The Golden State Warriors have abandoned their plan to build an arena on Piers 30-32 just south of the Bay Bridge and instead have purchased a site in San Francisco's burgeoning Mission Bay to hold a new 18,000-seat venue.

The Warriors bought the 12-acre site from Salesforce.com at an undisclosed price in a deal signed Saturday night, said Rick Welts, the Warriors' president and chief operating officer. The team plans to have the arena ready for the 2018-19 NBA season.

The shift in location provides the Warriors with predictability and fewer regulatory hurdles. It also eliminates any need for voter approval, which may have become necessary for the Pier 30-32 venue that Mayor Ed Lee once called "my legacy project."

The change has assuaged some of the project's most vocal critics, who opposed building a 125-foot-high arena near the Embarcadero amid concerns about traffic, environmental harm during construction and blocked views of the Bay Bridge.

"To me, everybody wins here," Welts said. "We never lost sight of the overriding goal, which was to bring the Warriors to San Francisco and build this world-class sports and entertainment venue that the city has never had."

The Mission Bay site, where Salesforce once intended to build its corporate campus, has a Muni T-Third stop in front and has two adjacent parking garages that can hold a combined 2,130 cars. A new off-ramp from Interstate 280 will drop cars about two blocks away.

The site has street access on four sides, rather than only one side at Piers 30-32, easing pinch points. A waterfront park is planned across from the arena.

When the Central Subway opens - projected for 2019, the year after the Warriors plan to open the arena - the line will provide essentially a straight shot to the Powell Street Muni/BART Station downtown.

Private financing

The Warriors will own the site outright, rather than leasing it from the Port of San Francisco, and the team says the arena will be entirely privately financed - a rare instance of a modern sports venue that would use no taxpayer funds or public land.

The new site off Third Street does not, however, have the iconic feel and stunning views of the Bay Bridge. Instead, the view is of a dry dock, an industrial pier and rusting old pilings that dot the water. Visible across the bay are the cranes and skyline of Oakland, the Warriors' home after the team played in San Francisco from 1962 to 1971.

The Warriors' planned arena is part of a redevelopment area and growing biotech hub, with a UCSF Benioff Children's Hospital being built diagonally across from the arena site.

Lee and other officials see the arena as a catalyst for development in the neighborhood, a former rail yard that has little foot traffic at night, that will help as the city grows into the former industrial spaces on its southeast side, such as Pier 70 and the Hunters Point Shipyard.

"The mayor recognizes, and we recognize, that the city is moving south," Warriors co-owner Joe Lacob said. "There are some great advantages for the city in this as well."

Among them, construction on the parcel slated for the arena will trigger the creation of a 5.5-acre bayfront park, paid for by the master developer as part of the redevelopment plan for the area.

Former Mayor Art Agnos and former Board of Supervisors President Aaron Peskin, leading opponents of the Warriors' plan to build on Piers 30-32, said they support the team building a similarly sized arena in Mission Bay.

"This is a historic victory for the people of San Francisco because we have protected our precious bay and waterfront, as well as gained a new hometown basketball team," Agnos said.

The "process has worked," Peskin said. "San Francisco is going to have its cake and eat it too."

The Warriors have already spent about $20 million on design, engineering, consultants and other work for building on Piers 30-32. Some of that will transfer over, Welts said.

Impact on arena design

The interior of the arena will likely remain the same, although the exterior design could change to reflect the new surroundings, including possibly eliminating a public pedestrian walkway and lookout deck that had been planned for the previous site, Welts said. The arena will remain about the same height, 125 feet in the center - well below the 160-foot height limit for the property.

Whatever the final design, the arena will be a commanding presence, said Warriors co-owner Peter Guber.

"It has to be iconic, not just in design but in operation," Guber said.

The team has yet to decide what else it will seek to build on the 12-acre site, but Welts said it could include office space and retail geared toward arena visitors.

The site had been considered by the Warriors earlier but was ruled out as too expensive.

Salesforce bought 14 acres in Mission Bay in November 2010 to build its corporate campus. The San Francisco software giant announced in February 2012 that it was shelving its plan to build there.

The Warriors are buying a portion of the property - bounded by Terry Francois Boulevard and 16th, Third and South streets. UCSF is in advanced negotiations to buy another part of it.

The entire Salesforce site cost $248 million, but that figure doesn't include $23.3 million for "perpetual parking rights" in at least one nearby garage, or interest costs and property taxes since the purchase, according to a Salesforce filing with the Securities and Exchange Commission in November.

"The total carrying value of the land, building improvements and perpetual parking rights was $321.1 million" as of Oct. 31, according to the filing.

Costs of plan mounted

The Warriors would not disclose how much they paid for their 12-acre piece, but the site became more attractive after the cost to rebuild Pier 30-32 roughly doubled from the team's original projection two years ago to $180 million. When you add in the $40 million cost of building a terraced public park that had been planned to cover a parking garage on Piers 30-32, the team was looking at $220 million as a starting point, Lacob said.

Besides having to go to voters for approval in November, an arena on Piers 30-32 would have required approvals from agencies like the Bay Conservation and Development Commission, State Lands Commission, and Army Corps of Engineers. Building on the Mission Bay site requires approvals only from city agencies.

"We paid a very pretty penny," Lacob said. "At the end of the day, you have to remember, it's important to envision something great for the city, for our fans, but it's also really important to get it done."

The specific location of an arena in the city is secondary, Lee said.

"The legacy for me," Lee said, "was getting the Warriors to come back to San Francisco."