment.