Yale scientists are returning to a campus that will soon include vastly expanded lab facilities, though just how the space will be used is at this point a matter of speculation.

The University’s surprise purchase of the Bayer HealthCare complex in West Haven and Orange in June — a monumental deal that will increase the size of the campus by roughly one-third — has been met with resounding excitement and approval on campus. But questions remain as to how a University already in physical transition will incorporate another 137-acre property and 1.5 million square feet of buildings into its operation.

Administrators rushed to finalize the deal in a matter of weeks after the University learned that it had won an auction for the property, with an offer that Bayer and Yale declined to disclose but Associated Press reports placed at around $100 million. The motivating factor, administrators said after the announcement, was the 550,000 square feet of laboratory space.

Because of the deal’s unique circumstances, the purchase agreement was kept under tight wraps until its announcement in mid-June. The deal’s haste and secrecy precluded any discussion of what research activities might go on at the new campus, which administrators are trying to brand “Yale West.” Even though Yale did not make the purchase for any particular program or initiative, the prospect of so much lab space for such a low price was irresistible, University President Richard Levin said.

“This is a once-in-a-century opportunity,” he said.

According to figures offered by Levin, it would have cost the University at least $360 million to build the lab space from scratch. He said Yale will use all of the lab space for its own researchers and will not lease any of it out, contrary to speculation during the week before the deal was announced. He said the new campus will be used solely for research, not education, and that no faculty will be “forced” to move their labs there.

Discussions on how to use the new space started after the announcement was made, but no decisions have been reached, Levin said.

“This is not going to happen overnight,” he said.

In interviews with the News, more than a dozen professors at Yale Medical School expressed their excitement, some calling it the most important — and potentially lucrative — move Yale has made in recent years. Ideas for use of the facility included cutting-edge neuroscience research and the development of cancer treatments.

The new facilities will dramatically increase Yale’s ability to attract top-notch researchers and, consequently, the grant dollars that they bring in through their projects, Medical School Dean Robert Alpern said.

“If I want to get a really good researcher from another school, I would need at least 50,000 square feet of research space,” he said. “And then the idea is once you recruit that person he would bring in other people.”

Alpern said it would be a priority to make sure the new campus is not seen as a less desirable alternative to central campus labs for second-tier researchers. He said he and Provost Andrew Hamilton will have a dialogue with the Medical School faculty, the Faculty of Arts and Sciences and the Engineering faculty, most of whom learned about the acquisition the day of its announcement, to decide how best to use the space.

Some faculty members and administrators suggested that the site could also be used to house large-scale scientific initiatives, like the Institute for Nanoscience and Quantum Engineering at Yale that opened last October or the Broad Institute at the Massachusetts Institute of Technology and Harvard University, which specializes in genomics research.

In addition to the lab space, the Bayer complex includes 600,000 square feet of warehouse space, which administrators said will be used to store some of the collections of the Peabody Museum of Natural History and the Yale University Art Gallery. The plans for the 275,000 square feet of administrative space on the site are more nebulous, but some said it could possibly be used to house the Medical School program for continuing education, which enrolls practicing physicians.

Yale’s acquisition comes in the midst of an unprecedented period of physical growth largely intended to make the sciences a priority, with a billion-dollar development initiative on Science Hill and other large capital projects around campus. The University will continue to add to the 12 million square feet of buildings already on the New Haven campus within the next few years.

Bayer announced in November that it was vacating the property as part of a corporate restructuring. At the time, Connecticut Governor M. Jodi Rell appointed Vice President for New Haven and State Affairs Bruce Alexander, whose office is overseeing Yale’s deal with Bayer, to a board that considered alternatives for the site. When Bayer announced that it would open the site up to auction, Yale was one of 15 bidders, Levin said, and was informed it had won in April. Most of the 15 original bidders were real estate developers who would not have used the facility for science purposes, he said.

Bayer will fully vacate the site by 2008.