Cleanup Levels at DOE Environmental Restoration Sites. Margaret MacDonell, Fred Kirchner, Kurt Picel, John Peterson, and Lynne Haroun, Argonne National Laboratory, 9700 S. Cass Ave., EAD/900, Argonne, IL 60439
The Department of Energy (DOE) is conducting a massive cleanup program at sites across the country that were contaminated by past operations. The determination of appropriate residual levels for radionuclides and chemicals at these sites is directly tied to future land use plans and represents the endpoint of concern for many stakeholders. It is also a critical issue for budgeting the cleanup dollars, which are projected to exceed $200 billion for the entire program. The concentrations of contaminants to be left behind in soil and water are typically determined by combining applicable standards with the results of site-specific risk assessments. While the Environmental Protection Agency has promulgated some standards for water, few exist for soil, which has been estimated to account for more than 50 million cubic meters of contaminated material across the DOE complex. Thus, site-specific risk analyses that incorporate relevant exposure scenarios and fate factors are essential to sound decision making. Oversight agencies have often pushed for conservative default values (e.g., for distribution coefficients used to estimate leaching to groundwater) and exposure assumptions (notably residential land use), even where the likelihood of such conditions at a given site is low. For example, areas of many larger sites are expected to continue to be used as ecological reserves. Nevertheless, such analyses can be used to evaluate the practicability and cost-effectiveness of various cleanup options per DOE’s "as low as reasonably achievable" risk-reduction process. At many sites, the indication of natural attenuation as a reasonable response option for "self-mitigating" radioactive contamination (such as tritium in ground water) has also been an issue for oversight agencies, who historically have been disinclined to support such passive measures involving institutional controls over many decades. Cleanup levels established to date at various DOE sites will be described and compared, and critical risk factors will be identified.
Work supported by U.S. Department of Energy, Assistant Secretary of Environmental Management, under contract W-31-109-Eng-38.