The Pueblo Chemical Depot is a chemical weapons storage site located in Pueblo County, Colorado, United States. The Pueblo Chemical Depot is one of the last two sites in the United States with chemical munitions and chemical material. The Pueblo Chemical Agent Destruction Pilot Plant (PCAPP) which is under the Assembled Chemical Weapons Alternatives (ACWA) program will destroy its stockpile of 155-mm and 105-mm artillery shells and 4.2-in. mortars, all of which contain a form of the chemical agent mustard.
The depot houses 2,611 tons (2,369 metric tons) of mustard agent in approximately 780,000 munitions, equivalent to about seven percent of the original chemical material stockpile of the United States. The current course of action for the Pueblo Chemical Agent-Destruction Pilot Plant, included in the President's Fiscal Year 2010 Budget Request, will allow for acceleration of the project schedule. After systemization and pilot testing of the facility, destruction operations began in spring 2015 with full-scale operations beginning later in 2016. Destruction of all munitions is expected to be complete in 2019.
Sulfur agent is destroyed through neutralization and biotreatment. Energetic components are first removed through robotics and disposed. The weapon body is then robotically accessed to wash out the sulfur agent using water at a high pressure. The sulfur agent is neutralized with caustic solution and hot water producing a byproduct of hydrolysate. Biotreatement occurs when the hydrolysate is further broken down with microbes, producing biosludge and water. Biosludge is filtered and sent to a disposal facility. Metal weapon parts are further decontaminated at high heat then recycled  The Army's Explosive Destruction System (EDS) is used for problematic munitions that cannot be destroyed through neutralization and biotreatment. Problematic munitions are those that have leaked or are in poor physical condition making it difficult for automated equipment processing.
A specialized facility named the PCAPP Training Facility is located at the Pueblo Memorial Airport Industrial Park and offers training courses and simulations for employees. Training are designed to ensure the safety of the employees and the surrounding environment. Employee are trained to operate the equipment and use Demilitarization Protective Ensemble or DPE. The DPE is an encapsulated air-supplied chemical protective suit. Samples are taken at multiple stages and analyzed for any leakage of the chemical agent.
The plant will operate until all the chemical weapons have been destroyed. Closure activities (shut-down, dismantling, and restoration of site) are slated to be wrapped up by 2022. This is far outside the deadline set by the Chemical Weapons Convention (April 2012). PuebloPlex will head the redevelopment of Pueblo Chemical Depot. Once the mustard agent has been treated and environmental restoration is complete, the depot will be transferred to the community with possibilities of solar farming to contribute energy to the military complex in Colorado Springs, Fort Carson, Peterson and Schriever Air Force bases.