Board members voted 8-1 to approve the deal, minus the provision that would give workers six weeks of paid annual leave to care for sick family members. The transit agency said the provision could cost $44 million over four years if one-third of union workers take six-week leaves each year.
BART officials announced last week that the provision had been inadvertently included in the proposed contract due to an error.
The parties agreed to a tentative deal Oct. 21 after six months of agonizing negotiations and two strikes that caused headaches for hundreds of thousands of people who ride the nation's fifth-largest commuter rail system.
"We hope the unions will take the agreement, minus the six weeks of additional paid leave that was mistakenly included in the final document, back to their members," BART President Tom Radulovich said. "Simply put, (BART) cannot afford to give its employees another six weeks of paid leave, on top of the generous leave already allowed in the BART employee benefit package."
The decision creates uncertainty about the fate of the tentative contract. Representatives from the Amalgamated Transit Union Local 1555 and Service Employees International Union Local 1021 called the move by the board an unfair labour practice.
The unions intend to discuss the matter with attorneys and members to determine the next step.
"I am deeply disappointed in the actions that the board took," ATU Local 1555 President Antonette Bryant said after the vote. "To take this action on something that was not presented to our members speaks to the fact that they are not adhering to the negotiation process."
She later told the board that it was "a slap in the face to the negotiation process."
"You vote on a contract in its entirety — up or down. We expected the board to step up and act with integrity and credibility," Bryant said. "We did not get to pick or choose what we wanted to leave in or to leave out."
The unions did not mention the possibility of a third strike this year.
Zakhary Mallet, the lone BART board member who voted against the tentative deal, said it was too costly and shortsighted.
"I feel for the negotiations we went too far, too quickly," Mallet said. "I don't find it financially sustainable."
A labour expert who was an invited observer to the BART bargaining sessions said Thursday that the Family Medical Leave Act provision was routinely mentioned among the parties among the items they had agreed upon as talks resumed.
John Logan, the director of Labor and Employment Studies at San Francisco State University, said the provision was seemingly resolved as the talks remained contentious over salary, benefits and safety conditions.
"The idea that this provision was included as a mistake would come as a complete surprise to the unions because it was settled earlier," Logan said. "Whether it was included in the contract due to gross incompetence or a mistake, that's the contract you're supposed to be voting on."
Logan said he can't recall hearing anything similar and suspects that the unions will be "highly reluctant" to renegotiate and will likely look into possible legal actions.
He said another strike is not entirely out of the realm of possibility.
"But I don't think anyone is considering a third strike because that would be the worst possible outcome for both parties," Logan said.
The unions went on strike for nearly five days in July and for another four days last month, angering commuters who had to find alternative ways to work.
During the second strike, two BART workers were killed by a train operated by an employee undergoing training. The parties soon returned to the bargaining table.