THERMAL TECHNIQUES FOR THE IN-SITU CHARACTERIZATION AND REMEDIATION OF MERCURY: INSIGHTS FROM DEPLOYMENT OF THE MEMBRANE INTERFACE PROBE

This presentation focuses on how thermal energy can effectively be used to enhance characterization, promote the remediation, and aid in delivering a sequestering agent to stabilize elemental mercury in subsurface soils. Slides and speaker notes are provided

Innovative Strategy For Long Term Monitoring Of Metal And Radionuclide Plumes

Many government and private industry sites that were once contaminated with radioactive and chemical wastes cannot be cleaned up enough to permit unrestricted human access. The sites will require long term management, in some cases indefinitely, leaving site owners with the challenge of protecting human health and environmental quality at these "legacy" sites. Long-term monitoring of groundwater contamination is one of the largest projected costs in the life cycle of environmental management at the Savannah River Site, the larger DOE complex, and many large federal and private sites. There is a need to optimize the performance and manage the cost of long term surveillance and monitoring at their sites. Currently, SRNL is initiating a pilot field test using alternative protocols for long term monitoring of metals and radionuclides. A key component of the approach is that monitoring efforts are focused on measurement of low cost metrics related to hydrologic and chemical conditions that control contaminant migration. The strategy combines careful monitoring of hydrologic boundary conditions with measurement of master variables such as chemical surrogates along with a smaller number of standard well analyses. In plumes contaminated with metals, master variables control the chemistry of the groundwater system, and include redox variables (ORP, DO, chemicals), pH, specific conductivity, biological community (breakdown/decay products), and temperature. Significant changes in these variables will result in conditions whereby the plume may not be stable and therefore can be used to predict possible plume migration. Conversely, concentration measurements for all types of contaminants in groundwater are a lagging indicator plume movement - major changes contaminant concentrations indicate that contamination has migrated. An approach based on measurement of master variables and explicit monitoring of hydrologic boundary conditions combined with traditional metrics should lead to improved monitoring while simultaneously reducing costs. This paradigm is being tested at the SRS F-Area where an innovative passive remedial system is being monitored and evaluated over the long term prior to traditional regulatory closure. Contaminants being addressed at this site are uranium, strontium-90, iodine-129, and tritium. We believe that the proposed strategies will be more effective in early identification of potential risks; these strategies will also be cost effective because controlling variables are relatively simple to measure. These variables also directly reflect the evolution of the plume through time, so that the monitoring strategy can be modified as the plume 'ages'. This transformational long-term monitoring paradigm will generate large cost savings to DOE, other federal agencies and industry and will provide improved performance and leading indicators of environmental management performance

Evapotranspiration And Geochemical Controls On Groundwater Plumes At Arid Sites: Toward Innovative Alternate End-States For Uranium Processing And Tailings Facilities

Management of legacy tailings/waste and groundwater contamination are ongoing at the former uranium milling site in Tuba City AZ. The tailings have been consolidated and effectively isolated using an engineered cover system. For the existing groundwater plume, a system of recovery wells extracts contaminated groundwater for treatment using an advanced distillation process. The ten years of pump and treat (P&T) operations have had minimal impact on the contaminant plume – primarily due to geochemical and hydrological limits. A flow net analysis demonstrates that groundwater contamination beneath the former processing site flows in the uppermost portion of the aquifer and exits the groundwater as the plume transits into and beneath a lower terrace in the landscape. The evaluation indicates that contaminated water will not reach Moenkopi Wash, a locally important stream. Instead, shallow groundwater in arid settings such as Tuba City is transferred into the vadose zone and atmosphere via evaporation, transpiration and diffuse seepage. The dissolved constituents are projected to precipitate and accumulate as minerals such as calcite and gypsum in the deep vadose zone (near the capillary fringe), around the roots of phreatophyte plants, and near seeps. The natural hydrologic and geochemical controls common in arid environments such as Tuba City work together to limit the size of the groundwater plume, to naturally attenuate and detoxify groundwater contaminants, and to reduce risks to humans, livestock and the environment. The technical evaluation supports an alternative beneficial reuse (“brownfield”) scenario for Tuba City. This alternative approach would have low risks, similar to the current P&T scenario, but would eliminate the energy and expense associated with the active treatment and convert the former uranium processing site into a resource for future employment of local citizens and ongoing benefit to the Native American Nations

STUDIES TO SUPPORT DEPLOYMENT OF EDIBLE OILS AS THE FINAL CVOC REMEDIATION IN T AREA SUMMARY REPORT

The purpose of these studies was to determine the feasibility of using edible oils for remediation of the low but persistent chlorinated solvent (cVOC) groundwater contamination at the SRS T-Area. The following studies were completed: (1) Review of cVOC degradation processes and edible oil delivery for enhanced bioremediation. (2) Column studies to investigate placing neat oil on top of the water table to increase oil saturation and sequestration. (3) Analysis of T-Area groundwater geochemistry to determine the applicability of edible oils for remediation at this site. (4) Microcosm studies to evaluate biotic and abiotic processes for the T-Area groundwater system and evaluation of the existing microbial community with and with out soybean oil amendments. (5) Monitoring of a surrogate vadose zone site undergoing edible oil remediation at the SRS to understand partitioning and biotransformation products of the soybean oil. (6) Design of a delivery system for neat and emulsified edible oil deployment for the T-Area groundwater plume. A corresponding white paper is available for each of the studies listed. This paper provides a summary and overview of the studies completed for the remediation of the T-Area groundwater plume using edible oils. This report begins with a summary of the results and a brief description of the preliminary oil deployment design followed by brief descriptions of T-Area and current groundwater conditions as related to edible oil deployment. This is followed by a review of the remediation processes using edible oils and specific results from modeling, field and laboratory studies. Finally, a description of the preliminary design for full scale oil deployment is presented

Scientific Opportunities for Monitoring at Environmental Remediation Sites (SOMERS): Integrated Systems-Based Approaches to Monitoring

Through an inter-disciplinary effort, DOE is addressing a need to advance monitoring approaches from sole reliance on cost- and labor-intensive point-source monitoring to integrated systems-based approaches such as flux-based approaches and the use of early indicator parameters. Key objectives include identifying current scientific, technical and implementation opportunities and challenges, prioritizing science and technology strategies to meet current needs within the DOE complex for the most challenging environments, and developing an integrated and risk-informed monitoring framework

Scientific Opportunities for Monitoring of Environmental Remediation Sites (SOMERS) - 12224

ABSTRACT The US Department of Energy (DOE) is responsible for risk reduction and cleanup of its nuclear weapons complex. DOE maintains the largest cleanup program in the world, currently spanning over a million acres in 13 states. The inventory of contaminated materials includes 90 million gallons of radioactive waste, 6.4 trillion liters of groundwater, and 40 million cubic meters of soil and debris. It is not feasible to completely restore many sites to predisposal conditions. Any contamination left in place will require monitoring, engineering controls and/or land use restrictions to protect human health and environment. Research and development efforts to date have focused on improving characterization and remediation. Yet, monitoring will result in the largest life-cycle costs and will be critical to improving performance and protection. Through an inter-disciplinary effort, DOE is addressing a need to advance monitoring approaches from sole reliance on cost-and labor-intensive point-source monitoring to integrated systems-based approaches such as flux-based approaches and the use of early indicator parameters. Key objectives include identifying current scientific, technical and implementation opportunities and challenges, prioritizing science and technology strategies to meet current needs within the DOE complex for the most challenging environments, and developing an integrated and risk-informed monitoring framework

Shifting the Paradigm for Long Term Monitoring at Legacy Sites to Improve Performance while Reducing Cost

A major issue facing many government and private industry sites that were previously contaminated with radioactive and chemical wastes is that often the sites cannot be cleaned up enough to permit unrestricted human access. These sites will require long-term management, in some cases indefinitely, leaving site owners with the challenge of protecting human health and environmental quality in a cost effective manner. Long-term monitoring of groundwater contamination is one of the largest projected costs in the life cycle of environmental management at the Savannah River Site (SRS), the larger DOE complex, and many large federal and private sites. Currently, most monitoring strategies are focused on laboratory measurements of contaminants measured in groundwater samples collected from wells. This approach is expensive, and provides limited and lagging information about the effectiveness of cleanup activities and the behavior of the residual contamination. Over the last twenty years, DOE and other federal agencies have made significant investments in the development of various types of sensors and strategies that would allow for remote analysis of contaminants in groundwater, but these approaches do not promise significant reductions in risk or cost. Scientists at SRS have developed a new paradigm to simultaneously improve the performance of long term monitoring systems while lowering the overall cost of monitoring. This alternative approach incorporates traditional point measurements of contaminant concentration with measurements of controlling variables including boundary conditions, master variables, and traditional plume/contaminant variables. Boundary conditions are the overall driving forces that control plume movement and therefore provide leading indication to changes in plume stability. These variables include metrics associated with meteorology, hydrology, hydrogeology, and land use. Master variables are the key variables that control the chemistry of the groundwater system, and include redox variables (ORP, DO, chemicals), pH, specific conductivity, biological community (breakdown/decay products), and temperature. A robust suite of relatively inexpensive tools is commercially available to measure these variables. Traditional plume/contaminant variables are various measures of contaminant concentration including traditional analysis of chemicals in groundwater samples. An innovative long term monitoring strategy has been developed for acidic or caustic groundwater plumes contaminated with metals and/or radionuclides. Not only should the proposed strategy be more effective at early identification of potential risks, this strategy should be significantly more cost effective because measurement of controlling boundary conditions and master variables is relatively simple. These variables also directly reflect the evolution of the plume through time, so that the monitoring strategy can be modified as the plume 'ages'. This transformational long-term monitoring paradigm will generate significant cost savings to DOE, other federal agencies and industry and will provide improved performance and leading indicators of environmental management performance

In Situ Monitoring of Groundwater Contamination Using the Kalman Filter.

This study presents a Kalman filter-based framework to establish a real-time in situ monitoring system for groundwater contamination based on in situ measurable water quality variables, such as specific conductance (SC) and pH. First, this framework uses principal component analysis (PCA) to identify correlations between the contaminant concentrations of interest and in situ measurable variables. It then applies the Kalman filter to estimate contaminant concentrations continuously and in real-time by coupling data-driven concentration-decay models with the previously identified data correlations. We demonstrate our approach with historical groundwater data from the Savannah River Site F-Area: We use SC and pH data to estimate tritium and uranium concentrations over time. Results show that the developed method can estimate these contaminant concentrations based on in situ measurable variables. The estimates remain reliable with less frequent or no direct measurements of the contaminant concentrations, while capturing the dynamics of short- and long-term contaminant concentration changes. In addition, we show that data mining, such as PCA, is useful to understand correlations in groundwater data and to design long-term monitoring systems. The developed in situ monitoring methodology is expected to improve long-term groundwater monitoring by continuously confirming the contaminant plume's stability and by providing an early warning system for unexpected changes in the plume's migration

<i>In Situ</i> Monitoring of Groundwater Contamination Using the Kalman Filter

This study presents a Kalman filter-based framework to establish a real-time <i>in situ</i> monitoring system for groundwater contamination based on <i>in situ</i> measurable water quality variables, such as specific conductance (SC) and pH. First, this framework uses principal component analysis (PCA) to identify correlations between the contaminant concentrations of interest and <i>in situ</i> measurable variables. It then applies the Kalman filter to estimate contaminant concentrations continuously and in real-time by coupling data-driven concentration-decay models with the previously identified data correlations. We demonstrate our approach with historical groundwater data from the Savannah River Site F-Area: We use SC and pH data to estimate tritium and uranium concentrations over time. Results show that the developed method can estimate these contaminant concentrations based on <i>in situ</i> measurable variables. The estimates remain reliable with less frequent or no direct measurements of the contaminant concentrations, while capturing the dynamics of short- and long-term contaminant concentration changes. In addition, we show that data mining, such as PCA, is useful to understand correlations in groundwater data and to design long-term monitoring systems. The developed <i>in situ</i> monitoring methodology is expected to improve long-term groundwater monitoring by continuously confirming the contaminant plume’s stability and by providing an early warning system for unexpected changes in the plume’s migration