Demonstrating In Situ Remedies for Contaminated Sediment in Norway: Applicability to Sandefjord Harbor and Beyond

摘要

Background/Objectives. Marine sediments in many coastal waters of Norway are impactedby various organic and metallic contaminants, often present as mixed contamination.At many sites, one or more of the sediment contaminants pose unacceptable risksto human health and/or the environment, risks for which some type of active remedy isrequired.Sandefjord Harbor, located in southern Norway, is one such impacted marine site.Extensive investigations across the harbor, which is approx. 1,600,000 m2 in total sizeand representative of many other impacted Norwegian harbors in various ways, indicateunacceptably high levels of sediment contamination by PCBs, PAHs, TBT and/or heavymetals in a number of areas. An action plan was recently developed for remediating sedimentcontamination and related risks across the harbor, a plan which will ultimatelyincorporate the use of one or more in situ contaminated sediment remedies in somefashion.Approach/Activities. In 2009, the environmental authorities approved establishment ofan approximately 34,000 m2 portion of the inner harbor’s impacted seabed, referred to asthe Biologge Field (Field). The Field displays a broad range of sediment characteristicsand site conditions (contaminant types and levels; bathymetry; current flow; influence ofboat and ship traffic; benthic habitat; etc.), conditions that are found elsewhere throughoutthe harbor. As such, selected portions of the Field have been (and will continue to be)used to showcase the effectiveness of and costs for implementing an equally broad rangeof in situ sediment remedies at pilot scale.In situ remedial approaches receiving the greatest attention in pilot-scale demonstrationsat the Field include isolation and thin-layer capping using conventional materials aswell as innovative materials and engineered products. The pilot studies have and willcontinue to focus on key elements related to demonstrating controlled material placementas well as evaluating short- and long-term remedy effectiveness (reductions in contaminantbioavailability, benthic recolonization, erosion protection, etc.).Results/Lessons Learned. Presented in this paper are results of in situ pilot-scale remedialstudies already completed at the Field as well as results available from ongoingstudies.It is anticipated that the technical and cost information gained from the remedialdemonstrations at the Field will not only have direct and practical scale-up applicabilitythroughout Sandefjord Harbor when it comes time to design and implement a harborwidesediment management plan, but will also have relevance and applicability to remediatingcontaminated sediments at other impacted harbor sites in Norway and beyond.