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Visiting the Lab
Mine Water Rises
By Bill Harlan, Journal Staff Writer
LEAD - Water is rising in the 8,000-foot-deep Homestake gold mine in Lead, even as scientists are passing around the first draft of their proposal to convert the closed mine into the deepest, most sophisticated underground science laboratory in the world.
Underground labs protect sensitive experiments from cosmic rays, and Homestake is 8,000 feet deep. But the giant mine is slowly filling with surface runoff, at a rate of about 700 gallons a minute.
By Nov. 6 the water had risen to the "5600 level," which is 5,600 feet below the surface.
"We have sensors every 600 feet," South Dakota Science and Technology Authority director Dave Snyder said Monday. "The water is rising just slightly slower than we expected."
Homestake has hundreds of miles of horizontal tunnels arrayed in "levels" every 150 feet. The water could rise to the 5000 level by next fall, Snyder said.
The state science authority and a team of scientists from throughout the nation want to keep the 4850 level dry. They hope to use it as an interim lab while the National Science Foundation, the White House and Congress decide whether to build a national Deep Underground Science and Engineering Laboratory.
A DUSEL at Homestake would be 7,400 feet underground, but Snyder said pumping to protect the so-called "interim DUSEL" site at 4,850 feet could begin by September.
Former mine owner Barrick Gold Corp. of Toronto turned off underground pumps at Homestake more than two years ago, but since then, Barrick has donated the mine to South Dakota for use as an underground lab.
The National Science Foundation has picked Homestake and the Henderson molybdenum mine in Colorado as two finalist sites for an underground lab.
Teams of scientists supporting either Homestake or Henderson are working on 250-page conceptual design reports that are due at the NSF by Jan. 9.
Physicist Kevin Lesko of the Lawrence Berkeley Laboratory in California, who is leading the Homestake science team, said 40 or 50 scientists at about two dozen universities and research organizations have been working on the Homestake proposal this fall. "We've reformatted, enhanced and enlarged the work we did last year," Lesko said Monday.
Last summer, teams from Henderson and Homestake submitted 100-page proposals, thinking the NSF would choose one site based on those reports. Instead, the NSF asked for more detailed reports from both teams. The new 250-page Homestake proposal will have more engineering details, a thorough risk assessment and more geotechnical data, Lesko said.
Snyder and Lesko said they expected the NSF to choose the lab site by April, but the NSF has often taken longer than expected to make decisions about the proposed underground laboratory.
Even if the NSF picks Homestake for an underground lab and if the White House and Congress approve the project, construction wouldn't begin until fiscal 2009 at the earliest.
That's where the so-called interim DUSEL comes in. An NSF-approved Homestake lab would be 7,400 feet underground, but the state science authority hopes to open an interim lab at the 4850 level first - partly to demonstrate that a lab can operate at Homestake. So this winter, engineers and technicians are planning a re-entry into Homestake. That includes a scheme to start pumping at least enough water to keep the 4850 dry. "That's always been our plan," Snyder said.
In June, the science authority sent a remote video camera to the bottom of the Yates Shaft, 4,850 feet underground. Greg King, a 30-year Homestake veteran, was pleased by what he saw. "It was in good condition," he said.
King was maintenance supervisor at Homestake, and he has worked throughout the mine, from the top of the towering headframe above the Yates Shaft to the deepest sump 8,000 feet underground. Now he manages the mine property for the science authority, and he's optimistic about a smooth re-entry. "We feel it's definitely do-able," King said.
If the NSF approves the deeper lab, it would probably be at the 7400 level, which would require pumping much more water and rehabilitating shafts that drop from the 4850 to the 8000 level.
Henderson, in contrast, is a working mine, so it's dry. But Snyder argues that to get Henderson to Homestake's depth, the Colorado team would have to remove rock. That's tougher than removing water.
Snyder also points out that engineers don't need to get into Homestake to evaluate the rock there. The science authority recently moved Homestake's massive core-sample inventory into a huge building that was once a metal-fabrication shop. The collection's 39,000 boxes contain 600 tons of rock samples offering a detailed geology of the entire mine - which will be available in a computer database by early 2007.
Snyder and Lesko think Homestake is the front-running underground lab site, though they admit the approval process for big science projects is fraught with uncertainty. DUSEL is no exception. For example, when the NSF asked the Henderson and Homestake teams to resubmit longer, more detailed proposals, the agency also re-opened the process to proposals from other sites - including several proposals previously rejected.
So far, no additional sites have emerged, at least in public, and Homestake and Henderson have big head starts. Still, the deadline for submitting the next lab proposals isn't until Jan. 9.