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SF's Millennium Tower fix will not resume as planned. Report shows work was causing further sinking.
Andrew Chamings
Sep. 13, 2021
The Millennium Tower, 301 Mission St, San Francisco, California.
Justin Sullivan/Getty Images
Work on fixing San Francisco's beleaguered Millennium Tower will not resume any time soon after a new report found that the fix itself was likely causing further sinking.
After abruptly tilting another inch over just a few weeks during construction in June and July, a temporary stop was put on all work on Aug. 23.
Principal engineer on the project, Ronald Hamburger of Simpson Gumpertz and Heger, told SFGATE that the pause was intended for "two to four weeks." But now no restart date is planned after San Francisco officials at the Department of Building Inspection asked the tower's management not to resume construction.
The sudden drop of an inch on the Fremont Street side was observed after crews had drilled halfway down
to bedrock to install new piles, and translates to 5 inches of lean on the 58th floor. Thirty-nine of the 52 new piles have so far been installed as part of the $100 million “perimeter pile upgrade.”
"That moratorium has been effective in halting the construction-related settlement and tilting," Hamburger told SFGATE on Monday. "We are presently working to develop modified construction methods so that construction can safely proceed, while keeping DBI and their expert review panel informed of our plans."
The city's request came after an engineering report revealed the building’s sinking stopped when the construction stopped, concluding that the construction likely caused the abrupt settling in July. The report also stated that the building is structurally safe.
Supervisor Aaron Peskin is now calling for a new independent review of the project.
“I would like there to be a pause until we know what we’re doing, and I think that construction should not resume until we can panel the best experts that this country has,” Peskin told KPIX.
Since its construction in 2009, the luxury high-rise — where some condos sold for $10 million on opening — has sunk 17 to 18 inches into the earth on the northwest corner.
The blue-gray glassy modernist tower at 301 Mission Street is the tallest residential building in the city and won numerous engineering awards upon its construction.
In May 2016 residents in the 58-story high-rise were informed that the main tower that housed their luxury condos was sinking. The foundation was built into deep, dense sand but not bedrock, unlike many downtown towers. (Though some other large downtown buildings are also constructed in the same way, including the Embarcadero Center, SFMOMA, the Marriott and 101 California.)
The blame game and series of complex lawsuits began.
The building's homeowners association sued the main contractor Webcor, and the developer Millennium Partners. The city of San Francisco also filed suit against the tower's developers. The developer blamed the problem on the Transbay Joint Powers Authority, which was responsible for construction of the neighboring Transbay Transit Center. All suits were later consolidated into a global agreement. The current fix on the tower is partly paid for as a portion of the settlement.
In 2018, a solution to the building's tilt from Hamburger at Simpson Gumpertz and Heger was finally proposed and approved.
"There has been no material harm to the building and it remains fully safe," Hamburger said. "Once pile installation is complete and load is transferred to the new piles, the building will experience substantial improvement and begin to recover some of the tilting that has occurred over the years."
Andrew Chamings
Sep. 13, 2021
The Millennium Tower, 301 Mission St, San Francisco, California.
Justin Sullivan/Getty Images
Work on fixing San Francisco's beleaguered Millennium Tower will not resume any time soon after a new report found that the fix itself was likely causing further sinking.
After abruptly tilting another inch over just a few weeks during construction in June and July, a temporary stop was put on all work on Aug. 23.
Principal engineer on the project, Ronald Hamburger of Simpson Gumpertz and Heger, told SFGATE that the pause was intended for "two to four weeks." But now no restart date is planned after San Francisco officials at the Department of Building Inspection asked the tower's management not to resume construction.
The sudden drop of an inch on the Fremont Street side was observed after crews had drilled halfway down
to bedrock to install new piles, and translates to 5 inches of lean on the 58th floor. Thirty-nine of the 52 new piles have so far been installed as part of the $100 million “perimeter pile upgrade.”"That moratorium has been effective in halting the construction-related settlement and tilting," Hamburger told SFGATE on Monday. "We are presently working to develop modified construction methods so that construction can safely proceed, while keeping DBI and their expert review panel informed of our plans."
The city's request came after an engineering report revealed the building’s sinking stopped when the construction stopped, concluding that the construction likely caused the abrupt settling in July. The report also stated that the building is structurally safe.
Supervisor Aaron Peskin is now calling for a new independent review of the project.
“I would like there to be a pause until we know what we’re doing, and I think that construction should not resume until we can panel the best experts that this country has,” Peskin told KPIX.
Since its construction in 2009, the luxury high-rise — where some condos sold for $10 million on opening — has sunk 17 to 18 inches into the earth on the northwest corner.
The blue-gray glassy modernist tower at 301 Mission Street is the tallest residential building in the city and won numerous engineering awards upon its construction.
In May 2016 residents in the 58-story high-rise were informed that the main tower that housed their luxury condos was sinking. The foundation was built into deep, dense sand but not bedrock, unlike many downtown towers. (Though some other large downtown buildings are also constructed in the same way, including the Embarcadero Center, SFMOMA, the Marriott and 101 California.)
The blame game and series of complex lawsuits began.
The building's homeowners association sued the main contractor Webcor, and the developer Millennium Partners. The city of San Francisco also filed suit against the tower's developers. The developer blamed the problem on the Transbay Joint Powers Authority, which was responsible for construction of the neighboring Transbay Transit Center. All suits were later consolidated into a global agreement. The current fix on the tower is partly paid for as a portion of the settlement.
In 2018, a solution to the building's tilt from Hamburger at Simpson Gumpertz and Heger was finally proposed and approved.
"There has been no material harm to the building and it remains fully safe," Hamburger said. "Once pile installation is complete and load is transferred to the new piles, the building will experience substantial improvement and begin to recover some of the tilting that has occurred over the years."
