LEAD - Board members of the South Dakota Science and Technology Authority descended 1,400 feet into the Homestake gold mine Friday afternoon to inspect progress toward re-opening the mine for use as a laboratory.
Board member Casey Peterson of Rapid City said their first stop was at a level 1,250 feet underground. (There are "levels" in Homestake every 150 feet, all the way down to the bottom at 8,000 feet.)
"Where it was wet at the 1250 before, it's totally dry now," Peterson said, because of air circulation.
At the 1400 level, the board inspected steel frames called "sets" that stabilize the 5,000-foot Ross Shaft. "There's steel that's been there since the 1930s, when they drilled that hole," Peterson said. "It's amazing to see what's accumulated."
Some of the sets must be replaced, which is slowing the re-entry into the 5,000-foot Ross Shaft. (Crews from Dynatec Mining Corp., the contractor hired to re-open Homestake, so far have descended as deep as 2,150 feet.)
The ride in the Ross cage, from 1,400 feet up to the surface, took 3 minutes and 45 seconds, Peterson said, with the hoist operating at one-third speed. "It was a very smooth ride," he said.
Gold mining ended at Homestake in 2001. The mine was sealed shut in 2003. Since then, it has been slowly filling with water, which reached the 5000 level last summer.
The state science authority is re-opening Homestake for two underground labs. An interim lab, run by the science authority, would be 4,850 feet underground. A bigger, deeper lab run by the National Science Foundation would be at the 7400 level.
The science authority had hoped to begin pumping before the water reached the important 4850 level, but board members learned Friday that might not be possible.
Water could reach the 4850 by January or February. Dr. Jorge Alonso, recently hired to direct the interim laboratory, said crews might not reach the 4850 with pumps until April. "This is just the feeling I have," Alonso emphasized.
Dynatec Mining Corp. has a contingency plan if water reaches the 4850 level before the pumps, Alonso said.
There was also better news. The re-entry crew discovered they can use an existing high-voltage cable for the pumps. That will save 17 days, Alonso said. Pumping from reservoirs and sumps on upper levels of the mine could begin by mid-January.
When all of the pumps are in place down to the 4850 level, water will be pumped to the surface in 1,200-foot jumps - first to the 3650 level, then to the 2450, to the 1250 and to the surface.
The 4850 is an important infrastructure level, with miles of tunnels and access to shafts that go even deeper. The late Ray Davis won a Nobel Prize for his neutrino experiment at the 4850, and scientists hope to use the same cavern.
However, scientists also have bigger plans.
In July, the National Science Foundation picked Homestake as the site for a proposed national Deep Underground Science and Engineering Laboratory. Scientists, especially physicists, use deep labs to shield sensitive experiments from cosmic rays. A DUSEL 7,400 feet underground would be the world's deepest lab - if it is funded.
The science authority's interim lab is already funded. It will be called the Sanford Underground Science and Engineering Laboratory, named for Sioux Falls philanthropist T. Denny Sanford, who donated $70 million to the project. (Alonso is lab director for SUSEL.)
After his trip to the 1400, Peterson said he had confidence in that plan. "It was very uplifting to see the progress," he said.
Contact Bill Harlan at 394-8424 or bill.harlan@rapidcityjournal.com
