Location: Ormefjorden and Eidangerfjorden, Telemark, Norway
Year: 2009
Project Type(s): Sediment remediation
Project Description: This project was conducted to examine the effectiveness and environmental impacts of thin layer capping in Ormefjorden and Eidangerfjorden. In 2009, thin layer capping with limestone, marine clay, and marine clay amended with 2-3% activated carbon (AC) was applied at both sites. Box-core samples were collected from the test fields and reference locations to evaluate biogeochemical fluxes and dioxin bioavailability in the overlying water and uptake in two sediment-dwelling organisms. In all box core samples collected in 2009 and in boxes from clay and AC treatments transferred in 2010, bioaccumulation and leakage of dioxins was reported to be 67% – 91% lower than at the uncapped reference fields. At the two fields treated with limestone gravel and dredged clay without activated carbon, that cap efficiencies decreased to less than 46%. It was concluded that a cap thicknesses of <5 cm applied in the field experiments, was adequate to obtain satisfactory cap performance with respect to biogeochemical processes.
