The remediation of sediments in the harbour of Oskarshamn

The sediments in the harbour of Oskarshamn are contaminated with more than 1000 tonnes of heavy metals which have been accumulating in the sediments since the end of the 19th century. The contaminants in the sediment origins mostly from industrial activities in the harbour area. Many of , the industries are no longer active, and the ones who are have strongly reduced their environmental impact during the last decades. The identified sources for the main contaminants are a copper industry (copper, zinc, lead, cobalt and dioxin), a shipyard (arsenic, TBT, lead and organic solvent), a battery factory (cadmium and nickel) and a municipal treatment plant (all types of hazardous substances).

Models show that approximately 1 tonne of zinc, 500 kg copper, 300 kg lead, 100 kg arsenic, 5 kg cadmium and 0.1 g of dioxin disperse every year from the sediments in the harbour to the Baltic Sea. The main target with the remediation is to decrease the dispersion of contaminants from the sediments to the Baltic Sea with 90 %. At the same time the port must remain in operation, maintain its character and maintain the possibility to develop future environmental friendly transport systems.

Approximately 500 000 cubic meters of sediments will be dredged. The dredged sediments will be dewatered and stabilized and transported to a landfill specifically built for this purpose. Dredging is scheduled to begin in 2016 and the execution time is from 2 to 4 years. The total cost for the project is estimated to around 500 million SEK.