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 DecadeMilestones1950s Pueblo Ordnance Depot (later redesignated as the U.S. Army Pueblo Chemical Depot) began storage of chemical weapons containing mustard agent.1980s Public Law 99-145 designated the U.S. Army responsible for the destruction of the U.S. chemical weapons stockpile.1990s The United States Congress established the PEO ACWA program under the Department of Defense (DOD) to identify and demonstrate alternatives to incineration. Congress ratified the Chemical Weapons Convention treaty, which directs all member nations to destroy their chemical weapons and production facilities.2000s DOD selected neutralization followed by biotreatment as the destruction method for the Colorado stockpile. The Bechtel Pueblo Team was awarded a contract to design, build, and operate PCAPP. PCAPP groundbreaking was held. Design work and preliminary construction were suspended pending evaluation of cost reduction measures. PCAPP redesign was approved by the DOD, and construction work resumed. The Secretary of Defense affirmed to Congress that there were no options by which the U.S. could destroy 100 percent of its chemical stockpile by the extended Chemical Weapons Convention treaty deadline of April 29, 2012. The DOD accepted the final design for PCAPP. Above-ground vertical construction began with the erection of the Multipurpose Building. Public Laws 110-116 and 110-181 were enacted, mandating the destruction of the chemical stockpile by April 2012 or, in no case, later than December 31, 2017. PCAPP received the U.S. Department of Labor Occupational Safety and Health Administration Voluntary Protection Program Star Status certification in recognition of safety excellence. PCAPP construction was more than halfway complete, with interior and exterior work ongoing in multiple buildings, including the Agent Processing Building, Control and Support Building, Enhanced Reconfiguration Building, Biotreatment Electrical Building, Entry Control Facility, Immobilized Cell Bioreactor and Off-Gas Foundation Pads, and Munitions and Energetic Service Magazines.2010s Construction continued with interior and exterior work ongoing in multiple buildings, including the Agent Processing Building, Control and Support Building, Enhanced Reconfiguration Building, Biotreatment Electrical Building, Multipurpose Building, Filter Press Building, PCAPP Medical Clinic, Entry Control Facility, Laboratory Facility, Immobilized Cell Bioreactor, Brine Reduction System, Off Gas Foundation Pads, and Munitions and Energetics Service Magazines. The systemization phase began at PCAPP. Construction teams turned over the first subsystems to the start-up groups for systemization testing and commissioning to begin to prepare the facilities for chemical weapons destruction operations. To meet the requirements of the National Environmental Policy Act (NEPA) and Title 32 Code of Federal Regulations Part 651, PEO ACWA, in conjunction with the U.S. Army Pueblo Chemical Depot, completed an environmental assessment regarding the possible use of EDTs in Pueblo. Following a public comment period and extensive review by DOD leadership, the environmental assessment is withdrawn. As part of systematizing the facility, Assembled Chemical Weapons Alternatives Test Equipment arrived for practice and training use. PCAPP was formally notified by the U.S. Department of Labor's Occupational Safety and Health Administration (OSHA) that the PCAPP project was re-certified as a Star Worksite under OSHA's Voluntary Protection Program. In April 2012, Pueblo Chemical Depot and PEO ACWA completed an environmental assessment to meet the requirements of the NEPA and Title 32 Code of Federal Regulations Part 651 to address any potential impacts of the installation and operation of EDT at the depot. The environmental assessment concluded that the installation and operation of an EDT would have no significant environmental impacts. A draft Finding of No Significant Impact was prepared and provided for public comment for a 60-day period. It was concluded that no additional analysis was necessary for the proposed action under NEPA. On December 12, 2012, PCAPP declared construction complete and moved into the systemization phase of the project. On April 18, 2013, Program Executive Officer Conrad F. Whyne announced his selection of the U.S. Army's EDS to augment PCAPP. The decision followed a lengthy review of several EDTs designed for the safe destruction of chemical munitions unsuited for processing by the main plant's automated equipment. Construction began and was completed on the PCAPP EDS site, located at the U.S. Army Pueblo Chemical Depot, in 2014. The first of two EDS units arrived on site, aligning with the completion of specially designed environmental enclosures that will house them for added protection. Provisional Operations, a two-month period in which operations and maintenance staff practice training with simulated munitions and agents, began at PCAPP in 2014. This extensive training is conducted on a large scale to ensure employees are better prepared for plant operations. Chemical stockpile destruction in Colorado was initiated on March 18, 2015, by the EDS, located on the U.S. Army Pueblo Chemical Depot near PCAPP. This event marked the first step towards eliminating the final 10 percent of the U.S. chemical weapons stockpile. In 2015, the Bechtel Pueblo Team earned recertification of Star Status in OSHA's Voluntary Protection Program. On February 11, 2016, the EDS successfully completed its first destruction campaign, eliminating 265 105 mm projectiles, 196 155 mm projectiles, 88 4.2-inch mortar rounds and 11 Department of Transportation bottles for a total of 560 munitions.560 shells, bottles of mustard agent destroyed in Colorado KRDOChemical weapons destruction well underway at Pueblo depot, The Pueblo Chieftain Systemization was completed, and operations began on September 7, 2016. On September 7, 2016, main plant operations began at PCAPP to destroy the stockpile of chemical weapons stored at the U.S. Army Pueblo Chemical Depot in Colorado. The plant utilized neutralization followed by biotreatment as the technology to destroy 780,078 munitions containing more than 2,600 tons of mustard agent. Additionally, the Army's EDS is on standby to augment the main plant to destroy problematic chemical munitions that cannot be easily processed using its automated equipment. On November 16, 2016, the Anniston Field Office destroyed the first non-contaminated energetics removed from munitions at PCAPP. PCAPP operations were paused on November 20, 2016, due to an industrial hazardous waste spill of approximately 450 gallons of hydrolysate. The spill was associated with a seal failure of one of the agitators located on the side of a hydrolysate storage tank. On November 23, an unrelated second issue was discovered; rainwater had leaked through the liner of the secondary containment system surrounding the Brine Concentrator Feed Tanks. These tanks hold the effluent produced in the Immobilized Cell Bioreactors and are essential to the operation of the biotreatment process. PCAPP operations resumed on January 12, 2017. Under the purview of the Colorado Department of Public Health and Environment, the agitators were removed from one of the hydrolysate storage tanks, and the openings were sealed with blind flanges. Additionally, the liners, from the floor and partway up the walls of the secondary containment system around Brine Concentrator Feed Tanks, were removed. On April 27, 2017, the Biotreatment Area at the Pueblo plant began processing hydrolysate, which is the product of the neutralization of mustard agent. From July to September 2017, PCAPP temporarily shipped wastewater off-site for treatment and disposal at the Veolia Environmental Services Hazardous Waste Incinerator in Port Arthur, Texas. The wastewater, known as hydrolysate, is the product of the neutralization of chemical agent at the plant. A total of 52 truckloads safely transported 236,473 gallons to Veolia for disposal. In September 2017, PCAPP marked its first full year of the pilot testing phase in which the plant destroyed 253 U.S. tons of mustard agent and 42,897 155 mm projectiles. On September 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 February 15, 2018, PCAPP ordnance technicians reached a plant milestone when the last of more than 28,000 105 mm projectiles went through Baseline Reconfiguration. On April 12, 2018, PCAPP ordnance technicians started the baseline reconfiguration process for the 4.2-inch mortar rounds. At the end of this campaign, more than 97,000 of these rounds underwent this process.