A 58-story skyscraper in San Francisco is sinking and people are fighting over whose fault it is
Millennium Tower rises 58 stories above San Francisco's Financial District.
The city's fourth tallest skyscraper contains over 400 multimillion-dollar condo units. It soars 645 feet, providing residents with unparalleled views of the Bay Area.
Source: Wikipedia
Completed in 2008, Millennium Tower includes top-notch amenities, including a pool, fitness center, wine cellar and tasting room, and concierge service.
It's no surprise that in the first five weeks, Millennium Tower sold $100 million worth of condos, the San Francisco Chronicle reported. The penthouse is currently for sale.
Source: San Francisco Chronicle
Some pretty famous tenants have called Millennium Tower home, including former San Francisco 49ers quarterback Joe Montana and late venture capitalist Tom Perkins.
Source: Business Insider
But residents weren't happy after learning in June 2015 that the building is sinking. It's sunk 16 inches into soil and tilted two inches to the northwest since opening in 2009.
Source: Business Insider
The building's developers, Millennium Partners, argue that construction nearby is to blame for any sinking or tilting. A transportation hub, the Transbay Transit Center, broke ground next door in 2010, two years after the Millennium Tower was completed.
Source: Business Insider
The new terminal, developed by a transportation agency called the Transbay Joint Powers Authority, includes a 60-foot hole for the train tunnel and an underground buttress between the Millennium Tower and the transit site.
Source: San Francisco Business Times
A founding partner of Millennium Partners says there's "only one issue" — that construction for the Transbay terminal pumped too much water out of the ground.
"Dewatering" is the process of removing groundwater or surface water from a construction site to provide a safe work environment and prevent erosion of the soil.
When the water levels under the Millennium Tower dropped, the sand compressed and caused the building to settle, according to Chris Jeffries, a founding partner at Millennium Partners.
The issue came to light in 2010, five years before tenants were notified, when the Transbay Joint Powers Authority hired a consultant to find out how excavation could affect the tower.
The Transbay Joint Powers Authority maintains it is not at fault for the building's sinking.
The agency released a statement on its website in October condemning the allegations against it as a "distraction from the exclusive cause" of the tower's tilt: "inadequate foundation."
The statement also points out that Millennium Tower's vertical settlement began two years before the Transbay Joint Powers Authority began doing any underground work.
In August, a group of residents filed a class-action lawsuit against Millennium Partners and the Transbay Terminal developers to recover the losses in property value.
Source: SFist
The San Francisco City Attorney's office also put Millennium Partners in its crosshairs when it announced in November that it was suing the developers of the sinking skyscraper.
Now the developers of the tower and terminal, city officials, and Millennium Tower residents are asking what could have been done to save the building from its crooked fate.
San Francisco supervisor Aaron Peskin kicked up drama in September, when he raised suspicion that city officials knew the building might sink before anyone moved in.
Peskin, who served on the Board of Supervisors from 2005 to 2009 and was reelected in 2015, uncovered documents from 2009 allegedly showing the city's building inspection department expressed concerns about the tower's unusual settling to the developers.
Six months later, the tenants of Millennium Tower were approved for move-in.
"I believe, and I know this is a very serious allegation, that there was some level of political interference," Peskin told reporters on September 13.
There's also confusion about why the building's developers were allowed to anchor the building 80 feet into packed sand rather than 200 feet down to bedrock.
The Transbay Joint Powers Authority hired a consulting firm in 2010 to investigate the new transit center's impact on the environment. It found that Millennium Tower's tilting and sinking was due "entirely to the failure of the foundation piles for the Tower to reach bedrock," according to Scott Boule, a TJPA spokesman.
In other words, the terminal developers blame Millennium Partner for not digging deeper.
The design isn't all that unusual. Some of the city's best known buildings, including the Embarcadero Center and SF MOMA, were built on sand instead of bedrock.
Millennium Tower sits on an array of nearly 1,000 pillars shoved into the ground.
Its own weight combined with the resistance of the soil underneath should keep it in place under most conditions, a professor of architectural design told Curbed.
Source: ABC7
Millennium Tower probably won't fall, in part because it's sinking too slowly to take anyone by surprise.
The building's developers, Millennium Partners, hired engineers to drill holes around the building in order to test soil samples and figure out why the tower is sinking and what can be done to prevent it from sinking further.
The biggest cause for concern is the looming possibility of an earthquake.
For years, scientists have warned that the Bay Area is overdue for a devastating earthquake.
Millennium Tower sits on land that is prone to liquefaction, the process by which loose sand and silt behaves like a liquid in the event of an earthquake. The seismic activity causes water pressure in the sediment to increase and grains of sand to lose contact with each other, the US Geological Survey (USGS) explains. The soil may give out under large and heavy structures.
Oftentimes, the solution for tall buildings built in liquefaction zones is drilling down to bedrock. Millennium Tower's neighbors, the $1.1 billion Salesforce Tower and the luxury high-rise 181 Fremont, are both anchored to bedrock. They're still under construction.
Millennium Tower will "most likely" sink an additional eight to 15 inches in the coming years, for a total of 31 inches.
Source: The San Francisco Chronicle
The "leaning tower of San Francisco" can even be seen sinking from space.
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