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At least 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Unique Regulatory Approach for Licensing the Port Hope Remediation Project in Canada - 13315

The Port Hope remediation project is a part of a larger initiative of the Canadian Federal Government the Port Hope Area Initiative (PHAI) which is based upon a community proposal. The Government of Canada, through Natural Resources Canada (NRCan) is investing $1.28 billion over 10 years to clean up historic low-level radioactive waste in the Port Hope Area and to provide long-term safe management of the low-level radioactive wastes in the Port Hope Area. These wastes arose from the activities of a former Federal Crown Corporation (Eldorado Nuclear) and its private sector predecessors. In Canada, historic waste are defined as low-level radioactive waste that was managed in a manner no longer considered acceptable, but for which the original producer cannot reasonably be held responsible or no longer exists and for which the Federal Government has accepted responsibility. In Canada, under the current regulatory framework, the environmental remediation is not considered as a distinct phase of the nuclear cycle. The regulatory approach for dealing with existing sites contaminated with radioactive residues is defined on the basis of risk and application of existing regulations. A unique regulatory approach was taken by the Canadian Nuclear Safety Commission (CNSC) to address the various licensing issues and to set out the requirements for licensing of the Port Hope Project within the current regulatory framework. (authors)

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DOE OSTI2013

Lower Three Runs Remediation Safety Preparation Strategy - 13318

The Savannah River Site (SRS) is a 310-square-mile United States Department of Energy (US DOE) nuclear facility located along the Savannah River near Aiken, South Carolina that contains six primary stream/river systems. The Lower Three Runs Stream (LTR) is one of the primary streams within the site that is located in the southeast portion of the Savannah River Site. It is a large blackwater stream system that originates in the northeast portion of SRS and follows a southerly direction before it enters the Savannah River. During reactor operations, secondary reactor cooling water, storm sewer discharges, and miscellaneous wastewater was discharged and contaminated a 20 mile stretch of Lower Three Runs Stream that narrows and provides a limited buffer of US DOE property along the stream and flood-plain. Based on data collected during the years 2009 and 2010 under American Recovery and Re-investment Act funding, the stream was determined to be contaminated with cesium-137 at levels that exceeded acceptable risk based limits. In agreement with the Environmental Protection Agency and the South Carolina Department of Health and Environmental Control, three areas were identified for remediation [1] (SRNS April 2012). A comprehensive safety preparation strategy was developed for safe execution of the LTR remediation project. Contract incentives for safety encouraged the contractor to perform a complete evaluation of the work and develop an implementation plan to perform the work. The safety coverage was controlled to ensure all work was observed and assessed by one person per work area within the project. This was necessary due to the distances between the fence work and three transects being worked, approximately 20 miles. Contractor Management field observations were performed along with DOE assessments to ensure contractor focus on safe performance of the work. Dedicated ambulance coverage for remote worker work activities was provided. This effort was augmented with access to medical evacuation services. The areas where the work was performed were remote and difficult to get emergency vehicles to in a timely manner in case of an accident. Satellite phones were utilized due to intermittent phone coverage. High visibility vests were utilized to enable any hunters in the area to see the workers; due to the limited buffer areas along the stream route. An innovative approach to providing the necessary protection for workers during periods of extreme heat and humidity was also employed, which included the use of 'heat islands' with fans and crew trailers and ice vests for workers. (authors)

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DOE OSTI2013

Remediation of Highland Drive Landfill: Technical Challenges of Segregating Co-Mingled LLRW and Municipal Solid Waste in an Urbanized Area - 13319

Highland Drive Landfill is an inactive Municipal Solid Waste (MSW) Landfill which received waste from the 1940's until its closure in 1991. During a portion of its active life, the Landfill received low-level radioactive waste (LLRW) which currently exists both in a defined layer and co-mingled with MSW. Remediation of this site to remove the LLRW to meet established cleanup criteria, forms part of the Port Hope Project being undertaken by Atomic Energy Canada Limited (AECL) and Public Works and Government Services Canada (PWGSC) as part of the Port Hope Area Initiative (PHAI). The total volume of LLRW and co-mingled LLRW/MSW estimated to require removal from the Highland Drive Landfill is approximately 51,900 cubic metres (m{sup 3}). The segregation and removal of LLRW at the Highland Drive Landfill presents a number of unique technical challenges due to the co-mingled waste and location of the Landfill in an urbanized area. Key challenges addressed as part of the design process included: delineation of the extent of LLRW, development of cut lines, and estimation of the quantity of co-mingled LLRW in a heterogeneous matrix; protection of adjacent receptors in a manner which would not impact the use of adjacent facilities which include residences, a recreational facility, and a school; coordination and phasing of the work to allow management of six separate material streams including clean soil, MSW, co-mingled LLRW/MSW, LLRW, un-impacted water, and impacted water/leachate within a confined environment; and development of a multi-tiered and adaptive program of monitoring and control measures for odour, dust, and water including assessment of risk of exceedance of monitoring criteria. In addition to ensuring public safety and protection of the environment during remedy implementation, significant effort in the design process was paid to balancing the advantages of increased certainty, including higher production rates, against the costs of attaining increased certainty. Many of these lessons may be applicable to other projects. (authors)

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DOE OSTI2013

Successful Characterization and Remedial Contour of Highly Contaminated Mercury Soil at the Y-12 National Security Complex - 13593

An area known as the 81-10 pad within the footprint of the Y-12 National Security Complex, suspected to be heavily contaminated with mercury, was slated for characterization in support of a Federal Facilities Agreement (FFA) milestone to be accomplished by September 30, 2012. A full remedial design report (RDR) required the soil in Exposure Unit -9 (EU-9) to be fully characterized for a number of contaminates of concern including mercury. The goal of this characterization effort was to determine what soil, if any, would need to be removed for the protection of industrial workers and impacts to the surface and ground water. Funding for this project was made available using buy-back scope under the American Recovery and Reinvestment Act (ARRA). The EU-9 soil unit involved 3 different classifications which were determined as follows: Class 1: Known to have been impacted, contamination is likely; Class 2: Suspected to have been impacted, contamination is unknown; Class 3: Area not known to have been impacted, contamination unlikely. Due to various sampling and analysis events since the 1980's, significant mercury contamination was expected under the concrete pad of an area known as 81-10. Mercury contamination outside of the boundary of this pad within the EU-9 footprint was not known and therefore an original planned estimate of 1,461 cubic meters of material were expected to be heavily contaminated with mercury requiring removal, treatment and disposal. Through the use of a highly effective nature and extent sampling and analysis design that involved a hybrid of statistically-based and judgmental sampling, the actual remedial contour requiring removal was approximately 717 cubic meters, roughly 12% of the original estimate. This characterization approach was executed in full compliance with the Record of Decision (ROD) [1] documents that were agreed upon by the U.S. Department of Energy, Environmental Protection Agency and Tennessee Department of Environment and Conservation. In addition, the RDR was completed ahead of the FFA milestone date of September 30, 2012. (authors)

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DOE OSTI2013

Sulfur-Modified Zero-Valent Iron for Remediation Applications at DOE Sites - 13600

Many DOE remediation sites have chemicals of concern that are compounds in higher oxidation states, which make them both more mobile and more toxic. The chemical reduction of these compounds both prevents the migration of these chemicals and in some cases reduces the toxicity. It has also been shown that zero-valent iron is a very effective substance to use in reducing oxygenated compounds in various treatment processes. These have included the treatment of halogenated hydrocarbons in the form volatile organic compounds used as solvents and pesticides. Zero-valent iron has also been used to reduce various oxidized metals such as chromium, arsenic, and mercury in order to immobilize them, decrease their toxicity, and prevent further transport. In addition, it has been used to immobilize or break down other non-metallic species such as selenium compounds and nitrates. Of particular interest at several DOE remediation sites is the fact that zero-valent iron is very effective in immobilizing several radioactive metals which are mobile in their oxidized states. These include both technetium and uranium. The main difficulty in using zero-valent iron has been its tendency to become inactive after relatively short periods of time. While it is advantageous to have the zero-valent iron particles as porous as possible in order to provide maximum surface area for reactions to take place, these pores can become clogged when the iron is oxidized. This is due to the fact that ferric oxide has a greater volume for a given mass than metallic iron. When the surfaces of the iron particles oxidize to ferric oxide, the pores become narrower and will eventually shut. In order to minimize the degradation of the chemical activity of the iron due to this process, a modification of zero-valent iron has been developed which prevents or slows this process, which decreases its effectiveness. It is called sulfur-modified iron, and it has been produced in high purity for applications in municipal water treatment applications. Sulfur-modified iron has been found to not only be an extremely economical treatment technology for municipal water supplies, where very large quantities of water must be treated economically, but it has also been demonstrated to immobilize technetium. It has the added benefit of eliminating several other harmful chemicals in water supplies. These include arsenic and selenium. In one large-scale evaluation study an integrated system implemented chemical reduction of nitrate with sulfur-modified iron followed by filtration for arsenic removal. The sulfur-modified iron that was used was an iron-based granular medium that has been commercially developed for the removal of nitrate, co-contaminants including uranium, vanadium and chromium, and other compounds from water. The independent study concluded that 'It is foreseen that the greatest benefit of this technology (sulfur-modified iron) is that it does not produce a costly brine stream as do the currently accepted nitrate removal technologies of ion exchange and reverse osmosis. This investigation confirmed that nitrate reduction via sulfur-modified iron is independent of the hydraulic loading rate. Future sulfur-modified iron treatment systems can be designed without restriction of the reactor vessel dimensions. Future vessels can be adapted to existing site constraints without being limited to height-to-width ratios that would exist if nitrate reduction were to depend on hydraulic loading rate'. Sulfur-modified iron was studied by the Pacific Northwest National Laboratory (PNNL) for its effectiveness in the reduction and permanent sequestration of technetium. The testing was done using Hanford Site groundwater together with sediment. The report stated, 'Under reducing conditions, TcO{sub 4} is readily reduced to TcIV, which forms highly insoluble oxides such at TcO{sub 2}.nH{sub 2}O. However, (re)oxidation of TcIV oxides can lead to remobilization. Under sulfidogenic conditions, most TcIV will be reduced and immobilized as Tc{sub 2}S{sub 7}, which is less readily re-mobilized, even under oxic conditions. This process should be favored by stimulation of sulfidogenic conditions'. The sulfur-modified iron provides the sulfur, together with the iron, to maintain this stable sequestration of technetium. As a result of these and other studies demonstrating the cost-effectiveness of sulfur-modified iron in treating technetium and other hazardous compounds in Hanford Site groundwater and its cost-effectiveness in reducing nitrate, the Richland Operations Office of the Department of Energy issued a change order to the Central Plateau Contractor providing for the testing of sulfur-modified iron in a mobile pilot unit at the Hanford Site. Further testing is anticipated to produce refinements in operating conditions and further optimization of the existing process. (authors)

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DOE OSTI2012

Design, Development, Pre-Testing and Preparation for Full Scale Cold Testing of a System for Field Remediation of Vertical Pipe Units at the Hanford Site 618-10 Burial Grounds -12495

At the Hanford site, in the 1950's and 60's, radioactive waste materials, including Transuranic (TRU) wastes from a number of laboratories were stored in vertical pipe units (VPUs) in what are now the 618-10 and 618-11 burial grounds. Although the current physical condition of the VPUs is unknown, initial R and D studies had shown that in-ground size reduction and stabilization of VPU contents was feasible. This paper describes the R and D work and testing activities to validate the concept of in-ground size reduction and stabilization of VPU contents, and the design and pre-testing of major plant items and augering systems on full size simulated VPUs. The paper also describes the full size prototype equipment which will be used in full size cold testing of simulated VPUs off the Hanford site, to prove the equipment, develop operating procedures, and train operators prior to deployment on site. Safe and effective field remediation, removal and disposal of the VPUs in the 600 area are critical to the success of the River Corridor Closure Contract at the U.S. Department of Energy's Hanford Site. Safe and effective field remediation, removal and disposal of the VPUs in the 600 area are critical to the success of the River Corridor Closure Contract at the U.S. Department of Energy's Hanford Site. (authors)

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DOE OSTI2017

Chaotic Advection and Unsteady Flow in Groundwater Remediation - 17237

This paper reviews an ongoing research program of numerical and laboratory studies on chaotic advection applied to groundwater remediation, including numerically simulated effects of sorption and heterogeneity, and experiments aimed at demonstrating chaotic advection in refractive index matched (i.e., transparent) porous media. Additionally, this paper outlines a proposed approach to test chaotic advection at an appropriate field site. If shown to be successful in a field application, chaotic advection offers the possibility of better hydraulic control of contaminant plumes, accelerated remediation, consequent reduction in cost, and improvement in environmental health. (authors)

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DOE OSTI2017

Remediation of 130 mSv/hr. Soil Contamination Under a Hot Cell - 17301

Department of Energy (DOE) contractor CH2M HILL Plateau Remediation Company (CH2M) is currently engineering a system to safely remove and dispose of highly contaminated soil underneath Building 324 located adjacent to the Columbia River on the Hanford Site in Washington State. Cleaning up the waste site will allow for the eventual demolition of the building, which is a top priority for DOE and CH2M due to the proximity of the Columbia River and City of Richland. Building 324 at Hanford was originally constructed in 1966 and was operated for a number of years serving various missions. One of the missions involved development of treatment processes for liquid high activity waste. As of result of one particular mission, liquid high activity waste was spilled in one of the building's hot cells (known as 'B' Cell) and the liquid leaked from a breach in a sump and through construction joints in the hot cell floor and into the soil. Sampling efforts using borehole technology revealed significant under-building contamination with dose rates measuring has high as 130 mSv/hr (13,000 R/hr.). The Hanford Federal Facility Agreement and Consent Order (Tri-Party Agreement) between the Washington State, Department of Ecology (Ecology), the U.S. Environmental Protection Agency and the DOE has established a 2021 milestone for demolition and removal of the Building 324. Before building demolition can be undertaken, the highly contaminated soil must be removed from beneath the hot cell while the hot cell structure remains in place to provide shielding and containment during the soil remediation. CH2M will fabricate and install remotely operated equipment that will remove debris and grout in the cell, the floor of the hot cell, and the contaminated soil beneath the hot cell and package that soil for disposal. To ensure that the structure remains intact and does not shift during soil removal, support for the building structure must also be constructed as a prerequisite for the planned work. CH2M will use a full-scale mock-up of the Building 324 B Cell and airlock area to assist in the testing of the remotely operated equipment and the training of the soil removal team in a contamination-free environment to ensure efficient and safe performance of the challenging work of the project. (authors)

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DOE OSTI2017

Emerging Contaminants: Investigation and Remediation of Poly- and Perfluoroalkyl Substances in the Environment - 17339

The group of chemicals known as PFAS (poly- and perfluoroalkyl substances) has come under increasing scientific and regulatory scrutiny in recent years as more is understood about their toxicity, their environmental persistence and their potential to bio-accumulate. PFAS are used in a wide range of industrial applications and commercial products due to their unique surface tension and levelling properties. They include stain repellents for textiles and carpeting, grease-proof paper, water- and oil-resistant coatings, and mist suppressants. PFAS are also major components of the class B fire fighting foams known as aqueous film forming foam (AFFF), Fluoro-protein Foams (FP) and Film Forming Fluoro-protein Foams (FFFP) commonly used at Federal and Commercial facilities throughout the world. Long chain PFASs (>5 or 6perfluroalkyl-carbons) such perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), bio-accumulate. Currently, PFOS, PFOA, and a few other PFASs are increasingly regulated outside of the U.S., and at varying levels in drinking water or groundwater in select U.S. states. The U.S. EPA recently established a long-term exposure criteria of 70 ng/L for combined PFOS and PFOA in drinking water. While PFOS and PFOA have the most regulatory attention, there are thousands of chemicals in the PFAS class; some PFASs are precursor compounds capable of transforming to PFOS and PFOA or analogs. The remedial options available to address PFAS contamination are limited by the unique physico-chemical properties of these compounds. Technologies currently used for the remediation of PFAS contaminated sites include soil incineration or excavation to landfill, and groundwater extraction with PFAS adsorption onto activated carbon or resins. Emerging technologies for PFAS, include stabilization in soil, photolysis/ photo-catalysis, reductive decomposition, advanced oxidation, reduction and sonolysis for groundwater. However, the evidence that these technologies effectively break the fully fluorinated backbone of PFAS, or can treat or sequester all carbon chain lengths is limited. To date these technologies are unproven or considered infeasible for high flowrate, low concentration applications. New in-situ techniques, including an oxidation / reduction method known as ScisoR{sup R} (Smart combined in situ oxidation and Reduction), are currently being tested in the lab and some are being applied in field demonstrations. (authors)

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DOE OSTI2017

An IAEA Initiative to Provide Effective Stakeholder Support Services for International Decommissioning and Environmental Remediation - 17341

The International Atomic Energy Agency (IAEA) has initiated a collaborative effort to promote stakeholder support activities through a stakeholder engagement advisory program (SEAP) as part of Phase II of the Constraints to Implementing Decommissioning and Environmental Remediation (CIDER II) program. CIDER II is a collaborative project involving a broad range of Member States, large and small, with ongoing and/or planned decommissioning and environmental remediation (D and ER) programs. The intent of this sub-group of CIDER II is to facilitate better sharing of information and knowledge in areas of stakeholder communication, engagement and participation, and a framework for directly using stakeholder input in the decision making process. The goal is to support trust building in D and ER decisions for radioactive contamination and facilities. A main premise of the CIDER II program is that stakeholder acceptance is necessary for successful D and ER decisions to be made. This paper introduces some of the major challenges to implementing such a broad scale of support for stakeholder engagement, and approaches to overcoming those challenges. Major challenges include the need to address D and ER decision making in different countries with their different languages, cultures, religions, management structures, and politics. For example, in some cases it might be important strategically to first garner support from upper levels of social, management or political hierarchies, including for example, approaching community leaders, and allowing those leaders to directly address their community. Other sites might have more success, for example, if stakeholder interaction starts with the community members. A specific project strategy also probably depends on who makes the request for stakeholder support services. Once the CIDER II SEAP gains traction, there will be a need to prioritize requests from Member States for assistance in connection with specific D and ER projects. A prioritization tool will be developed based on stakeholder engaged structured decision making (SDM). The projects in which support will initially be focused will span a wide range of D and ER problems, types of stakeholder groups, and technical issues such as potential risk to human health and the environment. A database management system will also be designed to capture information from the different proposed projects and will be expanded to house implemented projects for future reference. The case study database will be an integral part of a web-based system that also contains technical approaches for stakeholder involvement depending on the situational environment. A community of practice will be formed that will involve technical experts in stakeholder engagement and structured decision making, and informed representatives from Member States. This will address the need for SEAP to build capacity and provide education for solving D and ER problems. The web-based system will include technical tools for use by the projects, such as: identification of stakeholder groups; social network analysis (how stakeholders are connected); case study forms; best practice forms; information sheets; and 4tools that will directly support optimization of stakeholder guided solutions to D and ER problems. (authors)

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DOE OSTI2017

Formerly Utilized Sites Remedial Action Program - Program Update - 17530

The legacy of the United States' early atomic energy program is an important piece of our Nation's history. That legacy however, left low-level radiological contamination at properties now owned and operated by commercial, private and/or local government entities. Although many of these contaminated sites were identified by the Government in the past, additional properties continue to be identified. The United States Government, thru the US Department of Energy (USDOE) and the US Army Corps of Engineers (USACE), is addressing these sites with the Formerly Utilized Sites Remedial Action Program (FUSRAP) and has been doing so since the 1970's. The USDOE and the USACE both have roles in the Program. The USACE FUSRAP Program has an important task but faces many challenges to achieve a success conclusion. Since the implementation of 'sequestration cap' budgeting by Congress in 2012, the annual budget for the Program has decreased significantly compared to the funding levels in prior years. The Program complies with USACE Civil Works budgetary reprogramming rules that requires close coordination between the project and program teams to appropriately and efficiently obligate and expend Program funding. The very nature of environmental remediation work results in consistently finding additional unknowns during each phase of a project. The Program is required to follow Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) guidance and conduct cost recovery activities but does not have authorities such as those held by the US Environmental Protection Agency (USEPA). In order to pursue cost recovery actions, conclude a settlement agreement or file an administrative order, USACE must engage the US Department of Justice or USEPA to act on their behalf as USACE does not have the authority to do so themselves. Twenty years later, USACE continues to carry out the FUSRAP mission and work in coordination with the USDOE Office of Legacy Management (DOE-LM) to ensure that the Government's responsibilities are addressed. Success is measured by finishing each site cleanup so they can be turned back to their property owner and stakeholders for safe use. USACE continues to seek new technologies and methods of approach to improve and expedite site investigations and clean ups. (authors)

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DOE OSTI2015

A paradigm shift - the key to optimal, defensible and transparent waste management, disposal and remediation decisions - 15236

Current methods for structuring nuclear waste management, disposal, and remediation decisions are subject to three major limitations. First, they are based on a series of extraordinarily conservative assumptions. The dominant way of thinking is that, for example, conservative models yield better, safer decisions. Second, they lack methods to meaningfully address and incorporate the 'human dimension'. The dominant way of thinking is that the current approach is sufficient to bring together the values and interests of both internal and external stakeholders in making a decision. And third, they lack a formal method through which both internal and external stakeholders are encouraged collectively to 'think through' complex problems that contain multiple competing objectives so that wise, socially acceptable, and scientifically-defensible decisions are made. To overcome these limitations, a paradigm shift is needed towards a holistic, integrated approach to structure nuclear waste management, disposal and remediation decisions. The first requirement of this paradigm shift is the realization and recognition that the problems faced are decision problems, and that there is a formal theory of decision analysis that can, and should, be used to support finding the best solutions. Decision analysis, very simply, is formalized common sense. The reason it is needed for complex problems is that there are too many moving parts (variables) for humans to manage with out the formalism. Decision analysis leads to addressing problem solving using a combination of a science-based model and a costs/values model. Expectation ('realism') and uncertainty are addressed in the science-based models, whereas stakeholder values, preferences, and desires are addressed when modeling costs and value judgments. Science-based modeling tools have been developed, improved, and used since the current regulatory setting was introduced about 30 years ago. However, modeling of costs and value judgments has not often been addressed using any formal approach, despite the openings that exist in regulations (e.g., CERCLA's modifying criteria and the concept of 'as low as reasonably achievable' referenced in DOE Orders). A discussion of the need and rationale for this paradigm shift is presented, followed by a description of the technical basics of this approach to decision modeling, and ending with an explanation of the steps that are taken in this approach to structured decision-making. A software framework program called Guided Interactive Statistical Decision Tools (GiSdT - pronounced 'gist') is introduced that supports this paradigm shift. (authors)

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DOE OSTI2015

Functional diversity in oxic sediments from the Hanford 200 West Area and implications for remediation - 15425

Past plutonium enrichment and recovery processes at the Hanford site have resulted in sediments and groundwater contaminated with various mixtures of carbon tetrachloride, uranium, chromium, technetium-99, iodine-129, nitrate and tritium. Initial efforts to understand functional dynamics of the microbial community from sediment and groundwater samples recovered from beneath the 200-UP-1 Operable Unit will provide valuable insight that could be used in developing remedial strategies. Core samples were taken from three depths (10, 30 and 50 ft.) below the water table for two extraction wells being drilled in the 200-UP-1 OU. Physical, geochemical and contaminant properties were analyzed on these Ringold formation sediments. Aerobic and anaerobic enrichments using a number of carbon and electron sources were performed. Meta-genomes were developed targeting the16S rRNA gene to determine phylogenetic diversity. Functional diversity was determined using quantitative polymerase chain reaction (qPCR) and focused on aerobic heterotrophs, chemilithotrophs, nitrate reducers, iron reducers and sulfate reducers. Enrichments were also performed to establish stable communities exposed to contaminants such as iodine-129, technetium-99, nitrate and uranium. Preliminary results indicate that cultivable microorganisms in these oxic sediments were primarily represented by aerobes, fermenters and denitrifying communities; however some iron reducing bacteria were present also. These results indicate that while oxic conditions predominate in these sediments samples, that facultative anaerobes with the functional capacity to bio-transform radionuclide contaminants in the aquifer exist and would likely grow if carbon was added to the aquifer. Implications for findings related to biological remedies for groundwater beneath the 200 West Area will be discussed. (authors)

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DOE OSTI2015

Hydrogeologic modeling and the development of preliminary remediation goals for the Guterl Specialty Steel Site, New York - 15431

The Former Guterl Specialty Steel Corporation Site (Guterl Site) is located 32 kilometers (20 miles) northeast of Buffalo, New York, in Lockport, Niagara County, New York. Between 1948 and 1952, up to 15,875 metric tons (35 million pounds) of natural uranium metal (U) were processed at the Guterl Site. The resulting milling dust, shavings, thermal scale, and associated on-site land disposal contaminated both the facility and soils. These combined manufacturing and disposal processes promoted the development of a large-scale uranium plume in the groundwater underlying the site. Site soils are anthropogenic fill and re-worked, glacially-derived sediments that vary between 0.6 meters (m) and 3 meters (2.0 to 10.0 feet [ft]) in thickness. These soils blanket a highly permeable weathered and fractured zone in the upper Lockport Dolostone bedrock. Aerial recharge through the thin soils flushes soluble constituents to groundwater, as exemplified by variations in specific conductivity and groundwater levels in the bedrock during precipitation events. Seasonally higher groundwater levels also promote contact with uranium contamination in deeper soil, thus complicating the transport characteristics of the site (e.g., oxidizing metallic uranium in the soil that increases leach rates). The Seasonal Soil (SESOIL) compartment model was used to simulate a series of site soil conditions and predict the leaching of uranium to groundwater. The SESOIL input included physical soil characteristics, uranium profiles common in five soil areas, climate data, and an assumed oxidation-state (or chemical valence) for metallic uranium in the soil. The iterative modeling process evaluated site-specific variables to achieve a final deterministic set of input that was applied to the five soil areas. The leaching simulations estimated time-dependent influx rates for uranium, which were input to a numerical groundwater flow (MODFLOW) and transport (MT3DMS) model. The combined modeling effort produced spatially and temporally variable transport conditions that were simulated over a 1,000-year period. The leaching models predicted a preliminary remediation goal (PRG) for uranium of 11 milligrams per kilogram (mg/kg) that is protective of groundwater. However, this low uranium PRG has field implementation concerns, so a modified direct-exposure PRG of 70 mg/kg was developed and evaluated in the flow and transport model. The primary difference in the PRGs is the longevity and location of the uranium plume, which will affect the remedial costs and potential stakeholder acceptance. (authors)

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DOE OSTI2015

Radioactive contamination from 1920-50's at an urban site of the New York City and interim remedial action - 15630

The former Wolff-Alport Chemical Company operated at the location in densely populated urban area in Queens, New York, between 1920 to about 1954. The company imported, stored on-site and processed monazite sand ores from the Belgium Congo. The extracted refined products enriched in rare-earth metals were sold on the commercial market. The process residues, rich in thorium and its progeny, were originally disposed of directly to the city sewer line and probably on-site also. The site's buildings are currently occupied by the auto shops, corner delicatessen store, light construction company, ice maker/distributor, and two residential apartments. Preliminary site investigations found multiple areas with elevated levels of direct gamma radiation with the maximum reported rates of 22 micro-sievert/hour (2.2 milli-rem/hour) at surface level and 40 micro-sievert/hour (4 milli-rem/hour) inside sewer manhole access. The thoron (Rn-220) gas air concentration in outdoor areas was reported reaching 13.5 kBq/m{sup 3} (366 pCi/L) and the radon (Rn-222) gas air concentrations was reported exceeding 148 Bq/ m{sup 3} (4 pCi/L) in some buildings. The dose assessments indicated that, under realistic scenarios, some members of the public were likely to receive the radiation exposure from this contamination in excess of the New York City and Nuclear Regulatory Commission general public radiation dose limit of 1 milli-sievert /yr (100 milli-rem/yr). The interim remedial action was planned and conducted by the U.S. Environmental Protection Agency (U.S. EPA) Region 2 in close cooperation with the New York City and New York State in 2012-13. The purpose of the action was to take necessary interim measures to reduce annual public dose below limit of 1 milli-sievert/yr (100 milli-rem/yr) and reduce radon gas concentration levels in impacted indoor spaces below U.S. EPA Action Level for residencies of 148 Bq/ m{sup 3} (4 pCi/L). In order to achieve these goals, the following actions were taken: detailed radiological and occupancy surveys; development of realistic exposure scenarios; dose assessments; installation of the fence and gates around the 'backyard' portion of the site; vegetation removal; development and detailed assessment of the radiation shielding options; application of the multilayer radiation shielding in some buildings, portions of the sidewalk and unpaved areas; mitigation of radon/thoron gas entry point; and installation of the radon mitigation system in one of the buildings. The preliminary post-action analyses indicated that the action goal would likely be achieved. The interim remedial action was conducted in a tight urban setting; it has significantly reduced public health risk from radiation without closure of businesses that continued operating within the site perimeter. (authors)

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2015

Modeling the effectiveness of remediation efforts in contaminated urban areas: An EMRAS II Urban Areas Working Group exercise - 15631

The Urban Areas Working Group was part of the IAEA's EMRAS II (Environmental Modelling for Radiation Safety) Programme during 2009-2011. The Working Group's goal was to test and improve the capabilities of models used in assessment of radioactive contamination in urban settings. The 'contaminant transport and countermeasures' exercise was focused on modeling the effectiveness of potential countermeasures or remediation efforts with respect to reduction of human exposures and doses. The exercise was based on a hypothetical situation involving an initial concentration of Co-60 or Pu-239 in air in a specified urban area. Participants were given detailed input information, including descriptions of test locations in two types of urban areas, (1) a business area with buildings and asphalt, and (2) a park area near an apartment town. Several kinds of initial weather conditions (dry, light rain, and heavy rain) were explored. Modeling endpoints included contamination densities, dose rates (from each contributing surface and total), annual and cumulative doses (internal and external) for specified reference individuals, and effectiveness of countermeasures and remediation efforts in terms of dose rate reduction and dose reduction. External doses were emphasized for Co-60 and internal doses for Pu-239. Approaches and model predictions from five models are compared, and explanations for similarities and differences among model predictions are offered. Understanding the effects of different approaches, assumptions, and parameter values is essential to a comparison of results from different models and to understanding both the usefulness and the limitations of any given model. (authors)

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Interactive statistical decision tools (GiSdT): An open source software integration of decision analysis and stakeholder judgment for sustainable waste management, disposal and remediation - 15650

The vast majority of remediation and waste management decisions are made without quantitative consideration of economic and socio-political factors. They are made instead based on quantitative metrics of human health risk. Sustainable decisions need to be made based on all three 'pillars of sustainability' (economics, environment and social), and require understanding and characterization of the costs and values associated with each pillar. In addition, such decisions need to conform to regulatory or other legal requirements, which often constrains the decision space of interest. Although efforts are often made to include factors across all three pillars (for example, for decisions made under CERCLA), these efforts are usually qualitative, and hence difficult to defend. They lack technical defensibility, transparency and traceability. The purpose of GiSdT (Guided Interactive Statistical Decision Tools) is to provide a quantitative framework whereby all aspects of a decision problem, such as remediation and waste management decisions, can be addressed quantitatively, and hence, defensibly, transparently and traceably. Most decision-makers do not currently have access to useful or usable methods and approaches when are presented with choices that have significant impacts across all three pillars of sustainability. The goal of GiSdT is to provide that access by identifying or developing effective and user-friendly decision methods and approaches that empower decision-makers to explicitly and routinely incorporate all aspects of sustainability into their decision-making. To identify and develop these methods and approaches, GiSdT provides the tools needed for decision-makers and stakeholders to understand and characterize their knowledge of their current decision-making processes, and what methods and approaches they need to pro-actively and quantitatively address all aspects of sustainability in their decisions. GiSdT is an open source interactive framework program that provides the tools needed to address the relevant components of a sustainability-based decision problem, including describing the decision landscape, translating that landscape into goals and objectives, valuing the measurable attributes that describe each objective, identifying decision options and addressing the uncertainty in the attributes (e.g., human health risk, institutional controls) through appropriate probabilistic models. In addition to addressing these quantitative technical components, the GiSdT program is aimed at facilitating stakeholder involvement so that the perspectives, values and objectives are all relevant stakeholders are addressed explicitly in the decision making process. The technical underpinnings of our software program, called Guided Interactive Statistical Decision Tools (GiSdT), are described. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Evaluating Contaminant Transport in the Vadose Zone to Support Remedy Decisions at Aqueous-Waste Disposal Sites - 16195

Inorganic contaminants in aqueous waste disposed at land surface have a potential to contaminate groundwater. However, contaminant concentrations are attenuated during transport through the vadose zone. Quantifying contaminant attenuation and the resulting temporal concentration profile of in underlying groundwater is important for assessing the need for, and type of, remediation in the vadose zone and groundwater. An approach was developed for evaluating vadose zone transport and attenuation of aqueous wastes containing inorganic (non-volatile) contaminants that were disposed at land surface (i.e., directly to the ground in cribs, trenches, tile fields, etc.) and their effect on underlying groundwater. The approach provides a structured method to estimate transport of contaminants through the vadose zone and the resulting temporal profile of groundwater contaminant concentrations. A series of numerical model simulations was applied to investigate how different factors affect contaminant transport in the vadose zone and the conditions for which individual factors are important. This analysis demonstrated that, while water flow and contaminant transport can be complex during aqueous-waste disposal, conditions will change over time after disposal ceases and fewer factors will control the contaminant transport rate and resulting temporal profile of groundwater contaminant concentrations. Data verifying that these conditions have been reached can be provided by a few key metrics such as the vertical profile of moisture content, the temporal profile of recharge at the site, and basic information about waste disposal and subsurface properties. Under these conditions, and with information about specific contaminant transport parameters (e.g., for partitioning), estimates of contaminant transport can be made and used to support remedy decisions. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗