U Plant Area

Pump-and-treat operations are ongoing to contain and reduce the mass of uranium and technetium-99 in the groundwater adjacent to U Plant. Unlike the 100 Areas interim actions, the remedial action objectives for these sites are not based on compliance with the drinking water or other aquatic water quality standards. Substantial reductions in the concentrations of uranium and technetium-99 have been detected throughout the plume. It is likely that the remedial action objective to cease treatment by 2006 will be achieved.

Efforts are now underway to evaluate the mobility of uranium and technetium-99 in the vadose zone and the groundwater, to assess the potential impact of these contaminants and their associated sources on downgradient water quality, and to set final remedial action objectives. Much of this activity is focused on refining our understanding of the transport of uranium in the subsurface and developing a better conceptual model of how it migrates in the groundwater.

Should it be determined that technetium-99 and uranium still represent a risk to groundwater even though the interim action cleanup objectives were met, an alternative to the current use of the Effluent Treatment Facility as the treatment facility will be required by 2006. However, at that time the capacity of the Effluent Treatment Facility will be completely utilized to support retrieval of tank waste from single-shell tanks.

Finally, plans to complete source control actions for high-risk waste sites in the U Plant area and measures to eliminate artificial recharge and preferential pathways for contaminant migration by the end of 2006 should preserve the long-term performance of the containment remedy and limit the need for active groundwater remediation in the future.

For questions or comments, please send a message to Carl Connell.