"Inventory of historical contaminated sediment in Rhine Basin and its tributaries"After extensive reduction of emissions by point sources (industrial and municipal) along the Rhine as a consequence of the Action Program “Rhine” of the ICPR and other initiatives like the Rhine Research Project of the Port of Rotterdam, those sediments now gain in importance, which had been contaminated in the past and accumulated in areas of low water current. The relative contribution of these sediments to the exceedence of regulatory concentration limits for relocation will increase. Non-compliance with the required chemical criteria demands expensive disposal options. The concern with regard to historical contaminated sites is, that their contribution to port sediment contamination may continue on an undetermined time frame: Their exact location and extent is often unknown and once found the sites have to be managed, unless consolidation processes prevent resuspension effectively.
In the present report, the risk for the Port of Rotterdam due to those historical contaminated sites is assessed. This risk addresses the probability that sediment in the Eastern part of the port may be contaminated above current sea/Slufter threshold values, regulated by the Dutch “Chemistry –Toxicity Tests (CTT)-levels”, due to resuspension processes upstream. Exceedance of the CTT-values not only increases the ecological risk, but leads to cost-intensive actions as this material has to be disposed in a contained disposal facility (the Slufter) rather than be relocated at the North Sea.