As Google embarks on its ambitious plans to create a signature headquarters, the company's building spree is now stretching into Moffett Field. In recent weeks, the tech giant has started preparations to build a new 1.1 million square foot facility on the western side of Moffett Field, in what will be the company's largest construction project reported so far.

But specifics on what the tech giant intends for the 42-acre site known as Bay View remain scarce. While Google and NASA officials confirmed the project's size and amenities, they initially declined to give much in the way of specifics on the design.

Despite their reticence, detailed architecture drawings from last year of Google's plans for Bay View were posted to NASA's website. The plans show Bay View developed with three canopied dome-buildings that closely match the futuristic design Google is pursuing at its Charleston East site in Mountain View.

On Wednesday, a Google spokesman confirmed to the Voice that the plans were for Bay View, but he said aspects of the design have been modified since they were submitted. Updated plans for the site would be available in the coming weeks, he said.

Much like the company's plans for North Bayshore, Google officials have been developing a strategy for building out the Bay View site for quite a while. The company first inked a tentative deal with NASA for the mostly vacant, L-shaped parcel in 2005.

Three years later, the national space agency awarded a long-term lease for the 42-acre site to Google's subsidiary, Planetary Ventures. The lease stipulates a 40-year lifespan that could be extended through 2098. Google agreed to pay about $3.65 million per year, which will be adjusted with inflation and occasional reappraisals of the property value.

Speaking on Tuesday, NASA Ames Associate Center Director Deborah Feng hailed the future Bay View campus as an example of a well-executed partnership that would mutually benefit both NASA and Google.

"Planetary Ventures has been a great partner for us," she said. "The great story here is that we've found a way to do an innovative public-private partnership for technology and research advancement."

The Bay View lease was given to Google after the company emerged as the top applicant after the opportunity was posted publicly, Feng said. She could not immediately say whether there were any other applicants.

Written into the 2008 lease is an agreement between Google and NASA to cooperate on projects on data management, distributed computing, developing the private space industry and "bio-info-nano convergence." As part of the deal, Google agreed to take on six infrastructure projects to improve the Ames campus, including widening R.T. Jones Road, the main access route to Bay View, building two fire-suppression water storage tanks, adding a cooling tower for the Ames Supercomputer facility and paying for a new recreational park for NASA employees.

Originally, Google officials envisioned a nine-building office campus at Bay View that would be finished around 2015. But that plan ran into snags as the company approached the city of Mountain View with proposals to build up to three bridges across Stevens Creek to allow workers to more easily access Moffett Field. The plans sparked an outcry as environmentalists complained the bridge crossings could end up harming the wildlife habitat along the creek.

In 2013, as city officials seemed poised to reject the bridge proposal, Google officials announced they were pulling back the entire Bay View project to retool its design. Since then, Google officials evidently incorporated elements of the eye-catching design they were pursing in North Bayshore into the Bay View project.

Last month, as the Mountain View City Council discussed transportation management in North Bayshore, Google officials confirmed that they were launching construction of the Bay View project. During that discussion, City Council members expressed support for the allowing Google to build a bridge for transit and service vehicles across Stevens Creek either at Charleston Road or La Avenida Street.

As many as 5,000 new employees are expected to occupy the new Bay View buildings, which should be complete by 2020, according to NASA officials. For now, the construction workers are grading the site with plans to begin construction in June. Google has been heavily involved in widening R.T. Jones Road from two lanes to four lanes and adding traffic signals to the intersection at Moffett Boulevard. Google officials said workers at the new campus would be heavily encouraged to take alternate forms of transportation.

The Bay View plans from last year call for three office buildings of 53,900, 202,500 and 360,000 square feet in size. On the eastern side of the site, the company is proposing to build a parking lot and garage as well as a short-term corporate housing of an unspecified size.