Twenty-three years after the Waste Isolation Pilot Plant (WIPP) near Carlsbad, N.M., was first proposed, the controversial $2.5 billion underground storage facility is scheduled to open this spring.

The Department of Energy formally approved the project on Jan. 23, and the Environmental Protection Agency is expected to certify it in May. Department of Energy officials say they'll open the site after they get EPA approval. The pilot plant is designed to accept barrels of plutonium residues, contaminated clothing and equipment used in nuclear weapons production, now housed at sites throughout the country. Site administrators plan to store about 2 percent of the nation's nuclear weapons waste at the plant.

But some believe WIPP faces another roadblock. Many of the barrels contain "mixed wastes' - chemical as well as radioactive waste - and the state of New Mexico is responsible for permitting the disposal of chemical waste, says Nathan Wade from the New Mexico Environment Department. To satisfy state requirements, he says, WIPP administrators will have to get a permit or go through a "characterization" process to prove the barrels contain only radioactive waste.

But DOE says it will go ahead with or without a permit. Kent Walter, a WIPP site manager, says the DOE has a characterization process already in place. He also says the state has been slow and uncommunicative. "We just don't know how long we'd have to wait," says Walter. "Technically speaking, they might never issue us a permit."

New Mexico Attorney General Tom Udall, a vocal opponent of the Waste Isolation Pilot Plant, has said that he may sue the DOE over its failure to obtain a state permit and over several safety concerns, including the possible collapse of underground storage caverns and the risks posed by oil and gas drilling near the site. Environmental groups appear ready to join his effort. "It's an unnecessary and dangerous project," says Don Hancock of the Albuquerque-based Southwest Research and Information Center. "We're willing to go back and sue them again."

*Michelle Nijhuis