The United States manufactured and stockpiled about 31,000 tons of two nerve agents, GB and VX, and one blister agent, sulfur mustard agent. The mustard agent is in three forms: H mustard is an impure form of mustard agent containing other products produced during the chemical synthesis; HD is the distilled product of H, nominally pure mustard agent; and HT is a mixture of H with T, a related compound, which provides a eutectic that lowers its freezing point below cold winter temperatures because pure mustard agent freezes at 14.5°C. These chemical agents and munitions were stored at nine sites, eight of them in the continental United States and one at Johnston Atoll in the Pacific, about 700 miles southwest of Hawaii.

In 1985, Congress mandated that the Army establish a program to destroy at least 90 percent of the nation’s unitary chemical stockpile (Public Law 99-145) with particular emphasis on M55 rockets. The U.S. Army selected incineration as the most effective method of destroying the chemical munitions in the stockpile. Incineration is very “democratic,” i.e., it oxidizes chemical compounds to stable chemical forms such as water and carbon dioxide and inorganic salts of sulfur, phosphorus, and fluorine. The first site where an integrated prototype facility was built, namely, the Johnston Atoll Chemical Agent Disposal System, completed disposal operations in 2001. The plant has since been demolished and following closure of the site in 2003, the part of Johnston Atoll where the facility was located, Johnston Island, is now abandoned and is being allowed to return to its original natural condition. In August 1996, the Tooele Chemical Agent Disposal Facility (TOCDF) at the Deseret Chemical Depot in Tooele, Utah, which originally stored about 45 percent of the total stockpile, was the first continental U.S. site to begin destruction operations. It has completed the destruction of all the GB and VX munitions stored at the Deseret Chemical Depot, including all of the M55 rockets, which are considered to have the highest risk, and is presently destroying the remaining mustard agent stockpile. In the course of the mustard agent destruction campaign, analysis has revealed that some of the mustard agent ton containers contain varying amounts of mercury, a RCRA-controlled substance. This unexpected development has led to modifications in the plant and process designs, including the use of sulfur-impregnated activated carbon, which will adsorb mercury from the stack gases before they are released to the atmosphere. Three other sites that use incineration are now also in operation: the Umatilla Chemical Agent Disposal Facility (UMCDF) in Umatilla, Oregon, the Anniston Chemical Agent Disposal Facility (ANCDF) in Anniston, Alabama, and the Pine Bluff Chemical Agent Disposal Facility (PBCDF) in Pine Bluff, Arkansas.

Public Law 102-484 of 1993 mandated destruction of the entire chemical weapons stockpile and required the Secretary of the Army to evaluate potential alternatives to the Army’s baseline disassembly and incineration process, considering whether—initially for a low-volume site—the application of such alternatives could complete demilitarization operations by December 31, 2004, the deadline set at that time, in a significantly safer manner than the baseline disassembly and incineration process and at least as cost-effective. This congressional directive led to the use of chemical neutralization (hydrolysis) at two sites where only bulk agent in ton containers was stored. Caustic NaOH solution at 194°F was the neutralization reagent used at the Newport Chemical Agent Disposal Facility (NECDF) in Newport, Indiana, where VX had been manufactured and stored. Hot water at 194°F was the neutralization reagent used at the Aberdeen Chemical Agent Disposal Facility (ABCDF) at Aberdeen Proving Ground, Maryland, where HD in ton containers had been stored. NECDF and ABCDF have completed destruction operations and ABCDF has completed closure.

Congress then mandated (Public Laws 104-201 and 104-208) that the facilities at the two remaining sites, the Pueblo Chemical Agent Destruction Pilot Plant (PCAPP) in Colorado and the Blue Grass Chemical Agent Destruction Pilot Plant (BGCAPP) in Kentucky, use a method other than incineration to destroy chemical agent. The Army has selected chemical neutralization, followed at PCAPP by bioremediation and at BGCAPP by supercritical water oxidation. Construction of these two plants was under way at the time this report was being prepared. At all operating sites, activated carbon continues to be used to filter the ventilation air and process gas streams prior to their release into the atmosphere and to protect personnel from accidental releases.

In 1997, the U.S. Congress ratified the CWC, an international treaty banning the use and stockpiling of chemical weapons. The CWC required that all signatory nations destroy their entire stockpiles within 10

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