Top 10 uses for Super Collider tunnel.

When Congress killed the Superconducting Super Collider (SSC) in October 1993, comedians had no trouble thinking up uses for the $2 billion section of tunnel already drilled. For example: world headquarters for the Cold Fusion Research Institute; an oxygen storage tank for Biosphere 2.

Geophysicists are now coming forward with some ideas of their own. They have proposed a suite of potential experiments and hope to forestall closure of the 22.5-kilometer-long, 45-meter-deep tunnel. In the Nov. 29 Eos, Herbert F. Wang of the University of Wisconsin-Madison and his colleagues contend that the SSC site has value as a research tool because it offers scientists superb access to rocks underground.

"It's an ideal opportunity to test new methods. It's actually a rare opportunity. In the earth sciences, we usually do not have the chance to get underground access to the tests we do. And that always leads to ambiguity in drawing conclusions about whether you have really done what you have thought you have done from the surface," says one of the study's coauthors, Larry R. Myer of the Lawrence Berkeley (Calif.) Laboratory.

Because the tunnel runs through fractured beds of chalk and shale, scientists could use it to test how fractures help and hinder fluid flow underground. "There are many environmental problems in which chemicals and toxic substances have gotten into the groundwater system, and the groundwater travels primarily through fractures. These are difficult to map out and characterize," Myer says.

Engineers could use part of the tunnel to learn more about the properties of shale, a type of rock that presents problems for construction projects. But according to Wang, geophysicists interested in the SSC site must find funding quickly in order to take advantage of the opportunity. Under an agreement with the state of Texas, the U.S. Department of Energy plans to fill the entrance shafts to the tunnel soon.