Since the Pine Bluff Arsenal began incinerating its aging stock of chemical weapons last year, hundreds of thousands of rockets containing deadly nerve gas have been destroyed, and the arsenal is on schedule to destroy its stockpile by the 2012 deadline, officials said last week.

The Arsenal's Chemical Agent Disposal Facility marked its first year of operation March 29.

"For us, it’s a significant milestone," said Randy Long, the facility's site project manager. "We've had a very successful year. A very good start like the one you have here is very important."

The United States is working to destroy its stockpile, stored at eight sites around the country including Pine Bluff Arsenal, by 2012 to comply with an international treaty.

Since incineration began with the draining of two rockets filled with the nerve agent GB, the facility has destroyed 34,207 GB rockets, about 38 percent of its stock, and 352,782 pounds of the GB nerve agent, about 5 percent of its stock.

The arsenal won't disclose the exact amount of chemical agents it stores in underground igloos, citing security reasons, but at the start of the project it was storing 12 percent of the Army's chemical weapons stockpile. So far, 16 underground igloos have been emptied.

The arsenal opened in 1941 to manufacture mustard blister agents and lewisite and to assemble munitions. Production of chemical weapons ended in 1969.

Since the 1970s, the arsenal has produced nonlethal chemical agents, tested chemical defense equipment and manufactured such munitions as white phosphorus.

The focus for the past year has been on the arsenal's stock of GB, known as sarin. The rockets are first drained of the GB nerve agent and sheared into eight pieces.

The drained nerve agent is destroyed in an incinerator, and the sheared rocket pieces are incinerated in a deactivation furnace.

The process has changed over the course of the year, partly in response to flare-ups during incineration at the Pine Bluff Arsenal and a disposal site in Umatilla, Ore., said David Reber, the project general manager for Washington Group International, which operates the incinerator.

Sprays used to keep the rockets cool when they are cut into pieces come on more often and stay on longer than they did originally. Maintenance crews clean the area more often to prevent residue from igniting.

Since the start of incineration, seven fires here occurred at the facility, the most recent on Dec. 20.

Five fires occurred during incineration, and the other two resulted from residues of chemical agents in drain pans.

None of the fires resulted in injuries or the release of chemical agents. All took place in a containment room, which has two-foot-thick walls of steel and reinforced concrete.

While none of the fires posed a threat to the public, the failure to report the first fire in May did spark some criticism. Subsequent fires were reported to local officials and the news media.

Long said the arsenal also benefited from the experience of other disposal sites, since it was the last one to begin operations. Other sites provided insight on how often to schedule various repairs, for instance.

Changes to speed the transport of the agents have helped keep the Pine Bluff facility on schedule.

Workers are now able to unseal containers that carry the agents in a matter of minutes. The process used to take hours.

While no rockets have been processed since mid-January, the facility is still bustling.

Plastic piping in the facility's pollution-abatement system is being replaced with piping made from a metallic alloy.

The pipes carry a cleaning solution used in the system that cools and cleans exhaust gases from the incinerator furnaces. Similar work has been done at the Umatilla site and the facility in Anniston, Ala.

The piping should be replaced and the incinerators back up and running by mid-May, Reber said.

Each week, a day of maintenance is planned, he said. A staff of 15 or 20 people maintain the incinerator and are on hand for any repairs or routine maintenance 24 hours a day, he said.

Every three months or so, the incinerator is shut down for a week for maintenance. Although the piping project was planned, not all maintenance can be foreseen, he said. The arsenal should be able to stay on track if any unexpected repairs are needed.

Last week, Pine Bluff began destroying protective suits, tools and other paraphernalia that had been exposed to chemical agents during the incineration.

The arsenal built an area at the facility to hold such items so they wouldn’t have to be transported to the igloos for storage, Reber said. Tools and other material that can be decontaminated are reused. But suits and some tools can't be reused, he said. The destruction of the materials should be finished at the same time the remainder of the GB is destroyed.

The plan is to have all of the GB destroyed by the spring of 2007, Long said. After a cleanup and some changes to the incinerator's monitors, the destruction of VX, another nerve agent, will begin in the fall of 2007.

Rockets and then land mines will be incinerated. The last chemical agents to be destroyed will be mustard blister agents, stored in bulk containers.

Betsy Francis, the vice chairman of the Citizens Advisory Commission, said that the first year of the project sped by. "The first year went by so quickly. I can't believe it's been a year. There was so much buildup to get there."

She said that arsenal officials and Washington Group International have worked hard to keep the commission and community informed. She said the early criticism wasn't overlooked. "They have taken it, as I think we have, as lessons learned."

Francis, a real estate agent who grew up in White Hall and who has two children who work at the arsenal, added: "They are such a good neighbor to the community, they have just proven themselves."

She also said the community will be safer once the aging weapons are gone. "We've never had chemicals like that stored for the length of time they've been stored there."