Sioux Falls philanthropist T. Denny Sanford this week provided $20 million to the state for the underground laboratory in the former gold mine at Lead.

The payment is the second installment of his $70 million pledge to help the South Dakota Science and Technology Authority convert the Homestake Mine into the world's deepest, largest underground laboratory. He paid $15 million a year ago.

Gov. Mike Rounds in a news release expressed his gratitude to Sanford for his commitment to the long-term project. Mining stopped in 2001, and the underground operation started filling with water after pumps were turned off in 2003. Pumping resumed this past March.

Sanford's $35 million is being used to reopen Homestake to the 4,850-foot level, where science experiments were conducted before the mine closed. Sanford directed that another $20 million be used to build a surface science education center at Homestake. The final $15 million will be used to help reopen Homestake's deepest levels.

The state Legislature also has invested about $35 million in the project, and South Dakota received a $10 million Community Development Block Grant to help refurbish Homestake.

The University of California at Berkeley has received a $15 million grant from the National Science Foundation to design a national Deep Underground Science and Engineering Laboratory. That facility could reach to the bottom of the mine, 8,000 feet underground. If approved by the National Science Board and funded by Congress, the lab could operate for decades, hosting a number of major experiments.