Oak Ridge Mercury Cleanup: Opportunities Exist to Enhance Risk Management and Technology Development

What GAO Found

The U.S. Department of Energy's (DOE) Oak Ridge Office of Environmental Management (OREM) oversees the cleanup of mercury contamination at the Y-12 National Security Complex in Tennessee. OREM has identified mercury contamination there as the greatest environmental risk at Oak Ridge. The scope of mercury cleanup includes the construction of a mercury treatment facility, the deactivation and demolition (D&D) of four large mercury-contaminated buildings, and soil and water remediation activities. The mercury cleanup is expected to cost at least $3.2 billion and to be completed in 2043. However, there are uncertainties related to these estimates. Since these estimates were approved in 2023, various changes have occurred that will likely affect cost and schedule of the cleanup. For example, construction of the mercury treatment facility is behind schedule, and OREM has yet to reach agreements with state regulators regarding the mercury waste disposal assumptions on which these estimates are based.

Map of the Oak Ridge Reservation’s Y-12 National Security Complex and Key Mercury Cleanup Areas

OREM has identified about 250 risks related to mercury cleanup projects and activities with a total potential cost impact ranging from $180 million (best case) to $1.2 billion (worst case). Earlier in 2024, GAO reported that OREM manages risk primarily within individual projects, rather than at the program or site level. However, OREM's management of mercury cleanup risks at the individual project level does not comprehensively reflect the potential impact of risks that affect multiple projects. For example, 10 of the 15 highest-cost risks with the greatest likelihood of occurrence and potential consequence across the mercury-related projects and activities are related to waste disposal. This includes unexpected waste volumes from several projects and disposal of waste that does not meet waste acceptance criteria for the new waste disposal facility. As DOE's Risk Management Guide states, looking for risks with common causes could present opportunities for risk mitigation strategies.

In addition, managing risks at the project level does not capture interdependency risks—where risks from one project affect another project's risks and preferred risk responses. For example, this approach does not identify the potential for delays in the National Nuclear Security Administration's high-security fence relocation project to delay the schedules of two D&D projects or substantially increase their costs. OREM officials said these risks were not included because the delays in those projects had not yet occurred. Enhancing risk management could better enable OREM to minimize the potential negative effects on the cost and schedule of mercury cleanup.

Since 2018, OREM has received $3 million annually in funding for technology development activities. OREM identified goals for the technology development program in a 2017 plan. These goals are to support the D&D of mercury-contaminated buildings by improving worker safety, increasing cost-savings, and reducing cleanup schedule and risk. However, OREM has not conducted assessments of the mercury technology development program to ensure it is supporting these goals. By assessing the program's outcomes, OREM could better ensure that these technologies deliver on their potential to improve the cleanup process.

Why GAO Did This Study

From 1950 through 1982, during nuclear weapons production at DOE's Oak Ridge Reservation in Tennessee, DOE released an estimated 700,000 pounds of mercury to the surrounding ecosystem. In addition to soil and surface water contamination, these releases also contaminated structures on the site. An additional 1.3 million pounds of mercury are unaccounted for at Oak Ridge's Y-12 National Security Complex and may also have been lost to the environment.

OREM and the U.S. Environmental Protection Agency identified this mercury contamination as the greatest environmental risk at Oak Ridge due to the offsite migration of mercury in streams and continued high levels of mercury in local fish populations. Moreover, the four mercury-contaminated buildings slated for deactivation and demolition are adjacent to active National Nuclear Security Administration missions. These missions need additional land, which depends on the completion of mercury cleanup.

Senate Report 118-58 includes a provision for GAO to assess OREM's efforts to clean up mercury contamination at Oak Ridge. This report provides information on the planned scope, cost, and schedule of mercury cleanup; relevant regulatory framework; associated risks; and mercury technology development activities.

GAO assessed documents and data related to mercury cleanup activities, regulatory requirements, and technology development. GAO visited Oak Ridge to better understand how OREM plans, oversees, and executes mercury cleanup activities. GAO interviewed OREM officials and state and federal regulators.