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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

In Situ Redox Manipulation of Subsurface Sediments from Fort Lewis, Washington: Iron Reduction and TCE Dechlorination Mechanisms

Description: The feasibility of chemically treating sediments from the Ft. Lewis, Washington, Logistics Center to develop a permeable barrier for dechlorination of TCE was investigated in a series of laboratory experiments.
Date: March 17, 2000
Creator: Szecsody, James E.; Fruchter, Jonathan S.; Sklarew, Deborah S. & Evans, John C.
Partner: UNT Libraries Government Documents Department

Feasibility of In Situ Redox Manipulation of Subsurface Sediments for RDX Remediation at Pantex

Description: This laboratory study was conducted to assess RDX (hexahydro-1,3,5-trinitro-1,3,5 triazine) abiotic degradation by chemically reduced sediments and other geochemical aspects of the application of this technology to remediation of RDX contamination in groundwater at the U.S. DOE Pantex facility...
Date: December 31, 2001
Creator: Szecsody, James E.; Fruchter, Jonathan S.; Mckinley, Mark A.; Resch, Charles T. & Gilmore, Tyler J.
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

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

Overcoming Barriers to the Remediation of Carbon Tetrachloride through Manipulation of Competing Reaction Mechanisms

Description: Most approaches that have been proposed for the remediation of groundwater contaminated with carbon tetrachloride (CCl4) produce chloroform (CHCl3) as the major product and methylene chloride (CH2Cl2) as a minor product. Both of these products are nearly as persistent and problematic as the parent compound, but competing reaction pathways produce the more desirable products carbon monoxide (CO) and/or formate (HCOO-). Results scattered throughout the chemical and environmental engineering literature show that the branching between these reaction pathways is highly variable, but the controlling factors have not been identified. If we understood the fundamental chemistry that controls the branching among these, and related, product-formation pathways, we could improve the applicability of a host of remediation technologies (both chemical and biological) to the large plumes of CCl4 that contaminate DOE sites across the country. This project will provide the first complete characterization of the mechanisms and kinetics of competing degradation reactions of CCl4 through laboratory experiments in simple model systems closely coordinated with theoretical modeling studies. The results provide strategies for maximizing the yield of desirable products from CCl4 degradation, and the most promising of these will be tested in column model systems using real site waters and matrix materials.
Date: June 1, 2004
Creator: Tratnyek, Paul G.; Amonette, James E. & Bylaska, Eric J. and Szecsody, James E.
Partner: UNT Libraries Government Documents Department

Overcoming Barriers to the Remediation of Carbon Tetrachloride through Manipulation of Competing Reaction Mechanisms

Description: Most approaches that have been proposed for the remediation of groundwater contaminated with carbon tetrachloride (CCl{sub 4}) produce chloroform (CHCl{sub 3}) as the major product and methylene chloride (CH{sub 2}Cl{sub 2}) as a minor product. Both of these products are nearly as persistent and problematic as the parent compound, but competing reaction pathways produce the more desirable products carbon monoxide (CO) and/or formate (HCOO{sup -}). Results scattered throughout the chemical and environmental engineering literature show that the branching between these reaction pathways is highly variable, but the controlling factors have not been identified. If we understood the fundamental chemistry that controls the branching among these, and related, product-formation pathways, we could improve the applicability of a host of remediation technologies (both chemical and biological) to the large plumes of CCl{sub 4} that contaminate DOE sites across the country. This project will provide the first complete characterization of the mechanisms and kinetics of competing degradation reactions of CCl{sub 4} through laboratory experiments in simple model systems closely coordinated with theoretical modeling studies. The results provide strategies for maximizing the yield of desirable products from CCl{sub 4} degradation, and the most promising of these will be tested in column model systems using real site waters and matrix materials.
Date: June 1, 2003
Creator: Tratnyek, Paul G.; Amonette, James E.; Bylaska, Eric J. & Szecsody, James E.
Partner: UNT Libraries Government Documents Department

Overcoming Barriers to the Remediation of Carbon Tetrachloride through Manipulation of Competing Reaction Mechanisms

Description: Most approaches that have been proposed for the remediation of groundwater contaminated with carbon tetrachloride (CCl{sub 4}) produce chloroform (CHCl{sub 3}) as the major product and methylene chloride (CH{sub 2}Cl{sub 2}) as a minor product. Both of these products are nearly as persistent and problematic as the parent compound, but competing reaction pathways produce the more desirable products carbon monoxide (CO) and/or formate (HCOO{sup -}). Results scattered throughout the chemical and environmental engineering literature show that the branching between these reaction pathways is highly variable, but the controlling factors have not been identified. If we understood the fundamental chemistry that controls the branching among these, and related, product-formation pathways, we could improve the applicability of a host of remediation technologies (both chemical and biological) to the large plumes of CCl{sub 4} that contaminate DOE sites across the country. This project will provide the first complete characterization of the mechanisms and kinetics of competing degradation reactions of CCl{sub 4} through laboratory experiments in simple model systems closely coordinated with theoretical modeling studies. The results provide strategies for maximizing the yield of desirable products from CCl{sub 4} degradation, and the most promising of these will be tested in column model systems using real site waters and matrix materials.
Date: June 15, 2004
Creator: Tratnyek, Paul G.; Amonette, James E.; Bylaska, Eric J. & Szecsody, James E.
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

SERDP ER-1421 Abiotic and Biotic Mechanisms Controlling In Situ Remediation of NDMA: Final Report

Description: This laboratory-scale project was initiated to investigate in situ abiotic/biotic mineralization of NDMA. Under iron-reducing conditions, aquifer sediments showed rapid abiotic NDMA degradation to dimethylamine (DMA), nitrate, formate, and finally, CO2. These are the first reported experiments of abiotic NDMA mineralization. The NDMA reactivity of these different iron phases showed that adsorbed ferrous iron was the dominant reactive phase that promoted NDMA reduction, and other ferrous phases present (siderite, iron sulfide, magnetite, structural ferrous iron in 2:1 clays) did not promote NDMA degradation. In contrast, oxic sediments that were biostimulated with propane promoted biomineralization of NDMA by a cometabolic monooxygenase enzyme process. Other monooxygenase enzyme processes were not stimulated with methane or toluene additions, and acetylene addition did not block mineralization. Although NDMA mineralization extent was the highest in oxic, biostimulated sediments (30 to 82%, compared to 10 to 26% for abiotic mineralization in reduced sediments), large 1-D column studies (high sediment/water ratio of aquifers) showed 5.6 times higher NDMA mineralization rates in reduced sediment (half-life 410 ± 147 h) than oxic biomineralization (half life 2293 ± 1866 h). Sequential reduced/oxic biostimulated sediment mineralization (half-life 3180 ± 1094 h) was also inefficient compared to reduced sediment. These promising laboratory-scale results for NDMA mineralization should be investigated at field scale. Future studies of NDMA remediation should focus on the comparison of this in situ abiotic NDMA mineralization (iron-reducing environments) to ex situ biomineralization, which has been shown successful in other studies.
Date: September 30, 2009
Creator: Szecsody, James E.; McKinley, James P.; Crocker, Fiona H.; Breshears, Andrew T.; Devary, Brooks J.; Fredrickson, Herbert L. 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

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

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

Hanford 100N Area Apatite Emplacement: Laboratory Results of Ca-Citrate-PO4 Solution Injection and Sr-90 Immobilization in 100N Sediments

Description: This report summarizes laboratory scale studies investigating the remediation of Sr-90 by Ca-citrate-PO4 solution injection/infiltration to support field injection activities in the Hanford 100N area. This study is focused on experimentally testing whether this remediation technology can be effective under field scale conditions to mitigate Sr-90 migration 100N area sediments into the Columbia River. Sr-90 is found primarily adsorbed to sediments by ion exchange (99% adsorbed, < 1% in groundwater) in the upper portion of the unconfined aquifer and lower vadose zone. Although primarily adsorbed, Sr-90 is still considered a high mobility risk as it is mobilized by seasonal river stage increases and by plumes of higher ionic strength relative to groundwater. This remediation technology relies upon the Ca-citrate-PO4 solution forming apatite precipitate [Ca6(PO4)10(OH)2], which incorporates some Sr-90 during initial precipitation and additionally slowly incorporates Sr-90 by solid phase substitution for Ca. Sr substitution occurs because Sr-apatite is thermodynamically more stable than Ca-apatite. Once the Sr-90 is in the apatite structure, Sr-90 will decay to Y-90 (29.1 y half-life) then Zr-90 (64.1 h half-life) without the potential for migration into the Columbia River. For this technology to be effective, sufficient apatite needs to be emplaced in sediments to incorporate Sr and Sr-90 for 300 years (~10 half-lives of Sr-90), and the rate of incorporation needs to exceed the natural groundwater flux rate of Sr in the 100N area. A primary objective of this study is to supply an injection sequence to deliver sufficient apatite into subsurface sediments that minimizes initial mobility of Sr-90, which occurs because the injection solution has a higher ionic strength compared to groundwater. This can be accomplished by sequential injections of low, then high concentration injection of Ca-citrate-PO4 solutions. Assessment of low concentration Ca-citrate-PO4, citrate-PO4, and PO4 solutions show greater Sr and Sr-90 incorporation during initial ...
Date: October 1, 2007
Creator: Szecsody, James E.; Burns, Carolyn A.; Moore, Robert C.; Fruchter, Jonathan S.; Vermeul, Vincent R.; Williams, Mark D. et al.
Partner: UNT Libraries Government Documents Department

100-NR-2 Apatite Treatability Test: Fall 2010 Tracer Infiltration Test (White Paper)

Description: The primary objectives of the tracer infiltration test were to 1) determine whether field-scale hydraulic properties for the compacted roadbed materials and underlying Hanford fm. sediments comprising the zone of water table fluctuation beneath the site are consistent with estimates based laboratory-scale measurements on core samples and 2) characterize wetting front advancement and distribution of soil moisture achieved for the selected application rate. These primary objectives were met. The test successfully demonstrated that 1) the remaining 2 to 3 ft of compacted roadbed material below the infiltration gallery does not limit infiltration rates to levels that would be expected to eliminate near surface application as a viable amendment delivery approach and 2) the combined aqueous and geophysical monitoring approaches employed at this site, with some operational adjustments based on lessons learned, provides an effective means of assessing wetting front advancement and the distribution of soil moisture achieved for a given solution application. Reasonably good agreement between predicted and observed tracer and moisture front advancement rates was observed. During the first tracer infiltration test, which used a solution application rate of 0.7 cm/hr, tracer arrivals were observed at the water table (10 to 12 ft below the bottom of the infiltration gallery) after approximately 5 days, for an advancement rate of approximately 2 ft/day. This advancement rate is generally consistent with pre-test modeling results that predicted tracer arrival at the water table after approximately 5 days (see Figure 8, bottom left panel). This agreement indicates that hydraulic property values specified in the model for the compacted roadbed materials and underlying Hanford formation sediments, which were based on laboratory-scale measurements, are reasonable estimates of actual field-scale conditions. Additional work is needed to develop a working relationship between resistivity change and the associated change in moisture content so that 4D images of moisture ...
Date: April 14, 2011
Creator: Vermeul, Vincent R.; Fritz, Brad G.; Fruchter, Jonathan S.; Greenwood, William J.; Johnson, Timothy C.; Horner, Jacob A. et al.
Partner: UNT Libraries Government Documents Department

Factors Effecting the Fate and Transport of CL-20 in the Vadose Zone and Groundwater: Final Report 2002 - 2004 SERDP Project CP-1255

Description: This SERDP-funded project was initiated to investigate the fate of CL-20 in the subsurface environment, with a focus on identification and quantification of geochemical and microbial reactions of CL-20. CL-20 can be released to the surface and subsurface terrestrial environment by: a) manufacturing processes, b) munition storage, and c) use with low order detonation or unexploded ordnance. The risk of far-field subsurface migration was assessed through labora-tory experiments with a variety of sediments and subsurface materials to quantify processes that control CL-20 sorption-limited migration and degradation. Results of this study show that CL-20 will exhibit differing behavior in the subsurface terrestrial environment: 1. CL-20 on the sediment surface will photodegrade and interact with plants/animals (described in other SERDP projects CU 1254, 1256). CL-20 will exhibit greater sorption in humid sediments to organic matter. Transport will be solubility limited (i.e., low CL-20 aqueous solubility). 2. CL-20 infiltration into soils (<2 m) from spills will be subject to sorption to soil organic matter (if present), and low to high biodegradation rates (weeks to years) depending on the microbial population (greater in humid environment). 3. CL-20 in the vadose zone (>2 m) will be, in most cases, subject to low sorption and low degradation rates, so would persist in the subsurface environment and be at risk for deep migration. Low water content in arid regions will result in a decrease in both sorption and the degradation rate. Measured degradation rates in unsaturated sediments of years would result in significant subsurface migration distances. 4. CL-20 in groundwater will be subject to some sorption but likely very slow degradation rates. CL-20 sorption will be greater than RDX. Most CL-20 degradation will be abiotic (ferrous iron and other transition metals), because most deep subsurface systems have extremely low natural microbial populations. Degradation rates will range from ...
Date: June 1, 2005
Creator: Szecsody, James E.; Riley, Robert G.; Devary, Brooks J.; Girvin, Donald C.; Resch, Charles T.; Campbell, James A. et al.
Partner: UNT Libraries Government Documents Department

Research Plan: Foam Delivery of Remedial Amendments to Deep Vadose Zone for Metals and Radionuclides Remediation

Description: Research proposals were submitted to the Scientific and Technical Basis for In Situ Treatment of Metals and Radionuclides Technical Working Group under the US Department of Energy (DOE) Environmental Management Office (specifically, EM-22). After a peer review and selection process, the proposal, “Foam Delivery of Remedial Amendments to Deep Vadose Zone for Metals and Radionuclides Remediation,” submitted by Pacific Northwest National Laboratory (PNNL) was selected for support by the program. A research plan was requested for this EM funded project. The overall objective of this project is to develop foam delivery technology for the distribution of remedial amendments to deep vadose zone sediments for in situ immobilization of metal and radionuclide contaminants. The focus of this research in FY 2009 is on the physical aspects of the foam delivery approach. Specific objectives are to 1) study the foam quality (i.e. the gas volume fraction in foam) influence on injection pressure, 2) study the sediment air permeability influence on injection pressure, 3) investigate liquid uptake in sediment and determine whether a water front will be formed during foam delivery, 4) test amendment distance (and mass) delivery by foam from the injection point, 5) study the enhanced sweeping over heterogeneous systems (i.e., low K zones) by foam delivery relative to water-based delivery under vadose zone conditions, and 6) numerically simulate foam delivery processes in the vadose zone. Laboratory scale experiments will be conducted at PNNL to study a range of basic physical aspects of the foam propagation in sediments, including foam quality and sediment permeability influence on injection pressure, liquid uptake, and foam sweeping across heterogeneous systems. This study will be augmented with separate studies to be conducted at MSE Technology Applications, Inc. (MSE) to evaluate foam transport and amendment delivery at the intermediate-scale. The results of intermediate-scale tests will be used ...
Date: January 16, 2009
Creator: Zhong, Lirong; Hart, Andrea T.; Szecsody, James E.; Zhang, Z. F.; Freedman, Vicky L.; Ankeny, Mark et al.
Partner: UNT Libraries Government Documents Department

Remediation of Uranium in the Hanford Vadose Zone Using Ammonia Gas: FY 2010 Laboratory-Scale Experiments

Description: This investigation is focused on refining an in situ technology for vadose zone remediation of uranium by the addition of ammonia (NH3) gas. Objectives are to: a) refine the technique of ammonia gas treatment of low water content sediments to minimize uranium mobility by changing uranium surface phases (or coat surface phases), b) identify the geochemical changes in uranium surface phases during ammonia gas treatment, c) identify broader geochemical changes that occur in sediment during ammonia gas treatment, and d) predict and test injection of ammonia gas for intermediate-scale systems to identify process interactions that occur at a larger scale and could impact field scale implementation.Overall, NH3 gas treatment of low-water content sediments appears quite effective at decreasing aqueous, adsorbed uranium concentrations. The NH3 gas treatment is also fairly effective for decreasing the mobility of U-carbonate coprecipitates, but shows mixed success for U present in Na-boltwoodite. There are some changes in U-carbonate surface phases that were identified by surface phase analysis, but no changes observed for Na-boltwoodite. It is likely that dissolution of sediment minerals (predominantly montmorillonite, muscovite, kaolinite) under the alkaline conditions created and subsequent precipitation as the pH returns to natural conditions coat some of the uranium surface phases, although a greater understanding of these processes is needed to predict the long term impact on uranium mobility. Injection of NH3 gas into sediments at low water content (1% to 16% water content) can effectively treat a large area without water addition, so there is little uranium mobilization (i.e., transport over cm or larger scale) during the injection phase.
Date: December 1, 2010
Creator: Szecsody, James E.; Truex, Michael J.; Zhong, Lirong; Qafoku, Nikolla; Williams, Mark D.; McKinley, James P. et al.
Partner: UNT Libraries Government Documents Department

Anoxic Plume Attenuation in a Fluctuating Water Table System: Impact of 100-D Area In Situ Redox Manipulation on Downgradient Dissolved Oxygen Concentrations

Description: Anoxic Plume Attenuation in a Fluctuating Water Table System: Impact of 100-D Area In Situ Redox Manipulation on Downgradient Dissolved Oxygen Concentrations
Date: June 14, 1999
Creator: Williams, Mark D.; Vermeul, Vincent R.; Oostrom, Martinus; Evans, John C.; Fruchter, Jonathan S.; Istok, J. D. et al.
Partner: UNT Libraries Government Documents Department

Sequestration of Sr-90 Subsurface Contamination in the Hanford 100-N Area by Surface Infiltration of a Ca-Citrate-Phosphate Solution

Description: The objective of this project is to develop a method to emplace apatite precipitate in the 100N vadose zone, which results in sorption and ultimately incorporation of Sr-90 into the apatite structure. The Ca-citrate-PO4 solution can be infiltrated into unsaturated sediments to result in apatite precipitate to provide effective treatment of Sr-90 contamination. Microbial redistribution during solution infiltration and a high rate of citrate biodegradation for river water microbes (water used for solution infiltration) results in a relatively even spatial distribution of the citrate biodegradation rate and ultimately apatite precipitate in the sediment. Manipulation of the Ca-citrate-PO4 solution infiltration strategy can be used to result in apatite precipitate in the lower half of the vadose zone (where most of the Sr-90 is located) and within low-K layers (which are hypothesized to have higher Sr-90 concentrations). The most effective infiltration strategy to precipitate apatite at depth (and with sufficient lateral spread) was to infiltrate a high concentration solution (6 mM Ca, 15 mM citrate, 60 mM PO4) at a rapid rate (near ponded conditions), followed by rapid, then slow water infiltration. Repeated infiltration events, with sufficient time between events to allow water drainage in the sediment profile can be used to buildup the mass of apatite precipitate at greater depth. Low-K heterogeneities were effectively treated, as the higher residual water content maintained in these zones resulted in higher apatite precipitate concentration. High-K zones did not receive sufficient treatment by infiltration, although an alternative strategy of air/surfactant (foam) was demonstrated effective for targeting high-K zones. The flow rate manipulation used in this study to treat specific depths and heterogeneities are not as easy to implement at field scale due to the lack of characterization of heterogeneities and difficulty tracking the wetting front over a large subsurface area. However, the use of real-time ...
Date: March 1, 2009
Creator: Szecsody, James E.; Rockhold, Mark L.; Oostrom, Martinus; Moore, R. C.; Burns, Carolyn A.; Williams, Mark D. et al.
Partner: UNT Libraries Government Documents Department

SERDP ER-1376 Enhancement of In Situ Bioremediation of Energetic Compounds by Coupled Abiotic/Biotic Processes:Final Report for 2004 - 2006

Description: This project was initiated by SERDP to quantify processes and determine the effectiveness of abiotic/biotic mineralization of energetics (RDX, HMX, TNT) in aquifer sediments by combinations of biostimulation (carbon, trace nutrient additions) and chemical reduction of sediment to create a reducing environment. Initially it was hypothesized that a balance of chemical reduction of sediment and biostimulation would increase the RDX, HMX, and TNT mineralization rate significantly (by a combination of abiotic and biotic processes) so that this abiotic/biotic treatment may be a more efficient for remediation than biotic treatment alone in some cases. Because both abiotic and biotic processes are involved in energetic mineralization in sediments, it was further hypothesized that consideration for both abiotic reduction and microbial growth was need to optimize the sediment system for the most rapid mineralization rate. Results show that there are separate optimal abiotic/biostimulation aquifer sediment treatments for RDX/HMX and for TNT. Optimal sediment treatment for RDX and HMX (which have chemical similarities and similar degradation pathways) is mainly chemical reduction of sediment, which increased the RDX/HMX mineralization rate 100 to150 times (relative to untreated sediment), with additional carbon or trace nutrient addition, which increased the RDX/HMX mineralization rate an additional 3 to 4 times. In contrast, the optimal aquifer sediment treatment for TNT involves mainly biostimulation (glucose addition), which stimulates a TNT/glucose cometabolic degradation pathway (6.8 times more rapid than untreated sediment), degrading TNT to amino-intermediates that irreversibly sorb (i.e., end product is not CO2). The TNT mass migration risk is minimized by these transformation reactions, as the triaminotoluene and 2,4- and 2,6-diaminonitrotoluene products that irreversibly sorb are no longer mobile in the subsurface environment. These transformation rates are increased 13 times further by chemical reduction of sediment. Dithionite reduction alone is not an effective treatment for TNT (intermediates that irreversibly sorb are ...
Date: August 7, 2007
Creator: Szecsody, James E.; Comfort, Steve; Fredrickson, Herbert L.; Boparai, Hardiljeet K.; Devary, Brooks J.; Thompson, Karen T. et al.
Partner: UNT Libraries Government Documents Department