Pueblo Chemical Agent-Destruction Pilot Plant

The Pueblo Chemical Agent-Destruction Pilot Plant (PCAPP) is a chemical weapons destruction facility built to destroy the chemical weapons stockpile stored at the former U.S. Army Pueblo Chemical Depot (PCD) in southeastern Colorado. The stockpile originally contained 2,613 U.S. tons of mustard agent in 155 mm projectiles, 105 mm projectiles, and 4.2-inch mortar rounds. The weapons had been stored at the 23,000-acre (93-km²) depot since the 1950s. On June 16, 2023, the main plant at PCAPP destroyed its last munition, a 4.2-inch mortar round. On June 22, 2023, the last munition in the stockpile of chemical weapons in Colorado, an overpacked 155 mm projectile containing mustard agent, was destroyed using a Static Detonation Chamber (SDC). The last munition in the declared U.S. stockpile was destroyed in July 2023 in Kentucky. PCAPP used neutralization followed by biotreatment to destroy the majority of the stockpile, and SDC technology to augment the main plant. Non-contaminated energetics removed from the munitions as part of the destruction process were destroyed in the Anniston, Alabama, SDC. Destruction of this stockpile was a requirement of the Chemical Weapons Convention, an international treaty to which the United States is a party. The Organisation for the Prohibition of Chemical Weapons (OPCW) is the implementing body of the Chemical Weapons Convention and monitored the progress of the nation's declared destruction programs. The Program Executive Office, Assembled Chemical Weapons Alternatives (PEO ACWA) oversaw the safe and environmentally compliant destruction of the nation’s chemical weapons stockpile and is now responsible for closing the plants in Colorado and Kentucky. The Bechtel Pueblo Team (BPT; consisting of Bechtel National, Inc.; Amentum; Battelle Memorial Institute; and GP Strategies) designed, constructed, pilot-tested, operated, and is closing PCAPP. Planning of activities Agent destruction began in 2016 and concluded on June 22, 2023. Closure activities (shutdown, dismantling, and restoration of site) will be complete in Fiscal Year 2028. In 2010, the Pueblo Chemical Depot, in conjunction with the PEO ACWA program, completed an environmental assessment (EA) to meet the requirements of the National Environmental Policy Act, or NEPA, and Title 32 Code of Federal Regulations Part 651 regarding the construction and operation of the U.S. Army's Explosive Destruction System (EDS) and/or other explosive destruction technologies (EDT), at the U.S. Army Pueblo Chemical Depot in Colorado. The EA was withdrawn, and a new EA was completed in 2012. The new EA focused on the use of EDT for destroying overpacked and rejected munitions. In April 2013, Program Executive Officer Conrad F. Whyne announced his selection of EDS to augment PCAPP for the safe destruction of chemical munitions unsuited for processing by the main plant's automated equipment. In spring 2018, the decision was made to end EDS and utilize three SDC units to augment the main plant. History of chemical demilitarization in Colorado Technology The Department of Defense conducted studies to evaluate potential impacts of the elimination of these weapons using incineration and non-incineration methods. Four technologies were considered: incineration chemical neutralization followed by supercritical water oxidation chemical neutralization followed by supercritical water oxidation and gas-phase chemical reduction electrochemical oxidation Neutralization followed by biotreatment was selected for the destruction of the Colorado stockpile. The technology comprised the following steps: Robotic equipment removed energetics (explosives) from the weapon, including the fuze and the burster. The energetics were disposed of at a permitted facility off-site. The inside of the weapon was remotely accessed, and mustard agent was washed out with high-pressure water. The mustard agent was mixed with hot water. The resulting mixture was neutralized with a caustic solution. The byproduct was called hydrolysate. The hydrolysate was treated biologically. The water was recovered for reuse in the destruction process and the excess activated sludge was secured in containers for disposal at an off-site permitted facility. Metal parts were heated to 1,000 °F (538 °C) for 15 minutes for thermal decontamination and were then recycled. Explosive Destruction Technology (EDT) After an assessment of problem munitions showed that their destruction would be difficult using neutralization and biotreatment, ACWA decided to explore the use of Explosive Destruction Technology (EDT), also known as Explosive Demolition Technology or Explosive Detonation Technology, for these projectiles. EDT uses heat and pressure from an explosion or heat to destroy the munitions; it is not considered incineration and does not require disassembly of the weapons. There are three general types of technologies that can destroy chemical weapons: Detonation technology – destroys the majority of the agent and explosive in the munition by detonating donor explosives wrapped around the munition. The resulting off-gases are processed through secondary treatment to ensure agent destruction. Examples of detonation technology include the Transportable Detonation Chamber (TDC), and the DAVINCH (Detonation of Ammunition in a Vacuum-Integrated Chamber). Neutralization technology – uses small explosive shaped charges to open the munition and consume the explosive in the burster and fuze. The agent is destroyed by subsequent neutralization. The U.S. Army's Explosive Destruction System (EDS), is an example. Thermal destruction – uses the heat of the electrically heated containment vessel to deflagrate the munition and destroy the agent and energetics. The resulting gases are treated in an off-gas treatment system. The Static Detonation Chamber, or SDC, is an example of thermal destruction technology. In April 2013, Program Executive Officer Conrad F. Whyne announced his selection of the U.S. Army's EDS to augment the PCAPP for the safe destruction of chemical munitions unsuited for processing by the main plant's automated equipment. The PCAPP EDS started destruction on March 18, 2015, with the elimination of Department of Transportation (DOT) bottles, which contained chemical agent drained from selected munitions over the years, to assess the condition of the stockpile. On April 8, 2015, the first munitions were successfully processed. In June 2015, operators at the PCAPP EDS took things up a notch with the introduction of 4.2-inch mortars into the destruction process. The first three mortars were joined by three 105 mm projectiles. All were safely detonated in the vessel on June 18, 2015. On July 16, 2015, the first 155-mm projectiles from Pueblo's stockpile were safely destroyed in the PCAPP EDS. The PCAPP EDS completed its first campaign in February 2016, destroying 549 munitions that leaked or were sampled in the past and 11 bottles containing mustard agent. The second and final campaign ran from June 25 to December 5, 2018. Static Detonation Chamber (SDC) In spring 2018, PCAPP announced a proposal to procure three Static Detonation Chambers (SDC). Due to performance issues identified during the first year of pilot testing, and in order to complete the destruction of the stockpile by 2023, this technology was chosen to augment the main plant under a proposal by the ACWA program. To meet the requirements of the National Environmental Policy Act and federal regulations, an Environmental Assessment was conducted. A Finding of No Significant Impact resulted from the assessment. Preparations at the SDC site began in June 2019. The first SDC components arrived at the depot on August 6, 2019, in a convoy of more than a dozen flatbed trucks. Assembly began on October 31, 2019. Protective, tension fabric coverings were erected around each unit, with construction beginning in September 2019. They were completed in June 2020. On February 19, 2022, chemical-agent destruction began at the Pueblo SDC complex with the processing of a portion of the 4.2-inch mortar rounds. SDC operations marked the beginning of the third and final chemical weapons destruction campaign at PCAPP. On June 22, 2023, the last munition in the chemical weapons stockpile stored at the Pueblo Chemical Depot, an overpacked 155-mm projectile, was destroyed in the plant's SDC complex. State regulators approved the SDC closure plan on November 5, 2024, allowing workers to begin executing the plan to transfer the units to other government agencies. Approval by state regulators of Reuse Readiness Reports on May 9, May 29, and June 13, 2025, for SDC Units 1, 2, and 3, respectively, allowed for the disassembly and transfer of each unit to other Defense Department organizations. In July 2025, the plant completed decontamination, disassembly, packaging, and transport of the three Static Detonation Chamber units to U.S. Army organizations in Maryland and Alabama. Closure The plant has been in the closure phase since state environmental regulators approved the PCAPP closure plan on March 29, 2024. Closure activities are expected to continue through 2028. Closure is the final phase of the project, coming after completion of chemical weapons destruction operations in 2023. Closure encompasses planning, preparation, and disposal of agent-contaminated and non-contaminated secondary waste; facility and equipment decontamination; and decommissioning and demolition of facilities in accordance with public law and U.S. Army direction. In addition, personal property is disposed of, and real property is returned to the U.S. Army or PuebloPlex, the local redevelopment authority. The last stage is closure of contracts and environmental permits. Public Outreach The Pueblo Chemical Stockpile Outreach Office permanently closed to the public in 2023, but staff continues to be available at pueblooutreach@iem.com. The Pueblo Chemical Stockpile Outreach Office was established in 1997 to serve as the community's primary information resource on chemical weapons destruction in Colorado. The staff responded to inquiries, provided information materials, coordinated guest speakers for various civic groups and organizations, and interfaced with the governor-appointed Colorado Chemical Demilitarization Citizens' Advisory Commission. The project's environmental permitting information is available for review during regular business hours at: · Robert Hoag Rawlings Public Library, 100 E. Abriendo Ave., Pueblo, CO 81004 · McHarg Community Center, 405 Second Lane, Avondale, CO 81022 · Boone Community Center, 421 E. First St., Boone, CO 81025 Additional information is also available on the following websites: https://cdphe.colorado.gov/hm/HMWMD-public-notices army.mil See also Pueblo Chemical Depot Pueblo Depot Activity Blue Grass Chemical Agent-Destruction Pilot Plant Base Realignment and Closure References This article incorporates public domain material from the United States Army External links Centers for Disease Control – Chemical Demilitarization Chemical Stockpile Emergency Preparedness Program PuebloPlex - We Are Ready