City expert panel says Millennium Tower meets seismic criteria but long‑term settlement and fix remain unresolved

An expert panel convened by the City of San Francisco told the Government Accountability and Oversight Committee on Aug. 1 that, based on available analyses, the 301 Mission Street tower known as Millennium Tower meets the city's seismic performance criteria for a maximum considered earthquake, but long‑term settlement and what a definitive structural fix would require remain unresolved.

"Based on the analyses we reviewed, 301 Mission is safe in the event of a maximum considered earthquake," said Professor Greg Deierlein, a civil and earthquake engineering professor who led the city's expert engineering panel. He said updated modeling by Simpson Gumpertz & Heger (SGH) shows the building's expected seismic story drift (about 2.2 percent) is below the Administrative Bulletin 83 threshold of 3 percent.

The panel’s review, Deierlein said, relied on SGH’s finite‑element and nonlinear "Perform" modeling and on documents including the SGH ("Hamburger") reports from 2014, 2016 and 2017. Deierlein cautioned that the panel did not independently re‑survey raw settlement measurements and that evaluating future settlement scenarios and causes was outside the panel’s contracted scope. "We did not verify the original surveys," he said.

Supervisor Aaron Peskin, who called the hearing during the board’s summer recess, pressed for answers about future settlement and potential remedies. "What we need to know is what do we know, when did we know it, and what are we going to collectively do about it," Peskin said. He noted the latest publicly reported numbers: the tower had settled roughly 17 inches and tilted about 14 inches toward Fremont Street at the top.

Naomi Kelly, San Francisco’s city administrator, said the city is continuing oversight. "SGH's analysis and our expert panel's review point to continued monitoring," Kelly said, adding the city has not received a formal proposed fix from Millennium Partners or the homeowners association and would subject any proposal to expedited peer review once submitted.

Department of Building Inspection (DBI) staff reported focused life‑safety follow‑up inspections. Bill Straub of DBI said inspectors re‑inspected common areas on July 18 and issued a correction notice for missing fire caulking around a sprinkler assembly in the basement; DBI received notice from the building’s engineer that the work was completed and planned a verification inspection.

Residents who live in Millennium Tower told the committee they remain worried about both the building’s movement and the condition of individual units. Paula Pretlow, an owner of Unit 31B, said testing by a private firm found large gaps that she says permit air and odor transfer; she called the defects a "serious fire and life safety concern." DBI confirmed it had scheduled a unit inspection.

Several public commenters and owners criticized the reliance on SGH work paid for by the developer and urged an independent verification of survey data and a scenario‑based analysis of future settlement. Jerry Dodson, who testified on behalf of some owners, said the panel’s approach "did not assist" on future settlement and called for a truly independent review.

Panelists and staff emphasized what the technical review did and did not cover. Deierlein said the modeling showed the building’s seismic performance criteria are met despite observed settlement to date, and that key structural components such as coupling beams and outriggers may experience more deterioration than ideal; he said the settlement itself had, to date, not materially degraded seismic response in the models. "If we knew settlement would stop tomorrow, that would be one situation," Deierlein said. "But we did not study future settlement or causation."

Committee members said policy work is also needed. Members discussed Administrative Bulletin 83, peer review rules, and options—such as heightened peer review of tall buildings or targeted code changes—to reduce the risk of similar problems in the future. Deierlein recommended heightened scrutiny and double peer review rather than a blanket technical mandate that all foundations reach bedrock.

The committee received several requests that the Transbay Joint Powers Authority (TJPA) be held to EIR commitments that callers said required underpinning or special measures where adjacent construction might cause ground movement. The committee said it would follow up on those questions.

After public comment the committee moved to continue the item to the call of the chair so staff, DBI and the city administrator can report further developments and any submitted fix proposals. The committee did not take a formal vote about the building's legal or remediation responsibilities; members said litigation pending between owners, the developer and others means some questions will be resolved in court but that the city will continue oversight and life‑safety follow up.

What’s next: the city said it will verify the completed correction notice items, inspect reported owners' units, accept and peer‑review any formal fix proposals when submitted, and the committee will continue oversight at future hearings.