Its neighbor, the Millennium Tower, might be sinking, but — get this — the new $2.2 billion Transbay Transit Center has the potential to go in the opposite direction. One of the main challenges the builders faced was keeping the three-block-long monster from rising.

“It’s like a ship — we are tying it down,” Transbay Joint Powers Authority Executive Director Mark Zabaneh explained at a news conference Wednesday when asked if the cracked beams that forced the new terminal’s closure might be the result of the building sinking.

According to the Transbay’s website, “Unlike adjacent high-rises that generally have foundations anchored into bedrock to keep from sinking, the transit center’s foundation must keep the building from floating up.”

The reason is that unlike the 58-story-tall Millennium, which has all of its weight bearing down on a half-block base, the transit center is akin to taking the Millennium and laying it down on its side.

In effect, the transit center is like a 1,500-foot-long barge floating atop a lake of deep mud.

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And believe it or not, the underground water pressure downtown is strong enough to lift the center — a building made of 25,000 tons of steel and 200,000 cubic yards of concrete.

“For that reason, we did not go to bedrock,” as you would with a high-rise, Zabenah said.

Instead, the building is tied down — held in place — by 1,896 eighty-foot-long anchors embedded in the mud.

Asked whether the beams could crack because the transit center might be rising, Zabenah said: “No, it’s a localized issue” happening only above ground.

Still, it does offer some insight into how tricky building on landfill can be.

Sorry to say: LaSonya Wells, whose arrest on kidnapping charges for stealing a prominent local politician’s cell phone raised questions about race and fairness in San Francisco’s judicial system, is back in jail.

Once again for robbery. And at the same location.

Wells was convicted last year of grabbing then-Supervisor Scott Wiener’s iPhone as he was walking near the 16th Street BART Station. After being robbed, Wiener quickly negotiated with Wells — and her 20-year-old son — to accompany him to a nearby Wells Fargo ATM, where he withdrew $200 in return for the phone.

In addition to theft, the district attorney also charged Wells with kidnapping for ransom, a charge that could have sent her to prison for life.

At the time, Public Defender Jeff Adachi called the kidnapping charge “positively medieval” and said that prosecutors may have been motivated more by Wiener’s status than the facts of the crime.

The case ended with a deal: Wells pleaded guilty to felony extortion, with credit for time served.

Fast-forward to June 28, when Wells was arrested outside the same BART station where she robbed Wiener. This time, she and a male accomplice allegedly tried to rob a man of $100 and steal his cell phone in what may have been a drug deal gone bad.

The incident was caught on a nearby surveillance video camera.

Wells, who has a long history of substance abuse, was booked for felony robbery and misdemeanor possession of a cocaine-based substance. She posted a $100,000 bond. However, she subsequently missed her court appearances and a bench warrant was issued.

“I have no idea why she missed court,” said Assistant Public Defender Eric McBurney, who is representing Wells.

She was picked up during a traffic stop on Sept. 18 and is back in custody.

“I really hoped she would get her life back together and get on track,” Wiener said. “It’s disappointing to hear she is in trouble again.”

Never mind: Last week, we reported that BART boardwoman Debora Allen was heading off to the annual American Public Transit Association’s conference in Nashville before the transit district’s new policy kicked in that banned travel to states with anti-LGBTQ policies.

Well, at the last minute, Allen opted not to go, telling us after we went to print that she simply was too busy.

Allen claims she told BART staff of her decision days before the conference. The district’s press office said they never were informed and hence they still believed she was going when we called late in the week to confirm that both she and two district staffers were still planning to attend.

Anyway, despite not going, Allen says the trip still cost her — because her cancellation meant she would have to eat the price of her airfare.

Changing times: Rep. Barbara Lee has agreed to take part in a League of Women Voters candidate forum on Oct. 5 at Oakland City Hall, and no one was more surprised than her little-known Green Party challenger Laura Wells.

In her news release, Wells recalled that eight years ago, when she was running for governor of California, “I was arrested and put in handcuffs for just trying to be in the audience of a debate in which I rightly should have been one of the candidates on the stage.”

“I think I will be safe this time in the hands of League of Women Voters,” she told us Friday.

San Francisco Chronicle columnists Phillip Matier and Andrew Ross appear Sundays, Mondays and Wednesdays. Matier can be seen on the KPIX TV morning and evening news. He can also be heard on KCBS radio Monday through Friday at 7:50 a.m. and 5:50 p.m. Got a tip? Call 415-777-8815, or email matierandross@sfchronicle.com. Twitter: @matierandross