The US Army Chemical Demilitarization programme reached noteworthy milestone yesterday when the Umatilla Chemical Agent Disposal Facility (UMCDF) at Hermiston, Oregon, destroyed the oldest container of sulphur mustard ever stored at the Umatilla Depot. Bulk mustard agent is generally stored in “ton containers”. These are steel tanks gel capsules that are about the size of an industrial water heater. The ton container in question, which the facility’s staff had nicknamed “Grandpa”, was more than 70 years old. It had been manufactured in 1940 and, in 1946, was filled with 1,768 pounds of HD (distilled sulphur mustard) at the Rocky Mountain Arsenal near Denver, Colorado. Some time between 1962 and 1969, “Grandpa” was shipped to Umatilla where it was placed in storage - in a building that, in recent years, had come to be known as “Grandpa’s House”.
The Umatilla Depot was built in 1941 and supported US participation in all of the major conflicts in the Pacific of the 20th Century. In 1994, the Depot’s role was altered slightly; all conventional munitions were removed and it became solely a storage depot for chemical weapons awaiting destruction, and was declared as such by Washington pursuant to paragraph 1 of Article III of the CWC. The Depot was used principally for storage of unitary CW of all types; in 2007, for example, UMCDF completed a campaign to neutralize and destroy more than 60,000 8-inch and 155-mm artillery projectiles containing more than 250 tonnes of GB (Sarin, O-isopropyl methylphosphonofluoridate). This was slightly less than 10% of all the CW agent destroyed by the US in 2007 (3071 tons).
Most of the destruction work at UMCDF has been relatively straightforward; the nature of the agents and containers being dealt with are less problematic than those being handled elsewhere (for example, at the Newport Chemical Agent Disposal Facility in Indiana, where the reaction products of the hydrolysis of VX must be shipped off-site for further treatment as a toxic chemical hazard prior to being disposed of). That said, Umatilla and other destruction facilities dealing with mustard (e.g., the Toelle Chemical Agent Disposal Facility in Utah) have their own difficulties. Some batches of mustard have been found to be contaminated with high levels of mercury, precluding incineration of the neutralized reaction mass at least until appropriate emissions controls for heavy metals have been retrofitted to vent stacks; while the older containers - artillery shells, aircraft bombs, and ton containers like “Grandpa” - often contain “heels”. These are polymerized masses of mustard that are resistant to organic solvents, and are thus very hard to get rid of.
It is one of the enduring ironies of chemical weapons that no matter how difficult they may be to make, store, transport, use and defend against, they are usually even more difficult to destroy. Despite these challenges, it’s noteworthy that UMCDF - which has, since it began operations in 2004, destroyed more than 218,000 munitions and other containers containing 4,000,000 pounds of GB, VX and HD (1,752 tons, about 47% of the total stockpile at the Depot) - recently reached six million man-hours of destruction activity without a lost day due to accident.
For more information on the destruction of ‘Grandpa’, see [http://www.cma.army.mil/fndocumentviewer.aspx?DocID=003683381].
If you’re interested in more information on the US chemical demilitarization programme, the US Army Chemical Materials Agency website is a useful resource [http://www.cma.army.mil/].