A $100 million construction project to fix the sagging and tipping problems at the Millennium Tower, a notorious leaning luxury condominium structure in San Francisco’s SoMa neighborhood, is essentially complete, according to the building’s homeowners association.
The association said it completed a major engineering project earlier this month that involved driving 18 concrete piles into bedrock deep beneath the property at 301 Mission St. and transferring some of the building load to the new structures.
The completion marks a major milestone in a year-long saga of multiple lawsuits, millions of dollars and an embarrassing mistake in building one of the city’s top luxury high-rises.
“With a 60-story structure and a load of 18 million pounds, no one has ever done that,” said Ron Hamburger, senior director at Simpson Gumpertz & Heger, the firm tasked with stabilizing the leaning tower.
Hamburger said his company employed a relatively common engineering technique called underpinning — though the sheer scale of the effort made the project unusual. The modernization will relieve the ground beneath the building on its north and west sides, which had collapsed under the weight of the structure and led to the subsidence and tipping problems.
The refurbishment underpins the more affected corner of the building, while the rest of the building is expected to continue to stabilize and stabilize over time. Completion of maintenance access systems and restoration of transit lines, sidewalks and landscaping on the Fremont and Mission streets affected by the construction work will be completed by August.
The Millennium Tower towers over the greenery of Salsforce Park, the rooftop garden in downtown San Francisco, California on Tuesday, November 1, 2022. | Camille Cohen/The Standard
“We look forward to completing the remaining non-structural elements of the perimeter piling modernization over the coming months and are confident that the engineering modernization will restore our building’s reputation and condominium value while addressing any remaining questions about the stability of the tower will clean up,” said Howard Dickstein, president of the Millennium Tower Homeowners Association, in a statement.
The homeowners association’s lawsuit against the developer over the subsidence and tilting issues was settled in 2020, paving the way for the retrofit to move forward.
The solution is a scaled-down version of a solution originally proposed by Hamburger, which envisaged the use of 52 piles. However, as the installation of these piles began, further subsidence of the building occurred.
In 2021, work was paused for months as construction and engineering teams developed a stripped down version of the solution, which was eventually implemented.
“It’s a great relief,” Hamburger said. “It was a challenging project, both technically and because of the high publicity it had and every incident was widely reported from coast to coast.”
The property opened to residents in 2009 and is the tallest residential skyscraper in San Francisco. The 419 units were sold over the next four years, generating approximately $750 million in total revenue for developer Millennium Partners. Past residents of the tower have included Kevin Durant, Joe Montana and the late billionaire venture capitalist Thomas Perkins.
Hamburger said the project not only addressed the problems of subsidence and tipping, but also made the structure more earthquake-resistant. As part of the San Francisco-imposed building permit process, the tower is subject to a 10-year monitoring plan in which surveys and measurements are regularly recorded and submitted to city officials.
