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DOE OSTI2019

Assessment of Technologies for I-129 Remediation in the 200-UP-1 Operable Unit

Iodine-129 (I-129) generated at the U.S. Department of Energy Hanford Site during plutonium production was released to the subsurface, resulting in several large, dilute plumes in the groundwater, including the plume in the 200-UP-1 operable unit (OU). A requirement in the Record of Decision (ROD) for interim remedial action at the 200-UP-1 OU is to “evaluate potential treatment options for I-129 as part of the selected remedy through further technology evaluation. If one or more viable technologies are identified, treatability tests will be conducted for those technologies.” The requirements also state: “In the event a viable treatment technology is not available, the use of a technical impracticable waiver under 40 CFR 300.430(f)(l)(ii)(c) may need to be considered as part of the final remedy.” Recent work has increased the understanding of iodine behavior in the Hanford subsurface. A thorough review of potential remediation technologies has also been completed, including laboratory testing of promising technologies to evaluate their effectiveness for the iodine conditions at the 200-UP-1 OU. Using the combined information from these efforts, this report evaluates potential remediation technology options for the 200-UP-1 OU with respect to the need for conducting treatability tests and to document the technology status in support of future OU decisions for addressing the I-129 plume.

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DOE OSTI2017

Identification of Promising Remediation Technologies for Iodine in the UP-1 Operable Unit

Iodine-129 ( 129 I) generated at the U.S. Department of Energy (DOE) Hanford Site during plutonium production was released to the subsurface, resulting in several large, though dilute, plumes in the groundwater, including the plume in the 200-UP-1 operable unit (OU). Because 129 I is an uncommon contaminant, relevant remediation experience and scientific literature are limited, though work is under way to better understand the fate and transport of 129 I in the environment and the effectiveness of potential remediation technologies. The recent UP-1 Evaluation Plan for Iodine and report on the Conceptual Model of Iodine Behavior in the Subsurface at the Hanford Site provide information on the history of contamination in the 200-UP-1 OU, relevant controlling processes (biological and geochemical), risk, the conceptual site model, and potential remedial options, which provided a foundation for this study. In this study, available information was compiled and used to categorize potential remediation technologies, culminating in a recommendation of promising technologies for further evaluation. Approaches to improve the technical information about promising technologies are also recommended in this study so that a subsequent evaluation of potential remediation alternatives can assess these technologies.

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DOE OSTI2016

Remediation using trace element humate surfactant

A method of remediation at a remediation site having one or more undesirable conditions in which one or more soil characteristics, preferably soil pH and/or elemental concentrations, are measured at a remediation site. A trace element humate surfactant composition is prepared comprising a humate solution, element solution and at least one surfactant. The prepared trace element humate surfactant composition is then dispensed onto the remediation site whereby the trace element humate surfactant composition will reduce the amount of undesirable compounds by promoting growth of native species activity. By promoting native species activity, remediation occurs quickly and environmental impact is minimal.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2017

FUSRAP Maywood Site Remediation of Redstone Park, Lodi, NJ - 17534

The Formerly Utilized Sites Remedial Action Program (FUSRAP) is the U.S. government program started in 1974 to identify, investigate and clean up or control sites that became contaminated as a result of the nation's early atomic programs. FUSRAP was administered by the U.S. Department of Energy (DOE) until 1997, when it was transferred to the U.S. Army Corps of Engineers (USACE) by congressional action. Redstone Park is a 1.5-acre municipal park located in a residential neighborhood in Lodi, Bergen County, New Jersey, USA. The park is a designated vicinity property of the FUSRAP Maywood Superfund Site. This paper will summarize the FUSRAP history of the property spanning over 20 years and then focus on the construction and community relations challenges of recent FUSRAP actions at the site. All of Redstone Park except for a portion bordering a residential property was remediated under FUSRAP in 1996. This remaining portion was remediated in 1998. The 1996 remediation included some hand-digging of surface contamination around the roots of several large mature trees in the park. As part of this action, the DOE proposed alternate cleanup standards whereby subsurface contaminated soil would remain in place around the root balls of the trees and in deeper areas (greater than 1.2 meters [m]) under a large storm drain pipe (or culvert) that runs through the park. This proposal was made to preserve the natural value of the trees and to protect the drainage pipe from damage. After careful review which included an assessment of potential health hazards, the U.S. Environmental Protection Agency (EPA) approved this proposal. The Borough of Lodi also supported the proposal as a way to preserve the trees for the enjoyment of park users. In 2009, EPA conducted a mandatory Five-Year Review of the FUSRAP Maywood Site. The review identified data gaps which prevented a full assessment of remedy effectiveness at Redstone Park. The USACE reviewed all the historic soil data from the park [1] and developed a characterization plan to address those gaps. Field surveys and sampling confirmed that the material around the tree roots and under the pipe did not comply with the current FUSRAP Maywood Site unrestricted use soil cleanup criteria (an average of 5 pico Curies per gram of radium-226 and thorium-232 combined above background) as established in the site's Soils and Buildings Record of Decision [2]. As noted earlier, USACE also considered the widespread uprooting of trees in the region during Hurricane Sandy in 2012 in its re-evaluation of the earlier decision to leave the trees in the park in place. That re-evaluation concluded it was in the best interest of all stakeholders to remove the residual contamination in Redstone Park. USACE subsequently excavated the soil under and around the drainage pipe as Phase 1 of a two-phased approach to address this residual contamination. 1,116 cubic yards of soil were removed for safe offsite disposal during this action in June-July 2016. Phase 2 (removal of contaminated soil around the tree roots) began in September 2016 with expected completion by December 2016. The work was staged in two phases so as not to impact the park during the summer school vacation months when park use is heaviest. (authors)

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2016

Simulation and Optimizing Groundwater Investigations, Conceptual Design Analysis, Model Calibration and Remedial Design Using Parallel Numerical Methods: Theory and Application - 16578

Optimization of environmental restoration efforts at complex groundwater sites involves the development of a conceptual and often numerical flow and transport models. Typically, a limited number of simulations are done to assess the impact of parameter uncertainty, to evaluate remedial alternatives and develop a remedy, or to modify an existing remedy. A limited number of simulations are performed because each simulation can take upwards of several hours per simulation and until now the ability to conduct the 100's to 1000's of simulations needed to derive an optimal remedy was beyond the reach of the everyday practitioner. HGL has developed and implemented new parallel simulation and optimization methods in their software and has successfully deployed applications on high performance Cloud-based computing platforms. This advancement removes the impediment of burdensome and unpredictable runtime requirements these types of projects have typically exhibited using heuristic trial-and-error or even automated serial computation approaches. A parallel numerical solver has been added to the subsurface flow and transport simulator MODFLOW-SURFACT{sup TM} and has demonstrated reductions in solution time by as much as a factor of 9.8. This is accomplished by distributing the numerical computations of every time step over multiple processors. The integrated parallel simulation and optimization method uses the breadth and depth search approach; iteratively producing sets of tens or 100's of candidate solutions that are evaluated concurrently instead sequentially (i.e. one model evaluation at a time). Solutions within 80-100% of the globally optimal solution are regularly found expending only 5-10% of the usual computational effort using this new parallel optimization method (reducing computation effort by 10 to 20 times). Distributing optimal search runs across multiple processors additionally reduces calendar time to solutions. Practitioners evaluating multiple conceptual site models, model calibration by auto-calibration methods and remedial design by heuristics can enjoy significant reductions in model solution time by using the parallel numerical matrix solver in the physics-based simulator. Combining investigation and design analysis with breadth and depth parallel optimization methods, projects at the fringe of practical optimization, along with projects that were beyond the reach of formal optimization methods are now wholly feasible and tractable optimization problems. (authors)

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DOE OSTI2018

Numerical Simulation and Model Analyses of In-situ Biogeochemical Remediation of Chromium at the LANL - 18306

Environmental management problems associated with contamination of groundwater resources with heavy metals (such as chromium) typically require complex biogeochemical model simulations and analysis of in situ remediation. Frequently, the in situ remediation is the only viable treatment option. In these cases, a three-dimensional reactive transport model of relevant biogeochemical processes is invaluable. Recently, we have developed a novel unique biogeochemical simulator called CHROTRAN (http://chrotran.lanl.gov; Hansen et al. 2017, Vesselinov et al. 2018a) capable to represent the full three-dimensional dynamics of processes associated with in situ biogeochemical remediation of heavy metals in heterogeneous aquifers. CHROTRAN accounts for spatial and temporal transients of (1) the heavy metal to be remediated, (2) introduced amendments (e.g., through well injection), and (3) biomass growth and decay. The introduced amendments can include (1) an electron donor (e.g., molasses), (2) a nontoxic-conservative bio-inhibitor (e.g., ethanol), and (3) a biocide (e.g., dithionite). In addition, direct abiotic reduction by donor-metal interaction as well as donor-driven biomass growth and bio-reduction are modeled in CHROTRAN. Other critical processes, such as donor sorption, bio-fouling and biomass death are also modeled. CHROTRAN can simulate the groundwater flow dynamics introduced due a series of injection and extraction wells and account for reduction of aquifer permeability near the wells due bio clogging. CHROTRAN is based on the existing PFLOTRAN (http://pflotran.org; Lichtner et al, 2017a) code framework, taking advantage of the reaction interface allowing for implementation of complex model features and leverage other facets of PFLOTRAN, such as multi-component geochemistry and high-performance computing. Here, we present numerical simulations and model analyses related to the Los Alamos National Laboratory (LANL) chromium site. The analyses are performed by coupling of CHROTRAN with MADS (Model Analysis and Decision Support; http://mads.lanl.gov; Vesselinov et al., 2018b). We present analyses related to uncertainty quantification of model predictions, sensitivity of model parameters and remedial decision support. (authors)

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DOE OSTI2015

Development of a process for remediation of enriched uranium coolant tanks at AWE Aldermaston - 14520

Machining processes involving Enriched Uranium (EU) at the UK Atomic Weapons Establishment have historically required the use of a liquid coolant to ensure product quality and to provide protection against hazards associated with ignition of the EU swarf in the non-inert gloved air box atmosphere. This coolant is typically provided by closed circuit re-circulating systems utilising large volume tanks to contain the bulk coolant. Small losses of EU to the coolant tank are experienced during the machining process leading to accumulation over time. This is expected and appropriate measures are put in place to control such accumulations to ensure criticality safety during the operational phase. The original design intent made no specific provision for recovery of the EU as it was not expected to be required based on the anticipated losses and design lifetime of the tanks. However, in support of ongoing operations it has become necessary to develop a process to remediate out of service coolant tanks to recover the EU and to replace the coolant and some of the end-of-life tank components. Detailed optioneering has been undertaken to develop a process that addresses all the relevant hazards, including nuclear criticality safety. Non-destructive assay techniques have been developed to help determine the inventory of EU present and consequently the level of control required during the remediation process. This has led to the selection of favourable geometry collection vessels that not only afford significant defence-in-depth against criticality hazards during the remediation work but also satisfy interim storage requirements. These vessels may also be of interest to other operators. This paper presents an overview of the history of operation of the coolant tanks and proposed remediation process and provides an overview of the criticality safety case that has been developed to support it. It is anticipated that the remediation work will be undertaken before 2019 allowing the findings and lessons learnt (including validation of non-destructive assay results on expected hold up) to be reported at the next ICNC. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2015

Bench-scale electrokinetic remediation for cesium-contaminated sediment at the Hanford Site, USA

Electrokinetic (EK) remediation has been applied to extract various contaminants such as radionuclides, heavy metals, and organic compounds from contaminated sediment and soil using electric currents. We conducted a laboratory experiment to investigate the efficiency of EK remediation method for Hanford sediment (76% sand and 24% silt-clay) after artificial contamination with nonradioactive 133Cs (0.01 M CsNO3) as a surrogate for radioactive 137Cs. The initial 133Cs concentration in the bulk sediment was 668 mg kg-1, with a higher 133Cs concentration for the silt-clay fraction (867 mg kg-1) than for the sand fraction (83 mg kg-1). A significant removal of cationic 133Cs from the sediment occurred from the cathode side (-), whereas the removal was negligible from the anode side (+) during the EK remediation process for 68 days. Based on microwave-assisted total digestion, 312 mg kg-1 of 133Cs was removed from the bulk sediment, which corresponds to the removal efficiency of 47%. The EK method was significantly more efficient for the silt-clay fraction than for the sand fraction. X-ray diffraction (XRD) and scanning electron microscopy-electron dispersive spectroscopy (SEM-EDS) analyses indicate that change in major crystalline mineral phases was insignificant during the EK remediation and the removal of 133Cs from the Hanford sediment by the EK method is attributed mainly to cation exchange with K in clay minerals. The experimental results suggest that the EK method can effectively remove radioactive Cs from the surface or subsurface sediment contaminated by radioactive materials in the Hanford Site, Washington, USA.

Cation exchange↗

DOE OSTI2013

Mercury contaminated sediment sites—An evaluation of remedial options

Mercury (Hg) is a naturally-occurring element that is ubiquitous in the aquatic environment. Though efforts have been made in recent years to decrease Hg emissions, historically-emitted Hg can be retained in the sediments of aquatic bodies where they may be slowly converted to methylmercury (MeHg). Consequently, Hg in historically-contaminated sediments can result in high levels of significant exposure for aquatic species, wildlife and human populations consuming fish. Even if source control of contaminated wastewater is achievable, it may take a very long time, perhaps decades, for Hg-contaminated aquatic systems to reach relatively safe Hg levels in both water and surface sediment naturally. It may take even longer if Hg is present at higher concentration levels in deep sediment. Hg contaminated sediment results from previous releases or ongoing contributions from sources that are difficult to identify. Due to human activities or physical, chemical, or biological processes (e.g. hydrodynamic flows, bioturbation, molecular diffusion, and chemical transformation), the buried Hg can be remobilized into the overlying water. Hg speciation in the water column and sediments critically affect the reactivity (i.e. conversion of inorganic Hg(II) to MeHg), transport, and its exposure to living organisms. Also, geochemical conditions affect the activity of methylating bacteria and its availability for methylation. This review paper discusses remedial considerations (e.g. key chemical factors in fate and transport of Hg, source characterization and control, environmental management procedures, remediation options, modeling tools) and includes practical case studies for cleaning up Hg-contaminated sediment sites. -- Highlights: ► Managing mercury-contaminated sediment sites are challenging to remediate. ► Remediation technologies are making a difference in managing these sites. ► Partitioning plays a dominant role in the distribution of mercury species. ► Mathematical models can be used to help us understand the chemistry and processes.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2018

Remediation of contaminated soils by enhanced nanoscale zero valent iron

The use of nanoscale zero valent iron (nZVI) for in situ remediation of soil contamination caused by heavy metals and organic pollutants has drawn great concern, primarily owing to its potential for excellent activity, low cost and low toxicity. This reviews considers recent advances in our understanding of the role of nZVI and enhanced nZVI strategy in the remediation of heavy metals and persistent organic contaminants polluted soil. The performance, the migration and transformation of nZVI affected by the soil physical and chemical conditions are summarized. However, the addition of nZVI inevitably disturbs the soil ecosystem, thus the impacts of nZVI on soil organisms are discussed. In order to further investigate the remediation effect of nZVI, physical, chemical and biological method combination with nZVI was developed to enhance the performance of nZVI. From a high efficient and environmentally friendly perspective, biological method enhanced nZVI technology will be future research needs. Possible improvement of nZVI-based materials and potential areas for further applications in soil remediation are also proposed.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2021

Optimum concentration of fly ash nanoparticles to stabilize CO 2 foams for aquifer and soil remediation

Contamination caused by non-aqueous phase liquids (NAPLs) in aquifers and soil is an important challenge that requires effective remediation techniques. One potential approach is through the use of CO 2 foams to displace NAPLs from permeable media. CO 2 foams generated only by surfactants are not stable enough for the efficient removal of NAPLs contamination. This shortcoming may be alleviated via the use of nanoparticles (NPs)-surfactant mixtures as a stabilizing agent. This work focuses on the evaluation of the optimum concentration of fly ash nanoparticles for stabilizing CO 2 foam with the combined action of the surfactant. The performance of this foam is evaluated in remediating a contaminated 41 mm × 36 mm surrogate permeable medium in a microfluidic device. Mixtures of fly ash, a by-product of coal-burning power plants, and alpha-olefin sulfonate (AOS) and lauramidopropyl betaine (LAPB) surfactants are used to generate stable foams. The results show that a 1000 mg/L AOS-LAPB surfactant solution along with 1000 mg/L of fly ash NPs produces the best performance. Formation of deposits in the matrix is observed. These deposits, which are more prominent at higher NP concentrations, appear to adversely affect displacement, displacement efficiency and remediation of the medium. This study demonstrates that using fly ash nanoparticles and optimizing their concentration can effectively stabilize CO 2 foams and improve the displacement efficiency for aquifer and soil remediation.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2021

Post-remediation geophysical assessment: Investigating long-term electrical geophysical signatures resulting from bioremediation at a chlorinated solvent contaminated site

There is a growing need to assess long-term impacts of active remediation strategies on treated aquifers. A variety of biogeochemical alterations can result from interactions of the amendment with the aquifer, conceivably leading to a geophysical footprint of the long-term alteration of an aquifer. This concept of post-remediation geophysical assessment was investigated in a shallow, chlorinated solvent-contaminated aquifer six to eight years after amendment delivery. Surface resistivity imaging and cross-borehole resistivity and induced polarization (IP) imaging were performed on a transect that spanned treated and untreated zones of the aquifer. Established relationships between IP parameters and surface electrical conductivity were used to predict vertical profiles of electrolytic conductivity and surface conductivity from the inverted cross-borehole images. Aqueous geochemistry data, along with natural gamma and magnetic susceptibility logs, were used to constrain the interpretation. The electrical conductivity structure determined from surface and borehole imaging was foremost controlled by the electrolytic conductivity of the interconnected pore space, being linearly related to fluid specific conductance. The electrolytic conductivity (and thus the conductivity images alone) did not discriminate between treated and untreated zones of the aquifer. In contrast, inverted phase angles and surface conductivities did discriminate between treated and untreated zones of the aquifer, with the treated zone being up to an order of magnitude more polarizable in places. Supporting aqueous chemistry and borehole logging datasets indicate that this geophysical footprint of the long-term impact of the remediation on the aquifer is most likely associated with the formation of polarizable, dispersed iron sulfide minerals. The study opens the door to the possibility of employing time-lapse electrical geophysical measurements to assist with long-term environmental stewardship of legacy sites undergoing active remediation.

bioremediation↗

DOE OSTI2013

Integrated Systems-Based Approach to Monitoring Environmental Remediation

The US Department of Energy (DOE) is responsible for risk reduction and cleanup of its nuclear weapons complex. Remediation strategies for some of the existing contamination use techniques that mitigate risk, but leave contaminants in place. Monitoring to verify remedy performance and long-term mitigation of risk is a key element for implementing these strategies and can be a large portion of the total cost of remedy implementation. Especially in these situations, there is a need for innovative monitoring approaches that move away from the cost and labor intensive point-source monitoring. A systems-based approach to monitoring design focuses monitoring on controlling features and processes to enable effective interpretation of remedy performance.

environmental remediation↗

DOE OSTI2013

Remediation of the Highland Drive South Ravine, Port Hope, Ontario: Contaminated Groundwater Discharge Management Using Permeable Reactive Barriers and Contaminated Sediment Removal - 13447

The Highland Drive South Ravine (HDSR) is the discharge area for groundwater originating from the Highland Drive Landfill, the Pine Street North Extension (PSNE) roadbed parts of the Highland Drive roadbed and the PSNE Consolidation Site that contain historical low-level radioactive waste (LLRW). The contaminant plume from these LLRW sites contains elevated concentrations of uranium and arsenic and discharges with groundwater to shallow soils in a wet discharge area within the ravine, and directly to Hunt's Pond and Highland Drive South Creek, which are immediately to the south of the wet discharge area. Remediation and environmental management plans for HDSR have been developed within the framework of the Port Hope Project and the Port Hope Area Initiative. The LLRW sites will be fully remediated by excavation and relocation to a new Long-Term Waste Management Facility (LTWMF) as part of the Port Hope Project. It is projected, however, that the groundwater contaminant plume between the remediated LLRW sites and HDSR will persist for several hundreds of years. At the HDSR, sediment remediation within Hunt's Ponds and Highland Drive South Creek, excavation of the existing and placement of clean fill will be undertaken to remove current accumulations of solid-phase uranium and arsenic associated with the upper 0.75 m of soil in the wet discharge area, and permeable reactive barriers (PRBs) will be used for in situ treatment of contaminated groundwater to prevent the ongoing discharge of uranium and arsenic to the area in HDSR where shallow soil excavation and replacement has been undertaken. Bench-scale testing using groundwater from HDSR has confirmed excellent treatment characteristics for both uranium and arsenic using permeable reactive mixtures containing granular zero-valent iron (ZVI). A sequence of three PRBs containing ZVI and sand in backfilled trenches has been designed to intercept the groundwater flow system prior to its discharge to the ground surface and the creek and ponds in the HDSR. The first of the PRBs will be installed immediately up-gradient of the wet discharge area approximately 50 m from the creek, the other two will be installed across the area of shallow soil replacement, and all will extend from ground surface to the base of the water table aquifer through which the impacted groundwater flows. The PRBs have been designed to provide the removal of uranium and arsenic for decades, although the capacity of the treatment mixture for contaminant removal suggests that a longer period of treatment may be feasible. The environmental management plan includes an allowance for on-going monitoring, and replacement of a PRB(s) as might be required. (authors)

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DOE OSTI2013

Integrated Systems-Based Approach to Monitoring Environmental Remediation - 13211

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DOE OSTI2013

Case Study of Urban Residential Remediation and Restoration in Port Hope, Canada - 13250

The Canadian Municipality of Port Hope, Ontario, is located some 100 km east of Toronto and has been the location of radium and/or uranium refining since the 1930's. Historically, these activities involved materials containing radium-226, uranium, arsenic and other contaminants generated by the refining process. In years past, properties and sites in Port Hope became contaminated from spillage during transportation, unrecorded, un-monitored or unauthorized diversion of contaminated fill and materials, wind and water erosion and spread from residue storage areas. Residential properties in Port Hope impacted by radioactive materials are being addressed by the Canadian federal government under programs administered by the Low-Level Radioactive Waste Management Office (LLRWMO) and the Port Hope Area Initiative Management Office (PHAIMO). Issues that currently arise at these properties are addressed by the LLRWMO's Interim Waste Management Program (IWM). In the future, these sites will be included in the PHAIMO's Small Scale Sites (SSS) remedial program. The LLRWMO has recently completed a remediation and restoration program at a residential property in Port Hope that has provided learnings that will be applicable to the PHAIMO's upcoming SSS remedial effort. The work scope at this property involved remediating contaminated refinery materials that had been re-used in the original construction of the residence. Following removal of the contaminated materials, the property was restored for continued residential use. This kind of property represents a relatively small, but potentially challenging subset of the portfolio of sites that will eventually be addressed by the SSS program. (authors)

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DOE OSTI2012

Benefits of a Biological Monitoring Program for Assessing Remediation Performance and Long-Term Stewardship - 12272

The Biological Monitoring and Abatement Program (BMAP) is a long-running program that was designed to evaluate biological conditions and trends in waters downstream of Department of Energy (DOE) facilities in Oak Ridge, Tennessee. BMAP monitoring has focused on aquatic pathways from sources to biota, which is consistent with the sites' clean water regulatory focus and the overall cleanup strategy which divided remediation areas into watershed administrative units. Specific programmatic goals include evaluating operational and legacy impacts to nearby streams and the effectiveness of implemented remediation strategies at the sites. The program is characterized by consistent, long-term sampling and analysis methods in a multidisciplinary and quantitative framework. Quantitative sampling has shown conclusively that at most Oak Ridge stream sites, fish and aquatic macro-invertebrate communities have improved considerably since the 1980s. Monitoring of mercury and PCBs in fish has shown that remedial and abatement actions have also improved stream conditions, although in some cases biological monitoring suggests further actions are needed. Follow-up investigations have been implemented by BMAP to identify sources or causes, consistent with an adaptive management approach. Biological monitoring results to date have not only been used to assess regulatory compliance, but have provided additional benefits in helping address other components of the DOE's mission, including facility operations, natural resource, and scientific goals. As a result the program has become a key measure of long-term trends in environmental conditions and of high value to the Oak Ridge environmental management community, regulators, and the public. Some of the BMAP lessons learned may be of value in the design, implementation, and application of other long-term monitoring and stewardship programs, and assist environmental managers in the assessment and prediction of the effectiveness of remedial actions and pollution abatement. (authors)

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DOE OSTI2012

Success of the Melton Valley Watershed Remediation at the ORNL - 12351

The source remediation of the Melton Valley (MV) Watershed at the U.S. Department of Energy's (DOE's) Oak Ridge National Laboratory was completed 5 years ago (September 2006). Historic operations at the laboratory had resulted in chemical and radionuclide contaminant releases and potential risks or hazards within 175 contaminated units scattered across an area of 430 hectares (1062 acres) within the watershed. Contaminated areas included burial grounds, landfills, underground tanks, surface impoundments, liquid disposal pit/trenches, hydrofracture wells, leak and spill spites, inactive surface structures, and contaminated soil and sediments. The remediation of the watershed was detailed in the MV Interim Action Record of Decision (ROD) and included a combination of actions encompassing containment, isolation, stabilization, removal, and treatment of sources within the watershed and established the monitoring and land use controls that would result in protection of human health. The actions would take place over 5 years with an expenditure of over $340 M. The MV remedial actions left hazardous wastes in-place (e.g., buried wastes beneath hydraulic isolation caps) and cleanup at levels that do not allow for unrestricted access and unlimited exposure. The cleanup with the resultant land use would result in a comprehensive monitoring plan for groundwater, surface water, and biological media, as well as the tracking of the land use controls to assure their completion. This paper includes an overview of select performance measures and monitoring results, as detailed in the annual Remediation Effectiveness Report and the Five-Year Report. (authors)

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