Jan 11, 2022 - Politics & Policy

San Francisco skyscraper is tilting 3 inches per year

Stephen Lam/San Francisco Chronicle via Getty Images
Photo: Stephen Lam/San Francisco Chronicle via Getty Images

Engineers are working to stabilize a luxury San Francisco apartment building that is tilting about three inches per year, the AP reports.

Why it matters: At the current rate, the 58-story, 419-unit Millennium Tower is on track to reach a 40-inch tilt in a few years, which could render elevators and plumbing unusable, according to AP.

  • Residents have sued the developer and designers regarding the troubled building.
  • The building, located on Mission Street in the city's financial district, opened to residents in 2009, according to NBC.

Details: The tower's foundation sits on sand, soil and clay, which is compressing rapidly. Engineers on the project have proposed slashing the number of support piles and anchoring them into bedrock 250 feet below the structure to stabilize it.

  • The tower had already sunk 16 inches into the ground in 2016, with a 6-inch lean at the top of the building, per AP. It is now tilting 26 inches north and west, per NBC.
  • A review of the building's structural issues found a one- to four-day delay between excavating soil around the building and replacing it with grout could have worsened the leaning, an NBC investigation found.
  • The delay went against protocol and "could very well explain the comparatively rapid settlement and tilting that occurred during pile installation in August," according to NBC.
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