U.S. Army Pueblo Chemical Depot (PCD), Colorado, has completed many missions and has been known by many names for nearly eight decades. The equipment and procedures that provide safe chemical stockpile storage to support its final mission have evolved, and continue to be updated.When the depot’s supply of Single Round Containers (SRC) ran low due to lack of availability, PCD and its higher headquarters, U.S. Army Chemical Materials Activity (CMA), developed a unique way to contain chemical agent munition rejects through the use of Propelling Charge Canisters (PCC). Use of PCCs has saved approximately $125,000 to date and ensured the demilitarization of chemical weapons is not interrupted. PCD is projected to receive 1,600 PCCs, ultimately saving the Department of the Army more than $4 million.PCD originally stored 2,600 tons of mustard agent. More than half the agent has been destroyed at the Pueblo Chemical Agent-Destruction Pilot Plant (PCAPP), with PCD chemical operation crews transferring pallets of 155mm projectiles and 4.2-inch mortars to the plant every day. Crews encountered problematic rounds within the stockpile or during processing at PCAPP.Problematic rounds, often called rejects, are discovered when a round cannot be processed through the main plant due to issues during disassembly, or when leaking due to deterioration. A reject munition is over-packed into an SRC and returned to storage to await destruction in the Static Detonation Chambers (SDCs) that will be completed later this year. As PCAPP operations increased, a high number of unanticipated rejects were encountered.With a quarter million projectiles already processed, and with SRC inventory running low, an alternative was needed for the expensive and hard-to-secure containers. After discussion between leadership at CMA, PCD, PCAPP and its higher headquarters, the Program Executive Office Assembled Chemical Weapons Alternatives (PEO ACWA), all agreed to use PA92 PCCs, or “prop canisters”, to augment the dwindling supply of SRCs.Prop canisters, in use by the Department of Defense since 1973, are considered excess Navy stock, replaced by SRCs in 2005. SRCs are still produced at the Advanced Design and Manufacturing (ADM) Directorate, Maryland, and the Ammunition Equipment Directorate (AED), Tooele Army Depot, Utah, in support of the Blue Grass Chemical Agent-Destruction Pilot Plant (BGCAPP), PCAPP, and CMA stockpile storage operations.Chris Pulskamp, Chief of the PCD Environmental Management Office, submitted the permit modification with supporting documentation through the Colorado Department of Public Health and Environment (CDPHE) to allow the use of prop canisters. The permit modification, which needed two approvals, verified the canisters were a suitable substitute for SRCs. After discussion with CDPHE, the Army decided prop canisters would be used for non-leaking munitions only. PCD immediately began putting procedures into place to use them.Carlos Estrada, Accountable Property Officer at CMA Headquarters, located 60 prop canisters and had them shipped to PCD. Chemical operation crews noticed the PCCs were noticeably lighter and easier to use than SRCs, increasing safety and efficiency when handling problematic rounds in the field.“Prop canisters give us an operational flexibility to manage reject munitions in an operational environment within the PCAPP,” said Walton Levi, PCAPP Site Project Manager.As a bonus, prop canisters are also less expensive; an SRC costs $2,500, which a PCC costs less than $300.At the end of this year, the first of three SDCs will be operational. Chemical munitions, to include rejects in prop canisters and SRCs, will be destroyed at an increased rate, augmenting the plant in reaching its treaty deadline of December 2023. Soon after, PCD will close is gates with its final mission completed.“Our success not only lies with just finishing the job, but being able to work together as a team to find solutions to finish it safely,” said Col. Michael W. Cobb, PCD Commander.