Jeffrey P. Kulpa and John Hughes, Earthline Technologies.

This paper describes the development and deployment of a chemical extraction soil washing process that dramatically reduces the cost of soil remediation at facilities with radioactively contaminated soil. The carbonate extraction process flow is explained and the substantial cost savings that have resulted in processing over 14,000 tons of contaminated soil thus far are described. In addition, regulatory issues such as; permitting, volumetric free release of clean soil product, long term stabilization of residual uranium in the product, and disposal of plant residuals are explained. Finally, current efforts to expand the soil washing process to other contaminants such as Technetium-99, Radium, Thorium, and TCE are discussed. Earthline Technologies in Ashtabula, Ohio has developed a remediation approach for removing uranium contamination from soil. The treatment approach has been developed from bench scale testing and pilot plant operations through construction and successful operation of a 10 ton per hour chemical extraction soil washing plant. Soil treatment using carbonate extraction reduces the volume of contaminated material requiring off-site disposal which has the positive effect of lowering total project costs associated with soil remediation from $45 Million for ship and bury to $25 Million for treatment. This paper describes the design, construction, shakedown, and operation of this first of a kind, 10 ton per hour, continuous flow, soil treatment production plant. The soil washing process flow employed in Ashtabula is applicable to numerous radionuclide and hazardous contaminants present at many environmental remediation sites. The soil treatment production plant is the culmination of a 3 year effort to develop a cost effective method of remediating uranium contaminated soil. The developed carbonate treatment approach solves the difficult technical problem of treating contaminated high-clay content soil. This paper is unique in that it describes the operation of a first in the world chemical soil processing facility. The paper describes the project approach for minimizing capital investment risk as well as the multiple decision points used by Earthline to ensure the ultimate success of the soil treatment approach. Finally, the paper describes a wide range of technical issues which were addressed during the design and construction effort such as ensuring residual uranium in treated soil product was stabilized so as to avoid negatively impacting the site groundwater. The Earthline Technologies soil washing plant has successfully processed over 14,000 tons of contaminated soil. The operational lessons learned from plant operations are presented. In addition, a contaminant mass balance and cost savings summary are presented. Finally, plant improvements to allow treatment of soil contaminated with technetium-99, thorium, radium and also TCE are discussed.

Matthew W. Kozak, Monitor Scientific LLC, Lioudmila Voronina, VNIPI Promtechnologii, Russian Federation.

Mining of uranium reserves at the uranium mine at Krasnokamensk, in Chita Province of the Russian Federation, supplies a large portion of the raw materials needed for the Russian national nuclear industry. Mining and processing of uranium ores have been conducted at the site for more than 30 years. Thanks to progress made in hydrometallurgical processing technology, it is possible to develop uranium deposits of comparatively poor grades of ore. However, as a consequence of the mining of these poor grades of ore, large quantities of waste tailings have been produced from this operation. A tailings pond has been constructed to hold the wastes, which is 3.7 km² in area and contains nearly 5x10⁵ tonnes of hydrometallurgical solid waste.

A project is in progress to undertake a remediation of this tailings pond. The project, funded by the International Science and Technology Center (ISTC), involves processing the tailings to form an aggregate for the formation of a cementitious waste, which is reintroduced into the solution cavity formed by hydrometallurgical mining. The project involves several key steps:

• Characterization of the risk to humans and the environment associated with the current situation,
• Design and development of the disposal technology, to establish waste acceptance criteria for the waste form,
• Pilot-scale demonstration of the disposal technology, and
• Characterization of the risk associated with the remediated system, to determine the net benefit of the technology. This characterization includes assessment of the residual risk associated with waste remaining at the surface, along with potential long-term risks associated with the disposal of the tailings in the caverns spaces.

One year of a three-year project has been completed, and a number of interim goals have been met. This paper presents an interim progress report on the characterization of risk at the site, and a description of waste-form and pilot-scale demonstration activities.

Talaat Ljaz, Ph.D., GeoTrans, Inc.

Uncertainties associated with exposures from contaminants in soils can be attributed to a number of sources including the formulation of exposure scenarios and the parametric variabilities associated with input data. There is a distinction to be made between uncertainty and variability; uncertainty stems from a lack of knowledge, whilst variability is a function of the heterogeneity of data with respect to time, space or population. In order to isolate the major sources of uncertainty or variability, a soil-based exposure model was restructured to calculate frequency distributions that could be attributed to a number of individual components of the model. The model has been used to assess a number of exposure pathways for radioactively contaminated soils. The isolated components of the model include pathways of exposure, contaminant transport factors, and exposure scenarios. By isolating each component, direct comparisons can be made of the relative significance of each these components with regard to the overall dispersivity of exposure results. From these comparisons, inferences with regard to the significance of variability or uncertainty upon the model can be made.

Ray Wood and David Stunkel, Trinity Engineering Associates

Version 6 of the RESRAD code incorporates uncertainty analysis methods to perform risk assessment for radionuclide contamination in soils. The additional uncertainty capability provides a powerful tool to assist risk analysis, but complicates the parameter development process. Parameter development for uncertainty based analysis requires not just building statistical descriptors of the parameter values, but also understanding the relationship between correlated parameters. Using a case study, the parameter development process for an uncertainty based onsite resident scenario risk analysis is described here, with particular emphasis on understanding the relationship between related parameters such as distribution coefficients and soil-to-plant transfer factors, or between soil porosity and effective porosity. The case study presented is part of the modeling effort supporting the development of national guidelines on risk resulting from concentration of radionuclide contamination in sewage sludge, which is commonly applied to agricultural land as a fertilizer. The sources and values of the parameter distribution values developed to perform the risk analysis are presented, along with methods to account for correlated parameters.

Dale M. Timmons, R.G., ARI Technologies, Inc.

ARI Technologies, Inc. (ARI) has developed a patented thermochemical treatment technology that is effective in destroying organic contamination and immobilizing metals and radionuclides in a variety of waste media. The technology, is relatively simple, transportable, and is capable of achieving waste treatment rates that are sufficient to process waste economically.

The key to the process is the introduction of the proper type and quantity of fluxing agents followed by heating the waste to a temperature of 1,200° C for approximately one hour in a rotary hearth furnace. This process results in remineralization (solid solution) of asbestos and other silicate materials, and destruction of organic compounds including PCBs and dioxin. This process not only destroys asbestos fibers and organic compounds, but it also has the capability to immobilize metals and radionuclides by sintering the waste. The product produced by the process is a rock-like material that is suitable for recycling as construction material such as road gravel (provided it is not radioactive).

The thermochemical process has been approved and certified by the EPA for destruction of asbestos pursuant to 40 CFR 61.155 and has been granted a national TSCA operating permit by the EPA Office of Prevention, Pesticides and Toxic Substances for treatment of PCBs under 40 CFR 761.60. The versatility, mobility, and economic viability of the process has prompted the US Department of Defense (DoD) and the US Department of Energy (DOE) to use it to address some of their troublesome wastes.

The US Navy contracted with ARI to conduct a series of demonstrations involving the destruction of asbestos and PCBs at the Puget Sound Naval Shipyard. That contract was followed by another contract under which ARI designed and built a larger system intended for deployment on hazardous waste sites for the Department of Defense. This new system is about to be used to conduct a series of validation tests that will certify its operating parameters under TSCA. Following these tests, the new system will be deployed to Amchitka Island in the Aleutians where waste contaminated with PCBs, mercury, arsenic, lead, and cadmium will be treated during the summer of 2001. Prior to mobilization, treatability tests designed to identify the processing parameters required to immobilize and/or remove the metals will be conducted.

The DOE National Energy Technology Laboratory, Morgantown, PA has contracted with ARI to perform a technology deployment during which 10 tons of asbestos from an abatement project in Savannah River will be destroyed. One of the interests that the DOE has is how to address the problem of radioactive asbestos from the demolition of production facilities throughout the DOE complex. To address this problem, ARI will add elements that will act as surrogates for radionuclides to the asbestos prior to processing. The behavior of the surrogates will be carefully evaluated, as will other process parameters such as energy consumption, process temperatures, and volume reduction of the waste.

All of the tests and demonstrations described above will be conducted in February and March 2001. The paper will present a summary of the results of the data gathered from the tests and from the remediation on Amchitka Is.