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This report represents a synthesis and integration of basic and applied research into a system-scale model of the Hanford 300 Area groundwater uranium plume, supported by the U.S. Department of Energy (DOE) Richland Operations Office (RL). The report integrates research findings and data from DOE Office of Science (SC), Office of Environmental Management (EM), and DOE-RL projects, and from the site remediation and closure contractor, Washington Closure Hanford, LLC. The threedimensional, system-scale model addresses water flow and reactive transport of uranium for the coupled vadose zone, unconfined aquifer, and Columbia River shoreline of the Hanford 300 Area. The system-scale model of the 300 Area was developed to be a decision-support tool to evaluate processes of the total system affecting the groundwater uranium plume. The model can also be used to address "what if" questions regarding different remediation endpoints, and to assist in design and evaluation of field remediation efforts. For example, the proposed cleanup plan for the Hanford 300 Area includes removal, treatment, and disposal of contaminated sediments from known waste sites, enhanced attenuation of uranium hot spots in the vadose and periodically rewetted zone, and continued monitoring of groundwater with institutional controls. Illustrative simulations of polyphosphate infiltration were performed to demonstrate the ability of the system-scale model to address these types of questions. The use of this model in conjunction with continued field monitoring is expected to provide a rigorous basis for developing operational strategies for field remediation and for defining defensible remediation endpoints. The system-scale flow and reactive transport model of the 300 Area subsurface was implemented using the simulator eSTOMP ("e" for extreme scale), developed recently by Pacific Northwest National Laboratory (PNNL) under the laboratory-directed research and development program's Extreme-Scale Computing Initiative. This is a parallel version of the STOMP (Subsurface Transport Over Multiple Phases) simulator that was developed specifically to allow for simulation with faster run times and/or for larger-scale subsurface flow and reactive transport problems. All model simulations with eSTOMP were performed on Olympus, a high-performance computing cluster supported by PNNL's institutional computing program. Data from laboratory and field experiments performed for the Integrated Field Research Challenge (IFRC) project, supported by DOE-SC, and from other DOE-EM and DOE-RL projects, were used for model development and testing. A column experiment performed on an intact, uranium-contaminated core sample collected from the IFRC site was used as a small-scale validation test for a uranium surface complexation reaction network implemented with eSTOMP. Experimental data from this and other laboratory column experiments with 300 Area sediments were used to develop an alternative reaction network that also accounts for reactions associated with polyphosphate amen...
This report represents a synthesis and integration of basic and applied research into a system-scale model of the Hanford 300 Area groundwater uranium plume, supported by the U.S. Department of Energy (DOE) Richland Operations Office (RL). The report integrates research findings and data from DOE Office of Science (SC), Office of Environmental Management (EM), and DOE-RL projects, and from the site remediation and closure contractor, Washington Closure Hanford, LLC. The threedimensional, system-scale model addresses water flow and reactive transport of uranium for the coupled vadose zone, unconfined aquifer, and Columbia River shoreline of the Hanford 300 Area. The system-scale model of the 300 Area was developed to be a decision-support tool to evaluate processes of the total system affecting the groundwater uranium plume. The model can also be used to address "what if" questions regarding different remediation endpoints, and to assist in design and evaluation of field remediation efforts. For example, the proposed cleanup plan for the Hanford 300 Area includes removal, treatment, and disposal of contaminated sediments from known waste sites, enhanced attenuation of uranium hot spots in the vadose and periodically rewetted zone, and continued monitoring of groundwater with institutional controls. Illustrative simulations of polyphosphate infiltration were performed to demonstrate the ability of the system-scale model to address these types of questions. The use of this model in conjunction with continued field monitoring is expected to provide a rigorous basis for developing operational strategies for field remediation and for defining defensible remediation endpoints. The system-scale flow and reactive transport model of the 300 Area subsurface was implemented using the simulator eSTOMP ("e" for extreme scale), developed recently by Pacific Northwest National Laboratory (PNNL) under the laboratory-directed research and development program's Extreme-Scale Computing Initiative. This is a parallel version of the STOMP (Subsurface Transport Over Multiple Phases) simulator that was developed specifically to allow for simulation with faster run times and/or for larger-scale subsurface flow and reactive transport problems. All model simulations with eSTOMP were performed on Olympus, a high-performance computing cluster supported by PNNL's institutional computing program. Data from laboratory and field experiments performed for the Integrated Field Research Challenge (IFRC) project, supported by DOE-SC, and from other DOE-EM and DOE-RL projects, were used for model development and testing. A column experiment performed on an intact, uranium-contaminated core sample collected from the IFRC site was used as a small-scale validation test for a uranium surface complexation reaction network implemented with eSTOMP. Experimental data from this and other laboratory column experiments with 300 Area sediments were used to develop an alternative reaction network that also accounts for reactions associated with polyphosphate amen...
Current plans for treatment and disposal of immobilized low-activity waste (ILAW) from Hanford's underground waste storage tanks include vitrification and storage of the glass waste form in a near-surface disposal facility. This Integrated Disposal Facility (IDF) is located in the 200 East Area of the Hanford Central Plateau. Performance assessment (PA) of the IDF requires numerical modeling of subsurface flow and reactive transport processes over very long periods (thousands of years). The models used to predict facility performance require parameters describing various physical, hydraulic, and transport properties. This report provides updated estimates of physical, hydraulic, and transport properties and parameters for both near-and far-field materials, intended for use in future IDF PA modeling efforts. Previous work on physical and hydraulic property characterization for earlier IDF PA analyses is reviewed and summarized. For near-field materials, portions of this document and parameter estimates are taken from an earlier data package. For far-field materials, a critical review is provided of methodologies used in previous data packages. Alternative methods are described and associated parameters are provided. For far-field materials, consisting of both sand-and gravel-dominated facies underlying the IDF, a particular model has been used in previous PA modeling efforts to represent the saturation-dependent anisotropy of unsaturated hydraulic conductivity. We recommend that this model be replaced with a more recent and general tensorial pore-connectivity-tortuosity (TCT) model for saturation-dependent anisotropy. Simulation results from both the TCT and the earlier anisotropy model have been compared with observed data from a controlled vadose zone field injection experiment performed just south of the 200 East Area. The TCT model was shown to predict observed flow behavior at this site as well as or better than the model used in previous PA efforts, and with many fewer added model parameters (one versus eight). Recommended parameter estimates for the TCT model are presented. Previous estimates of dispersivities for vadose zone sediments were based on stochastic theory developed for saturated aquifer materials. An extensive literature review is presented that suggests these estimates may not be appropriate for unsaturated conditions. An alternative approach based on more fundamental physical property information is described and updated parameter estimates are presented.
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