A high-profile San Francisco development has already invested an additional $ 100 million to strengthen its foundations as part of a lawsuit, but the building is still sinking.
In May, construction crews began digging massive 100-foot-deep holes lined with steel sleeves under the Millennium Tower in San Francisco’s financial district, hoping to install new brackets anchored in the bedrock. rocky to consolidate luxury residential development after years of side tilt. and sinks deeper into the ground.
However, since then the building has continued to move, sinking an inch and leaning up to five inches at its top, for a total of 22 inches of tilt, according to NBC Bay Area, which monitored construction data.
“There has been no material damage to the building,” the building owners association recently told residents, “and it remains completely safe,” but would halt construction out of “an excess of caution.”
Doug Elmets, a spokesperson for the tower, said in a statement that the installation project, itself part of a legal settlement of a lawsuit brought by owners of apartments in the building, would be suspended for up to a month as engineers tried to find out more about the “increase in the settlement rate and means available to remedy it.”
The 58-story tower opened in 2009, and its 419 luxury apartments have been sold to a number of prominent Bay Area figures, including former San Francisco 49ers quarterback Joe Montana, the late venture capitalist Tom Perkins and the San Francisco Giants. outfielder Hunter Pence.
A decade later, the building had sunk about 16 inches and leaned 2 inches at its base and 6 inches at its peak, resulting in legal action from residents.
As part of a confidential settlement, it was agreed that $ 100 million would be spent to install 52 concrete piles, weighing a total of 140,000 pounds, to secure the project to a bedrock layer 250 feet underground. . Previously, the building’s foundation was not attached to bedrock, but rather to a 10-foot-thick concrete mat supported by 950 piles nestled in loose soil and burial soil.
David Williams, an Oakland-based structural engineering expert, told NBC Bay Area that developments around the sinking of the tower were “disturbing” and that to suspend construction is “obvious” until experts identify the problem. source of the problem.
“It’s very risky to play with something as complex as the foundation of this structure and not understand what’s going on,” he added.