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158 | Long-Term Surveillance and Maintenance at Closed NuclearWaste Sites Written by Karen W. Lowrie, based in part on an interview with Raymond M. Plieness, with comments by Keith Florig Background The cold war ended nearly 2 decades ago, but the environmental consequences of extensive nuclear weapons research, production, and testing activities carried out in the United States during the cold war will remain with us for many centuries. Although the U.S. Department of Energy (DOE) has spent billions of dollars since 1989 to clean up sites and has succeeded in reducing risks, some level of contamination will remain at many sites where radionuclides cannot be completely removed or are contained in storage. Although some radionuclides, those with short half-lives, naturally decay at a rapid pace into benign substances, some of the long-lived contaminants will be radioactive for tens of thousands of years or more. In addition, other chemical contaminants, such as PCBs, solvents, and heavy metals do not decay appreciably and can remain hazardous in perpetuity. To ensure that human health is protected for many generations, longterm stewardship must be carried out at sites after remediation is complete. According to estimates made in the late 1990s, more than 100 DOE sites are expected to require some type of stewardship, but the number could change. Some are as small as a football field and others are hundreds of square miles. Some are in close proximity to large human populations and others are in more isolated locations. Long-term stewardship has been defined as “all activities required to protect human health and the environment from hazards remaining at DOE sites after cleanup is complete” (DOE, 1999). The cleanup process addresses contaminated land, water, groundwater, facilities and materials in accordance with agreed-upon standards and requirements. However, a site could be cleaned up and even closed but still contain known hazards in the form of stored or buried wastes, entombed facilities, such as reactors, or residual contaminants that are left in place, sometimes subject to long-term treatment. Since 2001, the DOE refers to stewardship activities as “long-term sur- Long-Term Surveillance and Maintenance | 159 veillance and maintenance” (LTSM). The two general categories of LTSM are engineered controls and institutional controls. Engineered controls are manmade physical containment systems placed around landfills, vaults, tank farms, or other waste units. They include operating, maintaining, inspecting, and monitoring caps, erosion control systems, environmental sampling, wells, and pump-and-treat groundwater remediation systems. For example, the 62-acre Estes Gulch Disposal Cell near Rifle, Colorado, is designed to hold waste materials from uranium mining and milling operations with a plastic liner and up to 4–9 feet of stone, silt, and clay barrier materials. The Environmental Protection Agency refers to these engineered controls as “active” controls (40 CFR pt. 191), as well as activities such as monitoring the natural attenuation of some residual groundwater contaminants. Institutional controls are legal or access controls intended to reduce the risk of exposure by ensuring that land- and water-use restrictions are maintained . They include restrictions on land or water use, well-drilling prohibitions , deed notices, easements or other legal advisories or measures, and longterm information management. Access obstacles such as fencing, markers, and signs can be considered passive controls. Federal ownership in perpetuity is itself an institutional control. For example, long-term institutional controls will be necessary in portions of the huge Nevada Test Site north of Las Vegas to prevent inadvertent human exposure to widely dispersed radionuclides and other contaminants resulting from the explosion of thermonuclear weapons. Long-term support of LTSM activities will be important at both local and national levels to ensure proper and effective implementation. That is, the federal government must continue to evaluate new technologies to improve the effectiveness of remedies or remedial systems (reducing the need and costs for LTSM) and research into better understanding of contaminant movement and impacts of residual contamination. Also, components of LTSM that may need to be addressed and integrated at the local level are emergency response planning , oversight, information management, community land use, and natural resource planning. A recent survey shows that those who live near some of DOE’s largest facilities have high expectations regarding stewardship (Greenberg et al., 2007). LTSM activities are now centralized under the Division of Legacy Management (LM) within DOE. This office handles the DOE’s postclosure responsibilities , including long-term surveillance and maintenance, records management , property management, land use planning, and community relations. There are currently 70...

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