SAN FRANCISCO -- To cheers and applause from the audience, the Board of Supervisors unanimously approved a massive new neighborhood proposed for Treasure Island.

In the 11-0 vote the board rejected claims by groups such as the Sierra Club that the project would harm the environment and exacerbate traffic problems.

Instead, members of the board said the $1.5 billion project would breathe new life into the old Navy base in the middle of San Francisco Bay.

The plan, almost 15 years in the making, calls for 19,000 new residents to live in a new neighborhood wrapped in open space and dotted with high-rises, one as tall as 450 feet. Residential units would be within walking distance of shops, a grocery store, a school and new ferry terminal.

"This is a fantastic project," said Chris Meany, with Wilson Meany Sullivan, one of the project's developers. "This is the only right outcome. Obviously we're very gratified."

Public support of the plan was so overwhelming at the meeting that Supervisor Jane Kim, whose district includes the island, announced she would forgo making a statement in support of the project.

The public's comments were enough, she said. The rest of the supervisors followed suit.

Developers Wilson Meany Sullivan, Lennar Urban and Kenwood Investments said they hope to break ground as early as 2012. The board will cast a second, procedural vote on the project next week.

Over the next 20 to 30 years, they intend to morph the island from an aging former Navy base into a state-of-the-art neighborhood with a mix of affordable and market-rate homes, all designed to save water and energy.

Massive weight will compact the soil, keeping the island stable during earthquakes. A seawall will guard against sea level rise and possible tsunamis. Plans call for the ramps to and from the Bay Bridge to be redesigned and dedicated bus lines to run from the island to downtown San Francisco.

The plan was narrowly approved by the San Francisco Planning Commission in April, when some commissioners were worried by a last-minute cut to the number of affordable housing units and the impact cars would have on the already busy Bay Bridge.

Aaron Peskin, former Board of Supervisors president and a staunch opponent of the project, said he was disappointed by the "politically juiced" vote.

"This is a triumph of politics over public policy," he said. "This will be fantasy island."

He said the project would have significant impacts on traffic in the region and the costs would end up not penciling out.

"This is the beginning of a new and sustainable San Francisco neighborhood," Supervisor David Chiu said after the vote.