HERMISTON -- The Umatilla Chemical Depot announced Monday that the incinerator has now destroyed half the original stockpile of sarin rockets.

Originally the depot near Hermiston stored 91,442 M55 rockets filled with GB sarin nerve agent. Those rockets present the greatest danger to the surrounding communities, which is why they were destroyed first, officials said.

The incinerator was built to burn chemical nerve agents -- about 12 percent of the nation's chemical weapons stockpile -- stored at the depot in concrete bunkers, or "igloos."

"I'm especially pleased knowing that with each processing milestone, we reduce the public risk associated with storing these weapons," said Don Barclay, Army site project manager for the depot.

While the destroyed rockets are only about 7 percent of the original stockpile, eliminating them reduces the risk to the community by about 53 percent, he said. That's because those rockets have had many problems with leaks, and sarin is considered one of the most dangerous chemical agents.

But the process hasn't been without problems, including several shutdowns in the first months of operation because of workers entering areas without wearing the appropriate protection.

And the incinerator has had five small internal fires, the most recent on Dec. 5, when a cutting blade was cutting through a rocket.

Even with those problems, the facility has made good progress, said Doug Hamrick, project general manager for Washington Group International, which is contracted to run the incinerator for the Army.

In a comparison with the Anniston Chemical Depot in Anniston, Ala., the Oregon site has destroyed just 162 fewer rockets than the Alabama facility in the same amount of time, he said.

"We are essentially at the same point they were at," he said.

Hamrick also pointed out that while there were initial problems with the workers, the last worker error that caused a shutdown was about a year ago.

"They have really improved their performance," he said.

The facility also has been able to resume rocket destruction more quickly after a fire. After the Dec. 5 fire, a rocket destruction line that was not involved in the fire started up again after 10 hours and the line with the fire restarted the next day, he said.

In addition to destroying 45,721 sarin-filled rockets, the facility also has been processing GB bombs and four ton containers of sarin nerve agent.

The plant is expected to be finished with the sarin stockpile by October, he said.