A Salt Lake County man has filed a $500,000 lawsuit against the federal government claiming he was exposed to chemical warfare agents at Dugway Proving Ground during a 1986 construction project.

Roland Collard, an employee of Projects Unlimited of Murray, Utah, contends in the suit filed Tuesday in U.S. District Court that the Army and the U.S. Corps of Engineers failed to warn him of the danger and attempted to conceal the episode.Collard said he was excavating earth at the Munitions Support facility on June 17, 1986, when several canisters "believed to contain toxic chemical agents commonly used in chemical warfare" were unearthed.

Collard said the canisters began emitting "vaporous gases," sickening him and several other workers and forcing them to flee. He said that three days later, officials told him and the others that the substances to which they had been exposed were non-toxic and that they had been removed, making the area safe.

However, Collard said, more canisters were uncovered when excavation resumed, and he and the others again were exposed.

Collard contends the Army and Corps of Engineers failed to use care in storing, handling and disposing of chemical weapons by burying them in unmarked locations and "in a manner violative of various applicable safety regulations."

Moreover, he claims the officials failed to provide him with safety information describing the existence and possible location of the chemical agents; failed to check the area before construction began; failed to follow safety precautions after the first exposure; failed to advise Collard and the others to obtain medical care or to provide it at the post; and failed to notify the facility's Environmental Protection Agency representative of the incident.

Collard contends he has suffered damage to his liver, spleen and other internal organs and sustained loss of earnings and impairment of future earning capacity.

He said he submitted a written claim for $500,000 in September 1986 to the Army and the U.S. Corps of Engineers but had not received any notification of whether his claim had been accepted or rejected.

On May 17, two other subcontractors with Projects Unlimited filed a $1 million lawsuit seeking $500,000 each in the same incident.