After nearly a year of work, a Rapid City construction company has reopened the second deep shaft to the 4,850-foot level of the Sanford Underground Laboratory at Homestake.

"This is a significant step forward toward creating the Sanford Underground Laboratory," South Dakota Science and Technology Authority executive director Ron Wheeler said.

"Now we have direct secondary egress from the 4850 level."

The state science authority is reopening the former Homestake gold mine as an underground laboratory, where experiments will be protected from the background noise of cosmic radiation.

Homestake is 8,000 feet deep; the science authority also is pumping water out of the deepest levels of the mine.

Until Thursday, the only access to the 4,850-foot level was by the 5,000-foot Ross Shaft or by a series of underground ramps that connect levels in the mine.

Last November, RCS Construction of Rapid City won the contract to reopen the Yates Shaft, a project that has cost about $7 million.

RCS president Bob Scull rode the steel construction elevator -- called a cage -- from the surface to the 4,850-foot level early Thursday afternoon. It was the first Yates cage arrival on that level since 2003, when the gold mine was closed and sealed shut.

Scull and more than a dozen RCS workers were greeted with cheers and handshakes by Sanford Lab technicians already working on the 4850 level.

"We're pretty proud of our crew," Scull said. "Best of all, we didn't have a single accident because we hired the best guys to do the job."

The RCS crew of 19 includes 17 former Homestake miners -- among them Joe Nonnast of Sturgis, whose grandfather, Art Crowley, worked on the Yates Shaft more than a half-century ago.

Nonnast, a lead shaftman for RCS, brought 11 years of Homestake experience to the job.

He knew the Yates Shaft well, but reopening a deep shaft that had been closed since 2003 posed challenges. "Nothing looks the way you remembered it," he said.

Sanford Lab Project Engineer John Matthesen, who helped direct the project, also rode the first cage down to the 4,850-foot level.

"This is a great day," Matthesen said.

The current cage has two open work decks designed to support repair crews. It will be weeks before the Yates Shaft is used routinely for transportation because crews still have to replace some timbers in parts of the shaft.