Publications

The Sandia National Laboratories/New Mexico (SNL/NM)Environmental Restoration Project is currently excavating the Classified Waste Landfill in Technical Area II, a disposal area for weapon components for approximately 40 years until it closed in 1987. Many different types of classified parts were disposed in unlined trenches and pits throughout the course of the landfill's history. A percentage of the parts contain explosives and/or radioactive components or contamination. The excavation has progressed backward chronologically from the last trenches filled through to the earlier pits. Excavation commenced in March 1998, and approximately 75 percent of the site (as defined by geophysical anomalies) has been completed as of November 1999. The material excavated consists primarily of classified weapon assemblies and related components, so disposition must include demilitarization and sanitization. This has resulted in substantial waste minimization and cost avoidance for the project as upwards of 90 percent of the classified materials are being demilitarized and recycled. The project is using field screening and lab analysis in conjunction with preliminary and in-process risk assessments to characterize soil and make waste determinations in a timely a fashion as possible. Challenges in waste management have prompted the adoption of innovative solutions. The hand-picked crew (both management and field staff) and the ability to quickly adapt to changing conditions has ensured the success of the project. The current schedule is to complete excavation in July 2000, with follow-on verification sampling, demilitarization, and waste management activities following.

Typical Laboratory testing of Polycrystalline Diamond Compact (PDC) bits is performed on relatively rigid setups. Even in hard rock, PDC bits exhibit reasonable life using such testing schemes. Unfortunately, field experience indicates otherwise. In this paper, they show that introducing compliance in testing setups, provides better simulation of actual field conditions. Using such a scheme, they show that chatter can be severe even in softer rock, such as sandstone, and very destructive to the cutters in hard rock, such as sierra white granite.

Numerous sites in the United States and around the world are contaminated with depleted uranium (DU) in various forms. A prevalent form is fragmented DU originating from various scientific tests involving high explosives and DU during weapon-development programs, at firing practice ranges, or in war theaters where DU was used in armor-piercing projectiles. The contamination at these sites is typically very heterogeneous, with discrete, visually identifiable DU fragments mixed with native soil. The bulk-averaged DU activity is quite low, whereas DU fragments, which are distinct from the soil matrix, have much higher specific activity. DU is best known as a dark metal that is nearly twice as dense as lead, but DU in the environment readily weathers (oxidizes) to a distinctive bright yellow color that is quite visible. While the specific activity (amount of radioactivity per mass of soil) of DU is relatively low and presents only a minor radiological hazard, the fact that DU is radioactive and visually identifiable makes it desirable to remove the DU ''contamination'' from the environment. The typical approach to conducting this DU remediation is to use radiation-detection instruments to identify the contaminant and then to separate it from the adjacent soil, packaging it for disposal as radioactive waste. This process can be performed manually or by specialized, automated equipment. Alternatively, a more cost-effective approach might be simple mechanical or gravimetric separation of the DU fragments from the host soil matrix. At SNL/NM, both the automated and simple mechanical approaches have recently been employed. This paper discusses the pros/cons of the two approaches.

This paper discusses the development and application of process knowledge (PK) to the characterization of radioactive wastes generated during the excavation of buried materials at the Sandia National Laboratories/New Mexico (SNL/NM) Classified Waste Landfill (CWLF). The CWLF, located in SNL/NM Technical Area II, is a 1.5-acre site that received nuclear weapon components and related materials from about 1950 through 1987. These materials were used in the development and testing of nuclear weapon designs. The CWLF is being remediated by the SNL/NM Environmental Restoration (ER) Project pursuant to regulations of the New Mexico Environment Department. A goal of the CWLF project is to maximize the amount of excavated materials that can be demilitarized and recycled. However, some of these materials are radioactively contaminated and, if they cannot be decontaminated, are destined to require disposal as radioactive waste. Five major radioactive waste streams have been designated on the CWLF project, including: unclassified soft radioactive waste--consists of soft, compatible trash such as paper, plastic, and plywood; unclassified solid radioactive waste--includes scrap metal, other unclassified hardware items, and soil; unclassified mixed waste--contains the same materials as unclassified soft or solid radioactive waste, but also contains one or more Resource Conservation and Recovery Act (RCRA) constituents; classified radioactive waste--consists of classified artifacts, usually weapons components, that contain only radioactive contaminants; and classified mixed waste--comprises radioactive classified material that also contains RCRA constituents. These waste streams contain a variety of radionuclides that exist both as surface contamination and as sealed sources. To characterize these wastes, the CWLF project's waste management team is relying on data obtained from direct measurement of radionuclide activity content to the maximum extent possible and, in cases where direct measurement is not technically feasible, from accumulated PK of the excavated materials.

The Sandia National Laboratories/New Mexico (SNL/NM) Environmental Restoration Project is halfway through excavating the Classified Waste Landfill in Technical Area II, a disposal area for weapon components for approximately 40 years. While the planning phase of any project is important, it is only a means of getting to the field implementation phase where reality quickly sinks in. Documents outlining the general processes are developed, heavy equipment, supply needs, requisite skills, and staffing levels are anticipated, and contingencies for waste management are put in place. However, the nature of landfill excavation dictates that even the most detailed plans will probably change. This project is proving that trying to account for undefined variables and predicting the total cost of landfill remediation is very difficult if the contents are not well known. In landfill excavation, contingency cannot be minimized. During development of the waste management plan, it was recognized that even the best forecasting could not formulate the perfect cradle-to-grave processes because waste streams are rarely definable before excavation begins. Typically, as excavation progresses and waste streams are generated, new characterization information allows further definition of disposal options which, in turn, modify the generation/management process. A general plan combined with close involvement of waste management personnel to resolve characterization and packaging questions during generation has worked very well. And, as expected, each new pit excavated creates new waste management challenges. The material excavated consists primarily of classified weapon assemblies and related components, so disposition must include demilitarization and sanitization. The demilitarization task at the start of the project was provided by an SNL/NM group that has since lost their funding and operational capability. This project is having to take on the task of disassembly, destruction, and recycling of classified components, along with the associated costs and infrastmcture. Very stringent radiological controls were imposed on site operations during the planning phase. Radiological controls that are not justified significantly impact the efficiency and cost of operations. If the initial approach is too conservative, there should be well-defined provisions for scaling down the protective measures to reflect the actual risks. Once the effectiveness of early detection, monitoring, and surveys is proven, radiological controls and postings should be re-evaluated to verify that they are appropriate. High levels of heavy metals dust were not anticipated during the planning phase but were suspected, then confirmed, during material handling. Respiratory protection and monitoring were upgraded accordingly and the costs added to the baseline. In contrast to radiological constraints, industrial hygiene guidelines were worked into the process with a minimum of adverse impact. While a lot of unforeseen expenses occur, some expected costs can be reduced. During the planning phase, the anticipated need to adequately characterize a variety of radionuclides in soil led to using Large Area Gamma Spectroscopy (LAGS) to survey all the soil excavated. About a quarter of the way through the project, it was obvious that very little radioactive material was present in the excavated soils. Since all the soil is processed through a screen plant, producing a fairly homogeneous mix, a more common method of sampling soil piles was implemented to replace the LAGS unit, increase productivity, and reduce costs. In summary, the most important lesson is to expect and be ready to change. Excavating a landfill requires the flexibility to quickly adjust processes to handle the unknown variables, and close attention to detail so all the different facets of the project are kept under control.