Warnings About San Francisco Millennium Tower Repair Plans Raised Before Work Began
by Abigail Sterling and Max Darrow
SAN FRANCISCO (KPIX 5) -- Days after San Francisco officials put the construction to shore up San Francisco's leaning Millennium Tower on indefinite hold, there's new evidence that building officials were forewarned about the dangers of the current fix.
The city's Department of Building Inspection says it is examining an updated construction approach that engineers on the project have proposed after it was discovered pile-driving activity likely caused the luxury residential high-rise to sink another inch and lean another five inches.
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"I could see that at some point things were going to go haywire," said geotechnical engineer Robert Pyke two years ago when he took a closer look at the details of what was the new plan to stabilize and straighten San Francisco's leaning millennium tower.
The plan was announced at a news conference by prominent San Francisco engineer Ronald Hamburger. "It's not unusual to do this type of thing to a building; it's called underpinning. What is unusual about this is the size of the building, very large," said Hamburger at the time.
Pyke's main concern: the so-called "perimeter pile upgrade" calls for connecting only the sinking north and west side of the building to bedrock, leaving the south and east side unconnected. "It's asymmetrical. And an asymmetric foundation under earthquake loading is inherently a very bad thing," said Pyke.
So he submitted a letter of concern to the Engineering Design Review Team (EDRT) overseeing the project and to the city, with the headline: "The proposed Millennium Tower fix is a farce."
He's not the only engineer that sounded the alarm. "The problem is they have already done a lot of damage, said geotechnical engineer Lawrence Karp.
In a report to San Francisco supervisors, Karp and fellow geotechnical engineer Joshua Kardon warned that the "external asymmetrical plan" would cause "further loss of groundwater, which is likely to cause more irreparable damage to the building's substructure."
"I see the groundwater is dropping, which is what we said in our report," said Karp.
Karp preferred an alternate fix by the New York firm LERA founded by Leslie Robertson, the famed lead engineer of the World Trade Center. The LERA plan called for drilling new piles into bedrock symmetrically on both sides of the building from the inside.
"It was all inside the building, it was going through the foundation mat so it's level, it's masterful," said Karp.
Karp says he met with city building officials to discuss his concerns but never got feedback. Pyke says he never heard back, either.
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Two years and many lawsuits later, the luxury high rise's developer Millennium Partners chose the perimeter pile upgrade backed by Hamburger, while promising to pay for the $100 million fix in a confidential settlement with homeowners.
The Department of Building Inspection declined our request for an interview, but in a statement told us a team of experts monitoring the fix on behalf of the city did ask project engineers to address the critics' warnings. The engineers offered assurances and the warnings were dismissed. Now they're coming back to light.
"I'm deeply concerned," said San Francisco Supervisor Aaron Peskin, who now wants a new independent set of eyes on the project before construction resumes.
"I am frankly afraid that our Department of Building Inspection doesn't have the internal expertise over something this complicated, ranging from outriggers to foundation systems, and I want to make sure that we have the best people in the nation looking at this," said Peskin.
Peskin held hearings in 2016 after the leaning was first detected by residents and then confirmed by experts. He is calling for new hearings now.
"I don't want to have a Florida situation in San Francisco," said Peskin, referring to the June collapse of a 12-story condo in Surfside, Florida which killed 98 people. "I don't want to be alarmist, but we need to take this extremely seriously, we need to be very transparent about it."
"As a practicing engineer in the Bay Area, I don't have concerns with the level of transparency or the communications on this particular project," said Emily Guglielmo, past president of the Structural Engineers Association of Northern California.
Guglielmo told KPIX 5 the groundwater & asymmetrical design critiques were brought up and accounted for during the engineering team's design review period.
"Absolutely appropriate to question or debate a particular solution," said Guglielmo. "But it's also important to understand the level of design, the level of scrutiny, the level of approval that took place on this particular project."
Guglielmo says she doesn't think a solution like this has been done before with this level of visibility, however, "... the engineering techniques are very consistent. We do these on houses in San Francisco all the time. Underpinning, moving loads and foundations is very traditional."
Building officials have asked the Millennium Tower's General Manager and homeowners to refrain from resuming construction until DBI and the EDRT have reviewed an updated construction approach.
In a statement to KPIX 5, Department of Building and Inspection spokesman Patrick Hannan said:
"The Engineering Design Review Team (EDRT) did receive and review the letters from Karp & Kardon and Dr. Pyke as part of the EDRT's review of the permit request for the foundation retrofit designed by SGH (Simpson, Gumpertz and Heger). At that time, the EDRT asked SGH to respond to the points raised by the letters about SGH's retrofit design and the EDRT was satisfied with SGH's responses to those points."