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San Francisco ‘Leaning Tower’ residents compelled to pay $6.8M for failed repair

Daily SF News — Sun, 26 Nov 2023 07:17:00 +0000

News

By Isabel Keane

Published
Oct. 3, 2023, 10:57 a.m. ET

Residents of Millennium Tower, better known as the Leaning Tower of San Francisco, have been left to foot a $6.8 million bill after a much-needed renovation project failed to fix the troubled luxury building’s 29-inch tilt and caused nasty sewage spills.

Repairs to correct the infamous tower’s 29-inch tilt concluded with residents being billed $10 per square foot of condo space — costing tenants $6.8 million in total — as the project cost $20 million more than the $100 million expected, NBC Bay Area reported.

The 545-foot-tall tower continued to tilt and sink further west after architects attempted to repair its foundation last fall. While the issue has not been fixed, residents were told they had until October to pay for the so-called repairs.

“I don’t know what to do with this place, because it is costly – I cannot live in it,” said Mehrdad Mostafavi, who moved out in June after sewage began to flow out of his kitchen sink.

Residents of Millennium Tower have been hit with a massive bill following so-called repairs done to fix its tilt. San Francisco Chronicle via Getty Images

While scrambling to clean up the sewage backup, which Millennium fix engineers warned could happen due to the tower’s tilt, Mostafavi was slapped with a bill for nearly $14,000 from the Tower owners association.

“It’s a luxurious building and famous building, but unfortunately it is not like this for me as an owner,” Mostafavi told the outlet. “I am really suffering.”

Mehrdad Mostafavi moved out of the building in June after sewage began coming out of his sink. NBC Bay Area

Mostafavi said the bill had come after he already dipped into his retirement savings account to pay for his wrecked kitchen.

“I’m really having a hard time seeing how can I leave for the retirement — how to get out of this apartment and do my retirement” he said. “It is very costly…. they keep asking for more money and this is not acceptable for me.”

Mostafavi said he had to dig into his retirement savings to fix the damage the construction caused to his home. NBC Bay Area

Residents were charged $10 per square foot, costing Mostafavi nearly $14,000 for his condo. NBC Bay Area

After homeowners were compensated for lost property value, the tower association was given $150 million to cover costs — but it still was not enough given the troubled project’s numerous setbacks, the association said.

“The delays and the city’s heightened requirements resulted in significant unforeseen project cost increases,” the association’s letter to residents said.

The bill noticed shared a rough accounting for the $6.8 million owed by residents — and tried to assure homeowners that they were not alone in having to pay, since the tower’s developer and the fix contractor pitched in $10 million to offset overruns.

According to recent monitoring data, ever since the construction wrapped in June the building’s tilt has only improved by a fraction.

The 29-inch tilt was first revealed to the luxury building’s residents in 2016.

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One earthquake can put the leaning Millennium Tower at risk

Daily SF News — Wed, 14 Jun 2023 00:51:27 +0000

property

exclusive

From Mary K Jacob

June 13, 2023 | 5:50 p.m

The Millennium Tower, cheekily dubbed the Leaning Tower of San Francisco, finds itself in trouble when even a single earthquake shakes the city, The Post has learned.

Located at 301 Mission St., the 545-foot-tall building has steadily tilted and sunk further west since 2015, though the architects have tried their best to stabilize the swanky building.

The multimillion-dollar-per-unit tower slopes more than 29 inches at the corner of Fremont Street and Mission Street — a slope more than half an inch lower than previously announced.

Consulting engineer Robert Pyke, who specializes in geotechnical and seismic engineering, blamed designer Treadwell & Rollo – a company later acquired by Langan – for the foundation problems, citing a time crunch they found themselves in during the 2008 market crash were.

“There is a real possibility that the building will be red marked after an earthquake,” Pyke told The Post of the tower — a 58-story, 419-unit apartment building that was completed in 2009.

When a building is marked red, it means that the structure has been marked as so badly damaged that it is too dangerous to inhabit and entry to the property is prohibited without written permission from the regulatory authority.

Pyke cites the Hayward Fault Zone — a geologic zone located primarily at the western foot of the hills on the east side of San Francisco Bay — as capable of triggering destructive earthquakes.

A view of the Millennium Tower on August 11, 2016 in San Francisco.Getty Images

“A quake on the Hayward Fault in the East Bay could happen any day,” Pyke said. “And even this Hayward earthquake could be strong enough to significantly shake buildings in San Francisco, like the Millennium Tower. So I think there’s a longer-term risk that homeowners will actually have to move out, at least temporarily.”

In addition, Pyke stated that the tower would never get back to the same height.

And while collapse is unlikely, since it would require a “tens of feet” of incline, Pyke said if the tower got any closer to 40 inches, the elevators and plumbing would stop working, and neither would the occupants forced to move out.

The current solution hasn’t worked and probably won’t work because its original 2005 build switched from steel to concrete — making the change harder and harder, Pyke said.

“It turned out to be wrong because the effective increase in building weight was quite significant. It was a third or more higher than before. And so, technically, there was an overuse of the Old Bay Clay layer that was underneath the sand layer.”

The tilt was reportedly achieved by half an inch when engineers dug under the sinking condominium earlier this year to support the weight of the tower – which was built on a former landfill site – on either side.Bloomberg

Pyke said to prevent another tipping he would abandon the current attempt at repair, which he says “introduces too many uncertainties”.

Instead, he drilled bores (a cutting process that uses an indenting tool or drill head to enlarge an existing hole in a workpiece) on the south and east sides of the tower to remove some of the soil in the Old Bay Clay layer to level the building.

“Carefully!” said Pike.

“It’s similar to what was done on the Leaning Tower of Pisa. Probably then the progression of colonization would stop or slow down enough that it doesn’t matter, but if it does continue I might consider freezing the Old Bay Clay!”

Meanwhile, project engineer in charge of the building, Ron Hamburger, told NBC in a statement that roof data is vulnerable to weather variations and said foundation-only data is more reliable.

“We are absolutely confident that once the remaining design load has been transferred to the piles, there will be no further westward movement of the roof,” Hamburger said.

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Fixing San Francisco’s leaning skyscraper

Sun, 06 Mar 2022 10:40:01 +0000

Video hosted by Fred Mills.

THE MILLENNIUM TOWER was once considered a structural marvel. Opened in 2009, it won awards for its structural integrity, including the American Concrete Institution Award for Construction and the Structural Engineering Project of the Year.

Demand for its luxury condos was so great that owners were reselling their units at two to three times the price they originally paid for them, with the penthouse selling for $9.8M.

It’s fair to say that perception no longer holds true. All skyscrapers settle into the ground over the course of their lives, and the movement is planned for during design, but in 2016, it became apparent that the building was sinking much further and faster than expected. Worse, it was beginning to lean over.

Cue a media storm as developers, engineers, homeowners, and the city of San Francisco all rushed to blame — and sue — each other. With hundreds of millions of dollars on the line, that’s hardly a surprise. But what on earth actually happened here?

Above: The Millennium Tower, viewed from street level. Image courtesy Michael Vi.

What went wrong with the Millennium Tower?

Ron Hamburger, the engineer leading the project to fix the issue, blames construction work on a nearby site. While working on the Salesforce Transit Center, crews dug an 18-metre hole and pumped millions of liters of water out of the ground.

According to Hamburger, clearing that much water from the soil created an effect called “soil compaction,” which caused the soil under the tower to start compressing at a far faster rate than predicted. That said, plenty of water was pumped out of the soil directly under the Millennium Tower while it was being constructed, well before ground was broken at the Salesforce Transit Center.

The exact details remain unclear, but what is obvious is that the soil that the skyscraper sits on is not having as expected. While the tower remains habitable and, apparently, safe — as of writing the building is leaning 60 centimeters to the west and 20 centimeters to north — the situation needs to be stabilized as soon as possible.

But what goes into straightening out a 197-metre tall building?

How do you fix a sinking skyscraper?

The plan to correct the tilt looked like this. 52 additional piles — a type of foundation inserted deep into the earth — would be put under the north and south ends of the building, placed through the sidewalk and under the building’s main foundation.

These piles would extend beyond the original foundation, reaching 76 meters to the layer of bedrock below. This is a process called “underpinning”, and it’s fairly common. Hamburger intended these new piles to even out 50 percent of the building’s tilt over the following 10 years, leveling the rest of it over the next half a century.

Work started on the fix in November 2020. But by the following summer, it became clear that it wasn’t going entirely to plan. It was discovered that the installation of these new piles might actually be making the skyscraper’s tilt even worse, contributing to a further 12 centimeters of lean at the top.

The new piles were designed to stop the sinking when they were driven into the bedrock and attached to the skyscraper, an operation scheduled for later in 2022.

However, there are fears the holes that had been dug for the retrofit were causing even more soil movement, and it was later revealed that construction teams had also left a one to four day gap between removing the soil and putting in grout meant to reduce the risk of soil collapse.

Hamburger needed a new plan.

Above: The plan to retrofit Millennium Tower relies on underpinning the building with deep piles.

What’s next for the project?

At a hearing in January 2022, a new scheme for fixing the tower was outlined. The 52 new piles in the original fix would be replaced with 18. These 18 piles would go even deeper underground, and because there would be fewer of them there would be less disturbance to the soil under the building.

This new plan is currently under review and will be decided on by March 2022, it will likely go ahead but further balloon the cost of the fix from US$100M to an estimated US$500M.

Hamburger has claimed that the Millennium Tower would need to lean more than 180cm for it to be unable to withstand an earthquake, a far cry from its current 60cm tilt. That said, the building would be rendered uninhabitable if the plumbing and elevators stop working, and that could occur when the lean gets to 100cm.

So for the engineers it’s a race against time to stabilize the site, one with millions of dollars at stake. But this is more than a case study in what can go wrong — it’s also a reminder of just how robust the engineering of modern megaprojects really is.

Massive buildings with low fault tolerances are built on compactable soil in places all around the world, and virtually none of them suffer from the problems we’ve seen here in San Francisco. And the fact that Hamburger and his team of engineers can even try to un-tilt a 197m skyscraper is a testament to just how far the construction industry has come.

Let’s just hope that for the Millennium Tower, the third time’s the charm.

Video presented and narrated by Fred Mills. Additional footage, audio and images courtesy of NBC Bay Area, KPIX CBS SF Bay Area, Hydrogen Iodide, Google Earth, California High-Speed Rail Authority, and City of San Francisco Government Audit and Oversight Committee. SIDEPROJECTS and San Francisco Business Times were used as data sources.

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Leaning San Francisco skyscraper is tilting 3 inches per 12 months as engineers rush to implement repair

Wed, 26 Jan 2022 02:52:05 +0000

The engineer trying to stabilize the Millennium Tower, a luxury residential skyscraper in San Francisco that is sinking into the ground and now leaning over two feet off of center, said the building is now tilting three inches per year.

Structural engineer Ronald O. Hamburger made the comments Thursday at a city hearing in which he pitched an updated fix for the building’s foundation, NBC Bay Area reported.

The 58-story, 645-foot tall tower — opened to residents in 2009 — is now tilting 26 inches north and west at Fremont and Mission Streets in the heart of San Francisco’s financial district, according to NBC Bay Area.

Residents were informed that the building is settling unevenly and more than anticipated in 2016. The tower sits beside the Salesforce Transit Center, a bus terminal and potential future rail terminus for California’s high speed rail network currently under construction.

But efforts to stabilize the sinking and leaning skyscraper seemed to worsen matters. Engineers halted construction on the fix in summer 2021 so they could “determine why increased foundation movement was occurring and how this could be mitigated.”

To relaunch the stabilization, Hamburger on Thursday proposed slashing the number of support piles beneath the tower from 52 to 18 to “minimize additional building settlement.”

A letter to the Millennium Tower’s general manager last month said the new, quicker fix was needed after engineers identified two potential causes for apparent worsening of the building’s settlement: “vibration of the soils associated with pile installation activity, and unintentional removal of excessive soil as the piles were installed.”

Hamburger said the 18 steel piles will be anchored into bedrock 250 feet under the tower, cutting through rapidly compressing clay and sand soil that the building’s foundation sits upon today.

In a question and answer document, the engineer said if more than 18 piles are installed, “the construction schedule will be extended, and the building will settle and tilt a little more during this period.”

“We judge that the 18-pile solution offers an optimal solution between additional settlement and benefit gained.”

In an exclusive investigation, NBC Bay Area reported Wednesday that an expert review of the perimeter pile upgrade plan found there was a one- to four-day-long delay in summer 2021 between excavating the soil for the existing six pilings and injecting grout to minimize soil collapse.

That gap between excavating and injecting grout went against protocol and “could very well explain the comparatively rapid settlement and tilting that occurred during pile installation in August.”

In an email, Douglas Elmets, spokesperson for the Millennium Tower Homeowners Association, said the perimeter pile plan won’t stop the building’s sinking “until the piles are driven into bedrock and attached to the foundation, which will occur later this year.”

In a Thursday letter to the Millennium Tower Association, the San Francisco Department of Building Inspection said it approved a modified procedure to continue the preexisting pilot pile installation plan, and was reviewing Hamburger’s revised retrofit proposal.

In a statement to NBC News, spokesperson Patrick Hannan said SFDBI and the Engineering Design Review Team are “currently reviewing the proposed revised plan — which we only recently received.”

“Assuming we continue to receive information in a timely manner, we aim to complete our review by February 28 … the new proposal will need a revised permit to proceed,” Hannan added.

SFDBI said they would inspect between each additional pilot pile installation to ensure work was proceeding as expected.

NBC News reported in 2016 via a public records request that the Millennium Tower was previously expected by its builders to settle a maximum of 5.5 inches by the year 2028.

Tim Fitzsimons is a reporter for NBC News. he/him

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