Rep. Robert Andrews, D-N.J., pushed for the amendment.
If passed by the Senate, it could become a "permanent roadblock" to the plan, Andrews said Thursday.
"I think this is effectively a veto of the project," Andrews said.
The amendment, passed late Wednesday, is the latest setback for the Army, which wants to send the wastewater from the destruction of VX nerve agent at a depot in west-central Indiana to DuPont's Secure Environmental Treatment plant here for final treatment and discharge into the Delaware River.
It calls for the Army not to proceed with any transportation of VX until the health and environmental concerns raised by the Centers for Disease Control and Prevention and the Environmental Protection Agency are addressed."I don't think the EPA and CDC will ever sign off on this plan," said Andrews, a member of the House Armed Services Committee.
Andrews said that Rep. H. James Saxton, R-N.J., as chairman of the committee, and Rep. Frank LoBiondo, R-N.J., a member of the committee, were instrumental in getting the amendment attached to the defense bill.
Greg Mahall, a spokesman for the Army's Chemical Materials Agency, however, said the Army remains confident in its VX plan.
"We think it's a viable plan, a safe plan," he said.
He noted that the amendment is early in the process and must survive Senate action.
"If and when it becomes part of the financial authorization bill . . . the Army will salute and follow the law, as always," Mahall said.
Acting Gov. Codey may have bought the time Andrews needs to work the amendment through Congress by directing the Department of Environmental Protection last week to draft a permit DuPont needs to operate that does not include provisions for disposal of VX wastewater.
Codey also expressed his opposition to Francis J. Harvey, secretary of the Army.
The Army recently began small-scale destruction of the Cold War-era nerve agent, stored at its Newport Chemical Depot in Indiana. It is using hot water and sodium hydroxide to break down VX, one of the deadliest chemicals ever made, into nonlethal components.
DuPont spokesman Anthony Farina said the company continues to meet with EPA and CDC officials to discuss technology in order to address concerns raised by the CDC about the effects of the caustic wastewater, likened to household drain cleaner, on the river.
"It's very important to understand that our involvement hinges on this being done safely and effectively with no adverse impacts on employees, the community and the environment," Farina said. "We will not accept any wastewater if there is any detectable level of VX in it."