HERMISTON -- Umatilla Chemical Depot commander Lt. Col. David "Doc" Holliday likes what he sees.

So far, three of about 140 storage bunkers have been emptied of chemical weapons and have been destroyed or are in the process of destruction. While not statistically remarkable to the casual observer, this is big news for a facility that is home to one of the largest chemical warfare stockpiles in the world that has been sitting idle for several decades.

"I'm very pleased with the work done so far," Holliday said.

On Sept. 7, workers at the Umatilla Chemical Depot moved the first pallet of chemical weapons into the site's incinerator building. The next day, the facility destroyed the first M55 rocket containing GB sarin gas. Tuesday will mark six months that the incinerator has been operating.

And those six months have had good progress -- and some problems.

So far the depot has emptied three storage bunkers, destroyed 5,899 rockets and 31 tons of agent.

It is expected to take about 10 years to destroy the depot's stockpile of 220,604 munitions and containers filled with 7.4 million pounds of deadly nerve and mustard agents. The cache includes the most M55 rockets of the eight U.S. sites.

Depot officials say they are pleased with the progress so far.

Still, there have been glitches.

A bumped emergency stop button halted the destruction of the first rocket sent through the Umatilla Chemical Depot's incinerator for about four hours.

Less than a week later, two workers wearing only gas masks and rubber protective clothing accidentally entered an area where they could have been exposed to sarin nerve agent.

Then the disposal facility halted rocket destruction for most of December after two workers unclamped an incorrect door inside one of the plant's filter units, allowing nerve agent to leak into an adjacent room.

Workers were not exposed to nerve agent or injured in either incident.

Investigations showed that the unclamped door and entering the potentially contaminated area were partially to blame for habits developed before the incineration facility was destroying agent.

Don Barclay, depot site project manager, said, looking back, he would have done more to focus on breaking those habits.

People worked in the completed incinerator building for three years before it started destroying chemical weapons, Barclay said. That meant they developed habits, like opening certain doors, which later had to be changed.

"The biggest challenge is bringing the entire work force up to the same level of experience," said Doug Hamrick, project general manager for Washington Group International, the company contracted to operate the incinerator.

While about 40 percent of the facility's work force had previous experience working with chemical weapons, many of those people were managers, he said. The majority of those performing tasks like cleanup or maintenance had not worked with chemical agents before.

Workers with the least experience pose the greatest risk for managers, Hamrick said. "That one person can get you into trouble," he said.

Adding chemical weapons into the plant for disposal was a significant change, and the learning curve in the first six months has been steep, Hamrick said.

It's advice that officials have passed on to other depot sites preparing to start destroying stockpiles, like Pine Bluff, Ark., Hamrick said.

"If we had one thing we would change, it's getting a real focus on changing the culture as soon as possible prior to going hot," he said.

After the workers accidentally unclamped the wrong door, Washington Group International halted weapons destruction for about a month to retrain its employees.

Officials are hoping the lessons and training help.

"It's very important that we do what we do safely," Barclay said. "If we protect us, we protect the public."

The similarities in the two events raised the issue that the corrective actions taken the first time were not enough, said Dennis Murphy, administrator for the Oregon Department of Environmental Quality's chemical demilitarization program.

The additional training in December appears to have reduced problems, he said.

"The workers need to understand that they can inadvertently be exposed to agent not just in the (incinerator) building" but anywhere on the site, Murphy said.

Despite the two near misses, the incineration facility has gone about 2.1 million working hours without an injury, Hamrick said.

Because the incineration plant is an industrial facility, workers are susceptible to many of the same injuries that other industrial plants have, he said.

Another point of pride for Hamrick has been when workers have gone into highly contaminated areas wearing the highest level of protections.

"It's gone much better than we hoped for," he said.

The decontamination process with the hermetically sealed suit is difficult, he said. It's something the workers couldn't practice in simulations.

The December monthlong standdown also allowed workers to perform maintenance on some of the equipment used to destroy rockets and work out bugs in the system.

From the first day, one of the two rocket processing lines had minor problems. The equipment that measures the amount of nerve agent sucked from the rocket had been coming up with low measurements.

Workers were able to fix the machine's suction problems.

Now the line is performing better than its counterpart, Barclay said.

The number of rockets processed each day also has been increasing, Hamrick said. And officials are looking forward to more improvements in the next six months.

The incineration facility has started processing rockets during the night and day shifts and soon should be able to process liquid agent at a quicker rate.

Liquid agent from the rockets is extracted and stored in massive tanks. Once the tanks are full the liquid agent is burned.

Soon the plant will be able to burn the GB sarin agent as soon as they extract it from the rockets, Murphy said.

As they continue to get used to system, they can destroy rockets and agents faster.

The facility also is set to start processing bombs in the summer.

That step will mean that when the rocket processing line is stopped for maintenance, the plan still can be destroying agent, Hamrick explained.

Because the rockets include explosive devices, they are processed separately from the bombs. The rockets go into a special reinforced explosive containment room to be cut up.

Bombs, which don't have explosive components, are processed on a separate line. They are drained and the liquid is sent to holding tanks while the metal parts go to a separate furnace.

Other changes will be coming outside of the plant.

Holliday, who took command of the depot two years ago, will be leaving in July, he said. He doesn't know where his next assignment will be.

Most of his command has been preparing to burn chemical weapons, and he has succeeded in that.

The next commander, Lt. Col. Donna Rutten, will be able to plan for the future.

His replacement Rutten has experience working at the chemical stockpile in Aberdeen, Md., which has started destroying its stockpile using neutralization technique.

Since weapons destruction began, Holliday's focus has shifted some. The commander has started preparing for when the depot's mission is over and the stockpile is destroyed.

It makes sense to have a strategy plan in place to take care of the employees," Holliday said.

"Even though it seems to be a short period of time, there is still a lot to be done," he said.