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

Vermeul, V. R.; Williams, MD; Evans, Janice Perry; Szecsody, J. E.; Bjornstad, BN; Liikala, T.L.

doi:10.2172/765728

Cited by 2 publications

(2 citation statements)

References 14 publications

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“…Sodium dithionite is an effective uranium and iron phase reductant that can be injected under highly alkaline (aqueous) conditions, as demonstrated in laboratory and field scale Vermeul et al 2004). Dithionite can be used to reduce and precipitate UO 2 , then dissociates to sulfate over a period of days.…”

Section: Redox/ph Manipulation By Sodium Dithionite Injection (1% Water)mentioning

confidence: 99%

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

Szecsody¹,

Truex²,

Zhong³

et al. 2010

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This laboratory-scale investigation focused on decreasing uranium mobility 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 and ferric iron) to form specific precipitates. Reactants were advected into one-dimensional columns packed with uranium-contaminated sediment from the 200 Area of the Hanford Site as a reactive gas (for CO 2 , NH 3 , H 2 S, SO 2 ), with a 0.1% water content mist [for NaOH, Fe(III), HCl, PO 4 ] and with a 1% water content foam (for PO 4 ).Uranium is present in the sediment in multiple phases that include (in decreasing mobility) the following: aqueous U(VI) complexes, adsorbed uranium, reduced U(IV) precipitates, rind-carbonates, total carbonates, oxides, silicates, and phosphates. Geochemical changes were evaluated in the ability to change the mixture of surface uranium 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 of surface phase changes by electron microprobe analysis is in progress. Some of the changes in uranium mobility directly involve uranium phases, whereas other changes result in precipitate coatings on uranium surface phases. The long-term implication of the uranium surface phase changes to alter uranium mass mobility in the vadose zone was then investigated using simulations of one-dimensional infiltration and downward migration of six uranium phases to the water table.In terms of the short-term decrease in uranium mobility (in decreasing order), NH 3 , NaOH mist, CO 2 , HCl mist, and Fe(III) mist showed 20% to 35% change in uranium surface phases. Difference in treatment effectiveness between sediments likely reflects mineralogy. Phosphate addition (mist or foam advected) showed inconsistent change in aqueous and adsorbed uranium, but significant coating (likely phosphates) on uranium carbonates. The two reductive gas treatments (H 2 S and SO 2 ) showed little change. For long-term decrease in uranium reduction, mineral phases created that had low solubility (phosphates and silicates) were desired, so NH 3 , phosphates (mist and foam delivered), and NaOH mist showed the greatest formation of these minerals. In addition, simulations of uranium movement in the vadose zone showed that these treatments greatly decreased uranium transport to groundwater. Advection of reactive gasses was the easiest to implement into low water content sediments at the laboratory-scale (and presumably field-scale) experiments. Both mist and foam advection show potential and need further development, but current implementation techniques move reactants shorter distances relative to reactive gasses. Overall, the am...

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Section: Redox/ph Manipulation By Sodium Dithionite Injection (1% Water)mentioning

confidence: 99%

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

Szecsody¹,

Truex²,

Zhong³

et al. 2010

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“…A number of dynamic flowmeter surveys, however, have been successfully completed at other Hanford Site locations, e.g., 300 Area and 100-D Area, to provide detailed hydraulic-conductivity vs. depth-profile information (e.g., Newcomer, 2009). Examples of using EBF survey information to develop vertical depth profiles of hydraulic conductivity and geostatistical realizations within the surrounding aquifer materials at other, non-Hanford Site locations are also presented in Vermeul et al (2004) and Li et al (2008).…”

Section: 10mentioning

confidence: 99%

Field Test Report: Preliminary Aquifer Test Characterization Results for Well 299-W15-225: Supporting Phase I of the 200-ZP-1 Groundwater Operable Unit Remedial Design

Spane¹,

Newcomer²

2009

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A number of remedial action programs have been implemented on the Hanford Site that employ pump-and-treat well systems to control and treat contaminated groundwater as part of their remediation strategy. Predictive modeling and optimization of the design of large-scale pump-and-treat systems (particularly within thick unconfined aquifers), however, require additional hydrologic characterization information that is not commonly available at most extensively contaminated groundwater sites. To meet these objectives, the acquisition of large-scale hydraulic and storage properties and the vertical distribution profile of aquifer hydraulic conductivity are particularly critical in accurately modeling the performance of the pump-and-treat system. The addition of newly constructed extraction wells to a pump-and-treat system affords the opportunity to acquire both local hydraulic property versus depth profile information as well as large-scale aquifer characterization information. This hydraulic characterization information can be obtained both during well construction (i.e., selective well-depth characterization) and/or following construction of wells designed with long well-screen completions.This report examines the hydrologic test results for both local vertical profile characterization and large-scale hydrologic tests associated with a new extraction well (well 299-W15-225) that was constructed during FY2009 for inclusion within the future 200-West Area Groundwater Treatment System that is scheduled to go on-line at the end of FY2011. To facilitate the analysis of the large-scale hydrologic test performed at newly constructed extraction well 299-W15-225 (C7017; also referred to as EW-1 in some planning documents), the existing 200-ZP-1 interim pump-and-treat system was completely shut-down ~1 month before the performance of the large-scale hydrologic test. Specifically, this report 1) applies recently developed methods for removing barometric pressure fluctuations from well water-level measurements to enhance the detection of hydrologic test and pump-and-treat system effects at selected monitor wells, 2) analyzes the barometric-corrected well water-level responses for a preliminary determination of large-scale hydraulic properties, and 3) provides an assessment of the vertical distribution of hydraulic conductivity in the vicinity of newly constructed extraction well 299-W15-225. The hydrologic characterization approach presented in this report is expected to have universal application for meeting the characterization needs at other remedial action sites located within unconfined and confined aquifer systems. v Summary A final Record of Decision (EPA et al. 2008) for the 200-ZP-1 groundwater operable unit was signed by the U.S. Environmental Protection Agency (EPA), the U.S. Department of Energy (DOE), and the Washington Department of Ecology on September 30, 2008. The final selected remedy for this groundwater operable unit (OU) is a combination of pump-and-treat, monitored natural attenuation, flowpath con...

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

Cited by 2 publications

References 14 publications

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

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

Field Test Report: Preliminary Aquifer Test Characterization Results for Well 299-W15-225: Supporting Phase I of the 200-ZP-1 Groundwater Operable Unit Remedial Design

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