The Program Executive Office, Assembled Chemical Weapons Alternatives (PEO ACWA), the U.S. Army Pueblo Chemical Depot (PCD), and the surrounding communities worked together to select neutralization followed by biotreatment to destroy the chemical weapons stored at the depot. The Pueblo Chemical Agent-Destruction Pilot Plant (PCAPP) safely destroyed the weapons. PEO ACWA was responsible for completing stockpile destruction operations by the Chemical Weapons Convention treaty commitment of Sept. 30, 2023. U.S. public law mandates stockpile destruction by Dec. 31, 2023.

Prior to destruction operations, the chemical weapons stockpile at PCD comprised 2,613 U.S. tons of weaponized mustard agent in three types of munitions: 105mm and 155mm projectiles and 4.2-inch mortar rounds. The 4.2-inch mortar round campaign used the same neutralization followed by biotreatment process as the two previous projectile campaigns, with improved equipment to destroy mustard-filled mortars, and was the plant’s final campaign.

Terminology

Chemical Incident or Mishap Response and Assistance (CIMRA): Formerly Chemical Accident/Incident Response and Assistance, a CIMRA is an intentional or unintentional chemical event where a chemical agent may be released into the environment and has the potential to threaten unprotected personnel. A chemical incident is any event resulting from a deliberate or criminal act of terrorism where safety is of primary concern. A chemical mishap is any event resulting from a non-deliberate act where security is also of primary concern.

Chemical Agent Operation (also known as a Chemical Surety Operation): Any activity that involves chemical surety materiel is a chemical agent or chemical surety operation (for example, storage, shipping, handling, manufacturing, maintenance, test chamber activities, laboratory activities, surveillance, demilitarization, decontamination, disposal and training). On PCD, the chemical surety materiel is mustard (in three varieties, H, HD and HT), a blistering agent, that is stored in the Chemical Limited Area for demilitarization at PCAPP.

Chemical Event: A chemical event is a chemical surety material mishap or incident, or event of concern based on the commander’s experience and discretion. The anticipated response to a chemical event is the activation of all or a select portion of the Initial Response Force as necessary. If the event is a chemical incident, additional security forces will be deployed.

Chemical Surety Program: A system of control measures designed to provide protection to the local population, workers, and the environment by ensuring that chemical surety operations are conducted safely; that chemical surety materials are secure; and personnel involved in those operations meet the highest standards of reliability.

Engineering Controls: Measures taken to eliminate or reduce exposure to a chemical or physical hazard through the use or substitution of engineered machinery or equipment. Examples would include a device, room, or structure supported by a mechanical toxic exhaust system that provides containment of chemical agent vapor and/or liquid, preventing migration of the chemical agent hazard to immediate /adjacent areas or to the environment.

Initial Response Force (IRF): The emergency action organization tasked to provide first response to a chemical incident or mishap at PCD/PCAPP, under the command of the PCD commander. The IRF is composed of command and control elements and emergency teams capable of providing emergency medical services and initiating those actions necessary to prevent, minimize, or mitigate hazards to public health and safety, and to the environment.

Short-Term Exposure Limit (STEL): The maximum concentration to which unprotected chemical workers may be continuously exposed for up to 15 minutes. For mustard agent (H, HD and HT) exposures, a worker may only have one exposure per day at the STEL concentration. NOTE: The primary agent monitoring system at PCAPP measures on five-minute cycles, ensuring protective actions are taken well within the 15-minute duration.

Vapor Screening Level (VSL): The VSL is the equivalent to the absolute STEL concentration, but it is independent of a designated sampling time (for example, time weighted average) and may be used to define the level of item cleanliness, or alternately the readout for a near real time instrument.

Worker Population Limit (WPL): The level at which an unprotected worker can operate safely eight hours a day, five days a week, for a working lifetime without adverse health effects.