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Groundwater Data Package for Hanford Assessments

Description: This report presents data and interpreted information that supports the groundwater module of the System Assessment Capability (SAC) used in Hanford Assessments. The objective of the groundwater module is to predict movement of radioactive and chemical contaminants through the aquifer to the Columbia River or other potential discharge locations. This data package is being revised as part of the deliverables under the Characterization of Systems Project (#49139) aimed at providing documentation for assessments being conducted under the Hanford Assessments Project (#47042). Both of these projects are components of the Groundwater Remediation and Closure Assessments Projects, managed by the Management and Integration Project (#47043).
Date: January 2006
Creator: Thorne, Paul D.; Bergeron, Marcel P.; Williams, Mark D. & Freedman, Vicky L.
Partner: UNT Libraries Government Documents Department

100-D Area In Situ Redox Treatability Test for Chromate-Contaminated Groundwater

Description: A treatability test was conducted for the In Situ Redox Manipulation (ISRM) technology at the 100 D Area of the U. S. Department of Energy's Hanford Site. The target contaminant was dissolved chromate in groundwater. The ISRM technology creates a permeable subsurface treatment zone to reduce mobile chromate in groundwater to an insoluble form. The ISRM permeable treatment zone is created by reducing ferric iron to ferrous iron within the aquifer sediments, which is accomplished by injecting aqueous sodium dithionite into the aquifer and then withdrawing the reaction products. The goal of the treatability test was to create a linear ISRM barrier by injecting sodium dithionite into five wells. Well installation and site characterization activities began in spring 1997; the first dithionite injection took place in September 1997. The results of this first injection were monitored through the spring of 1998. The remaining four dithionite injections were carried out in May through July of 1998.These five injections created a reduced zone in the Hanford unconfined aquifer approximately 150 feet in length (perpendicular to groundwater flow) and 50 feet wide. The reduced zone extended over the thickness of the unconfined zone. Analysis of post-emplacement groundwater samples showed concentrations of chromate, in the reduced zone decreased from approximately 1.0 mg/L before the tests to below analytical detection limits (<0.007 mg/L). Chromate concentrations also declined in downgradient monitoring wells to as low as 0.020 mg/L. These data, in addition to results from pre-test reducible iron characterization, indicate the barrier should be effective for 20 to 25 years. The 100-D Area ISRM barrier is being expanded to a length of up to 2,300 ft to capture a larger portion of the chromate plume.
Date: October 12, 2000
Creator: Williams, Mark D.; Vermeul, Vincent R.; Szecsody, James E. & Fruchter, Jonathan S.
Partner: UNT Libraries Government Documents Department

Challenges Associated with Apatite Remediation of Uranium in the 300 Area Aquifer

Description: Sequestration of uranium as insoluble phosphate phases appears to be a promising alternative for treating the uranium-contaminated groundwater at the Hanford 300 Area. The proposed approach involves both the direct formation of autunite by the application of a polyphosphate mixture, as well as the formation of apatite in the aquifer as a continuing source of phosphate for long-term treatment of uranium. After a series of bench-scale tests, a field treatability test was conducted in a well at the 300 Area. The objective of the treatability test was to evaluate the efficacy of using polyphosphate injections to treat uranium-contaminated groundwater in situ. A test site consisting of an injection well and 15 monitoring wells was installed in the 300 Area near the process trenches that had previously received uranium-bearing effluents. The results indicated that while the direct formation of autunite appears to have been successful, the outcome of the apatite formation of the test was more limited. Two separate overarching issues impact the efficacy of apatite remediation for uranium sequestration within the 300 Area: 1) the efficacy of apatite for sequestering uranium under the present geochemical and hydrodynamic conditions, and 2) the formation and emplacement of apatite via polyphosphate technology. This paper summarizes these issues.
Date: May 1, 2008
Creator: Wellman, Dawn M.; Fruchter, Jonathan S.; Vermeul, Vincent R. & Williams, Mark D.
Partner: UNT Libraries Government Documents Department

Three-Dimensional Groundwater Models of the 300 Area at the Hanford Site, Washington State

Description: Researchers at Pacific Northwest National Laboratory developed field-scale groundwater flow and transport simulations of the 300 Area to support the 300-FF-5 Operable Unit Phase III Feasibility Study. The 300 Area is located in the southeast portion of the U.S. Department of Energy’s Hanford Site in Washington State. Historical operations involving uranium fuel fabrication and research activities at the 300 Area have contaminated engineered liquid-waste disposal facilities, the underlying vadose zone, and the uppermost aquifer with uranium. The main objectives of this research were to develop numerical groundwater flow and transport models to help refine the site conceptual model, and to assist assessment of proposed alternative remediation technologies focused on the 300 Area uranium plume.
Date: September 1, 2008
Creator: Williams, Mark D.; Rockhold, Mark L.; Thorne, Paul D. & Chen, Yousu
Partner: UNT Libraries Government Documents Department

Development of Models to Simulate Tracer Behavior in Enhanced Geothermal Systems

Description: A recent report found that power and heat produced from engineered (or enhanced) geothermal systems (EGSs) could have a major impact on the United States while incurring minimal environmental impacts. EGS resources differ from high-grade hydrothermal resources in that they lack sufficient temperature distributions, permeability/porosity, fluid saturation, or recharge of reservoir fluids. Therefore, quantitative characterization of temperature distributions and the surface area available for heat transfer in EGS is necessary for commercial development of geothermal energy. The goal of this project is to provide integrated tracer and tracer interpretation tools to facilitate this characterization. Modeling capabilities are being developed as part of this project to support laboratory and field testing to characterize engineered geothermal systems in single- and multi-well tests using tracers. The objective of this report is to describe the simulation plan and the status of model development for simulating tracer tests for characterizing EGS.
Date: June 1, 2010
Creator: Williams, Mark D.; Vermeul, Vincent R.; Reimus, P. W.; Newell, D. & Watson, Tom B.
Partner: UNT Libraries Government Documents Department

100-NR-2 Apatite Treatability Test: High-Concentration Calcium-Citrate-Phosphate Solution Injection for In Situ Strontium-90 Immobilization

Description: Following an evaluation of potential strontium-90 (90Sr) treatment technologies and their applicability under 100-NR-2 hydrogeologic conditions, the U.S. Department of Energy (DOE), Fluor Hanford, Inc. (now CH2M Hill Plateau Remediation Company [CHPRC]), Pacific Northwest National Laboratory, and the Washington State Department of Ecology agreed that the long-term strategy for groundwater remediation at the 100-N Area should include apatite as the primary treatment technology. This agreement was based on results from an evaluation of remedial alternatives that identified the apatite permeable reactive barrier (PRB) technology as the approach showing the greatest promise for reducing 90Sr flux to the Columbia River at a reasonable cost. This letter report documents work completed to date on development of a high-concentration amendment formulation and initial field-scale testing of this amendment solution.
Date: September 1, 2010
Creator: Vermeul, Vincent R.; Fritz, Brad G.; Fruchter, Jonathan S.; Szecsody, James E. & Williams, Mark D.
Partner: UNT Libraries Government Documents Department

100-NR-2 Apatite Treatability Test FY09 Status: High Concentration Calcium-Citrate-Phosphate Solution Injection for In Situ Strontium-90 Immobilization

Description: 100-NR-2 Apatite Treatability Test FY09 Status: High Concentration Calcium-Citrate-Phosphate Solution Injection for In Situ Strontium-90 Immobilization INTERIM LETTER REPORT
Date: December 16, 2009
Creator: Vermeul, Vincent R.; Fritz, Brad G.; Fruchter, Jonathan S.; Szecsody, James E. & Williams, Mark D.
Partner: UNT Libraries Government Documents Department

100-NR-2 Apatite Treatability Test: An update on Barrier Performance

Description: This report updates a previous report covering the performance of a permeable reactive barrier installed at 100N. In this report we re-evaluate the results after having an additional year of performance monitoring data to incorporate.
Date: May 1, 2011
Creator: Fritz, Brad G.; Vermeul, Vincent R.; Fruchter, Jonathan S.; Szecsody, James E. & Williams, Mark D.
Partner: UNT Libraries Government Documents Department

Site Characterization Plan: Uranium Stabilization through Polyphosphate Injection

Description: An initial feasibility study of options to treat the uranium plume at the 300-FF-5 Operable Unit considered hydraulic containment, slurry wall containment, and groundwater extraction as potential remedial action technologies. None were selected for interim action, and reduction of contamination levels by natural processes was considered a viable alternative while source removal actions continued. Subsequent planning for a Phase III feasibility study focused on methods that would reduce the concentration of uranium in the aquifer, including multiple methods to immobilize uranium using chemical-based technologies. Based on an initial technology screening, the polyphosphate technology was identified as the best candidate to treat the for further evaluation and selected for treatability testing. The overall objective of the polyphosphate treatability test is to evaluate the efficacy of using polyphosphate injections to treat uranium contaminated groundwater in situ. The objective of the work elements included in this site characterization plan is to collect site-specific characterization data that will be needed to design and implement a field-scale demonstration of the technology.
Date: December 1, 2006
Creator: Vermeul, Vince R.; Fruchter, Jonathan S.; Wellman, Dawn M.; Williams, Bruce A. & Williams, Mark D.
Partner: UNT Libraries Government Documents Department

Uranium Contamination in the Subsurface Beneath the 300 Area, Hanford Site, Washington

Description: This report provides a description of uranium contamination in the subsurface at the Hanford Site's 300 Area. The principal focus is a persistence plume in groundwater, which has not attenuated as predicted by earlier remedial investigations. Included in the report are chapters on current conditions, hydrogeologic framework, groundwater flow modeling, and geochemical considerations. The report is intended to describe what is known or inferred about the uranium contamination for the purpose of making remedial action decisions.
Date: February 29, 2008
Creator: Peterson, Robert E.; Rockhold, Mark L.; Serne, R. Jeffrey; Thorne, Paul D. & Williams, Mark D.
Partner: UNT Libraries Government Documents Department

Use of Polyphosphate to Decrease Uranium Leaching in Hanford 300 Area Smear Zone Sediments

Description: The primary objective of this study is to summarize the laboratory investigations performed to evaluate short- and long-term effects of phosphate treatment on uranium leaching from 300 area smear zone sediments. Column studies were used to compare uranium leaching in phosphate-treated to untreated sediments over a year with multiple stop flow events to evaluate longevity of the uranium leaching rate and mass. A secondary objective was to compare polyphosphate injection, polyphosphate/xanthan injection, and polyphosphate infiltration technologies that deliver phosphate to sediment.
Date: September 30, 2012
Creator: Szecsody, James E.; Zhong, Lirong; Oostrom, Martinus; Vermeul, Vincent R.; Fruchter, Jonathan S. & Williams, Mark D.
Partner: UNT Libraries Government Documents Department

Influence of Nitrate on the Hanford 100D Area In Situ Redox Manipulation Barrier Longevity

Description: The purpose of this laboratory study is to determine the influence of nitrate on the Hanford 100D Area in situ redox manipulation (ISRM) barrier longevity. There is a wide spread groundwater plume of 60 mg/L nitrate upgradient of the ISRM barrier with lower nitrate concentrations downgradient, suggestive of nitrate reduction occurring. Batch and 1-D column experiments showed that nitrate is being slowly reduced to nitrite and ammonia. These nitrate reduction reactions are predominantly abiotic, as experiments with and without bactericides present showed no difference in nitrate degradation rates. Nitrogen species transformation rates determined in experiments covered a range of ferrous iron/nitrate ratios such that the data can be used to predict rates in field scale conditions. Field scale reaction rate estimates for 100% reduced sediment (16 C) are: (a) nitrate degradation = 202 {+-} 50 h (half-life), (b) nitrite production = 850 {+-} 300 h, and (c) ammonia production = 650 {+-} 300 h. Calculation of the influence of nitrate reduction on the 100D Area reductive capacity requires consideration of mass balance and reaction rate effects. While dissolved oxygen and chromate reduction rates are rapid and essentially at equilibrium in the aquifer, nitrate transformation reactions are slow (100s of hours). In the limited (20-40 day) residence time in the ISRM barrier, only a portion of the nitrate will be reduced, whereas dissolved oxygen and chromate are reduced to completion. Assuming a groundwater flow rate of 1 ft/day, it is estimated that the ISRM barrier reductive capacity is 160 pore volumes (with no nitrate), and 85 pore volumes if 60 mg/L nitrate is present (i.e., a 47% decrease in the ISRM barrier longevity). Zones with more rapid groundwater flow will be less influenced by nitrate reduction. For example, a zone with a groundwater flow rate of 3 ft/day and 60 mg/L ...
Date: July 15, 2005
Creator: Szecsody, Jim E.; Phillips, Jerry L.; Vermeul, Vince R.; Fruchter, Jonathan S. & Williams, Mark D.
Partner: UNT Libraries Government Documents Department

2002 Initial Assessments for B-BX-BY Field Investigation Report (FIR): Numerical Simulations

Description: IIn support of CH2M HILL Hanford Group, Inc.'s (CHG) preparation of a Field Investigative Report (FIR) for the Hanford Site Single-Shell Tank (SST) Waste Management Area (WMA) B-BX-BY, a set of numerical simulations of flow and solute transport was executed to predict the performance of surface barriers for reducing long-term risks from potential groundwater contamination at the B-BX-BY WMA. This report documents the simulation of 14 cases involving two-dimensional cross sections through the B-BX-BY WMA. Two cross-sections were used for this analysis, one through the BX WMA from tanks BX-108 to BX-102, and another through the trench B-38 for simulating B trench discharges. The simulations were used to investigate the impact of surface barriers, water-line leaks, inventory placement, meteoric recharge and partitioning between the aqueous and sorbed phases. Three transported solutes were considered: uranium-238 (U-238), technetium-99 (Tc-99), and nitrate (NO3). For the BX tank simulations, results showed that simulations investigating water-line leaks demonstrated the highest peak concentrations. Interim barriers had a significant impact on peak concentrations in later times, but not in early times due to a high concentration zone of contaminants near the water table. Overall, simulation results for the BX WMA showed that only a small fraction of the U-238 inventory migrated from the vadose zone in most of the test cases. In general, similar peak WMA concentrations occurred for all of the simulations (<800 pCi/L for Tc-99 and <800 mg/L for NO3), with the exception of the water-line leak cases. In the B trench cases, simulations predicted that the U-238 would not migrate from the vadose zone to the aquifer in the thousand years that were simulated. The simulations also predicted that Tc-99 would appear quickly in the aquifer following the trench discharge in 1954, with peak concentrations occurring around 2020 to 2030.
Date: August 25, 2002
Creator: Freedman, Vicky L.; Williams, Mark D.; Cole, C. R.; White, Mark D. & Bergeron, Marcel P.
Partner: UNT Libraries Government Documents Department

Hanford 100-N Area In Situ Apatite and Phosphate Emplacement by Groundwater and Jet Injection: Geochemical and Physical Core Analysis

Description: The purpose of this study is to evaluate emplacement of phosphate into subsurface sediments in the Hanford Site 100-N Area by two different technologies: groundwater injection of a Ca-citrate-PO4 solution and water-jet injection of sodium phosphate and/or fish-bone apatite. In situ emplacement of phosphate and apatite adsorbs, then incorporates Sr-90 into the apatite structure by substitution for calcium. Overall, both technologies (groundwater injection of Ca-citrate-PO4) and water-jet injection of sodium phosphate/fish-bone apatite) delivered sufficient phosphate to subsur¬face sediments in the 100-N Area. Over years to decades, additional Sr-90 will incorporate into the apatite precipitate. Therefore, high pressure water jetting is a viable technology to emplace phosphate or apatite in shallow subsurface sediments difficult to emplace by Ca-citrate-PO4 groundwater injections, but further analysis is needed to quantify the relevant areal extent of phosphate deposition (in the 5- to 15-ft distance from injection points) and cause of the high deposition in finer grained sediments.
Date: July 1, 2010
Creator: Szecsody, James E.; Vermeul, Vincent R.; Fruchter, Jonathan S.; Williams, Mark D.; Rockhold, Mark L.; Qafoku, Nikolla et al.
Partner: UNT Libraries Government Documents Department

Effect of Geochemical and Physical Heterogeneity on the Hanford 100D Area In Situ Redox Manipulation Barrier Longevity

Description: The purpose of this study was to quantify the influence of physical and/or geochemical heterogeneities in the Hanford 100D area In Situ Redox Manipulation (ISRM) barrier, which may be contributing to the discontinuous chromate breakthrough locations along the 65-well (2,300 ft long) barrier. Possible causes of chromate breakthrough that were investigated during this study include: i) high hydraulic conductivity zones; ii) zones of low reducible iron; and iii) high hydraulic conductivity zones with low reducible iron. This laboratory-scale investigation utilized geochemical and physical characterization data collected on 0.5 to 1 foot intervals from four borehole locations.Results of this laboratory study did not provide definitive support any of the proposed hypotheses for explaining chromate breakthrough at the Hanford 100-D Area ISRM barrier. While site characterization data indicate a significant degree of vertical variability in both physical and geochemical properties in the four boreholes investigated, lateral continuity of high conductivity / low reductive capacity zones was not observed. The one exception was at the water table, where low reductive capacity and high-K zones were observed in 3 of four boreholes.Laterally continuous high permeability zones that contain oxic sediment near the water table is the most likely explanation for high concentration chromium breakthrough responses observed at various locations along the barrier. A mechanism that could explain partial chromate breakthrough in the ISRM barrier is the relationship between the field reductive capacity and the rate of chromate oxidation. Subsurface zones with low reductive capacity still have sufficient ferrous iron mass to reduce considerable chromate, but the rate of chromate reduction slows by 1 to 2 orders of magnitude relative to sediments with moderate to high reductive capacity.The original barrier longevity estimate of 160 pore volumes for homogeneous reduced sediment, or approximately 20 years, (with 5 mg/L dissolved oxygen and 2 ppm chromate) is reduced ...
Date: December 22, 2005
Creator: Szecsody, Jim E.; Fruchter, Jonathan S.; Phillips, Jerry L.; Rockhold, Mark L.; Vermeul, Vince R.; Williams, Mark D. et al.
Partner: UNT Libraries Government Documents Department

Effect of Geochemical and Physical Heterogeneity on the Hanford 100D Area In Situ Redox Manipulation Barrier Longevity

Description: The purpose of this study was to quantify the influence of physical and/or geochemical heterogeneities in the Hanford 100D area In Situ Redox Manipulation (ISRM) barrier, which may be contributing to the discontinuous chromate breakthrough locations along the 65-well (2,300 ft long) barrier. Possible causes of chromate breakthrough that were investigated during this study include: (1) high hydraulic conductivity zones; (2) zones of low reducible iron; and (3) high hydraulic conductivity zones with low reducible iron. This laboratory-scale investigation utilized geochemical and physical characterization data collected on 0.5 to 1 foot intervals from four borehole locations. Results of this laboratory study did not provide definitive support any of the proposed hypotheses for explaining chromate breakthrough at the Hanford 100-D Area ISRM barrier. While site characterization data indicate a significant degree of vertical variability in both physical and geochemical properties in the four boreholes investigated, lateral continuity of high conductivity/low reductive capacity zones was not observed. The one exception was at the water table, where low reductive capacity and high-K zones were observed in 3 of four boreholes. Laterally continuous high permeability zones that contain oxic sediment near the water table is the most likely explanation for high concentration chromium breakthrough responses observed at various locations along the barrier. A mechanism that could explain partial chromate breakthrough in the ISRM barrier is the relationship between the field reductive capacity and the rate of chromate oxidation. Subsurface zones with low reductive capacity still have sufficient ferrous iron mass to reduce considerable chromate, but the rate of chromate reduction slows by 1 to 2 orders of magnitude relative to sediments with moderate to high reductive capacity. The original barrier longevity estimate of 160 pore volumes for homogeneous reduced sediment, or approximately 20 years, (with 5 mg/L dissolved oxygen and 2 ppm chromate) is ...
Date: November 30, 2005
Creator: Szecsody, Jim E.; Vermeul, Vince R.; Fruchter, Jonathan S.; Williams, Mark D.; Phillips, Jerry L.; Devary, Brooks J. et al.
Partner: UNT Libraries Government Documents Department

In Situ Redox Manipulation Proof-of-Principle Test at the Fort Lewis Logistics Center: Final Report

Description: Pacific Northwest National Laboratory conducted a proof-of-principle test at the Fort Lewis Logistics Center to determine the feasibility of using the innovative remedial technology In Situ Redox Manipulation (ISRM) to treat groundwater contaminated with dissolved TCE. ISRM creates a permeable treatment zone in the subsurface to remediate redox-sensitive contaminants in groundwater. The permeable treatment zone is created by injecting a chemical reducing agent (sodium dithionite with pH buffers) into the aquifer through a well to chemically reduce the naturally occurring ferric iron in the sediments to ferrous iron. Once the reducing agent has been given sufficient time to react with aquifer sediments, residual chemicals and reaction products are withdrawn through the same well. Redox-sensitive contaminants such as TCE, moving in a dissolved-phase plume through the treatment zone, are destroyed. TCE is degraded via reductive dechlorination within the treatment zone to benign degradation products (acetylene, ehtylene). Analyses of sediment samples collected from post-test boreholes showed a high degree of iron reduction, which confirmed the effectiveness of the treatment zone.
Date: October 25, 2000
Creator: Vermeul, Vincent R.; Williams, Mark D.; Evans, John C.; Szecsody, James E.; Bjornstad, Bruce N. & Liikala, Terry L.
Partner: UNT Libraries Government Documents Department

Development of Models to Simulate Tracer Tests for Characterization of Enhanced Geothermal Systems

Description: A recent report found that power and heat produced from enhanced (or engineered) geothermal systems (EGSs) could have a major impact on the U.S energy production capability while having a minimal impact on the environment. EGS resources differ from high-grade hydrothermal resources in that they lack sufficient temperature distribution, permeability/porosity, fluid saturation, or recharge of reservoir fluids. Therefore, quantitative characterization of temperature distributions and the surface area available for heat transfer in EGS is necessary for the design and commercial development of the geothermal energy of a potential EGS site. The goal of this project is to provide integrated tracer and tracer interpretation tools to facilitate this characterization. This project was initially focused on tracer development with the application of perfluorinated tracer (PFT) compounds, non-reactive tracers used in numerous applications from atmospheric transport to underground leak detection, to geothermal systems, and evaluation of encapsulated PFTs that would release tracers at targeted reservoir temperatures. After the 2011 midyear review and subsequent discussions with the U.S. Department of Energy Geothermal Technology Program (GTP), emphasis was shifted to interpretive tool development, testing, and validation. Subsurface modeling capabilities are an important component of this project for both the design of suitable tracers and the interpretation of data from in situ tracer tests, be they single- or multi-well tests. The purpose of this report is to describe the results of the tracer and model development for simulating and conducting tracer tests for characterizing EGS parameters.
Date: May 1, 2013
Creator: Williams, Mark D.; Reimus, Paul; Vermeul, Vincent R.; Rose, Peter; Dean, Cynthia A.; Watson, Tom B. et al.
Partner: UNT Libraries Government Documents Department

Remediation of Uranium in the Hanford Vadose Zone Using Gas-Transported Reactants: Laboratory Scale Experiments in Support of the Deep Vadose Zone Treatability Test Plan for the Hanford Central Plateau

Description: This laboratory-scale investigation is focused on decreasing mobility of uranium in subsurface contaminated sediments in the vadose zone by in situ geochemical manipulation at low water content. This geochemical manipulation of the sediment surface phases included reduction, pH change (acidic and alkaline), and additions of chemicals (phosphate, ferric iron) to form specific precipitates. Reactants were advected into 1-D columns packed with Hanford 200 area U-contaminated sediment as a reactive gas (for CO2, NH3, H2S, SO2), with a 0.1% water content mist (for NaOH, Fe(III), HCl, PO4) and with a 1% water content foam (for PO4). Uranium is present in the sediment in multiple phases that include (in decreasing mobility): aqueous U(VI) complexes, adsorbed U, reduced U(IV) precipitates, rind-carbonates, total carbonates, oxides, silicates, phosphates, and in vanadate minerals. Geochemical changes were evaluated in the ability to change the mixture of surface U phases to less mobile forms, as defined by a series of liquid extractions that dissolve progressively less soluble phases. Although liquid extractions provide some useful information as to the generalized uranium surface phases (and are considered operational definitions of extracted phases), positive identification (by x-ray diffraction, electron microprobe, other techniques) was also used to positively identify U phases and effects of treatment. Some of the changes in U mobility directly involve U phases, whereas other changes result in precipitate coatings on U surface phases. The long-term implication of the U surface phase changes to alter U mass mobility in the vadose zone was then investigated using simulations of 1-D infiltration and downward migration of six U phases to the water table. In terms of the short-term decrease in U mobility (in decreasing order), NH3, NaOH mist, CO2, HCl mist, and Fe(III) mist showed 20% to 35% change in U surface phases. Phosphate addition (mist or foam advected) showed inconsistent ...
Date: January 4, 2010
Creator: Szecsody, James E.; Truex, Michael J.; Zhong, Lirong; Williams, Mark D.; Resch, Charles T. & McKinley, James P.
Partner: UNT Libraries Government Documents Department

Uranium Mobility During In Situ Redox Manipulation of the 100 Areas of the Hanford Site

Description: A series of laboratory experiments and computer simulations was conducted to assess the extent of uranium remobilization that is likely to occur at the end of the life cycle of an in situ sediment reduction process. The process is being tested for subsurface remediation of chromate and chlorinated solvent-contaminated sediments at the Hanford Site in southeastern Washington. Uranium species that occur naturally in the +6 valence state [U(VI)] at 10 ppb in groundwater at Hanford will accumulate as U(IV) through the reduction and subsequent precipitation conditions of the permeable barrier created by in situ redox manipulation. The precipitated uranium will be remobilized when the reductive capacity of the barrier is exhausted and the sediment is oxidized by the groundwater containing dissolved oxygen and other oxidants such as chromate. Although U(IV) accumulates from years or decades of reduction/precipitation within the reduced zone, U(VI) concentrations in solution are only somewhat elevated during aquifer oxidation because oxidation and dissolution reactions that release U(IV) precipitate to solution are slow. The release rate of uranium into solution was found to be controlled mainly by the oxidation/dissolution rate of the U(IV) precipitate (half-life 200 hours) and partially by the fast oxidation of adsorbed Fe(II) (halflife 5 hours) and the slow oxidation of Fe(II)CO3 (half-life 120 hours) in the reduced sediment. Simulations of uranium transport that incorporated these and other reactions under site-relevant conditions indicated that 35 ppb U(VI) is the maximum concentration likely to result from mobilization of the precipitated U(IV) species. Experiments also indicated that increasing the contact time between the U(IV) precipitates and the reduced sediment, which is likely to occur in the field, results in a slower U(IV) oxidation rate, which, in turn, would lower the maximum concentration of mobilized U(VI)...
Date: December 3, 1998
Creator: Szecsody, James E.; Krupka, Kenneth M.; Williams, Mark D.; Cantrell, Kirk J.; Resch, Charles T. & Fruchter, Jonathan S.
Partner: UNT Libraries Government Documents Department

Treatability Test Plan for 300 Area Uranium Stabilization through Polyphosphate Injection

Description: The U.S. Department of Energy has initiated a study into possible options for stabilizing uranium at the 300 Area using polyphosphate injection. As part of this effort, PNNL will perform bench- and field-scale treatability testing designed to evaluate the efficacy of using polyphosphate injections to reduced uranium concentrations in the groundwater to meet drinking water standards (30 ug/L) in situ. This technology works by forming phosphate minerals (autunite and apatite) in the aquifer that directly sequester the existing aqueous uranium in autunite minerals and precipitates apatite minerals for sorption and long term treatment of uranium migrating into the treatment zone, thus reducing current and future aqueous uranium concentrations. Polyphosphate injection was selected for testing based on technology screening as part of the 300-FF-5 Phase III Feasibility Study for treatment of uranium in the 300-Area.
Date: June 1, 2007
Creator: Vermeul, Vincent R.; Williams, Mark D.; Fritz, Brad G.; Mackley, Rob D.; Mendoza, Donaldo P.; Newcomer, Darrell R. et al.
Partner: UNT Libraries Government Documents Department

300 Area Uranium Stabilization Through Polyphosphate Injection: Final Report

Description: The objective of the treatability test was to evaluate the efficacy of using polyphosphate injections to treat uranium-contaminated groundwater in situ. A test site consisting of an injection well and 15 monitoring wells was installed in the 300 Area near the process trenches that had previously received uranium-bearing effluents. This report summarizes the work on the polyphosphate injection project, including bench-scale laboratory studies, a field injection test, and the subsequent analysis and interpretation of the results. Previous laboratory tests have demonstrated that when a soluble form of polyphosphate is injected into uranium-bearing saturated porous media, immobilization of uranium occurs due to formation of an insoluble uranyl phosphate, autunite [Ca(UO2)2(PO4)2•nH2O]. These tests were conducted at conditions expected for the aquifer and used Hanford soils and groundwater containing very low concentrations of uranium (10-6 M). Because autunite sequesters uranium in the oxidized form U(VI) rather than forcing reduction to U(IV), the possibility of re-oxidation and subsequent re-mobilization is negated. Extensive testing demonstrated the very low solubility and slow dissolution kinetics of autunite. In addition to autunite, excess phosphorous may result in apatite mineral formation, which provides a long-term source of treatment capacity. Phosphate arrival response data indicate that, under site conditions, the polyphosphate amendment could be effectively distributed over a relatively large lateral extent, with wells located at a radial distance of 23 m (75 ft) reaching from between 40% and 60% of the injection concentration. Given these phosphate transport characteristics, direct treatment of uranium through the formation of uranyl-phosphate mineral phases (i.e., autunite) could likely be effectively implemented at full field scale. However, formation of calcium-phosphate mineral phases using the selected three-phase approach was problematic. Although amendment arrival response data indicate some degree of overlap between the reactive species and thus potential for the formation of calcium-phosphate mineral phases (i.e., apatite ...
Date: June 30, 2009
Creator: Vermeul, Vincent R.; Bjornstad, Bruce N.; Fritz, Brad G.; Fruchter, Jonathan S.; Mackley, Rob D.; Newcomer, Darrell R. et al.
Partner: UNT Libraries Government Documents Department

Interim Report: 100-NR-2 Apatite Treatability Test: Low Concentration Calcium Citrate-Phosphate Solution Injection for In Situ Strontium-90 Immobilization

Description: Following an evaluation of potential Sr-90 treatment technologies and their applicability under 100-NR-2 hydrogeologic conditions, U.S. Department of Energy, Fluor Hanford, Inc., Pacific Northwest National Laboratory, and the Washington Department of Ecology agreed that the long-term strategy for groundwater remediation at 100-N Area will include apatite sequestration as the primary treatment, followed by a secondary treatment if necessary (most likely phytoremediation). Since then, the agencies have worked together to agree on which apatite sequestration technology has the greatest chance of reducing Sr-90 flux to the river at a reasonable cost. In July 2005, aqueous injection, (i.e., the introduction of apatite-forming chemicals into the subsurface) was endorsed as the interim remedy and selected for field testing. Studies are in progress to assess the efficacy of in situ apatite formation by aqueous solution injection to address both the vadose zone and the shallow aquifer along the 300 ft of shoreline where Sr-90 concentrations are highest. This report describes the field testing of the shallow aquifer treatment.
Date: July 11, 2008
Creator: Williams, Mark D.; Fritz, Brad G.; Mendoza, Donaldo P.; Rockhold, Mark L.; Thorne, Paul D.; Xie, YuLong et al.
Partner: UNT Libraries Government Documents Department