The U.S. chemical weapons stockpile served as an important deterrent for more than half a century, but by 1985, with the rise of international concern regarding the effects of chemical warfare, Congress directed the U.S. Army to destroy the stockpile. The Program Manager for Chemical Demilitarization, or PMCD, was the organization originally formed by the Army to carry out this mission. At the time, the only proven chemical weapons destruction technology was incineration. As plans for the destruction of the stockpile were developed, environmental organizations, community members living near stockpile sites and government regulatory agencies began discussing other means by which the stockpile might be destroyed.

In 1996, in response to these discussions, Congress mandated the Department of Defense under Public Law 104-208 to establish a program, the Assembled Chemical Weapons Assessment, or ACWA program, to identify and demonstrate at least two technologies as alternatives to incineration for the destruction of assembled chemical weapons. “Assembled” chemical weapons refers to munitions containing chemical agent configured with fuzes, explosives and propellants, rather than chemical agent stored in steel shipping containers, the destruction of which was already being explored by PMCD to eliminate bulk, non-explosively configured chemical agents.

In its initial 1996 law, and again in follow-on legislation two years later (Public Law 105-261), Congress directed that the ACWA program be conducted independently from the Army’s chemical demilitarization effort under PMCD, and further stipulated that the ACWA program manager report directly to the Office of the Secretary of Defense.

Upon ACWA’s successful demonstration of several alternative technologies from 1997 to 2000, the Department of Defense selected neutralization followed by biotreatment for destruction of the stockpile at the U.S. Army Pueblo Chemical Depot in Colorado in 2002, and neutralization followed by supercritical water oxidation in 2003 for the stockpile at the Blue Grass Army Depot in Kentucky.

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Legislation subsequently passed by Congress in 2002 (Public Law 107-248) assigned responsibility to the ACWA program manager for the safe destruction of the chemical weapons stockpile in Colorado and Kentucky, to include pilot plant construction, operation, closure and contract management, thus dual-tracking the national chemical demilitarization mission between PMCD and ACWA. PMCD would be responsible for destroying approximately 90 percent of the stockpile and ACWA, the remaining 10 percent. ACWA’s expanded mission resulted in a name change from “Assembled Chemical Weapons Assessment” to “Assembled Chemical Weapons Alternatives” in June 2003.

Late in 2002, ACWA awarded a task-order systems contract to the Bechtel Pueblo Team for the design, construction, systemization, pilot testing, operations and closure of the Pueblo Chemical Agent-Destruction Pilot Plant (PCAPP) at the U.S. Army Pueblo Chemical Depot in Pueblo, Colorado. A similar task-order systems contract was awarded to Bechtel Parsons Blue Grass in 2003 for the design, construction, systemization, operations and closure of the Blue Grass Chemical Agent-Destruction Pilot Plant (BGCAPP) at the Blue Grass Army Depot near Richmond, Kentucky.

In 2003, PMCD was redesignated the U.S. Army Chemical Materials Agency, or CMA. In addition to retaining its responsibility for chemical stockpile destruction at the sites other than Colorado and Kentucky, CMA was given authority over the safe and secure storage of the entire chemical weapons stockpile, including the weapons stored in Colorado and Kentucky.

On Sept. 18, 2004, ACWA held a groundbreaking open house to recognize the first stage of construction at PCAPP. Soon thereafter, however, design of processing facilities and Stage One construction activities were suspended while the program evaluated cost reduction measures. In March 2005, design and construction of PCAPP officially restarted.

In 2006, the start of construction in Kentucky was signaled with a groundbreaking for the BGCAPP facility.

In November 2007, ACWA initiated Operation Swift Solution at the Blue Grass Army Depot to safely eliminate three deteriorating steel containers holding a mixture of the chemical agent GB and its breakdown products that had occurred over time in storage. With support from the Edgewood Chemical Biological Center, the liquid mixture was neutralized, and the product from the neutralization process, called hydrolysate, was shipped from Kentucky to Veolia Environmental Services near Port Arthur, Texas, for final destruction.

In November 2007, ACWA was formally activated as the U.S. Army Element, Assembled Chemical Weapons Alternatives, a separate reporting activity under U.S. Army Materiel Command. Under this arrangement, ACWA received administrative and logistics support from Army Materiel Command, but the ACWA program manager continued to report directly to the Department of Defense as required by Public Law 105-261.

Effective Oct. 1, 2012, ACWA was redesignated as the Program Executive Office, Assembled Chemical Weapons Alternatives and administratively reassigned to the U.S. Army Acquisition Support Center. This transition was directed to raise the program’s visibility and obtain necessary support and resources. As mandated by law, the program’s direct reporting connection to the Department of Defense remained unchanged. Also in 2012, PCAPP marked the end of site construction.

In 2013, Explosive Destruction Technologies were selected to augment PCAPP and BGCAPP by destroying problematic chemical munitions stored. Problematic munitions included those which may have leaked or were sampled for testing purposes in the past and were overpacked, or projectiles with physical conditions unsuitable for processing by the plants’ automated equipment. The Explosive Destruction System, or EDS, was the U.S. Army system initially selected to destroy problematic munitions in Colorado, or approximately 0.2 percent of the total chemical weapons stockpile stored there. Construction began on the PCAPP EDS site in March 2014. The Static Detonation Chamber, or SDC, was the technology selected to destroy the entire mustard agent stockpile in Kentucky and reject chemical munitions in Colorado. Construction on the Blue Grass SDC began in December 2014.

In June 2014, the PEO ACWA Anniston Field Office was established to ensure that the technical expertise and experience of the staff at the former Anniston Chemical Agent Disposal Facility (ANCDF), as well as the facility’s SDC, would be preserved and leveraged during chemical weapons destruction in Colorado and Kentucky. ANCDF, one of seven CMA sites, finished safely eliminating the chemical weapons stockpile at the Anniston Army Depot in September 2011.

In March 2015, the EDS commenced the destruction of the chemical weapons stockpile stored at the U.S. Army Pueblo Chemical Depot in Colorado. The EDS operated two campaigns from March 2015 to December 2018, eliminating 951 items resulting in 3.82 U.S. tons of mustard agent being destroyed.

On Sept. 7, 2016, main plant operations began at PCAPP. The depot originally stored more than 2,600 U.S. tons of weaponized mustard agent. The plant utilized neutralization followed by biotreatment as the primary technology to destroy mustard agent-filled munitions. In 2018, Static Detonation Chamber technology was selected to augment the main plant by destroying problematic munitions.

In September 2017, the first full year of the pilot testing phase was completed at PCAPP, with 253 U.S. tons of mustard agent and 42,897 155mm projectiles destroyed. On Sept. 8, 2017, agent destruction operations were paused at PCAPP due to higher than anticipated amounts of solids being washed out of munitions and clogging agent neutralization systems.

On June 13, 2018, PCAPP resumed destruction operations after completing significant engineering and maintenance adjustments. By July, the BGCAPP systemization team turned over more than half of the 59 Blue Grass plant systems to operations. On Nov. 13, 2018, PCAPP staff initiated Integrated Facility Demonstrations. These demonstrations showed the plant operates as designed, which was the final step before the plant moved from pilot testing to full-scale operations in 2019.

On June 7, 2019, the BGCAPP SDC began operations to destroy the mustard agent-filled munitions stored at the Blue Grass Army Depot. In summer 2019, PCAPP SDC site work began, with arrival of the SDC components on Aug. 6, 2019. Assembly of the three SDC units began Oct. 31, 2019, and was completed in June 2020.

On Jan. 17, 2020, the BGCAPP main plant entered the operations phase with destruction of the first 8-inch projectile containing GB nerve agent. On Feb. 26, 2020, PCAPP reached destruction of half the agent stored at the U.S. Army Pueblo Chemical Depot. On May 11, 2020, the BGCAPP main plant destroyed all 8-inch projectiles containing GB nerve agent. This marked the completion of the first munitions campaign for the ACWA program. By June 20, 2020, PEO ACWA reached a mission milestone with the destruction of half the remaining stockpile, a combined 1,568 U.S. tons in Colorado and Kentucky. In August 2020, PEO ACWA determined the supercritical water oxidation system (SCWO) at BGCAPP would not be used to process hydrolysate, the product of the nerve agent neutralization process, due to system performance during testing. On Sept. 5, 2020, PCAPP completed its first munitions campaign with the destruction of nearly 300,000 155mm projectiles stored at the U.S. Army Pueblo Chemical Depot. On Dec. 11, 2020, PCAPP began destroying 105mm projectiles, the second of three munitions destruction campaigns.

On Jan. 10, 2021, BGCAPP began the second main plant munitions destruction campaign with the 155mm projectiles containing VX nerve agent. On Feb. 9, 2021, the ACWA program executive officer recommended nerve-agent hydrolysate generated at BGCAPP be treated off-site using incineration. Bechtel Parsons Blue Grass announced Veolia Environmental Services near Port Arthur, Texas, would receive and destroy the hydrolysate. On April 25, 2021, BGCAPP marked the destruction of 25 percent of total agent stored at the Blue Grass Army Depot. On April 26, 2021, PCAPP workers reached a milestone with the elimination of more than 50 percent of total munitions stored at the U.S. Army Pueblo Chemical Depot. On May 28, 2021, the BGCAPP main plant destroyed all 155mm projectiles containing VX nerve agent. This marked the completion of the second munitions campaign for BGCAPP. On July 9, 2021, the BGCAPP main plant began destroying VX nerve agent M55 rockets, the third of five campaigns to be conducted at the plant and the first time rockets were destroyed at the facility. On Sept. 4, 2021, the Blue Grass SDC completed destruction of the mustard-agent projectiles. The SDC unit then began undergoing an adaptation to destroy nerve-agent-contaminated secondary waste and was renamed the SDC 1200. A second, larger unit, the SDC 2000, was installed to destroy nerve agent rocket components and overpacked rockets.

On Jan. 14, 2022, PEO ACWA marked 75 percent destruction of the original chemical agent located in Colorado and Kentucky, with the safe elimination of 2,352 U.S. tons of chemical agent. On Feb. 19, 2022, the PCAPP SDC complex began operations with the destruction of the first 4.2-inch mortar rounds. On April 19, the BGCAPP main plant safely completed destruction of the VX nerve agent M55 rockets. This marked the total elimination of VX nerve agent in the U.S. stockpile. On July 6, 2022, the Blue Grass team destroyed the first M55 rocket containing GB nerve agent in the start of the fifth and final munitions destruction campaign in Kentucky. The GB M55 rockets represented more than 50 percent of the original chemical weapons stockpile safely stored at the Blue Grass Army Depot. On July 20, 2022, the Pueblo Chemical Agent-Destruction Pilot Plant team completed the destruction of more than 383,000 mustard agent-filled 105mm projectiles, the second of three campaigns undertaken since chemical weapons elimination began at PCAPP. By Sept. 9, 2022, the Blue Grass team destroyed 50 percent of the chemical agent originally stored at the Blue Grass Army Depot during its fifth and final destruction campaign. On Dec. 1, Pueblo crews began using an improved cavity access machine to destroy 4.2-inch mortar rounds in the main plant.

On Jan. 27, 2023, operators at the Blue Grass Chemical Agent-Destruction Pilot Plant began destroying containerized rocket warheads drained of GB nerve agent using the SDC 2000. On June 22, 2023, the last munition in the chemical weapons stockpile in Colorado was destroyed at the Pueblo Chemical Agent-Destruction Pilot Plant. On July 7, 2023, the last munition in the chemical weapons stockpile in Kentucky was destroyed at the Blue Grass Chemical Agent-Destruction Pilot Plant. These two events marked the completion of destruction of the United States’ declared chemical weapons stockpile.

On July 14, 2023, the Kentucky Department for Environmental Protection (KDEP) granted BGCAPP a Temporary Authorization Request to begin closure activities in the main plant. The permit modification request for closure was approved by KDEP Sept. 27, 2023.

On Aug. 2, 2023, the Anniston Field Office completed the destruction of non-contaminated explosive munitions components from PCAPP.

On March 29, 2024, the Colorado Department of Public Health and Environment (CDPHE) approved PCAPP’s main plant closure plan.

On June 3, 2024, the Metal Parts Treater (MPT) was decommissioned as part of closure activities after processing its last materials after more than four years of service at BGCAPP. The MPT was first-of-a-kind equipment used to treat metal munition bodies from which agent had been drained. It was a critical component of processing drained projectiles during the VX and GB campaigns, and it was also used to process metal parts during the main plant’s current closure phase.

On Aug. 5, 2024, the BGCAPP SDC 2000 reached 50 percent destruction of containerized rocket warheads containing residual amounts of GB nerve agent as part of secondary-waste destruction during the plant’s closure phase.

On Sept. 12, 2024, a deactivation ceremony at the U.S. Army Pueblo Chemical Depot marked the end of 82 years of history. The facility is now known as the U.S. Army Chemical Materials Activity-West and its reduced workforce will support closure activities at the Pueblo plant.

On Sept. 20, 2024, the BGCAPP SDC 1200 reached 50% destruction of containerized rocket warheads containing residual amounts of VX nerve agent as part of secondary-waste destruction during the plant’s closure phase.

On Nov. 5, 2024, CDPHE approved the closure plan for the PCAPP Static Detonation Chamber complex, setting the stage for future reuse of the three units by Department of Defense organizations.

On March 11, 2025, BGCAPP reached 75% destruction of containerized rocket warheads containing residual amounts of GB nerve agent as part of secondary-waste destruction in the Static Detonation Chamber 2000 during the plant’s closure phase.

On April 3, 2025, the Anniston Field Office team completed a decade of support to PCAPP and BGCAPP with the destruction of the final non-contaminated rocket motor from BGCAPP, concluding the destruction of more than 1 million energetic components removed from chemical munitions formerly stored in Colorado and Kentucky.

For additional program achievements and milestones visit our Program Timeline page.

For questions, visit the PEO ACWA Contact Us page.