2nd deep shaft reopened at old gold mine in SD

Crews pumping water out of the Sanford Underground Laboratory in Lead have reopened a second deep shaft that eventually will be used as the primary entrance and exit for science experiments.

The South Dakota Science and Technology Authority is rehabilitating the former Homestake gold mine and reopening the 4,850-foot level as an underground lab.

For the first time Thursday, crews were able to use the Yates shaft to send a cage down to that level, providing a new second exit for lab technicians who have been using the Ross shaft.

Crews rehabilitating the future lab space had had a second exit that used a series of underground ramps going from level to level.

"It was kind of a walking secondary access," lab spokesman Bill Harlan said. "Now it's much faster."

The steel Ross shaft is about a half-mile from the area to be used for the large experiments, while the Yates shaft is "right around the corner" from the Davis Cavern, once the site of Nobel Prize-winning physics research, Harlan said.

The Yates shaft was built with wood because of steel shortages during World War II. Harlan said the water that had been flowing down the shaft had helped preserve the wood.

RCS Construction has been working on the $7 million shaft restoration project.

The National Science Foundation in 2007 picked the former Homestake mine as the preferred site for a Deep Underground Science and Engineering Laboratory that will be 7,400 feet below the surface. South Dakota is building the Sanford Laboratory at the 4,850-foot level so some experiments can begin earlier.

The first dark matter experiment to be done there will be a project to detect weakly interacting particles that could give scientists greater insight into the Big Bang explosion believed to have formed the universe.

The lab has refurbished a warehouse on the surface where equipment can be assembled and tested. The Large Underground Xenon detector to be used in the experiment will be installed in the Davis Cavern next year, possibly by early summer, Harlan said.

The second major experiment will measure certain properties of ghostly particles called neutrinos. Harlan wasn't sure of its timetable.

Smaller scientific experiments using instruments such as tilt meters, seismometers and background radiation counters are already being done in the former mine from the 300-foot level down to the 4,550-foot level, he said.