The San Francisco Shipyard, a mixed-use development rising on the site of a former nuclear testing facility, is in limbo amid new allegations.

The Navy has found evidence that a government contractor hired to clean radioactive contamination from the area botched the cleanup.

Almost half of the cleanup work was later showed to be falsified or "suspect." Workers swapped soil samples from contaminated sites with clean ones.

A sprawling middle-class neighborhood is rising on the site of a former nuclear testing facility in San Francisco. 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 of radioactive contamination at the retired San Francisco Naval Shipyard, faked more soil tests than previously thought, in order to expedite the city's largest redevelopment project. Workers swapped samples from areas known to be highly contaminated with dirt from clean areas.

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."

These findings could cause the project to be delayed many years. The Navy is expected to release the results of its investigation into Tetra Tech in a public meeting on January 31.

This long-forgotten patch of the San Francisco waterfront holds promise for the city's strained housing market. The plan is to transform the retired shipyard into a bustling live-work community with 12,000 new homes and about five million square feet of office and commercial space. The project is being developed by Five Point, a spinoff of mega-developer Lennar.

The project has a price tag to match its hefty ambitions: $8 billion. That's on top of the $1 billion or more in taxpayer money that has been spent on the cleanup since the 1990s.

Hunters Point was a private commercial shipyard from 1869 until the start of World War II, when the Navy bought the property. The military repaired ships and submarines there. From 1948 to 1969, the shipyard hosted a then-secret laboratory that ran tests on ships exposed to nuclear weapons, as well as research on the effects of radiation on living organisms.

Military equipment and ships contaminated by atomic bomb explosions were left at Hunters Point, and toxic substances including petroleum fuels, pesticides, and heavy metals seeped into and polluted the soil at Hunters Point, the San Francisco Chronicle reported in 2015.

After the shipyard closed, it was declared a "superfund" site — a toxic-waste site where the United States Environmental Protection Agency can force parties responsible for the contamination to either perform cleanups or reimburse the government to do the work.

That burden fell on the Navy. It outsourced the work of decontamination and soil-testing to Tetra Tech. But several investigations into the nature of those efforts have led to scandals.

The City of San Francisco selected Lennar as the master developer of the shipyard in 1999. A year later, an investigation by SF Weekly found that the Navy mishandled the radioactive waste it produced there. It reportedly dumped huge amounts of contaminated sand into the San Francisco Bay and sprinkled radioactive material around the base to practice cleanup.

In 2017, several former employees of Tetra Tech admitted to faking soil tests. They described a company culture that valued speed over safety and accuracy. The whistleblowers led the federal Environmental Protection Agency to delay transfers of land from the Navy to the new master developer, Five Point.

The latest revelations suggest the cleanup was more questionable than previously thought.

Last fall, the Navy hired third-party contractors to conduct a review of Tetra Tech's data. A series of draft reports that those contractors presented to the Navy (and which Curbed SF reviewed via a public records request) showed that 853 "units" of land at the shipyard were tested. Of them, 414 were identified as falsified or suspect, representing 48% of total units.

The reports, which have not been publicly released, recommend retesting those 414 units.

Greenaction, a local non-profit fighting for health and environmental justice, has filed a petition with the Nuclear Regulatory Commission to strip Tetra Tech of its license to perform radiological cleanup. Tetra Tech received a $85 million contract from the EPA in October to assess the abandoned uranium mines in the Navajo Nation across the American southwest.

It's unclear what impact the new allegations leveled against Tetra Tech might have.

Construction on the mixed-use development at the (rebranded) San Francisco Shipyard began long ago. Five Point has sold about 300 townhouses and condominiums and plans to build 11,000 more units. A recent quarterly report from Five Point said it expects the Navy to deliver the last 408 acres it owns in phases between 2019 and 2022, instead of starting this year.

Five Point declined to comment on the draft reports and referred Business Insider to the Navy.

The Navy has said that residents who already live at the San Francisco Shipyard are "100 percent safe." The existing housing is located on land that was used for military housing and non-industrial activities, SF Curbed reported and a spokesperson with Five Point confirmed.

Bradley Angel, executive director of watchdog-group Greenaction, told Business Insider that he thinks prospective buyers will think twice before settling down at the shipyard.

"If I was living there, I would definitely be asking some questions," Angel said.