San Francisco's Treasure Island, a man-made island on the path of the important trans-bay bridge connecting San Francisco's financial district and Oakland, is more contaminated with radiation than has previously been disclosed, reports suggest.

San Francisco’s Treasure Island is a man-made island on the path of the important trans-bay bridge connecting San Francisco’s financial district and Oakland.[Photo by Chen Jia]

The suspected source of the contamination is related to the island's historic role as a Cold War repair and salvage operation for ships that may have been exposed to nuclear testing in the Pacific, according to a recent report in the San Francisco Chronicle.

Another potential source was a training ship the US Navy intentionally doused with low-level radiation so sailors could practice cleaning it.

The city of San Francisco bought Treasure Island from the Navy for $105 million in 1993. Today, the island has become a community for low-income residents and international students seeking inexpensive housing near pricey San Francisco. There are no supermarkets or high-rises on the island.

A redevelopment project on the 400-acre island got the China Development Bank and Chinese Railway Construction Corp involved in negotiations with Lennar Corp, one of the biggest homebuilders in the US, for a hefty investment up to $1.7 billion.

The project included the redevelopment of former Hunters Point Naval Shipyard in San Francisco.

However, the deal fell apart in April just after San Francisco Mayor Ed Lee's first trade visit to China. Prior to his trip, Lee had expressed his support and hopes for the contract, which would stimulate the area's economy and create jobs.

Sources familiar with the deal said it collapsed because the Chinese side wanted more control over the projects than their US partner expected. The real reason is still unclear as neither the Chinese bank nor the rail company has made any official comment.

As recently as May, the California Department of Public Health warned of the possibility of lingering radiation on Treasure Island, despite Navy and state agency assurances that cleanup work on the island had been thorough and the remaining risk was too minimal to raise concerns.

Internal e-mails and documents obtained by the Bay Citizen, however, reveal the Navy's cleanup was riddled with mistakes, according to the report in the Chronicle.

The earliest signs that Treasure Island may have been exposed to radiation from ships' exposure to nuclear testing in the Pacific appeared in a Navy draft report dated Aug 6.

The Navy had to prepare the draft report under pressure from state regulators, who said cleanup workers found radioactive waste in unexpected locations.

Local media quoted state public health official Peter Sapunor saying that Navy contractors had dug up 16,000 cubic yards of contaminated dirt, some of which had been confirmed with radiation levels 400 times the Environmental Protection Agency's human exposure limits for topsoil.

Extensive radioactive material might remain in the soil surrounding those excavations, it was reported.

San Francisco’s Treasure Island is a man-made island on the path of the important trans-bay bridge connecting San Francisco’s financial district and Oakland.[Photo by Chen Jia]