Quake won’t topple tilting tower, engineers say

A new engineering report has found that the Millennium Tower remains safe in the event an earthquake, but members of the San Francisco Board of Supervisors Tuesday expressed dissatisfaction with the slow pace of efforts to fix the sinking, leaning skyscraper and figure out what went wrong.

The report by an expert engineering panel, released by the city administrator’s office this week, found that the 58-story luxury high-rise at 301 Mission St., which was completed in 2009, should survive a major earthquake.

However the building, which has sunk 17 inches and developed a lean of 14 inches to the west and 6 inches to the north at the top, has continued to sink at a rate of around 1 inch a year since 2010, the report found.

The report states:

“…Our professional opinion is that the foundation settlement experienced by the Tower has not appreciatively affected the safety of the building at this time. … However, because the structure is still settling, continued monitoring and further study of the cause of the settlements is recommended to allow a better understanding of maximum future settlement.”

At a hearing Tuesday, City Administrator Naomi Kelly said that the developer and homeowner’s association, who are currently locked in litigation, have not yet come forward with proposals to fix the settlement problem.

The City is monitoring the situation, and also working to review safety standards and regulations around tall buildings in The City, Kelly said. However, an evaluation of other tall buildings in the area has not been completed.

Kelly said:

“We are moving forward to ensure that all tall buildings in this area are designed and constructed as safely as modern engineering allow.”

Since the first reports emerged last summer that the Millennium Tower was settling more than expected, the building has become the subject of a series of interrelated lawsuits. The developer and the Transbay Joint Powers Authority, which is building the Transbay Terminal next door, have each blamed the other for the building’s woes.

The Board of Supervisors has also held a series of hearings at the instigation of Supervisor Aaron Peskin, seeking to determine not just what caused the problems but why city building officials failed to learn about them or take action sooner.

Supervisors Tuesday expressed frustration that the report did not reach a conclusion about the future of the building, and pressed Stanford professor Greg Deierlein about the causes of the settlement.

Peskin said:

“If we can figure out what went wrong and how it went wrong we can figure out how to prevent it in the future.”

Deierlein, however, declined to specify, saying that there were multiple factors that could contribute including the nature of the soils on which the building sits, the groundwater table and the design of the foundation.

Board President London Breed expressed frustration at the lack of clear answers:

“I realize that there are all these layers of litigation, but I feel like we’re going around in circles. … We should be farther along than we currently are.”