NSF Nears Decision on Underground Lab Site

Some 20 years ago, University of Pennsylvania particle physicist Alfred Mann worked hard to create a national underground science laboratory in the US. He came close, but in the end couldn’t generate enough interest in the physics community. He was forced to take his neutrino research to the Kamiokande II detector in Japan.

“I realized at the time that [neutrino] physics was going to become more and more important and there was no place in the US to do it,” Mann said. There still isn’t, and that in part explains why Mann, now 82, boarded an airplane and flew from Pennsylvania to South Dakota in mid-April to try to stop the threatened flooding of the Homestake gold mine near the picturesque Black Hills town of Lead (pronounced leed ).

The April intervention of Mann, Penn astrophysicist Ken Lande, and other scientists, combined with the efforts of South Dakota Governor Mike Rounds and several local politicians, saved Homestake from flooding by its owner, the Barrick Gold Corp of Toronto. The mine’s fate now may be in the hands of NSF, which is expected to decide in early June which one of a short list of underground laboratory proposals will receive funding for an in-depth feasibility study.

If NSF chooses Homestake, efforts will resume to reach a permanent deal that will allow Barrick to donate the mine, and all of the environmental liability that goes with it, to South Dakota. Regardless of what NSF does, Barrick intends to shut off the water pumps in the mine within weeks and allow about 500 gallons of water per minute to accumulate in the lower shafts. The mining company is spending about $300 000 a month to keep the closed mine dry.

Homestake, a historic 125-year-old mine, produced 40 million ounces of gold and one Nobel Prize in Physics before being shut down in 2002. Physicist Raymond Davis won the 2002 Nobel Prize for an experiment he began in the mid-1960s with his chlorine neutrino detector nearly 1500 meters down in Homestake (see Physics Today, December 2002, page 16 ). The decision several years ago to close the mine was made by Home-stake Mining Co, which was acquired in December 2001 by Barrick. The announcement of the pending closure spurred the physics community to stake a claim on the facility to convert it into an underground laboratory.

At about the same time, a group of neutrino physicists met in Seattle, Washington, to determine the best way to develop a national underground laboratory. That meeting led to the formation of a committee, chaired by Institute for Advanced Study physicist John Bahcall, to evaluate the suitability of several proposed sites.

Other contenders

In addition to Homestake, the committee evaluated the Department of Energy’s Waste Isolation Pilot Plant in southeastern New Mexico, and Mt. San Jacinto near Palm Springs, California (see Physics Today, January 2001, page 23 ). The committee then endorsed Homestake and San Jacinto as primary candidates for an NSF study, and WIPP dropped from contention.

The San Jacinto proposal calls for a 7600-meter tunnel into the mountain, which would give an overburden of 2500 meters. Physicist Henry Sobel of the University of California, Irvine, is the principal backer of the San Jacinto site. Although his proposal is still on the table, he said, he hasn’t heard from NSF officials for many months. He said he had hoped that NSF would spend both the time and money to look at all of the “interesting” proposals in more detail, but NSF officials made clear recently that they will pick only one for detailed study.

In addition to Homestake and San Jacinto, the Soudan Mine in northern Minnesota has become a last-minute contender. University of Minnesota physicist Marvin Marshak submitted a proposal to NSF in mid-May to triple the depth of Soudan from its current 710 meters to 2500 meters—about the depth of Homestake. Soudan is home to the Main Injector Neutrino Oscillation Search, a University of Minnesota experiment being conducted in collaboration with Fermilab. Another lab in the mine contains the university’s Cryogenic Dark Matter Search experiment. Despite Soudan’s status as an active research facility, the current mine is too shallow for a national underground lab.

Marshak, long a supporter of the Homestake site, said his decision to enter Soudan into the competition came from frustration at what has happened in South Dakota. “Home-stake has important assets, but if you can’t get into the site, then at some point you have to look elsewhere,” he said. “We haven’t made any net progress [in acquiring the mine] in a couple of years. I haven’t seen any on-the-ground evidence that Barrick is going to [donate the mine for science]. They have been decommissioning the mine and they forced the removal of the Davis experiment within the last six months.”

Protection bill failed

Barrick officials originally planned to let the mine flood when it was shut down in 2002, but kept it dry through the first few months of 2003 as negotiations proceeded. Last year, a bill in the US Senate gave Barrick protection against future claims of environmental damage stemming from past operations of the mine. The congressional efforts failed, however, when Barrick wasn’t satisfied with changes made in the House version of the bill. While Congress failed, the NSF review is moving forward.

David Stonner, head of congressional affairs for NSF, said that after reviewing the underground laboratory proposals a panel of experts will pick the most promising site by early June. Then studies will get under way to determine what the actual cost of developing a deep lab would be. The ultimate cost for developing Soudan, Home-stake, or San Jacinto is estimated to be between $200 million and $250 million.

“Roughly a year from this summer, we’ll get back the cost information and then make a formal proposal to the National Science Board,” Stonner said. “We will do things in an orderly fashion, although I understand that in South Dakota, things can’t go quickly enough.” Homestake has been a powerful economic engine in western South Dakota for much of the state’s history, and state leaders are anxious to keep the mine operating, even if it is producing scientific research instead of gold. The earliest that serious money could be available for developing Homestake or one of the other sites would be fiscal year 2006.

Vince Borg, vice president for corporate communications at Barrick, explained that beyond the long-term liability issues that have to be resolved, the day-to-day operation of the pumps in the mine creates an immediate problem for the company. “If we continue pumping, it requires our crews to do the pumping. It is a safety issue, and we will be responsible for those on the site. Without the indemnification worked out, we don’t want to invest in that.” He also said that Barrick engineers don’t believe that letting the mine flood would have a detrimental effect on its eventual use as a science laboratory. The rock will remain in good condition, he said, and the antiquated equipment that would be flooded is inconsequential. For Barrick, Borg said, flooding is a “non-issue.”

Borg said Barrick intends to keep the pumps running for, at most, a few more weeks. “NSF has to decide on the site, then go through its own process and engineering work. If [conversion of Homestake to a science laboratory] could come to pass, that would be wonderful for Lead. But, despite some of the local expectations, the lab has never been just around the corner.”

Although several mining experts have said that flooding technically won’t damage the mine, Mann noted that, “from the scientist’s point of view, it would be so discouraging that we shouldn’t allow it to happen without trying to educate Barrick and the politicians about the value of the mine for science. We ought to object as scientists.” That is why Mann led the charge in Lead in April.