Probabilistic design of settling basins for environmental compliance

I would like to thank my graduation committee for their supervision, advice and support. I would also like to thank prof.dr.ir. L.C. van Rijn and dr.ir. J.C. Winterwerp for their valuable advices and dr.ir. M. van Koningsveld for providing the frame work of the model and for his comments and suggestions. Further I would like to thank my colleagues from the environmental department of Van Oord for answering my questions and the nice working environment. In particular, I thank my parents, family and friends for their interest and support. Summary There is an increasing public awareness for the potential negative environmental effects of dredging and reclamation projects. Therefore, almost every project requires an environmental impact assessment (EIA). These EIA's usually provide strict environmental requirements that must be taken into consideration in the design and execution of a project. These environmental requirements can form a high risk for contractors because the inability to meet the environmental requirements can result in large fines or downtime. The determination of the environmental impacts of these projects includes large uncertainties. This results in stringent environmental requirements and a conservative approach by the contractor. Understanding these uncertainties leads to a more realistic view of the situation and provides a better basis for establishing the environmental requirements. The environmental impacts caused by the release of suspended sediments are often an important issue in an EIA. The insight into the released amount of suspended sediment particles is an important link in the investigation into the environmental impacts caused by this release. These impacts can be an increased turbidity due to the suspended sediment. Especially corals are very vulnerable for increased levels of turbidity and it also causes a reduction of photosynthesis by marine life. This study is restricted to provide insight into the emission of suspended sediment particles due to the release of return water. This water is used to pump dredged material to the disposal area after which the excess water is released. Settling basins can be used to remove fines particles from the return water. The settling of the suspended sediment particles in a settling basin takes time. The remaining concentration of suspended particles in the outflowing water and the discharge give the emission of suspended sediment particles. This outflow concentration is hard to predict due to varying circumstances (e.g. wind, discharge and inflow concentration) and uncertainties in the settling process (e.g. agglomeration of clay particles). …