According to recent findings, San Francisco’s sinking condo tower just got a little bit more down to earth.
The 58-story Millennium Tower, designed by Handel Architects, has sunk nearly 17 inches since its opening in 2009. Last summer, controversy enveloped the failing monolith when the settling came to light, as residents posted videos online of objects rolling across their floors to demonstrate just how slanted the 419-unit building had become.
Recently, engineers with Arup—employed to work on the currently under-construction Salesforce Tower designed by Pelli Clarke Pelli Architects next door—inspected the Millennium Tower’s rooftop height and found that the tower had sunk an additional 2 ½ inches beyond the initial 14 ½–inch drop recorded last year. Increasingly, the tower is tilting precariously toward the Salesforce Tower, as the muddy and sandy soils beneath it give way. It is built on a foundation of concrete friction piles, driven between 60 and 90 feet into the soil, that do not rest on bedrock. The method is employed by several other developments in the area, though the type of settling occurring at the Millennium Tower has not been seen in any of those projects.
Troublingly, the tower is not only sinking, but it is sinking unevenly, resulting in a measurable slant to the 645-foot-tall complex. As the muddy and sandy soils beneath it give way, it continues to tilt precariously toward the Salesforce Tower. As of 2016, according to court documents, the tower exhibited a 2-inch westward tilt at the base and listed a whopping 10 inches at its top. Recent projections put the potential maximum drift at 10 inches every two years unless something is done to rectify the issue.
As can be expected, the structural deficiencies have resulted in a flurry of lawsuits, including one from the building’s homeowners’ association. The association is seeking to force Millennium Partners, developers and owners of the tower, to perform $150 million worth of foundation upgrades that would add 150 new end-bearing piles in an effort to rest the building on bedrock.
“This accelerated movement highlights the need to retrofit the foundation as soon as possible,” Daniel Petrocelli, attorney for the Millennium Tower homeowners’ association told NBC Bay Area. “The Millennium Tower Association will request an early trial in its ongoing lawsuit to hold the responsible parties accountable.”