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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Modeling and Quantitative Assessment of Green and Sustainable Remediation Options for the M1 Air Stripper System at DOE SRS - 15660

The effectiveness of remediation systems needs to be reviewed periodically to assess their performance over the years relative to efficiency and effectiveness. New technologies and Best Management Practices have emerged that can improve existing remediation systems. From a Green and Sustainable Remediation analysis, the higher energy and/or water usage of older systems might not be justified from an environmental protection rationale. For example, remediation systems can run intermittently and with slower flow rates, use less power, and still provide the required level of environmental remediation and protection. This research by the Applied Research Center at Florida International University (FIU) is the preliminary phase of a Green and Sustainable Remediation (GSR) analysis of the operations of the M1 air stripper and the A/M Area groundwater remediation system at the Savannah River Site (SRS). An initial baseline analysis has helped identify opportunities for implementing Green and Sustainable Remediation (GSR) practices while maintaining the hydraulic containment and effectiveness of the remediation system. This study included the collection of contaminant recovery data from SRS reports into a database of trichloroethene (TCE) and tetrachloroethene (PCE) removal from contaminant recovery wells RWM-1 through RWM-12. Presented below are data and preliminary findings from these recovery wells. Findings show that 7 of 12 recovery wells have transitioned to more PCE removal than TCE removal; the nearby steam injection remediation of 'Dynamic Underground Stripping' mobilized DNAPL and resulted in increased recovery in nearby wells. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Guidance for Monitoring Passive Groundwater Remedies Over Extended Time Scales

Passive remediation can be appropriate where natural processes and actions such as institutional controls mitigate exposure to contaminated groundwater, achieving remedial action objectives and protectiveness of human health and the environment. Monitored natural attenuation (MNA) is a prevalent passive remediation strategy supported by a regulatory framework and monitoring design guidance. MNA can also be used after active remediation has been completed (e.g., pump-and-treat) as a polishing step to reach ultimate remedial action objectives. However, MNA and existing monitoring guidance primarily target situations where the remedial action objectives are met within a few decades. When timescales for passive remediation extend to many decades, a corresponding change in monitoring strategy is needed to adapt to the extended time scale. This document provides guidance for implementing an extended-scale monitoring (ESM) approach appropriate for long-duration passive remediation. Extended-scale is defined in this document with respect to time (i.e., a long duration of remediation) and a large enough physical scale such that receptors will not be impacted within the remediation timeframe.

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DOE OSTI2025

Long-Term Evaluation of Remedial Technology Performance in the Laboratory: Multi-year Experimental Test Plan

An understanding of the long-term effectiveness of remediation technologies is central to sustainable environmental cleanup. Long-term experiments are valuable for reducing uncertainty and predicting remediation outcomes at scales required for regulatory compliance. However, these types of tests can be costly and challenging to interpret. Therefore, contaminated sites often rely on short-term laboratory experiments that may not account for the potentially significant effects of gradual, time- dependent processes governing contaminant retention, release, and species transformation. For example, short-term lab experiments (from months to a year) conducted with sediments from the unsaturated and saturated zones at the Hanford Site play an important role in initial evaluations of remediation technologies but cannot capture the full extent of time-dependent reactions, leaving uncertainties in field-scale deployment. Here, long-term testing will be conducted on select technologies based on their performance in short-term testing. The overall objective is to directly address the challenges described above by generating and analyzing data on long-term (2–10 years) efficacy of selected remediation technologies, integrating this understanding into models, and providing critical input for remediation planning, monitoring, and 5-year review cycles for field-implemented remedies. Specific objectives include: 1. Evaluating long-term efficiency of promising remedies under site-specific conditions. 2. Generating robust parameters for modeling, reducing uncertainty in predictive simulations. 3. Advancing integrated monitoring by combining geochemical and geophysical observations. 4. Informing field-scale implementation by incrementally advancing technologies, identifying failure mechanisms early, and prioritizing robust, cost-effective remedies. Through systematic evaluation of technologies in laboratory-scale column experiments, integrated monitoring, and modeling support, this project is designed to bolster confidence in the long-term robustness of selected technologies. The ultimate outcome is the identification and deployment of more reliable, cost-effective remedies that safeguard human health and the environment while reducing the uncertainties that have historically hindered cleanup progress at Hanford Site. An experimental approach was developed and initiated for long-term testing potentially up to 10 years. The table below summarizes the experimental approach developed for testing select technologies and presented in this multi-year experimental test plan.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2013

Alternative Endpoints and Approaches for the Remediation of Contaminated Groundwater at Complex Sites - 13426

The goal of United States (U.S.) Department of Energy's (DOE)'s environmental remediation programs is to restore groundwater to beneficial use, similar to many other Federal and state environmental cleanup programs. Based on past experience, groundwater remediation to pre-contamination conditions (i.e., drinking water standards or non-detectable concentrations) can be successfully achieved at many sites. At a subset of the most complex sites, however, complete restoration is not likely achievable within the next 50 to 100 years using today's technology. This presentation describes several approaches used at complex sites in the face of these technical challenges. Many complex sites adopted a long-term management approach, whereby contamination was contained within a specified area using active or passive remediation techniques. Consistent with the requirements of their respective environmental cleanup programs, several complex sites selected land use restrictions and used risk management approaches to accordingly adopt alternative cleanup goals (alternative endpoints). Several sites used long-term management designations and approaches in conjunction with the alternative endpoints. Examples include various state designations for groundwater management zones, technical impracticability (TI) waivers or greater risk waivers at Superfund sites, and the use of Monitored Natural Attenuation (MNA) or other passive long-term management approaches over long time frames. This presentation will focus on findings, statistics, and case studies from a recently-completed report for the Department of Defense's Environmental Security Technology Certification Program (ESTCP) (Project ER-0832) on alternative endpoints and approaches for groundwater remediation at complex sites under a variety of Federal and state cleanup programs. The primary objective of the project was to provide environmental managers and regulators with tools, metrics, and information needed to evaluate alternative endpoints for groundwater remediation at complex sites. A statistical analysis of Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) sites receiving TI waivers will be presented as well as case studies of other types of alternative endpoints and alternative remedial strategies that illustrate the variety of approaches used at complex sites and the technical analyses used to predict and document cost, time frame, and potential remedial effectiveness. This presentation is intended to inform DOE program managers, state regulators, practitioners and other stakeholders who are evaluating technical cleanup challenges within their own programs, and establishing programmatic approaches to evaluating and implementing long-term management approaches. Case studies provide examples of long-term management designations and strategies to manage and remediate groundwater at complex sites. At least 13 states consider some designation for groundwater containment in their corrective action policies, such as groundwater management zones, containment zones, and groundwater classification exemption areas. Long-term management designations are not a way to 'do nothing' or walk away from a site. Instead, soil and groundwater within the zone is managed to be protective of human health and the environment. Understanding when and how to adopt a long-term management approach can lead to cost savings and the more efficient use of resources across DOE and at numerous other industrial and military sites across the U.S. This presentation provides context for assessing the use and appropriate role of alternative endpoints and supporting long-term management designations in final remedies. (authors)

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2013

Remediation of Centre Pier, Port Hope, Ontario: Historical, Logistical, Regulatory and Technical Challenges - 13118

Centre Pier is a 3.9 ha property owned by the Commissioners of the Port Hope Harbour in the Municipality of Port Hope, Ontario, Canada. It is centrally located on the Port Hope waterfront and is bounded on the west by the Port Hope Harbour, on the east by the Ganaraska River, on the south by Lake Ontario, and on the north by a railway corridor. The property is currently leased by the Commissioners of the Port Hope Harbour to the Cameco Corporation which owns the four onsite building that are used as warehouse space for their uranium conversion facility located on the western side of the Harbour. Remediation of this site forms part of the Port Hope Project being undertaken by Atomic Energy of Canada Limited (AECL) and Public Works and Government Services Canada (PWGSC) as part of the Port Hope Area Initiative (PHAI). Soil impacts include radiological, metals and petroleum hydrocarbons resulting from long term historical industrial use. Radiological impacts in soil extend across most of the site primarily within the upper metre of fill. Metals-contaminated soil is present across the entire site in the underlying fill material. The metals-contaminated fill extends to a maximum depth of 2.0 m below grade at the north end of the site which is underlain by peat. However, the metals-contaminated soil could extend to the top of the bedrock on the remainder of the site. Based on the elevation of the bedrock in the adjacent river and Harbour Basin, the metals-contaminated soil may extend to a depth of 5.6 m or 6.5 m below existing grade. Petroleum-contaminated soil is present on the southeast side of the site, where a storage tank farm was previously located. Challenges include: - The complex history of the site both relating to site use and Pier construction. Pier development began in the 1800's and was undertaken by many different entities. Modifications and repairs were made over the years resulting in several different types of Pier walls and fill that must be considered during remediation. A wide variety of industrial activity on the Pier including extensive foundry operations as well as the industrial nature of the fill used to construct the Pier has resulted in extensive contamination distribution. The Pier structure will require reinforcement to permit both the remediation of the Pier and the adjacent Harbour and remediation techniques will need to be well suited to minimize disruption of wall structures as well as being able to deal with fill ranging from ash to boulders. - Multiple stakeholders are responsible for building demolition, remediation of radiological impacts, remediation of industrial impacts and the use of the site as a staging area for Harbour sediment remediation. The successful remediation of the Centre Pier will require careful negotiation and planning for the various remediation activities noted above. - The depth of contamination on the Pier would result in the complete removal of the Pier if all contamination were to be excavated. Therefore, a Risk Assessment will be conducted to determine the appropriate means for in situ risk management for materials to be left in place below a proposed depth of 1.5 m below current grade. With the concurrence of the property owners and Provincial regulators, the Risk Assessment will be undertaken in accordance with the Provincial requirements that will ensure adequate protection of the environment and future users of the site. - The end use of the Pier has yet to be confirmed by the Municipality. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Regulator Interface Strategies Implemented at the Y-12 National Security Complex Old Salvage Yard Soils Remediation Project, Oak Ridge, TN - 12162

The Oak Ridge Y-12 National Security Complex housed an area known as the Old Salvage Yard (OSY) that was approximately 7 acres. The OSY was used as an area for the accumulation, processing and storage of scrap metal and equipment from Y-12 operations extending from 1968 until 2009. Areas in the northern sections of OSY also have been used for the storage of used oils containing solvents and the accumulation and recycling or de-heading and crushing of 55-gal metal drums. Scrap metal operations historically involved the accumulation, sorting, storage, public sale or disposal of scrap metal and equipment. Non-containerised storage of scrap metal was routine until 1995 when scrap metal received at OSY was placed in B-24 and B-25 boxes. Under the American Recovery and Reinvestment Act (ARRA), approximately 26,759 cubic meters of scrap metal and debris were removed and disposed at both on and off-site disposal facilities including the on-site, Oak Ridge Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) landfill in 2010 and 2011. This removal action was performed in accordance with a CERCLA Record of Decision (ROD) and a close working relationship with both the U.S. Environmental Protection Agency (EPA) Region IV and Tennessee Department of Environment and Conservation (TDEC). Due to efficiencies and the excellent cooperative relationship forged with EPA Region IV and TDEC for Y-12 ARRA Cleanup Projects, a surplus of funding was available for additional remediation work that was completed in fiscal year (FY) 2011. The underlying OSY soils were targeted for characterization and potential remediation. To expedite these important activities, the U.S. Department of Energy Oak Ridge Environmental Management partnered with the regulators during detailed planning sessions through a variety of means to quickly and efficiently characterize and pinpoint areas requiring remediation according to previous ROD commitments. Data Quality Objectives (DQOs), data-sharing, real-time characterization reporting, surface and groundwater modeling and other interface planning activities were utilized to help facilitate and complete characterization and remediation activities. As a result of these strategies, the surgical extraction of one contiguous area of soil approximately 354 cubic meters is planned for FY12. The strategies discussed resulted in a major reduction of footprint remediation (i.e., 2.8% of the original estimate) which was originally estimated at over 26,759 cubic meters. The original estimate was developed using historical data collected at various times over the period of 20 years. By leveraging a hybrid sampling approach that involved both statistically-based and biased sampling locations, the area of contamination was significantly reduced resulting in both a compliant remedial design that is cost effective while mitigating a principle threat sources to surface and groundwater at the Y-12 plant. One remedial action boundary of 354 cubic meters was verified in the northern section of the Western OSY area known as the old drum de-header station for VOCs. The original estimate for disposal was in excess of 26,759 cubic meters. This area is scheduled for waste characterization and profile development in the first half of fiscal year 2012. The anticipated disposal facility is an on-site Oak Ridge CERCLA disposal landfill known as the Environmental Management Waste Management Facility (EMWMF). By utilizing the careful strategic planning, field-based screening and close cooperation of regulatory stakeholders as detailed in this paper, the total area of soil requiring remedial action within the Y-12 OSY footprint was 354 cubic meters or 2.8% of the original planned estimate. A potential waste reduction of 97.2% was realized over the original planned estimate for OSY Soils. Significant cost savings were achieved by - Minimizing the footprint of the remedial action; - Confirmatory analysis of soils instead of use of historical sampling results for waste profile development; - Targeting traditional laboratory analysis for soils that failed field screen protocols for radionuclides, heavy metals and VOCs; - Providing accurate and precise definition of RABs; and - Reduction of target contaminants for focused laboratory analysis instead of broad-range contaminants. (authors)

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DOE OSTI2012

Overview of the U.S. Department of Energy Formerly Utilized Sites Remedial Action Program - 12189

The U.S. Department of Energy (DOE) Formerly Utilized Sites Remedial Action Program (FUSRAP) was established in 1974 to address residual radiological contamination at sites where work was performed for the Manhattan Engineer District and U.S. Atomic Energy Commission. Initially, FUSRAP activities began with a records search for sites that had the potential to contain residual radiological contamination; 46 sites were identified that were eligible for and required remediation. Remedial action began in 1979. In 1997, Congress assigned responsibility for the remediation of FUSRAP sites to the U.S. Army Corps of Engineers (USACE). DOE retains responsibility for determining if sites are eligible for FUSRAP remediation and for providing long-term surveillance and maintenance (LTS and M) of remediated FUSRAP sites. DOE LTS and M activities are designed to ensure that FUSRAP sites remain protective of human health and the environment and to preserve knowledge regarding FUSRAP sites. Additional elements include eligibility determinations, transition of remediated sites from USACE to DOE, LTS and M operations such as inspections and institutional controls management, stakeholder support, preservation of records, and real property and reuse. DOE maintains close coordination with USACE and regulators to ensure there is no loss of protectiveness when sites transition to DOE for LTS and M. Over the life of the FUSRAP program from 1974 to the present, DOE's primary mission and responsibility has been to ensure that FUSRAP sites remain protective of human health and the environment. In fulfilling this mission, the DOE program includes the following key elements: eligibility determinations, transition of remediated sites from USACE to DOE, LTS and M operations such as inspections and institutional controls management, stakeholder support, preservation of records, and real property and reuse. DOE maintains close communication stakeholders as well as state and federal regulators. DOE programs are designed to preserve and present the information that future stewards and stakeholders will need to maintain site remedies and knowledge. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Groundwater remediation at the Fernald preserve, Cincinnati, Ohio modeling and resulting 2014 well field operational changes - 15324

The Fernald Preserve became a US DOE Office of Legacy Management site in November 2006, for long-term surveillance and maintenance following completion (with the exception of completing groundwater cleanup) of the Comprehensive Environmental Response, Compensation, and Liability Act; environmental remediation; and site restoration. When the site was turned over to the Office of Legacy Management, approximately 76 hectares (189 acres) of the Great Miami Aquifer (GMA) remained contaminated with uranium above the final remediation level of 30 micrograms per liter. Uranium contamination is being removed from groundwater in the GMA through a pump-and-treat operation that is predicted by groundwater modeling to continue until 2033. Certifying that cleanup objectives have been met and removing the remediation infrastructure after pump-and-treat (P and T) operations are complete will require a minimum of 3 additional years. The current P and T remedy has operated well. From August 1993 through December 2013 the remedy has been used to remove 5,345 kg (11,784 lb) of uranium from the GMA. A variety of metrics are used to track how the P and T operation is progressing and are reported each year in the Site Environmental Report for the Fernald site. The metrics show that the effectiveness of uranium removal is slowly decreasing (a common observation for P and T remedies) and that operational changes needed to be considered. Several different operational changes were modeled to determine if model-predicted cleanup dates could be shortened and if the effectiveness of the groundwater remediation could be improved. With the concurrence and support of US EPA, Ohio EPA, and site stakeholders, operational changes were agreed upon and implemented in 2014 that are predicted to increase the effectiveness of the ongoing operation and shorten cleanup times for a portion of the aquifer. Although the overall predicted length of the remediation was not shortened, modeling predicts that key areas of the uranium plume will be re-mediated sooner. This paper provides a status of the groundwater remediation under way at the Fernald Preserve near Cincinnati, presents the operational changes that were implemented in 2014, and summarizes the groundwater modeling that supported the changes. This paper also illustrates the potential benefits that can be gained by pro-actively managing a pump-and-treat operation and looking for innovative ways to adjust the operation. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

The SRNL technical assistance program: transferring lessons learned from two decades of remedial successes to the DOE complex - 15438

The Savannah River Site has an established history of developing implementable risk reduction strategies, developing and deploying innovative technological solutions, and collaboratively achieving realistic and protective environmental end states for complex environmental problems. Part of this success results from the strong historical collaboration between site environmental restoration groups and the Savannah River National Laboratory which results in the promulgation of innovative technical approaches and technologies from the laboratory to ongoing remediation campaigns. Much of the underlying research and development effort was funded by DOE's Office on Environmental Management through a series of applied technology demonstration projects (Integrated Demonstration Project, Integrated Programs and the Applied Field Research Site). Concomitant with the research efforts, SRNL has managed a dynamic and efficient national program that provides teams of technical experts with a broad experience base to recommend strategies that reduce risk and/or technical uncertainty for challenging environmental problems at other DOE facilities. At many of these sites, standard remedial approaches (e.g., excavation, pump and treat, soil vapor extraction) have either failed or proved to be too costly, inadequate, or ineffective. Alternatively, other sites struggle with implementation of innovative but less well understood approaches. The technical assistance teams use a structured process that based on several basic concepts, specifically, development of site specific technical frameworks, and careful matching of remedies to site-specific chemical, geological and physical conditions. Development of technical frameworks is a key strategy to apply basic science to an applied field problem. When directed toward understanding complex real-world environmental remediation challenges, frameworks are tools that support practical identification and incorporation of the key-controlling scientific processes and principles. Frameworks can also be used to minimize technical risks, encourage efficiency and effectiveness, and provide the basis for innovative and creative solutions. Efficient and effective environmental cleanup also requires matching the character of remediation and stabilization methods to the nature of the target zone of contamination as the nature of the target zone evolves through the life of the remedial project. A contaminant plume can be divided into the following zones: the source zone, the impact zone, and the transitional zone that then can be used to identify classes of technologies that are appropriate to that zone. For example, physical and chemical methods (e.g., trapping, immobilization, destruction, or isolation) that directly address the source contaminants are often appropriate for the disturbed zone during the remedial process. A variety of methods that include both active treatments (e.g., pump and treat or active bioremediation) and enhanced attenuation technologies (e.g., geochemical manipulation or reactive barriers) are often suitable for the primary contamination zone or impact zone. Various strategies based on natural attenuation processes may be applicable to the primary contamination zone and these methods are typically applied for the transition or baseline portions of the plume. Careful matching of remedies to site-specific conditions is critical to long-term success in environmental cleanup and restoration. The matching process facilitates selection of technologies with particular strengths that align with real-world needs and constraints, encourages strategic use of multiple or combined technologies to address major plume sub-domains, and supports transitioning technologies in space and time as remediation progresses. Since 2006, the SRNL Technical Assistance program has focused on providing support across the DOE complex. During this time, over 25 teams have visited eleven DOE sites and made recommendations that yielded an estimated cost savings of $100 M. Examples will be provided that illustrate key aspects and significant successes of the technical assistance program. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Well Design, Operation and Maintenance and Proactive Rehabilitation to Optimize Remediation Well Performance - 18605

Optimizing performance of extraction, injection and monitoring wells, which are integral components of groundwater remediation systems, result in lower life cycle costs and a higher probability of meeting project objectives. These wells provide the means to extract contaminated groundwater, inject reagents, treated water and clean water to create groundwater reaction/flushing zones, and to provide groundwater level, contaminant concentration and geochemical data. Initial costs associated with well installation and associated pipelines and treatment systems are significant project expenditures related to site remediation. However, the life cycle costs for wells are dominated by the long-term operation and maintenance (O and M) expenditures. Remediation wells are particularly susceptible to various types of fouling that impact well performance and, therefore, drive up operating costs. Simply defined, fouling is the result of any biological, geochemical or physical process that negatively impacts the intended performance of a remediation well. Fouling decreases well performance by effectively reducing hydraulic communication between the well and the surrounding formation. Oftentimes this occurs via clogging screens and/or gravel pack/formation pore space by bacterial or chemical byproducts and gases, which can lead to corrosion of metal components and spreading fouling deposits to pipelines and surface treatment systems. Ultimately, this results in reduced hydraulic performance in extraction and injection wells and result in erroneous water level and chemical parameter concentration measurements in monitoring wells. Remediation well fouling cannot be eliminated, and natural fouling processes are exacerbated by the installation and operation of remedial systems. Steps required to extend the life of remediation wells and to lower life cycle costs are discussed in this paper in order to establish the required approach to effective system management. These optimization approaches have been developed through years of operation and maintenance of complex large-scale plume remediation systems utilizing a variety of subsurface in-situ and ex-situ technologies. Remediation well performance can be improved by: - careful site characterization, - appropriate well design, - proper well installation and development, - thoughtful and adaptable operation and maintenance, - well performance maintenance tracking and, - proactive well rehabilitation. Clear understanding of the site hydro-stratigraphy and geochemical settings places constraints on the compatibility of well materials and the configurations of well screens. Proper well design, including collection and analysis (sieve/grain-size) of screen zone formation samples, assures that wells can be optimally installed, developed and redeveloped during well rehabilitation. Design considerations should include proper sizing of filter packs and well screens, casing/screen diameter, well material selection/compatibility, expected life/use, and well head configuration to allow for future access. Applying appropriate and effective well installation and development methods are of paramount importance and rely on a good understanding of site characteristics (e.g., geologic setting) as well as local drilling company expertise and experience. Different approaches to operation and maintenance can greatly affect the degree of fouling, these include limiting reagent concentrations, maintaining submerged well screens and filtering injection water to prevent the introduction of fouling enhancing constituents. Tracking well performance by monitoring changes in system operation and metrics such as specific capacity or injectivity for extraction and injection wells, respectively, or turbidity and chemical analyses for monitoring wells is key to identifying well maintenance issues early when well rehabilitation can be most effective. Proactive well rehabilitation can include mechanical brushing, surging and jetting, chemical treatment or other specialized approaches; however, the approach needs to be based on a site-specific understanding of the predominant fouling mechanisms. Collection and analyses of fouling deposits can provide guidance for selection of rehabilitation methods and chemicals that will be most effective. Application of these approaches have led to extended operational life for reagent injection wells, which can foul quickly, from months to years. Additionally, proper maintenance will often lead to increased and extended productivity of the well. For extraction wells, this translates to a higher sustainable yield, which means shorter cleanup times. Similarly, for injection wells, proper maintenance allows for the introduction of a greater volume of reagents over a shorter period, thus, shorter cleanup times that reduce overall project costs. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Mercury Remediation in Oak Ridge, Tennessee; Successes and Remaining Challenges - 19390

Mercury remediation is a high priority for the US Department of Energy's (DoE's) Environmental Management program in Oak Ridge, Tennessee because of large historical losses of mercury to the environment, and the potential health risks to humans and wildlife primarily through fish consumption. Remedial solutions for mercury contaminated aquatic systems are limited - many aquatic systems have diffuse sources of mercury (Hg) and depending on the environmental conditions, these low concentrations of inorganic Hg can result in fish consumption advisories due to the production of the more toxic methylmercury (MeHg) and its bioaccumulation and biomagnification. From the 1980's to the present, long-term monitoring of mercury concentrations in water and fish downstream of DOE facilities in Oak Ridge have provided an opportunity to assess the performance and effectiveness of various remedial and abatement actions to address mercury. Early actions in the mid-1980's focused on pollution control that positively affected mercury discharges to one local stream, including consolidation and elimination of untreated discharges, sanitary sewer relining, the construction of a pollution control facility, and the replacement of a contaminated settling basin. The 1990's were an intensive period of facility remedial actions designed to improve stream water quality and reduce mercury discharges. Actions included dechlorinating cooling water discharges, an additional phase of storm sewer relining, the addition of flow from a nearby reservoir, the addition of two small-scale mercury treatment systems, the bypass of stream flow around the settling basin, and the removal of high mercury-contaminated floodplain soils. Because of these multiple remedial actions total mercury concentrations in receiving streams decreased significantly; however, mercury concentrations in fish did not respond commensurately and remain a challenge to the present day. Although the mercury remedial strategy in Oak Ridge will continue to focus in the near-term on upstream facility source reduction, recent research suggests that understanding mercury transport, methylation, and bioaccumulation processes in the downstream environment is essential to reducing mercury fish concentrations. Since 2014, mercury remediation research and technology development activities have been underway to develop potential remedial solutions for the downstream environment, including use of sorbents to control soil leaching and the potential use of chemical or biological manipulations. The Oak Ridge mercury remediation story is a valuable case study for flowing systems that can inform our national-level understanding of potential mercury cleanup actions and their likely environmental response. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Resilient remediation: Addressing extreme weather and climate change, creating community value

Devastating hurricanes experienced in recent years demonstrated that extreme weather and climate change can jeopardize contaminated land remediation and harm public health and the environment. Since early 2016, the Sustainable Remediation Forum (SURF) has led research and organized knowledge exchanges to examine (1) the impacts of climate change and extreme weather events on hazardous waste sites, and (2) how we can mitigate these impacts and create value for communities. The SURF team found that climate change and extreme weather events can undermine the effectiveness of the approved site remediation, and can also affect contaminant toxicity, exposure, organism sensitivity, fate and transport, long-term operations, management, and stewardship of remediation sites. Further, failure to consider social vulnerability to climate change could compromise remediation and adaptation strategies. SURF's recommendations for resilient remediation build on resources and drivers from state, national, and international sources, and marry the practices of sustainable remediation and climate change adaptation. They outline both general principles and site-specific protocols and provide global examples of mitigation and adaptation strategies. Opportunities for synergy include vulnerability assessments that benefit and build on established hazardous waste management law, policy, and practices. SURF's recommendations can guide owners and project managers in developing a site resiliency strategy. Resilient remediation can help expedite cleanup and redevelopment, decrease public health risks, and create jobs, parks, wetlands, and resilient energy sources. Resilient remediation and redevelopment can also positively contribute to achieving international goals for sustainable land management, climate action, clean energy, and sustainable cities.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Mercury Remediation in Oak Ridge, Tennessee; Successes and Remaining Challenges

Mercury remediation is a high priority for the US Department of Energy’s (DOE’s) Environmental Management program in Oak Ridge, Tennessee because of large historical losses of mercury to the environment, and the potential health risks to humans and wildlife primarily through fish consumption. Remedial solutions for mercury contaminated aquatic systems are limited – many aquatic systems have diffuse sources of mercury (Hg) and depending on the environmental conditions, these low concentrations of inorganic Hg can result in fish consumption advisories due to the production of the more toxic methylmercury (MeHg) and its bioaccumulation and biomagnification. From the 1980s to the present, long-term monitoring of mercury concentrations in water and fish downstream of DOE facilities in Oak Ridge have provided an opportunity to assess the performance and effectiveness of various remedial and abatement actions to address mercury. Early actions in the mid-1980s focused on pollution control that positively affected mercury discharges to one local stream, including consolidation and elimination of untreated discharges, sanitary sewer relining, the construction of a pollution control facility, and the replacement of a contaminated settling basin. The 1990s were an intensive period of facility remedial actions designed to improve stream water quality and reduce mercury discharges. Actions included dechlorinating cooling water discharges, an additional phase of storm sewer relining, the addition of flow from a nearby reservoir, the addition of two small-scale mercury treatment systems, the bypass of stream flow around the settling basin, and the removal of high mercury-contaminated floodplain soils. Because of these multiple remedial actions total mercury concentrations in receiving streams decreased significantly; however, mercury concentrations in fish did not respond commensurately and remain a challenge to the present day. Although the mercury remedial strategy in Oak Ridge will continue to focus in the near-term on upstream facility source reduction, recent research suggests that understanding mercury transport, methylation, and bioaccumulation processes in the downstream environment is essential to reducing mercury fish concentrations. Since 2014, mercury remediation research and technology development activities have been underway to develop potential remedial solutions for the downstream environment, including use of sorbents to control soil leaching and the potential use of chemical or biological manipulations. The Oak Ridge mercury remediation story is a valuable case study for flowing systems that can inform our national-level understanding of potential mercury cleanup actions and their likely environmental response.

Peterson, Mark J.↗
DOE OSTI2018

Successful In Situ Remediation of Cr(VI)-Impacted Deeper Vadose Zone Soils for Groundwater Protection - 18603

Shallow soil at a former industrial wood treating facility was impacted with chromium, arsenic, and copper above cleanup goals and shallow soil has been excavated for protection of direct contact exposure pathways. Deeper vadose zone soil was predominantly impacted with chromium and was undergoing remediation for long-term groundwater protection. The 920-meter (m) long Cr(VI) groundwater plume has undergone full-scale remediation with groundwater recirculation and in situ bioremediation. Following approximately 4 years of operation, the Cr(VI) groundwater plume, with former source area groundwater concentrations over 10,000 micrograms per liter (μg/L), has been reduced to below the laboratory method reporting limit (0.50 μg/L). Approximately 23,000 cubic meters (m{sup 3}) of deeper (4.5 m - 11 m below ground surface, bgs) vadose zone soil required Cr(VI) remediation. The remediation strategy relied on reduction of Cr(VI) and geochemical fixation as trivalent chromium (Cr(III)) and iron hydroxide precipitates. Chromium reduction was facilitated by a carbon source (corn syrup and methanol) to establish and maintain biogeochemical reducing conditions and ferrous iron to support direct Cr(VI) chemical reduction. Combined, the injected soil moisture, carbon source and ferrous iron supported fast and sustained ferrous/ferric iron cycling and Cr(VI) reduction. Remedy performance monitoring included time-series water quality data from a network of vacuum lysimeters and confirmation soil borings. Reagent was applied either through liquid injection wells and direct-push injection points, or by deep soil mixing methodology in areas with difficult geology (i.e., fine-grained soils and discontinuous iron-silica hardpan layer). Following both phases of deep soil remediation, soils met long-term protection of groundwater remediation action objectives. In situ treatment of soils provides a cost-effective remedial solution compared to excavation, specifically when impacts are deep and long-term protection of groundwater is a primary remediation goal. The delivery methods employed in this case study can be applied to sites impacted with a broad range of contaminants amendable to geochemical fixation (e.g., chromium, uranium, strontium, nitrate, etc.). (authors)

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DOE OSTI2023

Spectral induced polarization signatures of smoldering remediation enhanced with colloidal activated carbon: An experimental study

Monitoring the remediation of soil and groundwater contaminated by organic compounds remains highly challenging. The spectral induced polarization (SIP) method exhibits significant promise for monitoring changes to the electrical properties of soils that are undergoing remediation. Thermal treatments, such as smoldering combustion, have become established remediation techniques for destroying contaminants. Smoldering combustion is now being supported by colloidal activated carbon (CAC), with CAC able to adsorb contaminants and supplement the fuel source for destroying contaminants. The objective of this study is to investigate the potential of SIP for tracking the smoldering remediation of imitated field soils supplemented with CAC. SIP column experiments were first conducted to assess the response of SIP to varying concentrations of CAC in field soils that contain, or do not contain, organic material (OM). Here these results demonstrate that increasing OM and CAC contents increase both the real and imaginary components of the complex conductivity, with the imaginary conductivity also showing frequency dependence. Next, a suite of smoldering and SIP column experiments was conducted to investigate if SIP can detect changes in imitated field soils of varying OM and CAC contents that have been remediated by smoldering combustion. The SIP results on the examined soils both before and after smoldering show that SIP can detect changes in the real conductivity, and particularly the imaginary conductivity, between different soil compositions and different stages of the remediation process. High resolution scanning electron microscopy (SEM) imaging was performed on all samples to validate the SIP and smoldering experiments, confirming significant reductions in carbon after smoldering. Overall, this study suggests that SIP has potential to detect changes in the electrical properties of field soils due to the addition of remedial fluids like CAC and contaminant destruction by smoldering remediation.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Role of uncertainties in protecting ecological resources during remediation and restoration

Cleanup of contaminated waste sites is a National priority to protect human health and the environment, while restoring land to productive uses. While there are uncertainties with under standing risk to individuals from exposure, the aim of this study was to focus on uncertainties and complexities for ecological systems, complicated by hundreds of species occupying any remediation site which participate in multiple-interacting food webs. The ability to better predict the effectiveness of remediation in fostering future ecosystems might facilitate remedy selection and improve strategic environmental management. This investigation examined (1) uncertainties in ecosystem processes, (2) uncertainties in exposure from contamination before remediation, and (3) uncertainties during remediation. Two Department of Energy sites Hanford Site and Savannah River Site were used as case studies to illustrate how the uncertainties affect eco-receptors. Several types of ecological, physical, and human dimension uncertainties are defined. Ecological uncertainties include temporal, spatial, individual, developmental, and exogenous types. Physical uncertainties are weather-related, watershed variations, slope/aspect, soil/sediment structure and form, unforeseen events, and temporal patterns. Human dimension uncertainties include current land use, future land use, extractive and non-extractive recreation. The effects of remedial strategies varied between the two sites because Hanford is a primarily arid shrub-steppe ecotype, while Savannah River is a wet forest ecotype. Defining the associated ecological sensitivities and uncertainties and providing examples might help policy-makers, managers, planners, and contractors to be aware of issues to consider throughout planning, remediation, and restoration. Adding ecological uncertainty analysis to risk evaluations and remediation planning is analogous to using safety factors in human health risk assessment.

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DOE OSTI2013

Remedy Evaluation Framework for Inorganic, Non-Volatile Contaminants in the Vadose Zone

Contaminants in the vadose zone may act as a potential long-term source of groundwater contamination and need to be considered in remedy evaluations. In many cases, remediation decisions for the vadose zone will need to be made all or in part based on projected impacts to groundwater. Because there are significant natural attenuation processes inherent in vadose zone contaminant transport, remediation in the vadose zone to protect groundwater is functionally a combination of natural attenuation and use of other remediation techniques, as needed, to mitigate contaminant flux to groundwater. Attenuation processes include both hydrobiogeochemical processes that serve to retain contaminants within porous media and physical processes that mitigate the rate of water flux. In particular, the physical processes controlling fluid flow in the vadose zone are quite different and generally have a more significant attenuation impact on contaminant transport relative to those within the groundwater system. A remedy evaluation framework is presented herein that uses an adaptation of the established EPA Monitored Natural Attenuation (MNA) evaluation approach and a conceptual model based approach focused on identifying and quantifying features and processes that control contaminant flux through the vadose zone. A key concept for this framework is to recognize that MNA will comprise some portion of all remedies in the vadose zone. Thus, structuring evaluation of vadose zone waste sites to use an MNA-based approach provides information necessary to either select MNA as the remedy, if appropriate, or to quantify how much additional attenuation would need to be induced by a remedial action (e.g., technologies considered in a feasibility study) to augment the natural attenuation processes and meet groundwater protection goals.

natural attenuation↗
DOE OSTI2012

An Overview of Public Domain Tools for Measuring the Sustainability of Environmental Remediation - 12060

The application of sustainability principles to the investigation and remediation of contaminated sites is an area of rapid development within the environmental profession, with new business practices, tools, and performance standards for identifying, evaluating, and managing the 'collateral' impacts of cleanup projects to the environment, economy and society coming from many organizations. Guidelines, frameworks, and standards of practice for 'green and sustainable remediation' (GSR) have been released and are under development by the Sustainable Remediation Forum (SURF), the American Society for Testing Materials (ASTM), the Interstate Technology Roundtable Commission (ITRC) and other organizations in the U.S. and internationally. In response to Executive Orders from the President, Federal government agencies have developed policies, procedures and guidelines for evaluating and reporting the sustainability of their environmental restoration projects. Private sector companies in the petroleum, utility, manufacturing, defense, and other sectors are developing their own corporate GSR programs to improve day-to-day management of contaminated sites and to support external reporting as part of their corporate social responsibility (CSR) efforts. The explosion of mandates, policy, procedures and guidance raises the question of how to determine whether a remediation technology or cleanup approach is green and/or sustainable. The environmental profession has responded to this question by designing, developing and deploying a wide array of tools, calculators, and databases that enable regulatory agencies, site managers and environmental professionals to calculate the collateral impacts of their remediation projects in the environmental, social, and economic domains. Many of these tools are proprietary ones developed by environmental engineering/consulting firms for use in their consulting engagements and/or tailored specifically to meet the needs of their clients. When it comes to the public domain, Federal government agencies are spearheading the development of software tools to measure and report emissions of air pollutants (e.g., carbon dioxide, other greenhouse gases, criteria air pollutants); consumption of energy, water and natural resources; accident and safety risks; project costs and other economic metrics. Most of the tools developed for the Government are available to environmental practitioners without charge, so they are growing in usage and popularity. The key features and metrics calculated by the available public-domain tools for measuring the sustainability of environmental remediation projects share some commonalities but there are differences amongst the tools. The SiteWise{sup TM} sustainability tool developed for the Navy and US Army will be compared with the Sustainable Remediation Tool (SRT{sup TM}) developed for the US Air Force (USAF). In addition, the USAF's Clean Solar and Wind Energy in Environmental Programs (CleanSWEEP), a soon-to-be-released tool for evaluating the economic feasibility of utilizing renewal energy for powering remediation systems will be described in the paper. (authors)

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