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REMEDIAL TECHNOLOGIES USED AT INTERNATIONAL JOINT COMMISSION AREAS OF CONCERN Ian Orchard Environment Canada ABSTRACT This paper discusses the need for various technological options for the remediation of contaminated sediments in 39 of 42 nearshore areas in the Great Lakes basin. These areas have been designated as "areas of concern" by the Interna- tional Joint Commission, established by the United States and Canada for the restoration and enhancement of water quality in the Great Lakes. There are three broad cate- gories of options for dealing with contaminated sediments leave them alone, remediate in situ, or dredge them. No technologies are presently available within the Great Lakes basin that can be used to remediate; the only real action alternative based on available technology is to dredge up contaminated sediments. Although considerable experience and technology is available to dredge large volumes of sediment, the disposal ~ ~ ~ ~ ~ . Presently, only shore- oase~, confined d' sposal facilities and upland landfill dis- posal of the entire volume of dredge material appear to be possible for large-scale operations. The lack of available space to build confined facilities and to locate landfills has resulted in an urgent need for the development of alter- native techniques. Some concentration (separation), inactivation, and des- truction techniques are operational elsewhere in the world but they remain largely at the laboratory (bench) scale or pilot-scale stages in the Great Lakes. Consequently, the focus of this paper will be upon the work of the sediment subcommittee of the International Joint Commission in the identification of appropriate remedial technologies for con- 0t this material remains a problem will be upon the work of laminated sediment BACKGROUND The government of Canada and the United States signed the Boundary Waters Treaty on January 11, 1909, which outlined the rights of each country in the use of Great Lakes waters. In the 1960s, growing public concern about the quality of water in the lower Great Lakes resulted in 280

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281 studies by both governments aimed at assessing the nature and extent of water quality degradation. As a consequence of these studies, Canada and the United States entered into agreements in 1972 and 1978 on Great Lakes water quality aimed at restoration and enhancement of water quality. An International Joint Commission (UC) established under the Boun- dary Waters Treaty functions as the administrative mechanism for ensur- ing compliance between the parties under the agreement. In 1987 a pro- tocol amending the 1978 agreement was signed between the governments. This protocol placed a greater emphasis on the governments to undertake specific initiatives so as to address the continuing contamination of the Great Lakes. The IJC has assumed a more evaluative role in ensur- ing that the parties meet the terms of the agreement. The U.S. Environ- mental Protection Agency (EPA) is the main agency responsible for deli- very of U.S. obligations under the agreement and Environment Canada (DOE) is the main Canadian agency. The development of remedial options for contaminated sediment dates back to the dredging subcommittee of the IJC, which was created under the Great Lakes Water Quality Agreement of 1978. At that time the com- mittee's objectives were to develop guidelines and criteria for dredg- ing activities, maintain a register of dredging projects, exchange information on technology and research, and identify criteria for the classification of polluted sediments in areas that were continually dredged. In 1986, the sediment subcommittee was created when it became clear that one of the key elements in the development of remedial action plans for areas of concern was the need to refine existing assessment techniques for polluted sediment as well as identify implementable reme- dial options for polluted sediment. Two work groups were created under the sediment subcommi ttee . The remedial options work group produced a draft report in November 1987. The report is currently being subjected to scientific and technical review. Its objectives report are to 1. review existing technologies for the remediation of ecosystem related impacts due to sediment contaminants; 2. evaluate the effectiveness and feasibility of existing technol- og~es; 3. develop a system for evaluating the most applicable technology to be used for remediating identified ecosystem impacts due to sediment contamination in the nearshore areas of the Great Lakes basin; a. identify research needs to further test existing technologies or establish new approaches to mitigate sediment contaminant problems; . establish in conjunction with the assessment work group and other committees, work groups or task forces, as necessary, a monitoring program to assess any adverse effects on the eco- system that may result from moving or otherwise isolating existing contaminated sediments from their present location.

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282 REMEDIAL OPTIONS The remedial options work group is evaluating remedial options for polluted sediment using the following criteria: 1. Description of Options Stages associated with the implementation of the option (out- line of the procedures involved) Is it currently used by jurisdictionts)? Has it been field validated? Specific case studies associated with the option (refer to title or give short summary of findings) Feasibility Engineering/design feasibility Cost (engineering, not socioeconomic costs) Time frame, from conceptualization through implementation. Limitations--geographic, engineering, scientific, technical, etc.? Can the option be implemented to deal with large-scale con- tamination (harborwide or can it deal with a small area size limitation)? Does this option deal with different degrees or ranges of contamination? 3. Environmental/Regulatory Criteria What guidelines/criteria exist relative to the implementation of this option? What assessment criteria are available during implementation and for follow-up (how clean is clean)? Does any need exist to develop assessment criteria to address this option's relative success? i. Long-Term vs. Short-Term Management Is this a quick-fix option that can be implemented in the short-term to deal with a hot spot? Is this a one-shot remedy that could preclude the use of other options in the future? Does this option require long-term management (is its imple- mentation incremental over a period of time)? The options currently being evaluated are open-water disposal, cap- ping in place, confined disposal, lake filling, agricultural land spreading, strip mine reclamation, decontamination treatment, and sol- idification. The options can be classified into the following cate- gories based on available data and need for additional testing and field validation: remedial options--commonly used techniques, remedial options--requiring some testing and assessment, remedial options--proposed and tested on a limited scale, and remedial options--some limitation and requiring more testing.

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283 A suggested guide for readers to follow has also been developed titled "Sediment Remedial Options" (Figure 1~. The guide suggests that one should not consider implementing a remedial option before taking steps to identify the nature and extent of contamination. The causes of contamination can be identified on the basis of available (or col- lected) baseline data. One must be careful not to propose remediation measures which only address symptoms of contamination. It can be seen from the options listed that we still have a lot of work to do. Most of the options identified require validation and testing. A short summary of the four categories of remedial options fol- lows. This is a very cursory identification and categorization of options. For a more detailed discussion of remedial technologies the reader is asked to refer to Technologies for the Remediation of Con- taminated Sediments in the Great Lakes; Report of the Sediment Subcom- mittee and its Remedial Options Work Group to the Water Quality Board of the International Joint Commission, July 1988. Commonly Used Techniques . Dredging and disposal into confined disposal facilities (CDFs) con- structed in the nearshore zone: estimated cost, $4, 00/yd3 (capital cost). Dredging and disposal on agricultural land: filling of low-lying agricultural land (material) must meet all regulatory require- ments). Estimated cost, $0.50/yd3/mi (pumping), $185,000/ ml-pipe (capital cost that can be amortized over the life of several projects), $0.45/yd3/mi (transport). Remedial Options Requiring Some Testing and Assessment Subaqueous confinement: field verification proved effectiveness of this option in preventing the movement of contaminants into water and biota. Capping/covering in-place: suitable for low-energy zones in the lake; contaminants isolated by cap material. Beach nourishment: material must match beach substrate and must not be erodable; documented for material containing a limited quantity of nutrients . Estimated cost, $0. 50/yd3/mi, pump- ing, $185,000/mi (pipe) capital cost. Remedial Options Proposed and Tested on a Limited Scale Depositional zone placement: minimum depth 30 m of 3 x maximum wave height must stay in place. Estimated cost, $0.26/yd3/mi (transportation). Solidification: proven technique for treatment of industrial/ municipal wastes . Estimated cost $4S-75/yd3 of wastes (not including cos t of removal and disposal).

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285 . . Dewatering and separation of sediment into coarse (clean) and fine (contaminated) fraction using centrifuges and hydrocyclones. 1. Further treatment of contaminated fraction by acid leaching/ion exchange (for metals), thermal treatment (for mercury), solvent extraction (for PAHs and oil). 2. Re-use of decontaminated material or landfill disposal This option reduces the volume of highly contaminated sediments but involves a high initial cost for equipment. Decontamination of PCB-contaminated sediments by low-temperature oxidation, chlorine removal, pyrolysis, removing and concentrating, vitrification, use of microorganisms or different chemical treat- ments. In situ containment of contaminated sediments by synthetic mem- branes. In situ chemical treatment and microbiological treatment. Various biological treatments. Some Limitations and Remedial Options Requiring More Testing Hydraulic control navigation relocation: suitable for docking slips/shipping channels; minimizes resuspension of contaminants during shipping activities. Reclamation of strip mines and quarries: proximity of site is the major constraint, groundwater impact must be considered. Estimated cost, $12.50/yd3/for 200 mi transportation. Landfill: considered as a poor use of available expensive landfill space. Estimated cost, $3.00/yd3 (disposal), $0.45/yd3/mi transport to site). Upland fill: Geographic limitations, availability of land, trans- port to the site. Estimated cost, $0.50/yd3/mi (pumping), $185,000/mi (pipe-capital cost). The complexity associated with the selection of suitable remedial options can be demonstrated by Table 1, which summarizes technologies associated with PCB-contaminated sediment. The technologies listed have been excerpted from PCB Sediment Decontamination: Technical/ Economic Assessment of Sel ected Al ternative Treatment, Research Triangle Institute for the U.S. EPA, December 1986. BASELINE MAPPING Before deciding an an appropriate remedial option, one must know the nature and extent of sediment contamination. Baseline mapping and sampling of an area in question is essential. Mapping identifies the geographic extent of sediment accumulation zones versus erosional areas. This information allows for making loading calculations (once the accumulation rate is known). Also, mapping leads to a subjective

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290 understanding of the physical conditions for implementing certain con- trols within an area of concern. Baseline maps provide the basis for modeling resuspension and trans- port in an area and gives additional information on sediment movement into a receiving water body. Equally important as mapping is the formulation of a comprehensive sediment collection program involving streams and suspended sediments, bottom sediments, sediment resuspension and transport, sediment chemis- try, nutrients, organics and sediment toxicity and bioavailability. OBSERVATIONS . A knowledge of the ranges of sediment contamination and hot spots determines the nature and feasibility of each option. Unless the material is clean, a potential for exposure to the eco- system already exists. Therefore, the remedial option chosen must minimize or eliminate that exposure pathway. Most options can involve removal of the potential risk of exposure to another compartment of the environment. There is a need to consider the long-term management of the option chosen (stewardship). When faced with a range of contamination one must investigate the utility of a variety of remedial options having both short-term and long-term feasibility. There is rarely a quick-fix option for areas possessing a range of contamination. CONCLUSIONS AND RESEARCH RECOMMENDATIONS 1. Technologies for remediating contaminated sediments, which are already being employed outside the Great Lakes basin require imme- diate, first-hand evaluation, and where feasible, they should be used in the Great Lakes. 2. These technologies presently at or near pilot-scale operation need to be comparatively tested in one or more large-scale demonstration projects. 3. The more rapid development of technologies currently under investi- gation in the laboratory needs to be supported and encouraged. 4. Further research associated with in situ treatment techniques, in particular, and techniques for inactivation and destruction are necessary.