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HERMISTON -- A ton container of mustard chemical weapon at the Umatilla Chemical Depot was incinerated Sunday, the first burning at the depot since late October.
The restart was allowed after lower limits were set on the size of the deposits of organic salts in the bottom of the containers undergoing incineration.
The lower limits are intended to meet air quality standards but will increase the time needed to destroy all the mustard agent at the depot.
On Friday, the Oregon State Department of Environmental Quality approved a draft permit for the trial burn that set the limit for salts in the ton-container at 435 pounds, said Rich Duval of the department's Chemical Demilitarization Program in Hermiston. Incineration at the Umatilla Chemical Agent Disposal Facility now is in the shakedown phase and is expected to progress to the trial burn phase after a public comment period.
URS, which operates the incineration plant, had been burning some ton containers with 600 to 700 pounds of salts during the testing phase before incineration was halted in late October.
Some of the 600-pound amounts did not cause a problem, said Hal McCune, URS spokesman. But others boiled over, leading to eight incidents when the plant exceeded its air quality emissions limit.
Ton containers of mustard agent, which may hold more than a ton of agent, are emptied of liquid mustard by punching holes in the container. Water then is sprayed at high temperature and pressure into the container to reduce the amount of organic salts that have formed at the tank bottom.
If too much of the salt and water remains in the container when it is sent through the metal-parts furnace for incineration, the material can boil out of the holes punched to empty the container and carbon monoxide is released. That's an indication there is not enough oxygen to allow complete combustion, Duval said.
The boil-over can lead to the potential of uncombusted material escaping through the stacks, said Rodney Skeen of the Confederated Tribes of the Umatilla Indian Reservation's Department of Science and Engineering.
URS will need to reduce the amount of the salts in some containers by more spraying, which will create more liquid waste that also will need to be destroyed and will extend the length of the incineration campaign.
The new limit not only limits the amount of material that can remain in the container to no more than 435 pounds, but it also limits the amount that can be solid salt to 300 pounds, said Skeen. The remainder would be water and salts.
The Umatilla Chemical Agent Disposal Facility has permission to continue the shakedown phase of mustard agent incineration while the state reviews the trial burn plan and takes public comment. Operating the plant without weapons incineration costs the government about $400,000 a day.
Incineration of the mustard agent is expected to take one to two years. It's the last of the chemical weapons at the depot to be destroyed.
Public comments will be accepted until March 8 and may be sent to cdp@ deq.state.or.us or Chemical Demilitarization Program, Oregon Department of Environmental Quality, 256 E. Hurlburt Ave., Suite 105, Hermiston, Oregon, 97838.
w Annette Cary: 582-1533; acary@tricity herald.com
