Disposal of Contaminated Sediments from Oslo Harbor in an Anoxic Deep-Water Basin

The remediation of Oslo Harbor requires that approximately 780,000 m³ of contaminated sediments be dredged and subsequently disposed. Several disposal methods have been assessed; however, due to elevated concentrations of both organic contaminants and heavy metals as well as the high content of fines, sediment treatment to reduce the disposal volume has been ruled out. Capped disposal in an anoxic deep-water basin has been selected due to its potential for safe and economical long-term storage of dredged contaminated sediments. The disposal of dredged contaminated sediments under water requires that great care is taken to avoid both short term and long term release of contaminants. This paper presents the conceptual model utilized to investigate the environmental risk associated with possible contaminant transport mechanisms during and after disposal in an anoxic deep-water basin. Experimental results from the specific site assessment for Oslo Harbor are presented as well.