The Millennium Towers: What’s causing one of the most expensive residential skyscrapers in San Francisco to sink?

As described in the Complaint filed by residents and unit owners of the Millennium Towers against the developer Millennium Partners I, Inc., and the Transbay Joint Powers Authority in August of 2016, the tower has allegedly sunk 16 inches as a result of defective foundation and the construction of the Transbay Transit Center.  According to the Complaint, the building has tilted 6 inches at the base, translating to a 15-inch tilt at the top of the building.  The building was anchored using 80-foot friction piles into dense sand, rather than into bedrock.  It is also alleged that the Transbay Joint Powers Authority contributed to the problem at the Millennium Towers when they dug a 60-foot hole next to the structure, removing lateral and subjacent support. While settlement of a building of this size is common and accommodated for in the design, the expected sink of three to six inches has been surpassed and the building’s performance is now in question.

We attended the public hearing concerning the Millennium Towers on September 22, 2016. San Francisco Board of Supervisor Aaron Peskin questioned various members of the Department of Building Inspectors (DBI) regarding what they knew about the proposed foundation, how it was approved, and when the DBI became aware of potential problems with the building’s foundation.  Differential settlement was allegedly known to have existed as early as 2009, and units were being sold between 2009 and 2013.  The tenants, some of whom paid upwards of $10M for a penthouse unit, were not advised of the settlement until a news article exposed the potential disaster.

Members of the DBI testified that the tower sits over landfill, bay mud, and a layer of dense sand called the “Colma Formation.”  Although buildings in the area have used friction piles, their frames are of different material (steel v. concrete) and magnitude compared with the Millennium Tower. Concrete buildings weigh significantly more than steel construction and four new concrete buildings under construction have dropped their pilings 200 feet down to bedrock for the first time in the area.

It was discovered that the DBI did not have any regulations in place on how to deal with buildings of this nature and stature.  During the permit process, and although the design of the building may have been code compliant, a peer review was called for by the DBI to address its structural and seismic integrity and safety.  DBI could not recall if any review had been conducted on the foundation, including the choice of piling.  It was disclosed that a geotechnical peer review was not performed.  The hearings will continue as Supervisor Peskin intends to expose more details surrounding what happened before, during and after the construction of the building.

The settlement issues were brought to the DBI and developer’s attention in 2009.  In February 2009, a member of the DBI authored a letter to the developer and the engineer of record after he obtained information regarding possible issues of settlement, including the rate of settlement at the building.  However, there was very little documentation or evidence to show that the issues and inquiries had been followed up or were resolved other than confirmation that the matter was “taken care of” and that an inspection revealed no obvious signs that needed to be addressed.  Not until a “311” call, which can be made to obtain non-emergency information or make service requests from the city, was placed by an anonymous neighbor following news in the summer of 2016 that the building was suffering significant settlement and that life and safety may be at danger, did the DBI conduct further investigation. At the next hearing the DBI has promised an updated protocol on document management, including how it will handle complaints.  The City Attorney’s office has subpoenaed all disclosures made to the residents at the time of purchase.

Soil experts retained by the Millennium Tower residents have started their investigation.  This includes drilling into bedrock near the building that will allow them to measure the building’s tilt, soil conditions, and details regarding settlement.

What will be revealed? How, and when, will this case ever be resolved? What’s next for this once distinguished member of San Francisco’s skyline?  Stay tuned for the next update!

Blog by: Wakako Uritani, Pamela Bumatay, and Paul Vaillancourt, San Francisco