The National Science Foundation (NSF) on Tuesday selected a small town in South Dakota over the Stevens Pass area as the preliminary site for one of the world's deepest underground laboratories.

The location is the former 8,000-foot-deep Homestake gold mine in a town called Lead (pronounced LEED) — population 3,000.

The South Dakota mine prevailed over sites in Washington and two other states to win the project and the potential for hundreds of millions of dollars in NSF funding. South Dakota not only proposed the deepest laboratory but also offered to pay $116 million in combined state and private money toward the project's final costs.

A University of Washington-led team, headed by physicist Wick Haxton, had proposed a site under Cowboy Mountain in the Stevens Pass area. The plan would have used the Pioneer Tunnel, dug in the 1920s, as an access and hauling route for crews constructing the Cascade Tunnel rail route.

"I was really pleased with the effort that the NSF made to review the four sites carefully," said Haxton, professor of physics at UW. "We thought we'd put on a really good show for Washington state, but we also support the decision that the NSF made. We intend to work hard to help [the project] move forward."

The project, called the Deep Underground Science and Engineering Laboratory (DUSEL), will seek to understand the history and composition of the universe by investigating an elusive subatomic particle called a neutrino (an infinitesimally small piece of matter with no charge and almost no mass). An underground lab is required since the experiments need to be done in the absence of cosmic rays (the radiation that bombards the Earth's surface).

"The review process was very extensive and exhaustive," said NSF spokeswoman Diane Banegas. "NSF formed a review panel of 22 recognized experts in all aspects of such an undertaking to assess the merits of the proposals."

The NSF will conduct a three-year, $15 million planning study before it makes the final decision to build the lab in South Dakota.

If it does, South Dakota could be awarded up to $300 million in NSF funds for erecting the lab and another $300 million for the first round of experiments.

Judy Chia Hui Hsu: 206-464-3315 or jhsu@seattletimes.com