San Francisco could be seeing its next tourist trap: the Leaning Tower of Frisco.
Since construction completed in 2008, the Millennium Tower - a symbol of the rich and famous with condos selling from $1.6 million and above $10 million - has sunk 16 inches and tilted 2 inches northwest. The 58-story tower was constructed on soft, sandy land using a concrete design instead of steel, relying on columns, shear walls, and beams. The building was anchored with a concrete slab and piles driven 80 feet deep into dense sand, according to the San Francisco Chronicle.
Though the building's owners are blaming the neighboring construction of the Transbay Transit Center for the issues. The Transbay Joint Powers Authority has been digging a tunnel 60 feet deep next door to the tower for the new bus and rail center.
Greg Deierlein, director of the John A. Blume Earthquake Engineering Center at Stanford University, who has been called on to evaluate the designs of downtown high rises, told the San Francisco Chronicle the issue isn't a safety concern as of yet, but could have a substantial financial impact on the building's home owners and investors.
It could also have a large financial impact on Bay Area tax payers. Back in 2008, the Transbay Joint Powers Authority signed an agreement with Millennium Partners, the developer, consenting to responsibility "to repair, at its own cost and expense... any damage to the development substantially caused by TJPA's construction activities."
In a statement released on Monday, the TJPA is denying any responsibility for the building's issues, claiming that had Millennium Partners drilled piles to bedrock - roughly 200 feet deep - the tilting would not be happening today. The authority also referred to a report from engineering consulting firm Arup, which was hired to analyze how excavation could affect the Millennium. The initial report revealed that in just two years after the building was completed, it had settled 10 inches, when the builders initially predicted it would only settle 6 inches in that timeline.
Critics are wondering how California - a state notorious for regulation - would allow a tower to be built insufficiently, but various builders will argue a concrete design is typical for a residential building and other towers in the Bay Area have been built with a similar design excluding steel. P.J. Johnston, spokesperson for Millennium Partners, cites skyscrapers including St. Regis and Interncontinental hotels have also used concrete designs.
The only suggested fixes to the problem as of yet are to pump cement underneath the base and drill new, deeper piles to secure the building, though nothing is being put into action now.
We'll be following how the legal battles between the TJPA and Millennium Partners unfold.