New Jersey leaders are redoubling their efforts to block the Army's plan to discharge treated wastewater from the destruction of the VX nerve agent into the Delaware River, despite a federal study that suggests DuPont can safely treat it.

During a news conference Monday at the RiverWinds community complex, U.S. Sen. Robert Menendez, D-Hoboken, and Rep. Rob Andrews, D-Haddon Heights, vowed the wastewater will never come to South Jersey.

"We send a very clear message: New Jersey is not a garbage dump, it is not a wasteland, and it will not accept the byproduct of VX . . . in the waters of the Delaware," Menendez said.

A federal Environmental Protection Agency study recently determined that DuPont developed a process to treat the caustic wastewater so that it won't harm fish and other aquatic life. The EPA based its finding on Army assurances that the wastewater will not contain detectable levels of VX, an extremely lethal chemical weapon developed during the Cold War.

The Army had hoped this would be the last major hurdle toward proving that DuPont's Secure Environmental Treatment facility in Carneys Point, Salem County, can safely treat the wastewater resulting from a VX neutralization process at the Newport Chemical Depot in west-central Indiana.

"The project can be done safely, and will be done safely," said Jeff Lindblad, spokesman for the Army's Chemical Materials Agency. "We've had some problems at Newport. That's why we're doing this with a slow, methodical start."

But the New Jersey lawmakers questioned the Army's integrity, pointing to a string of accidental spills at the Indiana facility over the past years, including one last week.

"A lot of this is about the issue of credibility, about whether what we've been told about the process of disposing of this VX residue is really true," said Andrews.

He fears traces of VX, one of the deadliest chemicals ever made, will pollute the river.

Menendez and Andrews, who were joined by local officials and environmentalists, outlined a multi-pronged plan.

They said they will work with Gov. Jon S. Corzine's administration to block a permit DuPont needs to discharge the wastewater, and will seek to block the project in a Defense Department authorization bill.

They also sent a letter to Norman Y. Mineta, secretary of the U.S. Department of Transportation, asking for a study to determine if communities along the route are adequately prepared to respond to spills and protect drinking water.

"If such a study is unsuccessful, we request that you make a recommendation to keep this chemical off America's roads and have the Army pursue further treatment and disposal in Indiana or in whichever depot they utilize to treat VX," the letter states.

Lindblad noted that the Centers for Disease Control and Prevention already determined the transportation plan is safe.

Following the news conference, state Sen. Stephen M. Sweeney, D-West Deptford, Assemblyman John J. Burzichelli, D-Paulsboro, and Assemblyman Douglas H. Fisher, D-Bridgeton, released a statement reiterating their opposition.

"We really think they just need to come up with a new plan because dumping used nerve gas in the Delaware River won't fly in New Jersey," they said.

So far, the Army has destroyed more than 144 tons of the 1,200-ton stockpile, resulting in nearly 300,000 gallons of wastewater awaiting shipment to DuPont.

Reach Lawrence Hajna at (856) 486-2466 or lhajna@courierpostonline.com