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Title: Updated Conceptual Model for the 300 Area Uranium Groundwater Plume

Abstract

The 300 Area uranium groundwater plume in the 300-FF-5 Operable Unit is residual from past discharge of nuclear fuel fabrication wastes to a number of liquid (and solid) disposal sites. The source zones in the disposal sites were remediated by excavation and backfilled to grade, but sorbed uranium remains in deeper, unexcavated vadose zone sediments. In spite of source term removal, the groundwater plume has shown remarkable persistence, with concentrations exceeding the drinking water standard over an area of approximately 1 km2. The plume resides within a coupled vadose zone, groundwater, river zone system of immense complexity and scale. Interactions between geologic structure, the hydrologic system driven by the Columbia River, groundwater-river exchange points, and the geochemistry of uranium contribute to persistence of the plume. The U.S. Department of Energy (DOE) recently completed a Remedial Investigation/Feasibility Study (RI/FS) to document characterization of the 300 Area uranium plume and plan for beginning to implement proposed remedial actions. As part of the RI/FS document, a conceptual model was developed that integrates knowledge of the hydrogeologic and geochemical properties of the 300 Area and controlling processes to yield an understanding of how the system behaves and the variables that control it. Recent resultsmore » from the Hanford Integrated Field Research Challenge site and the Subsurface Biogeochemistry Scientific Focus Area Project funded by the DOE Office of Science were used to update the conceptual model and provide an assessment of key factors controlling plume persistence.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1061419
Report Number(s):
PNNL-22048
830403000
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
300 Area; uranium; groundwater plume; vadose zone

Citation Formats

Zachara, John M., Freshley, Mark D., Last, George V., Peterson, Robert E., and Bjornstad, Bruce N. Updated Conceptual Model for the 300 Area Uranium Groundwater Plume. United States: N. p., 2012. Web. doi:10.2172/1061419.
Zachara, John M., Freshley, Mark D., Last, George V., Peterson, Robert E., & Bjornstad, Bruce N. Updated Conceptual Model for the 300 Area Uranium Groundwater Plume. United States. doi:10.2172/1061419.
Zachara, John M., Freshley, Mark D., Last, George V., Peterson, Robert E., and Bjornstad, Bruce N. Thu . "Updated Conceptual Model for the 300 Area Uranium Groundwater Plume". United States. doi:10.2172/1061419. https://www.osti.gov/servlets/purl/1061419.
@article{osti_1061419,
title = {Updated Conceptual Model for the 300 Area Uranium Groundwater Plume},
author = {Zachara, John M. and Freshley, Mark D. and Last, George V. and Peterson, Robert E. and Bjornstad, Bruce N.},
abstractNote = {The 300 Area uranium groundwater plume in the 300-FF-5 Operable Unit is residual from past discharge of nuclear fuel fabrication wastes to a number of liquid (and solid) disposal sites. The source zones in the disposal sites were remediated by excavation and backfilled to grade, but sorbed uranium remains in deeper, unexcavated vadose zone sediments. In spite of source term removal, the groundwater plume has shown remarkable persistence, with concentrations exceeding the drinking water standard over an area of approximately 1 km2. The plume resides within a coupled vadose zone, groundwater, river zone system of immense complexity and scale. Interactions between geologic structure, the hydrologic system driven by the Columbia River, groundwater-river exchange points, and the geochemistry of uranium contribute to persistence of the plume. The U.S. Department of Energy (DOE) recently completed a Remedial Investigation/Feasibility Study (RI/FS) to document characterization of the 300 Area uranium plume and plan for beginning to implement proposed remedial actions. As part of the RI/FS document, a conceptual model was developed that integrates knowledge of the hydrogeologic and geochemical properties of the 300 Area and controlling processes to yield an understanding of how the system behaves and the variables that control it. Recent results from the Hanford Integrated Field Research Challenge site and the Subsurface Biogeochemistry Scientific Focus Area Project funded by the DOE Office of Science were used to update the conceptual model and provide an assessment of key factors controlling plume persistence.},
doi = {10.2172/1061419},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2012},
month = {11}
}

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