The San Francisco Naval Shipyard was once home to a nuclear testing site where scientists ran tests on ships exposed to atomic weapons. Now, many San Franciscans call it home.

Developer Five Point, a spinoff of Lennar (the nation's largest housing builder), has set out to transform the abandoned San Francisco Naval Shipyard into a vibrant live-work community with 12,000 new homes and roughly 5 million square feet of office and commercial space.

But its future is uncertain amid new allegations of a botched cleanup.

The US Navy has learned that Tetra Tech, a government contractor tasked with the cleanup and testing of radioactive contamination at the shipyard, faked more soil tests than previously thought, to speed along the city's largest redevelopment project. Workers swapped samples from areas known to be highly contaminated with dirt from areas known to be clean.

According to investigations by Curbed SF and NBC Bay Area, almost half of the toxic waste-site cleanup was "suspect" or has "evidence of potential data manipulation or falsification."

Five Point has sold about 300 townhouses and condominiums and plans to build 11,000 more units at the (rebranded) San Francisco Shipyard. The Navy has said that residents who already live there are "100 percent safe." The existing housing is located on land that was used for military housing and non-industrial activities, a representative with Five Point confirmed.

Business Insider recently explored the ruins at the San Francisco Shipyard. Take a look.