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Recommendations for the Disposal of Chemical Agents and Munitions 3 Fundamentals of Disposal INTERMEDIATES AND END PRODUCTS OF AGENT DESTRUCTION The U.S. chemical agent and munitions stockpile consists of a diverse collection of toxic agents and associated munitions, which present a complex disposal task regardless of the technology used. For disposal of the stockpile, waste products must be released from Army control. They must therefore be detoxified to a degree suitable for such release. There are several possibilities for the release of residual products, depending upon the state of the processed material: direct, on-site environmental discharge; final destruction at off-site hazardous waste facilities; long-term storage such as off-site landfill; or release to the general public for material reuse. There are three conditions that must be satisfied for the discharge of these materials: (1) Chemical Weapons Convention of 1993 specifications; (2) the applicable state and federal environmental regulations for hazardous waste materials; and (3) public acceptance of destruction and disposal technologies. Disposal of these processed materials will likely be complicated by special requirements or concerns related to their agent-based origin. The selection of appropriate destruction technologies is bounded by the definition of acceptable end products from the processing of the chemical stockpile materials, including chemical agents and munition components. Determining whether a candidate process will yield acceptable end products requires a clear description of its residuals, including the physical and chemical states of the materials as well as their toxicity. Residual materials must lack toxicity for disposal according to national hazardous waste disposal standards. In order to comply with the Chemical Weapons Convention, the agents may have to be "irreversibly" altered so that remanufacture of agent is difficult. Waste streams from all destruction technologies will include gases that can be vented to the atmosphere (or, in some cases, chemically converted to salts in a chemical scrubbing unit); water, which can be released to the atmosphere as a vapor with other gases or as a liquid; and various solids. Each of these waste streams must meet all applicable standards for any trace contaminants released. The solid waste materials may be inherently dry (such
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Recommendations for the Disposal of Chemical Agents and Munitions as metals) or in solution or slurry forms (such as salts). There may be varying quantities of organic materials present, ranging from simple agent chemical decomposition products to sewage-treatment-like sludges generated by biological processes. As a practical matter, solutions or slurries must be dried to reduce their volume for landfill disposal, with the extracted water discharged as a vapor or liquid stream. The U.S. Army has conducted extensive health and safety tests and has established technical specifications on the maximum allowable concentrations of residual agent in various processed material streams, dependent upon the type of agent, the type of processing stream, and their subsequent disposition. The maximum allowable air concentrations have been defined and are relatively easily monitored in essentially homogeneous gaseous streams. Relevant air emission and exposure standards (the latter set by the Surgeon General' s Office) for agent are shown in Table 3-1, along with corresponding lethal doses. The standards have not been set for aqueous streams discharged from agent disposal operations. Drinking water standards might suffice, but it is possible that much higher standards will be established. The monitoring of solids or mixtures of solids and liquids is much more difficult since they are not homogeneous and may involve agent-solid material interactions that hide the agent until subsequent activities result in its release. Thus, two additional decontamination parameters, 3X and 5X, have been developed. A waste is deemed to be 3X material if an air sample taken over contained material at room temperature is below Army agent standards, when the most sensitive, currently available monitoring equipment is used. This level has been determined to be safe for unprotected handling by plant personnel, and 3X material can be shipped under Army control. However, since agent could still reside in the cracks and interstices of the solids or even in unopened areas (such as underneath a bolt), these materials cannot be released off-site unless sent to a controlled facility such as another Army chemical agent destruction facility or a licensed hazardous waste landfill. In order to be unconditionally released, or delisted, the solid must be submitted to a high-temperature treatment of 1000º F or greater for at least 15 minutes (5X material), which provides the needed assurance that residual agent will be destroyed. No single, established technology is capable by itself of producing waste materials that meet both treaty and hazardous waste disposal criteria. For example, incineration requires a downstream pollution abatement system such as scrubbers to capture the acid gases and to dry the products for discharge as salts. Neutralization could require subsequent treatment for conversion of detoxification products to products that meet treaty irreversibility criteria.
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Recommendations for the Disposal of Chemical Agents and Munitions TABLE 3-1 Air and Exposure Standards Permissible Hazard Levels in Air (mg/m3) Lethal Human Doses Agent Workersa Stack Emissionsb General Populationc Skin, LD50 (mg/kg) Intravenous, LD50 (mg/kg) Inhalation, LCt50 (mg-min/m3) GA 0.0001 0.0003 0.000003 14-21 0.014 135-400 GB 0.0001 0.0003 0.000003 24 0.014 70-100 VX 0.00001 0.0003 0.000003 0.04 0.008 20-50 H/HD/HT 0.003 0.03 0.0001 100 10,000 NOTE: The Army standards shown in the first three columns set the minimum level of performance required for gas release by any alternative process and are applicable to all four process streams. LCt50 and LD50 represent dosage and dose, respectively, that result in 50 percent lethality. LCt50 represents a concentration (mg/m3) times the exposure time (min). a For 8-hour exposure. b Maximum concentration in exhaust stack. c For 72-hour exposure. SOURCE: U.S. Army 1974, 1975, 1988; NRC, 1993a.
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Recommendations for the Disposal of Chemical Agents and Munitions The conversion of chemical agents and munitions to the most stable final products would result in the production of completely decontaminated metal parts (5x) and the most basic chemical products (gases: carbon dioxide, water, and nitrogen, as well as various salts [calcium, sodium, or potassium salts of phosphate, chloride, sulfate, carbonate, and fluoride], depending on the process and the particular agent). This complete destruction process is referred to as "mineralization" because no complex organic molecules remain in the processed residue. By a number of different processes, mineralization involves the following chemical transformations and mass balance characteristics: From Gel (Satin) From Vx From Hd (Mustard) The baseline system accomplishes this mineralization in a series of steps: primary burner, secondary burner, gas scrubbing, and salt recovery. Any new technology will be expected to do the same or nearly the same. Suggestions have been made for recovery of useful chemical materials from agent processing; the committee considers this impractical and not economically advantageous. Intermediate products will have to be followed by further oxidation to yield a mineralized product.
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Recommendations for the Disposal of Chemical Agents and Munitions In the mid-1970s, the U.S. Army disposed of more than 4,000 tons of GB by neutralization with caustic (NaOH) solution in water by the following reaction: The residue was dried (8 pounds of water extracted per pound of agent treated), and the salt was placed in a landfill. Complete neutralization does meet the 3X condition. However, this reaction may not satisfy the current Chemical Weapons Convention requirements for an irreversible reaction because the fluorine removed could be reattached by a subsequent chemical reaction. Chemical mineralization is not the only acceptable end point under the treaty. Biological processing of the products from a chemical neutralization of HD, for example, might produce acceptable residual products requiting no further treatment other than drying prior to hazardous waste landfill disposal. All technologies must convert the agents to products (generally mineralized) that can be disposed of safely. The mineralized products tend to be similar, but the distribution of products is different. It is not essential that all steps to agent destruction occur at one site if an intermediate form is suitable for safe transportation to another site for final destruction or disposition, and if such transport is publicly acceptable. As noted, the 3X condition has been accepted for shipment under Army control. It remains to be seen whether sites can be found that are willing and able to receive such materials, and whether acceptable transport routes can be found. The governor of Utah, for instance, is already on record opposing the shipment of neutralized material to Utah for final processing (Michael O. Leavitt, to the Board on Army Science and Technology, August 1993). Public concerns will have to be carefully addressed if this option is to be exercised. MATERIAL FEED AND PROCESSING STREAMS The baseline system divides the agents and munitions into four material feed streams: agent, energetics (explosives and propellants), metal parts, and dunnage (packing materials and other miscellaneous waste). All of these streams may be contaminated by chemical agent. Although this division is not a true ''fundamental of disposal,'' it provides an important perspective on
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Recommendations for the Disposal of Chemical Agents and Munitions destruction complexities. The four types of materials in these streams have widely differing physical properties that influence handling: the extremely toxic liquids may be pumped and stored with relative ease; energetic solids encased in thin metal containers burn vigorously if sufficiently exposed, and require careful treatment to avoid detonation; inert, heavy-walled metal vessels contain residual agent; and miscellaneous dunnage materials have various physical characteristics and chemical makeup. Separation of these materials into controlled processing streams allows optimal design of separate disposal processes for each, while simplifying the control and thereby maximizing the safety of operations. The benefits of separation apply equally to all disposal technologies, and no individual disposal technology is particularly well suited to processing mixed streams. The four main material feed streams are composed of the following materials: Agent: There are three different agent types—GB, VX, and mustard—in varying degrees of purity and quantity, depending upon site inventory. Liquid agent is drained from bulk containers and munitions. Energetics (explosives and propellants): M55 rockets, land mines, and some artillery projectiles contain energetic materials, including fuses, boosters, bursters, and solid rocket propellants. These energetics and associated small metal parts are often contaminated with agent. Metal parts: Large metal parts include drained containers without energetic materials (ton containers, bombs, spray tanks, and artillery projectile bodies). All of these materials will be contaminated with agent. Some may contain significant amounts of gelled agent that does not drain readily (particularly mustard). Dunnage: Miscellaneous wastes, which can be contaminated, include storage and handling pallets and packing materials, rags, protective clothing, and activated carbon from the ventilation air cleanup system. Two auxiliary processing streams also result from all destruction technologies: Decontamination fluids: Fluid materials, such as sodium hydroxide in water, are used throughout the facility, for example, to enable safe access to areas and equipment for maintenance. These fluids may contain minor residual agent contamination and dust or other particulate materials. Ventilation air: Air from the process buildings and laboratories contains agent vapors.
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Recommendations for the Disposal of Chemical Agents and Munitions PROCESSING OF NON-AGENT MATERIALS Most alternative technology attention has been centered on agent destruction. However, the disposal program must provide for the destruction or decontamination of all stockpile materials. Metal parts are relatively easy to treat thermally to a 5X condition that is suitable for general release. Ton containers and projectiles in this condition may be sold for scrap. Small metal components associated with energetics, M55 aluminum rocket bodies, and fiberglass launch tubes are similarly treated, but the resulting mixed material has no scrap value. Energetic materials cannot be disposed of safely in their existing state. They must be "deactivated," as are explosives from ordinary, nonchemical munitions. Of course, rocket propellants and explosives burn readily, but care must be taken to ensure that they burn rather than detonate. Complete destruction of these materials requires additional oxygen (typically from air) because the materials contain insufficient oxidant as formulated. Explosive elements from projectiles might be contaminated with agent; explosive and propellant elements from rockets are wetted by agent as now processed. Thus, any energetics disposal process must handle some agent as well as energetic materials. Other oxidation processes, such as supercritical water oxidation, are chemically applicable to energetic materials, but the physical extraction of cast-in-place bursters and propellants from their housings, and conversion to slurries that may be fed to these processes, would be difficult and perhaps hazardous. Reducing energetic materials to slurry form is a considerable complication over the relatively simple slicing or punching of housings as practiced in the baseline system. Dunnage includes wood, paper, and other ordinary industrial waste materials. Most dunnage is not contaminated with agent, but some is. Disposal of this mixed waste must therefore safely process some agent as well as a mixture of typical industrial materials. Alternatives to proper combustion or landfill are not evident. Some of the waste streams from specific munitions may contain heavy metals (e.g., lead, chromium, and cadmium) as well as other materials of concern that must be handled according to current state and federal regulations. WASTE STREAM REGULATIONS Federal and state environmental laws and regulations govern continental U.S. site operations; these include Environmental Protection Agency regulations, Department of Defense and Army standards, Department of
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Recommendations for the Disposal of Chemical Agents and Munitions Transportation regulations, and any local facility standing operating procedures. The regulatory provisions of the following federal statutes are applicable to the operation of all continental U.S. Facilities: Resource Conservation and Recovery Act; Toxic Substances Control Act (TSCA); Clean Air Act; Clean Water Act; and Hazardous Materials Transportation Act. In addition, releases of certain process or waste streams that are not in accordance with design for continental U.S. facilities may result in reporting obligations under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Through the RCRA permit, the U.S. Environmental Protection Agency establishes limits on the quantities of agent that may be emitted; however, some state regulations are more stringent than the federal standards. These restrictions are supplemented by Army policy and regulations. In addition, the RCRA permit regulates the more typical products of combustion that can be monitored on a more or less continuous basis (e.g., carbon monoxide that either may contribute to general pollution or may be indicative of incomplete combustion). It also sets detailed limits on operating conditions (e.g., temperature, residence time, oxygen levels) and metal emissions; establishes controls on the handling, storage, and disposal of hazardous materials; requires very detailed data collection, retention, and reporting; and requires a program to reduce the volume or quantity and toxicity of the hazardous waste generated and shipped off-site. TSCA regulates the incineration of PCBs (polychlorinated biphenyls). U.S. plants will need permits for regulated air emissions in accordance with the Clean Air Act. The potential high levels of NOx generated when destroying VX may require treatment prior to discharge-in nonattainment areas. As a result of the Programmatic Environmental Impact Statement, and pursuant to the Clean Water Act, National Pollutant Discharge Elimination System (NPDES) limits will be placed on the flow and discharge temperature of water discharged from the plant. In addition, recently promulgated regulations under the Clean Water Act will require monitoring and reporting of storm water discharges. The Stockpile Committee is issuing two reports in early 1994, one that deals extensively with the effectiveness of operations of the Johnston Atoll Chemical Agent Disposal System, Evaluation of the Johnston Atoll Chemical Agent Disposal System Operational Verification Testing: Part II (NRC, 1994b), and one that examines the monitoring activities of the stockpile disposal
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Recommendations for the Disposal of Chemical Agents and Munitions program, Review of Monitoring Activities Within the Army Chemical Stockpile Disposal Program (NRC, 1994a). These reports provide a relatively up-to-date assessment and analysis of what waste streams are resulting from the disposal process and how the Army is dealing with them.
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