Remediation of Contaminated Sediments Recommendations and viewpoints from the Norwegian Council on Contaminated Sediments

June 2006

Illustration on front page: Todd S. Bridges, USACE, US

Foreword The Norwegian Council on Contaminated Sediments has prepared a synthesis report reflecting the conclusions and recommendations based upon the Council’s activities from 1 October 2003 to 30 June 2006. The Council has consisted of the following persons: Georg Becher, Norwegian Institute of Public Health (2003-2005) Anders Beitnes, Foundation for Scientific and Industrial Research at the Norwegian Institute of Technology (SINTEF) Marius Dalen, Bellona Foundation Trine Eggen, Norwegian Institute of Agricultural and Environmental Research Einar Eik, Norwegian Coastal Administration c/o Department of Coastal Affairs Tore Frogner, Veidekke Gjenvinning AS Randi Skirstad Grini, Norwegian Geotechnical Institute Trond Guldbrandsen, Norsk Hydro ASA Audun Hauge, Norwegian Geotechnical Institute Guri Kirkhaug, Secora AS Jarle Klungsøyr, Institute of Marine Research Jens Laugesen, Det Norske Veritas Henrik Linders, SWECO VIAK AS (2003-2006) Ståle Navrud, Norwegian University of Life Sciences (UMB) Are Sletta, Norwegian Food Safety Authority Kjell Petter Solhaug, NCC Construction AS (2003-2005) Steinar Storelv, Norwegian Association of Local and Regional Authorities Berit Sørset, Federation of Norwegian Industries Terje Thorsnes, Geological Survey of Norway Torn Erik Økland, Norwegian Society for the Conservation of Nature Trygve Østmo, Federation of Norwegian Industries Tore Lundestad, Association of Norwegian Harbours (Vice-Chairman) Jens Skei, Norwegian Institute for Water Research (Chairman) Secretariat: Per Antonsen, Norwegian Pollution Control Authority (2003-2004) Øyvind Schreiner, Norwegian Pollution Control Authority (2005-2006) Arne Anders Sandnes, Norwegian Pollution Control Authority (2005-2006) Observers on the Council: Marit Kjeldby, Norwegian Pollution Control Authority Kari Kjønigsen, Norwegian Pollution Control Authority Oslo, June 2006

Jens Skei Chairman of the Norwegian Council on Contaminated Sediments 3

1. Background White Paper (Report to the Storting) No. 12, entitled ”Protecting the Riches of the Seas”, was published in 2002. It devoted a great deal of attention to contaminated sediments in coastal and fjord areas. The White Paper outlined the challenges involved in the clean-up work, the resources needed and the processes to be employed. The overall target for the sediment clean-up was defined in the White Paper as follows: ”...to bring concentrations of environmentally hazardous substances from discharges in bygone times down to a level which will not have serious biological effects or serious effects on the ecosystem.” The government also proposed the creation of ”a special council to compile data on this area and provide advice on conducting investigations and implementing measures.”This resulted in the Norwegian Council on Contaminated Sediments being appointed by the Norwegian Ministry of the Environment on 1 October 2003, with a mandate until 30 June 2006. The Council had members from different fields such as research, administration, consulting enterprises, contractors, as well as food product and environmental organisations. The Council’s mandate was to identify gaps in knowledge within the field, to contribute to the requisite knowledge being obtained and put into practice, to contribute ideas and proposals for solutions, to make recommendations to the Norwegian Pollution Control Authority (SFT) as well as other decision-makers and to contribute to embedding the results and strategies in the research community, in organisations and in society in general. During its operational lifespan, special emphasis was given to themes that reflect the mandate received by the Council, as well as to tackling any current and highly relevant ”sediment cases” where its advice was in demand.

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2. The Council’s view on the main long-term challenges ■ Sediment remediation involves extremely complex sets of problems that require a solid basis for decision-making. ■ There is insufficient knowledge about the quantifiable effects of contaminated sediments and the precise environmental benefits that can be achieved through different remediation options. Consequently, it is important to compile national/international experiences from specific remediation measures, pilot projects, research and the work done by the Council, as well as to continue to build on this in recognition of the great need for additional knowledge. ■ Sediment-related measures are expensive. Thus it is important to make a thorough assessment of whether the environmental benefits are proportionate to the investment. Thorough analysis of the anticipated environmental effect is necessary, and documentation of the effects of measures places substantial demands on the monitoring programmes. ■ The precise division of responsibility with respect to the financing of sediment-related measures must be clarified. Before this is in place, it is highly unlikely that there will be much progress in cleaning up the sediments. Under the White Paper, the state will have to carry out and finance the requisite clean-up measures in cases where it is not possible to identify any party economically responsible for such a clean-up. In many cases, it can turn out to be difficult to identify the parties responsible for the pollution. ■ The most important conclusions that emerged from the work of the Council, and which can serve as guidelines in relation to future sediment measures, can be summarised as follows: • Use suitable ”tools” prior to the decision-making process. They should analyse the possibility for achieving the goal, the uncertainty involved in doing this and the risk associated with remediation. Cost-benefit and environmental assessments require appropriate tools. Ideally, the level of risk and uncertainty should be quantified and incorporated into a decision-making model. The final decision on a measure must be based on expert knowledge of its effects and risks. • Establish clear and understandable environmental targets during the initial phase of the planning of a measure. The environmental targets must be realistic and testable. • In projects based upon voluntary co-operation and cost-sharing, the planning process must be transparent. Everyone who has a legitimate need to access the details shall be given the possibility. At the same time they should have the opportunity to influence the process and feel like part-owners.

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• Make sure that local user interests are well-surveyed in order to secure the measure with the general public, the business community and other organisations. Identify groupings that can ensure progress and that have a clear interest in the measure being carried out. Give them responsibility. • Make a careful assessment of alternative remediation technology. Take local conditions into account (locally adapted measures). In areas with high natural sedimentation rates, and where the environmental trend in the sediment is positive, intervention will often be unnecessary. The development should, however, be monitored. • Ensure that there is good communication between those who will carry out the remediation work (the owner/contractor of the measure) and those responsible for risk assessments and environmental monitoring. •Ensure that the measures are integrated and long-term and done in the correct sequence. Project planning of measures in multiple phases is often necessary in order to be able to predict the risk of the measure and in order to prepare predictable cost estimates. • Ensure that the environmental conditions and the degree of source control are thoroughly documented prior to implementation of the measure. This is a prerequisite for being able to carry out meaningful monitoring and documentation of the environmental benefits. • Monitoring and documentation of environmental benefits must be integrated into the plan for the measure and its costs. The monitoring programme should be part of the environmental impact assessment.

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3. Main tasks of the Council There have been many challenges and a very considerable and varied need for consulting in connection with the work on sediments at SFT and the environmental departments of the County Governors. It has also been necessary to plan the work of the Council in conjunction with the time schedule of the environmental administration. This may in some cases have led to time-related problems in relation to a thorough involvement by the Council. The Council has made the following concerns its primary working tasks: • Knowledge gained from completed projects • Environmental targets for clean-ups • The decision-making process and decision-making tools (risk guide, predictive tools for effects of measures, methods for cost-benefit assessments) • IIntervention against contaminated sediments (remediation techniques) • Gaps in knowledge Documents prepared in connection with cases that the Council has addressed are available on the Council’s homepage (www.sft.no).

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4. Experiences, recommendations and viewpoints The Council’s recommendations and viewpoints on the major challenges regarding future work with sediments are described below:

4.1 Knowledge gained from completed projects Only two full-scale sediment remediation projects have been carried out up to now in Norway. These are the in situ capping of Eitrheimsvågen in Odda (carried out in 1992 at a cost of approximately NOK 40 million) and the dredging and disposal at a near shore confined disposal site at Haakonsvern (performed in 2003 at a cost of approximately NOK 185 million). The experiences from these projects are that the capping of Eitrheimsvågen was technically successful, but a lack of source controls has led to recontamination of the cap layer. The dredging at Haakonsvern with the establishment of near shore confined disposal site was also evaluated to be a success technically. However, it has taken longer than expected to document the benefits in terms of reduced levels of PCB in fish and shellfish. In the spring of 2006, a major remediation operation was started in Oslo harbour. It involves the dredging of 650,000 m3 of contaminated harbour sediment that will be deposited in a deepwater disposal site and capped, and the capping of approximately 1 million m2 of contaminated seabed outside the dredging area. In addition, some smaller measures have been carried out in connection with the pilot projects. Environmental dredging has also been performed in some individual harbours where there has been a need to increase the depth of the harbour (maintenance dredging). This means that we are still in an early phase of the sediment remediation work in Norway. The pilot projects that were performed in Tromsø, Trondheim, Sandefjord, Kristiansand and Horten during the period 2001/2002 were motivated by a desire to learn how clean-ups of contaminated sediments could best be organised and carried out, as well as to gain more practical experience. The pilot projects have yielded much new knowledge and important experiences. The pilot projects have also contributed to increasing our understanding of contaminated sediments as an environmental problem. The Council is of the opinion that it is important that the work with the pilot projects is followed up and monitored thoroughly, and that this knowledge is exploited in new projects involving such measures. About NOK 100 million has been spent on the pilot projects, of which SFT has contributed NOK 60 million. The focus of the pilot projects has varied, in order to yield as broad a range of knowledge as possible: Tromsø:

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Biological effect measurements and risk assessment connected with contaminated sediments

Trondheim:

Remediation techniques, in particular in association with the stabilisation of sediments in land disposal sites (mixing in of cement and fly ash)

Sandefjord:

Testing of different dredging techniques as well as deposition in shallow water disposal sites and use of geotextile bags

Kristiansand: Effects of capping contaminated sediment with sand Horten:

Release and toxicity of TBT (tri-n-butyl) with respect to land disposal of contaminated sediments.

In the opinion of the Council, the most important lessons learned from the pilot projects can be summarised as follows: ■ Sediment remediation will seldom be 100% solutions. Residual contamination following dredging is a well recognized problem. How clean a sediment is after remediation is related to the scope of the measure. The scope is largely determined by the costs as compared to the benefits of the measure. ■ The effects of clean-up measures are complicated to document due to the influences of many different factors in the sea. It is important to monitor the site both before and after the clean-up, and to realize that it can take some time before one can expect a target to be fully achieved (see the chapter on environmental targets). ■ Planning, project management and organisation of measures are central elements in obtaining a successful result. This also involves a professional and open information strategy in order to avoid unfounded fears and misunderstandings. ■ As a part of the decision-making basis for a remediation project, an assessment must be performed of the risk associated with the bioavailability of the sediment bound contaminants and their toxicity. Increased knowledge of environmental effects and experience with ecotoxicological studies is desirable. In particular, there is a great need for increased knowledge about the environmental risks associated with TBT, which are still surrounded by considerable uncertainty. TBT is extremely widespread in harbour sediments and the substance is often the crucial parameter in assessing the need for remedial action. ■ The pilot projects have shown that it is important that sediment remediation should not be over-focused on hot spot areas (often small areas with a high level of contamination in the sediments). The clean-up within a small area that is surrounded by contaminated sediments will be of little value unless the area can be designated with certainty as a source area (large danger of dispersal). The interrelationship between a local remediation site and the environmental situation in the surrounding area must be understood and clarified so that realistic assessments can be made when evaluating the measure with respect to the environmental targets for the whole area. ■ The pilot projects have also shown that it is possible to carry out sediment remediation at a somewhat lower cost than previously expected. Experience with capping of contaminated sediments (low-cost measure) shows that capping functions well with respect to the placement of the cap layer. 9

Approximately NOK 350 million has been used on sediment measures in Norway up to the present, including the pilot projects.

4.2 Environmental targets and benefits In order to be able to justify large investments in sediment measures, the Council is of the opinion that it is essential that one knows precisely which environmental targets should be attained. Precise, testable and realistic targets are a challenge, and are significantly more complicated than visionary goals. The environmental targets should be site specific and customised in relation to local user interests. They ought to function both as a long-term milestone as well as success criteria in the short run. Consequently, it is feasible to divide the environmental targets into two categories: ■ Long-term administrative targets that apply, for example, to an entire fjord system. ■ Testable, operative objectives for a measure that apply to the site of the measure itself. The operative objectives for a measure must contribute to the fulfilment of the overall administrative target. The overall national target of sediment remediation, which appears in the White Paper is to ”bring concentrations of environmentally hazardous substances from discharges in bygone times down to a level which will not have serious biological effects or serious effects on the ecosystem”. This national target must be a guideline when the long-term administrative targets are set in connection with county remediation plans. It is obvious that the long-term administrative targets cannot be attained solely on the basis of sediment-related measures. However, such measures do contribute to the targets being obtained in the long run. The targets must be realistic and the costs must be in proportion to the benefits gained (the environmental benefits). The long-term perspective requires the prioritisation of measures that are carried out with respect to a given timetable. The sequence of the measures will often be decisive for whether the targets are attained and when. The Council suggests that the long-term targets must be overarching with respect to sectors and be of a holistic nature. The operative objectives of a measure will as a rule be set by the owner of the measure and approved by the pollution control authorities. Every measure must serve the longterm administrative target, and through a clear and testable goal formulation be rendered visible in this context. An example of an operative objective for a measure could be linked to SFT’s sediment quality criteria, which are easily testable. The level of ambition will largely be dependent on the scope of the environmental problem: ■ The lowest level of ambition is natural recovery (no action). The area must then have been assessed and it must have been documented that the trend in sediment quality is positive and that its present condition does not give substantial pollution-related drawbacks. 10

■ The next level of ambition is to prevent contaminants from being dispersed from contaminated areas to less contaminated areas, and to make sure that the level of contamination in the sediments is not an obstacle to the use of the area by the general public for recreation and tourism. ■ A somewhat higher level of ambition is associated with the utilisation of an area for recreational fishing and commercial fishing. Here, the requirement would be that contaminants in seafood do not exceed the Norwegian Food Safety Authority’s recommendations for consumption limits. It should be pointed out that there is no direct linkage between levels in seabed sediments and seafood, even though it often turns out that areas with consumption advice also have contaminated sediments. ■ The most comprehensive level of ambition is to ensure that the quality of the seabed sediments will not have any negative effects on the ecological status of the area. There are interpretation problems here as well, because it is difficult to find a direct connection between the degree of contamination in the sediments and, for example, the diversity of species in the fauna on the seabed. The more ambitious the target that is set in connection with sediment-related measures, the higher the costs that must be expected for the measures. An important factor in reaching the target is to have source control (new and old sources) of the additional contamination at the site to be remediated. The general perception is that sediment-related measures should not be carried out before it has been documented that no land-based sources exist that contribute to new pollution in an area that is to be cleaned up. In terms of experience, it turns out to be extremely difficult to be able to quantify sources of contaminants, because such sources are now mostly diffuse sources (run-off from contaminated soil, disposal sites, precipitation, ocean currents, etc.). The Council is of the opinion that as long as it can be rendered

Fig. 1. The picture shows substantial biological activity on the surface of fjord sediments. (Photo: Mats Walday, Norwegian Institute for Water Research)

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probable that the sediment is a significant source in relation to other sources, then sediment-related measures can be justified if, after an assessment of the recipient, it contributes to the attainment of environmental targets. If the requirement is that one must be able to document that there is 100% source control, sediment-related measures would hardly ever be carried out. It is a prerequisite that a sediment-related measure must have a long-term effect, but a certain amount of maintenance for the measure must be reckoned on as being expected in some cases.

4.3 Decision-making process and decision-making tools The decision-making process. Decisions about expensive remediation measures must necessarily be thorough and comprehensive. The Council discussed precisely which elements must be put into place and improved in order to ensure a sufficiently good decision-making basis and a good process without unnecessary complications. Assessments of environmental effects and the need for measures associated with contaminated sediments are in technical terms quite complicated. At the same time, the measures require approval at several points in the administrative chain. It is important that the different administrative bodies involved receive an adequate decision-making basis early in the process. The following areas stand out as having a particularly large potential for improvement: ■ The need for suitable ”tools” for quantifying the uncertainty in goal attainment and the risk of failure. A tool is required in addition to the risk guidelines for contaminated sediments. ■ Making the decision-making process transparent so that everyone with a legitimate need to access the details will be given the possibility. At the same time everyone should have the opportunity to influence the process and thereby feel like partowners. Information, communication and co-operation are central elements in the decision-making process. ■ It is the view of the Council that unclear division of responsibility and uncertainty connected with the public financing will be the largest obstacle associated with the implementation of sediment remediation that is otherwise sensible from a costbenefit perspective. In the current situation with a number of unclarified legal questions, the cost sharing model (mixed financing) and a distribution of responsibilities would probably be the best means of ensuring that the process does not come to a halt. If there are no obvious responsible parties, the state should be the driving force for the measure. The authorities need to decide on a number of matters of principle concerning how sediment-related measures will be financed in order to avoid any uncertainty on this subject. ■ The remediation projects must be planned and managed in the same manner as other complicated and financially demanding projects. It is important that no element be overlooked in the planning process and that existing project management competence for large projects should be utilised. The Council is of the opinion that it is also important to avoid overinvestment or malinvestment in remediation projects, and that sufficient time is set aside for improving the decision-making basis for the measure. In addition, one should not be pressured by opinions alleging that the process is going too slowly. ■ The Council is of the opinion that the decision-making process can become difficult if it cannot be demonstrated that the environmental benefit can be quantified and documented. 12

The preparation of regulation plans and requirements concerning environmental impact assessments are often time-consuming. The work with regulations can be particularly complicated because remediation measures can involve large seabed areas that cross the boundaries of municipalities. The regard for marine archaeological conditions in the sediment can also play a significant role in the decision-making process. In a number of harbours there are objects of archaeological interest buried in the sediments. This can affect the choice of measures and the extent of the costs. Decision-making tools. Risk assessment must be included as a decision-making basis for all sediment related measures that are intended to improve the environment. SFT initiated a project to develop risk guidelines that were to serve as a tool for ensuring a better decision-making basis for sediment-related measures. The Council has been an advisor during the execution of the project. It should be pointed out that the risk guidelines must be regarded as a dynamic tool that is revised as needed and in line with newly acquired knowledge and experience from using the guidelines. The Council has therefore recommended that the guidelines be revised during the course of 2007. Provided that land based sources are brought under control, the contamination of the seabed sediments will change over time via physical, chemical and biological processes. The Council thinks it is important to be able to predict effects of remediation and the consequences of not remediating a site. The Council has been oriented about the development of different types of decision-making tools such as SEDFLEX (flexible and integrated tool for ecological and economical decision-making analysis prepared by the Norwegian Institute for Water Research and the University of Stockholm). This is a tool for predicting the natural recovery of sediments over time and the effects of intervening. Furthermore, the Council’s agenda has involved assessing and providing advice on different methods for cost-benefit computations, since it is a prerequisite in ”Protecting the Riches of the Seas” that all sediment-related measures must be profitable in socioeconomic terms. The Council has discussed different methods and the use of studies looking at the willingness to pay. No specific advice has been given on the choice of methodology. County remediation plans Specific advice on the county remediation plans has been given priority in order to ensure that this advice is in step with the time schedule of the authorities for the remediation plans. Phase 1 and 2 for the county remediation plans have now been carried out. The challenge in the national planning work for sediment clean-up now is how these plans are to be pursued, how remediation should be prioritised and how the remediation will be financed. County remediation plans were prepared for 17 fjord areas from Hammerfest to Oslo Fjord. In the preparation of the plans, the newly developed ”Guidelines for risk assessment of contaminated sediments” have been used as a basis. They provide a common point of departure for planned processes, and they are primarily based upon the same tools for risk assessment, however the decision-making basis for the individual proposed measures can be on different levels depending upon local conditions and different data inputs. In an environmental context it is more relevant to focus on environmental effects, risks and risk contributions rather than on the concentration of contaminants in the sediments. The risk assessment must be viewed in conjunction with the level of ambition for environmental quality that is desired in an area.

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4.4 Sediment remediation options There are three main sediment remediation alternatives: ■ Dredging (a number of different dredging technologies are available) and deposition (land deposition, near shore confined disposal sites, shallow water disposal, deep water disposal). ■ Capping with uncontaminated sediments (thin layer placement or conventional thick layers) or the use of different residual materials from industrial enterprises. A combination where capping is used in addition to geotextiles (membranes). ■ Treatment and cleaning (dewatering, stabilisation, thermal, chemical or biological treatment).

Fig. 2. Example of grab dredging. (Photo: SFT)

Fig. 3. The picture shows the significance of using a silt curtain (”boom”) around the dredger. (Photo: Jon Egil Vinje, Office of the County Governor for Vest Agder)

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Fig. 4. The placement of a geotextile (membrane) as an underlay for a gravel cap outside a wharf area in Kristiansand Fjord. (Photo: Harald Eik, Falconbridge nikkelverk as).

There is little purpose in developing a universal remediation technique for general use. However, it is important to have specific functional requirements. Often, it will be appropriate to combine a number of different methodologies for remediation within one and the same area (for example dredging and capping).The Council is of the opinion that it is vital to select site specific solutions that take into account the type of contaminant and extent of contamination, the size of the area and volumes involved, what alternatives of local measures exist, whether there are possibilities for synergistic effects with other on-going projects, for example, for access to inexpensive cap material, etc. It is essential that the choice of solution will achieve an optimum environmental benefit in relation to the cost of a measure. In addition, it is important to assess environmental risk in connection with the remediation itself, and the likelihood of achieving established environmental targets. Dredging is a major physical intervention with the potential for dispersing contaminated sediments. Selection of dredging technology requires careful assessment. The choice of dredging method will depend upon the final disposal chosen for the dredged material. A persistent problem associated with dredging is residual contamination. Since dredging must be followed by disposal or cleaning (accelerating costs) the measure at present is primarily based on the need to maintain sufficient navigation depth in passages and harbours. All types of disposal involve a potential risk for leakage to the surroundings. In addition, areas often have to be requisitioned. In many cases this leads to user conflicts. However, it is also possible to create new areas through good disposal arrangements. Again, the local preconditions must be given especial weight in the selection of a disposal site.

Fig. 5. Example of cleaning equipment used for the cleaning of sediments from Trondheim Harbour. (Photo: SFT)

Capping consists of covering the contaminated sediments on the seabed so that any dispersal of contaminated sediments ceases or is reduced, and the animals living in the sediment are not exposed to the contaminated sediment below. The choice of cap material and the cap design will often play a decisive role as regards the effect that is achieved. Figure 4 shows the placement of a membrane underneath a cap of gravel outside a wharf area in Kristiansand Fjord. 15

Treatment can involve physical and chemical stabilisation of the sediments in a near shore confined disposal site or different forms of cleaning/separation of contaminated and clean particles. Technology and knowledge are available in Norway concerning most of the methodologies for remediation, but there is a need for further development of both the technology and the associated competence. Increased predictability in the market is, however, necessary if one is to secure sufficient investment in the development of further technology. An important condition for most of the treatment methods is that the end product after the treatment can be of beneficial use and does not create new environmental problems.

4.5 The need for knowledge Sediment-related measures must be based upon knowledge. Hence, it is important to identify critical knowledge for carrying out measures and to ensure that this knowledge exists in due time in relation to the remediation plans. When sediment clean-up is decided upon, it is on the basis of documented environmental risk. It is a prerequisite that there is sufficient knowledge to quantify risks and include measures that are properly dimensioned in relation to the problem, and that the desired environmental benefit can be documented. In its work the Council has recognised that it does not have sufficient expertise to cover all parts of the knowledge range associated with contaminated sediments, processes, effects and remediation techniques. Consequently, the Council has concentrated on some obvious gaps in knowledge that are critical in relation to the execution of the existing remediation plans. Ecosystem-related problem complexes. The seabed sediments are an important habitat for fauna. Contamination of this habitat can have an influence on the quantity of fauna (the biomass) and the diversity of species of the seabed fauna and thus affect the ecosystem and the food chains. Knowledge of the effect of contamination on the seabed fauna and the effects of different measures (dredging and capping) on fauna is fragmentary. Knowledge of the association between levels of contaminants in seabed sediments and fish and the extent to which contaminated sediments can be connected directly to consumption advice about fish and shellfish, continues to be unsatisfactory. Process-oriented problem complexes. There has been little focus on resuspension of contaminated sediments and transport of sediments in association with sediment measures and pollution. Likewise for the creation of nepheloid layers (layer of water near the seabed with a high content of fluffy particles). Deep water exchange in fjords and harbours is a physical process that affects the resuspension of sediments, particle transport and sedimentation, as well as the oxygen conditions near the bottom. All these physical processes are important, but the level of knowledge associated with the effects on contaminated sediments is low. The reworking of sediments by animals (bioturbation) is an important process that affects the mixture of sediments in the upper layers and which affects the fluxes of contaminants from the sediments. Knowledge concerning the mixing depth and the mixing effect are fundamental problem complexes in the assessment of the sediments as secondary pollution sources (Fig. 6.). 16

Problems related to remediation A pervasive problem associated with the dredging of contaminated sediments is residual contamination in the dredging area. This has in part been interpreted as a result of the dredging not being 100% effective with respect to the removal of fine grained, particulate matter and in part as a consequence of the addition of small particles from surrounding sediments that are also contaminated. The most serious gaps in our knowledge concern the actual environmental effect of a thin (1-2 cm) contaminated top layer with high water content in the dredging area after the dredging has been carried out and precisely which preventive measures ought to be performed. There is still lack of knowledge concerning the environmental benefit associated with capping contaminated sediments in both the short and the long run, the establishment of new seabed fauna and the recovery of a well-functioning ecosystem following the capping process. Since capping is becoming more and more common both nationally and internationally, it is important to be able to document quantitatively precisely which environmental benefit will be obtained in relation to the design of the cap (thickness), type of cap material, etc. In addition to traditional capping (>30 cm cap layer), the application of thin-layer placement (5-15 cm cap thickness) is now considered. However, there is a lack of documentation available concerning the long term environmental effects. There is a need for considerable knowledge of environmental technology to design dredging equipment adapted to the conditions in Norwegian fjords and harbours. It often involves highly organic and fine-grained sediments that represent a challenge in relation to both dredging and disposal. Dredging in areas where there are archaeological interests requires the use of dredging equipment that dredges in a careful manner. In some cases a conflict of interest may occur between the environmental and marine archaeological concerns. Mechanical, chemical, biological and thermal treatment of contaminated sediments also requires new R&D. In Norway, this competence exists spread out across a number

Fig. 6. The picture shows photographs of structures in the sediment. The yellow-brown layer on the top (0-1 cm) illustrates good oxygen conditions in the sediments due to intense mixing caused by bioturbation. The sediment has been analysed for contaminants. The level of PCB is strongly reduced in the surface due to reduced discharges in recent years. (Photo: Hans Nilsson, Norwegian Institute for Water Research)

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of smaller consulting companies. It is important to be able to develop new concepts that first and foremost can be used on small volumes of highly contaminated sediments. Special knowledge requirements A high level of TBT in sediments, particularly in harbours, creates large problems in the context of measures because there is a large amount of uncertainty surrounding the environmental risk associated with sediment-bound TBT. Recommendation of the Council on the acquisition of knowledge The Council recommends that a research programme is established that will focus on the gaps in knowledge that have become apparent in this report. Reference is also made to SFT’s report entitled ”Contaminants in Norwegian fjords (1774/2000)” which summarises the gaps in our knowledge and proposes a 5-year research programme with an annual budget of NOK 10-20 million. The alternative to creating a separate research programme is to carry out the research within the existing “Oceans and coastal areas Programme”, but with funds allocated for this research area. At present no substantial research is being conducted in the area of sediments and remediation, either in Norway or in Sweden. The decisions that are being made must therefore be on the basis of the modest level of the existing knowledge. In the opinion of the Council this gives rise to concern.

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5. Future plans With respect to the White Paper entitled ‘Protecting the Riches of the Seas”, a national plan has been initiated for the clean-up of contaminated sediments in harbours and fjords.The national plan will take into account the remediation plans of the individual counties where the prioritisation of the areas for remediation is to be done.This prioritisation will take place in 2006.This implies that as early as 2007 it is expected that some of the measures will be carried out. An exception is the remediation plan for Oslo harbour which started early in 2006, and which is expected to be completed during the course of 2008.This plan was expedited in order to follow the time schedule for other types of measures and activities in the harbour. It is expected that the integrated remediation plan for Oslo harbour will yield a great deal of experience that can be used in connection with future remediation projects. The time schedule for a national clean-up of contaminated sediments should be harmonized to our current knowledge with respect to the environmental effects of remediation. Therefore, it would not be appropriate to start many large remediation projects simultaneously, but rather await the results from those that, on the basis of a thorough decision-making process, have been initiated.This will allow us to evaluate whether it is a proper use of funds, whether the correct methods were used, etc. In the Council’s view a major challenge in the planning work for sediment remediation will be to formulate environmental targets that are testable and can be documented, and to predict the effects of possible measures.This requires further development in the understanding of the effects of remediation as well as of the development of decision-support tools. It will also require that some measures are carried out where the relationship between the costs of the remediation and the environmental benefits is clearly demonstrated. In this context it is important that the measures carried out are monitored carefully and over a long time period.There is a strong need to identify the effect of the completed measures.Thorough documentation and monitoring of the effects of remediation is vital to the development of our knowledge. In cases where long-term monitoring programmes would cause a general increase in the level of knowledge, it should be considered whether the monitoring programmes should in fact be financed by the government. Food safety and uncontaminated seafood is an important subject.The issues of sources and effects should again be assessed and especially the significance of the contamination of such large seabed areas along the Norwegian coast.There will be a need to clarify precisely what role the sediments play as a secondary source of contamination in seafood, in light of the sediments’ capacity to store large amounts of contaminants. Even if only a small part of this storage can be mobilised and influence the ecosystem, it can be sufficient to create insecurity. Special attention has been given to ”new” and partially unknown contaminants. In connection with their occurrence in sediments, the question about the need for sediment clean-up will receive a new dimension. Currently, there is little knowledge about how these substances (for example brominated flame retardants) behave in the sediments with respect to mobility and bioavailability.This will also be a challenge. It is also important to communicate a clear and realistic picture of the risks of sediment remediation to the general public.Their perception of the risk varies, as it is based partly upon technical facts and partly on emotions and irrational attitudes. Here, the Council is of the opinion that there is a great need for communication and information concerning the scale of risks, as well as the distinction between short-term risk in connection with a project phase and long-term risk. In this connection it is also important to present the risks from non-intervention (natural recovery).

The White Paper (Report to the Storting) No. 12, entitled ”Protecting the Riches of the Seas”, released in 2002, devoted a great deal of attention to contaminated sediments in coastal and fjord areas. The Norwegian Council on Contaminated Sediments was appointed by the Norwegian Ministry of the Environment on 1 October 2003, with a mandate until 30 June 2006. The Council had members from different fields such as research, administration, consulting enterprises, contractors, as well as food product and environmental organisations. The Council’s mandate has been to identify gaps in knowledge within the field of sediment remediation, to contribute to the requisite knowledge being obtained and put into practice, to contribute ideas and proposals for solutions, to make recommendations to the Norwegian Pollution Control Authority (SFT) as well as other decision-makers and to contribute to securing the results and strategies in

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