Following a recent inquiry, YIMBY has received an update from the Millennium Tower team about the progress of modifications to the original foundation in SoMa, San Francisco. Crews finished the installation of 18 piles by early 2022. Now, crews are working to tie the piles into the building. As for what this will do for the Millennium Tower, the principal engineer of the fix, Ronald Hamburger, says this work will “arrest its settlement and begin recovering tilt that has occurred.”
According to reporting by NBC Bay Area, “When work was shifted to the corner of Fremont to Mission in June, fix authorities said, they did not see more tilting during the digging there. They say that gave them confidence they could tie the building to bedrock at the corner without making the tilting worse.”
Millennium Tower initial and proposed foundation system circa 2019 with 52 piles, before plans were made more efficient with 18 piles, rendering by Simpson Gumpertz & Heger
The following statement below was provided by Hamburger:
Designers selected the original 52 piles based on calculations that indicated this was the maximum number that could be installed, not yet knowing if this would be sufficient to arrest settlement. When later geotechnical analysis confirmed 52 piles were sufficient, optimization was not performed.
In January this year, the MTA asked the design team if it would be possible to reduce the number of piles from the originally planned 52, to allow more rapid project completion and stabilization of the building. Following extensive analysis, the designers concluded, and the City and its outside reviewers concurred, that the presently planned 18 piles are sufficient. The negative declaration was a city formality undertaken as part of the process to revise the original permit from 52 to 18 piles. Work on the project, which initiated in November 2020, has never stopped.
The Millennium Tower is a 645-foot residential complex at 301 Mission Street with 419 apartments across 1.15 million square feet with on-site amenities and 8,000 square feet of ground-level retail. The larger tower is connected to a 125-foot podium structure connected with a two-story glass atrium.
Millennium Tower seen from across Beale Street, image by Andrew Campbell Nelson
Millennium Tower at sunset between the Salesforce Tower and 181 Fremont Street, image by Andrew Campbell Nelson
Millennium Tower from Main Street, image by Andrew Campbell Nelson
As of last month, NBC reported the building is leaning around 29 inches at the top at the northwest corner. Hamburger had previously said that the structure’s safety systems, including the elevator and sewage connections, may stop working if the tower leans 40 inches or more.
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