Roberta had coughing spells and agonizing chest pains, he says, that "went all the way through my back. ... Every day I went there, I had something weird going on."

Russell Kimberling, a former Indiana National Guard captain, had severe sinus troubles that forced his medical evacuation to Germany. After returning, he became alarmed one August day in 2003 while escorting some officials to the plant in the southern Iraqi city of Basra.

"I jumped out of the truck and I turned around and they (KBR staff) had full chemical gear on," he says. "I looked at some of my soldiers and said, 'This can't be very good.' ... They could have told us to put chemical suits on."

Ed Blacke, hired as plant health, safety and environmental coordinator, says he became worried after workers started having breathing problems and a former colleague sent him an internal KBR memo outlining the chemical's dangers. Blacke says he complained, was labeled a troublemaker and resigned under pressure.

"Normally when you take over a job, you have a briefing — this is what's out there, here's what you need for protective equipment," says Blacke, who testified at a Senate Democratic Policy Committee hearing last year. "There was nothing, nothing at all."

Blacke and Langford were among those whose civil claims were resolved in arbitration.

Kimberling is among nearly 50 current or former Guard members — most from Indiana, a smaller number from Oregon and West Virginia — who've sued.

Mike Doyle, a Houston lawyer representing the soldiers and civilians, maintains KBR knew as early as May 2003 the chemical was there, but didn't close the site until that September.

"Once they (KBR) found out about it, they didn't tell anybody and they did everything to conceal it," he contends. "Their staff was getting reports and soldiers and civilians who were in the field were told ... 'There's nothing to worry about.'"

The lawsuit cites minutes of an August 2003 KBR meeting that mentions "serious health problems at the water treatment plant" and notes "almost 60 percent of the people now exhibit the symptoms."

In a recent wide-ranging Associated Press interview, KBR chairman William P. Utt said the company has been unfairly targeted for its military work.

"People think there's an opportunity here in Iraq, let's paint it on KBR, then we'll worry about making the facts precise or correct later," he said.

As for the water plant, KBR says once it learned of the chemical, it took precautions to protect workers, notified the Army Corps of Engineers and led the cleanup. It says the Corps had previously deemed the area safe.