After spending years as one of the nation's worst Superfund sites, a former chemical plant has been deemed officially clean by the federal Environmental Protection Agency.

The EPA and local officials held a celebration Tuesday to mark the transformation of the former Vertac Inc. plant from a dangerous polluted eyesore to a field now covered with grass and trees. The cleanup took 17 years and about $150 million."Vertac was one of the most toxic and hazardous waste sites that the agency has dealt with nationwide," said Jerry Clifford, the EPA's deputy regional administrator.

The EPA had at one time rated the size, threat and cleanup cost at Vertac among the 20 worst of the nation's 1,300 Superfund sites, said Don Walters, the Superfund program's community involvement coordinator for the EPA's regional office in Dallas. The EPA no longer keeps such lists, he said.

The plant made herbicides and insecticides under various owners, starting in the 1940s. The last owner, Vertac, abandoned the site and declared bankruptcy in early 1987.

About 70 acres of the site have been set aside for future commercial or light industrial development. The remaining land, now covered largely with grass and trees, is being fenced off, Allen said.