Subcommittee on Contaminant Plumes

Statement of Task

The Plumes Subcommittee was established to assist the Committee on Environmental Management Technologies (CEMT) in identifying the major technological needs in the Department of Energy's (DOE) Plumes Focus Area. Plumes are an integral component of DOE's Environmental Management (EM) strategy. For the purposes of this report, plumes are defined as chemical and/or radiological contaminants exceeding background concentrations in ground water or soil outside an engineered barrier, including landfills.

This report will review the EM-50 assessment of the relative number, size, and importance of various categories of contaminant plumes at DOE sites, and whether remediation of the various classes of contaminant plumes is possible. In addition, the report will identify the most important technology needs regarding containment and remediation.

Scope of Problem and Needs

Currently, DOE is facing the need for cleanup of contaminant plumes at a dozen sites. However, the magnitude of the problem cannot be fully evaluated without a precise functional definition of a contaminant plume and a characterization of each identified plume in the DOE complex, a characterization that would include contaminant concentrations, volume of the affected area, hydrogeologic considerations, and other relevant information. These plumes contain radionuclides, heavy metals, organic compounds, light nonaqueous phase liquids (LNAPLs), and dense nonaqueous phase liquids (DNAPLs) and are the result of historic open dumping, leaking containers, leaking storage tanks, and other precursor events. The greatest challenge to restoration of these contaminant plumes—and indeed, to many current and future environmental and economic challenges—is finding or developing appropriate technological solutions, many of which may not exist at this time. In addition, the subsurface conditions and the physical and chemical contaminant



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--> Subcommittee on Contaminant Plumes Statement of Task The Plumes Subcommittee was established to assist the Committee on Environmental Management Technologies (CEMT) in identifying the major technological needs in the Department of Energy's (DOE) Plumes Focus Area. Plumes are an integral component of DOE's Environmental Management (EM) strategy. For the purposes of this report, plumes are defined as chemical and/or radiological contaminants exceeding background concentrations in ground water or soil outside an engineered barrier, including landfills. This report will review the EM-50 assessment of the relative number, size, and importance of various categories of contaminant plumes at DOE sites, and whether remediation of the various classes of contaminant plumes is possible. In addition, the report will identify the most important technology needs regarding containment and remediation. Scope of Problem and Needs Currently, DOE is facing the need for cleanup of contaminant plumes at a dozen sites. However, the magnitude of the problem cannot be fully evaluated without a precise functional definition of a contaminant plume and a characterization of each identified plume in the DOE complex, a characterization that would include contaminant concentrations, volume of the affected area, hydrogeologic considerations, and other relevant information. These plumes contain radionuclides, heavy metals, organic compounds, light nonaqueous phase liquids (LNAPLs), and dense nonaqueous phase liquids (DNAPLs) and are the result of historic open dumping, leaking containers, leaking storage tanks, and other precursor events. The greatest challenge to restoration of these contaminant plumes—and indeed, to many current and future environmental and economic challenges—is finding or developing appropriate technological solutions, many of which may not exist at this time. In addition, the subsurface conditions and the physical and chemical contaminant

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--> characteristics may be so complex that complete restoration (or cleanup) may not be possible, and thus only isolation and containment may be feasible (NRC, 1994). In response to this situation, the DOE has formed the Plumes Focus Area to implement effectively its new approach to overcoming major obstacles in the cleanup of DOE sites through environmental research and technology development. According to DOE briefings, the Plumes Focus Area is the closest of the five focus areas to emulating DOE's "new approach" to conduct a research and technology-development program that will address major obstacles in the restoration of their sites. The focus area's current goal is to oversee the environmental research that would result in the development of technologies to (1) contain plumes that pose imminent environmental and health risks, (2) provide significant advances over conventional pump and treat remediation methods, and (3) remediate soils overlying aquifers where contaminants pose a threat to ground water or human health. The current focus-area goal seems to center on near-term tactical issues such as remediation needs driven by compliance agreements and the commercialization potential of technology. Thus, the DOE-EM's strategic goal for the Plumes Focus Area appears to have been structured too narrowly through the focus on short-term needs and commercialization. This structure does not provide for prioritization of problems based on the number and size of sites or the existing risk, nor on the basis of gaps in existing technology. The following general recommendations, developed during two meetings of the Plumes Subcommittee, are intended to help DOE-EM improve technology development in the Plumes Focus Area. Recommendation: The Plumes Focus Area should enlarge its strategic vision to fully embrace the DOE EM's strategic goals for technology development. These broader-based strategic goals are to decrease health and environmental risks decrease cost of environmental restoration enable restoration to proceed, and apply resources to the most urgent problems on a priority basis. These strategic goals are directly applicable to the Contaminant Plumes Focus Area. Part of the challenge in implementing these goals for plume remediation is defining the problem. This problem definition requires an understanding of the relative health and environmental risks of the plumes sizes and numbers of plumes that are prime candidates for remediation costs of remediating the plumes capability of available technology to remediate the plumes, and prioritization to identify the most urgent problems.

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--> Although the focus area has begun a physical, hydrogeological, and chemical inventory of the DOE plumes, it also should obtain a global view of long-term remediation needs by identifying the major risk and cost drivers associated with their remediation. Solving the technological problems presented by those DOE plumes that contribute most to total long-term risk and cost should be a major strategic goal of the Plumes Focus Area. Recommendation: The Plumes Focus Area should (1) identify the major risk and cost drivers associated with remediation of DOE contaminant plumes and (2) develop an integrated systems approach to drive technology development that meets the EM strategic goals of risk reduction, cost efficiency, and environmental restoration. The strategic goal recorded in the Environmental Management Strategic Plan (USDOE, 1994) highlights the optimistic goal of reducing plume characterization expenditures by 50 percent by fiscal year 1997. An integrated systems approach might enable DOE to achieve such a cost reduction while still obtaining sufficient characterization data. This goal of reducing characterization expenses also might help meet the overall DOE-EM goals. This recommendation is especially important because numerous contaminant plumes still have not been characterized adequately. Recommendation: Appropriate internal and external peer reviews of the characterization efforts should be conducted and should become a fundamental part of this integrated systems approach (see Chapter 2, p. 13). Recommendation: A continuing integrated effort of EM-50 with EM-30 and EM-40 is needed for the Plumes Focus Area to achieve its remediation goals. Also, EM-50 should bring into its technology-development planning some external groups of expertise, including industry and academia, for guidance purposes. Expert or external advisory panels could fill this need. Although the Plumes Focus Area is working with various stakeholders (from industry, academia, the national laboratories, and other federal agencies) to identify technology needs and to develop technologies, these efforts are not well integrated and often lose focus on the end objective. The intent of this recommendation is to encourage DOE to collaborate more fully with external experts who have a strong interest in achieving such objectives. One particular EM-50

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--> program that has helped to leverage research in this way is the LASAGNATM6 technology project discussed in the next section. DOE is encouraged to form additional teams of this type to integrate their remediation efforts, both internally and externally. In-Situ Remediation of TCE — A Productive Industry/DOE/EPA Demonstration Using LASAGNATM Contamination in low-permeability soils poses a significant technical challenge to in-situ remediation. One demonstrated solution to this problem combines electro-osmosis with treatment zones established in the contaminated soils. The contaminant targeted in an initial field demonstration was trichlorethylene (TCE) at the DOE Gaseous Diffusion Plant in Paducah, Kentucky. The demonstration utilized a process called LASAGNATM. The consortium, known as the Remediation Technology Development Forum (RTDF), which was coordinated by Monsanto, consisted of DuPont and General Electric with participation from the DOE and the EPA. The program was facilitated by Clean Sites, Inc. and implemented by CDM Federal. Applications and benefits claimed for this process are treatment of organic and inorganic contamination, as well as mixed wastes; greatly reduced environmental impacts; increased cost effectiveness; minimal waste generation; increased treatment flexibility; and broad application for a wide range of sites and contaminants. Other attributes of this process are rapid technology development and royalty-free use of technology. The Phase I demonstration, completed in the summer of 1995, met and exceeded all expectations for quantitative (mass balance) removal of TCE. Phase II, now in preparation, will involve scale-up and remediation of the Paducah Site. Recommendation: An assessment of what has been accomplished and learned so far by the Plumes Focus Area is necessary. Each remediation or demonstration should be evaluated to identify successes and lessons learned addressing the questions of what it did and did not accomplish, and why. These lessons learned could be 6   The LASAGNATM technology, a trademark of the Monsanto Company, is a system or combination of components in a configuration of electrodes and degradation zones that permits in-situ treatment of contaminants in low-permeability environments. Monsanto Company has coined the word LASAGNA to identify its products and services based on this integrated in-situ remediation technology.

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--> valuable scientific data in charting progress and learning about remediation attempts and could serve as a guide for a future approach. It is important to look at all learning experiences as well as successes, because these experiences have valuable information content. Eventually, good rationale for technology development could be developed, ideally based on both field data and theoretical models. Cleanup Objectives Cleanup goals are an integral part of evaluation of appropriate technologies, remediation costs, and even feasibility of remediation. Goals often are set by regulations and typically are defined in terms of concentration of contaminants in the ground water or soil after remediation is complete. However, such cleanup goals can be elusive if the technical capabilities of existing and emerging technologies are not considered. For example, for most sites with complex hydrogeology and chemistry, attainment of current drinking-water standards generally is not possible with conventional technologies nor has it been demonstrated adequately with emerging technologies. The limitations of existing technologies, the implications of current cleanup standards, and alternative approaches to setting cleanup goals were discussed in Alternatives to Ground Water Cleanup (NRC, 1994). Risk-based goals, that result in site-specific cleanup goals, are alternatives that are receiving consideration by many agencies throughout the country. Technical impracticability issues also must be considered. Recommendation: DOE should establish a process for developing specific cleanup goals for each of its contaminated sites, because the appropriate approach for remediation of a site depends upon the cleanup goals, intended land use, and technical practicality issues. Recommendation: DOE should compile an inventory of the scope (size and type) of contaminant plumes including thorough documentation and quantitative evaluations of risk and costs posed by these plumes. Major technological needs to address high-risk and cost sites should be identified in this process. It is important to stress that setting priorities rationally is not possible until a problem is defined. Criteria The selection of end points in remediation is integral to technology development. How much technology development is done (characterization, containment, and remediation) depends on the criteria or end points that are established.

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--> The use of relevant criteria by which to characterize, contain, and remediate contaminant plumes, and the uses of risk and cost trade-offs were addressed by the subcommittee. During briefings, EM-50 indicated that their technology-development strategy is based on a three-step approach: containment of the biggest contaminant risks, treatment of ground water, and then treatment of soil contamination (which is considered a longer-term threat). The Plumes Focus Area technology-development strategy is driven by matching technology to EM needs using a Decision Analysis System to guide the process. The Decision Analysis System matches available or emerging technologies from government and industry with EM site problems and demonstrates where current technologies can provide solutions and where technology gaps exist. A problem is that the sites frequently do not have the information DOE needs to help make these kinds of decisions. Recommendation: EM-50 should complete quantification and prioritization of the contaminant plumes in the DOE complex. Status of Current Technologies and Needs According to EM-50 briefings, numerous technology-development/application activities are ongoing throughout the DOE complex. These efforts are organized into four areas: (1) site assessments, (2) contaminant characterization, (3) treatment technologies, and (4) containment technology. Methods for measuring aquifer properties, on-line remediation process controls, and subsurface exploration and access tools are under development to improve site-assessment approaches. Closely associated with these efforts are programs to characterize DNAPLs and other contaminants using noninvasive techniques. In addition, significant efforts are being directed toward identification of in-situ treatment of plumes to minimize worker and public exposure, waste generation, and costs. Coupled with the in-situ treatment technology focus are efforts to implement effective, reactive barriers for containment of the plumes. In addition, EM-50 is evaluating technologies that have application across three key research areas, such as robotics technology; characterization, monitoring, and sensor technology; and separations technology. Although these areas of technology development are numerous and are being pursued with great vigor and energy, the Contaminant Plume Subcommittee presently is not able to judge the appropriateness or progress of the program without additional information. This needed information consists of quantification and prioritization of the contaminant plumes in the DOE complex. Once this information is assembled, a more realistic assessment can be made regarding the effectiveness, appropriateness, and timeliness of current research activities, as well as major technology needs in the Plumes Focus Area.

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--> Recommendation: Tools to locate DNAPLs, as well as in-situ sensors to reduce burdensome laboratory costs, should be developed and/or refined. These efforts must be coordinated with other entities (both internal and external to DOE) that are performing similar activities. References National Research Council. 1994. Alternatives for Ground Water Cleanup. Washington, D.C.: National Academy Press. U.S. Department of Energy (USDOE). 1994. U.S. Department of Energy Environmental Management Program Strategic Plan. M917, Version 1.

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