Chemical Stockpile Emergency Preparedness Program

On June 22, 2023 the final round of the stockpile was safely destroyed. 

Pueblo Chemical Agent-Destruction Pilot Plant workers destroyed more than 780,000 mustard agent-filled projectiles and mortar rounds through three munitions destruction campaigns. A campaign refers to destruction of a particular type of chemical weapon. Destruction operations in Colorado began in March 2015, with more than 2,613 U.S. tons of chemical agent destroyed. One other chemical weapons stockpile site remains in Kentucky and is expected to finish destruction operations later this year.

The Colorado depot originally stored three kinds of mustard agent-filled weapons: 155mm and 105mm projectiles and 4.2-inch mortar rounds. Three different technologies were used to destroy the stockpile. The projectiles and a portion of the 4.2-inch mortar rounds were destroyed in the main plant under the supervision of trained operators using automated technology. The mustard agent was neutralized and the resulting product, known as hydrolysate, was broken down into salt, water and organics using living microbes in a biotreatment process.

Projectiles deemed unsuitable for automated processing and the remaining mortar rounds were destroyed by Static Detonation Chambers. Earlier, 951 problematic munitions were destroyed using an Explosive Destruction System between 2015 and 2018.

The accomplishment has been reported to the Organization for the Prohibition of Chemical Weapons, an intergovernmental organization that implements the Chemical Weapons Convention treaty. The Program Executive Office, Assembled Chemical Weapons Alternatives is responsible for eliminating the U.S. chemical weapons stockpile by the treaty commitment date of Sept. 30, 2023.

Now that the entire stockpile in Colorado has been destroyed, PCAPP will close. The closure phase, which will continue for three to four years, encompasses the disposal of all secondary wastes, decontamination and decommissioning of facilities and equipment, disposition of property, demolition of certain facilities, and closure of government contracts and environmental permits in accordance with laws and regulations. During closure, the safety of the workforce, public and environment will remain the project’s top priority. PCD is on the Base Realignment and Closure list and is being transferred to a local reuse authority, PuebloPlex.

The U.S. chemical weapons stockpile sites in Colorado and at the Blue Grass Army Depot in Kentucky accounted for the last 10% of what was originally a national stockpile of more than 30,000 tons of chemical weapons. The U.S. Army Chemical Materials Activity (then designated an Agency) destroyed the initial 90%, which was stored at seven other sites across the U.S. and on Johnston Atoll in the Pacific. Chemical weapons destruction in Kentucky began in 2019 and is on target to meet the treaty commitment date.

Background Information

The U.S. Army has maintained stockpiles of chemical munitions since the 1950s. In 1985, Congress passed Public Law 99-145 directing the Army to destroy the aging chemical weapons while providing maximum protection to the public and the environment. As part of the dedication to providing this protection, an agreement was developed between the Army and the Federal Emergency Management Agency establishing the Chemical Stockpile Emergency Preparedness Program (CSEPP).

The Chemical Stockpile Emergency Preparedness Program (CSEPP) is a readiness program to enhance the emergency preparedness of the communities around the stockpile sites. The program's goal is to improve emergency preparedness, response, and recovery activities.

Approximately 8.5 percent of the nation’s original stockpile is stored at the U.S. Army Pueblo Chemical Depot (PCD) located east of Pueblo.  The depot is situated on 23,000 acres in Pueblo County.  Its stockpile consists of mustard agent stored in projectiles and mortar rounds.  These munitions are stored in earth-covered structures in the depot’s chemical storage area.  The ammunition storage area is secured and the area is patrolled 24 hours a day.

Recovery Plan

The CSEPP Recovery Plan was updated in June 2016.


Colorado's Chemical Stockpile Emergency Preparedness Program

For more information about Colorado's CSEP Program visit the Pueblo County Sheriff's Office Emergency Services Bureau. The areas surrounding the Pueblo Chemical Depot are divided into emergency planning zones.  

Federal Emergency Management's CSEP Program

For more information on the United State's CSEP Program, visit the Federal Emergency Management Agency's Chemical Stockpile Emergency Preparedness Program (CSEPP).