The Millennium Tower, located in Yerba Buena next to the Transbay and Salesforce Tower constructions, is a symbol of the new San Francisco wealth. The tony high-rise, currently offering the most expensive one-bedroom in the city, houses such luminaries as Hunter Pence, Joe Montana, and a slew of tech brethren.
The building is also sinking.
That is the word from Matier & Ross. Rumors of the structure’s slow sinkage have been swirling over the last few months, but today the Chronicle has confirmed that the sleek, lauded building isn’t what it’s cracked up to be.
...[S]ince its completion in 2008, the 58-story building has sunk 16 inches, according to an independent consultant hired to monitor the problem. It has also tilted 2 inches to the northwest.
"That’s significant ... and of concern," said Professor Greg Deierlein, director of the John A. Blume Earthquake Engineering Center at Stanford University, who has been called in to evaluate the designs of a couple of San Francisco’s newer downtown high-rises.
In lieu of publicly taking responsibility, the building’s owners have placed the blame on neighboring construction.
The problem first came to light in 2010 when the Transbay Joint Powers Authority, the public agency constructing the transit center, hired the consulting firm Arup to gauge how the excavation could affect the tower.
According to the consultant’s initial report, by the time excavation began — two years after the $350 million Millennium was completed — the tower had already settled 10 inches. That was 4 inches more than its builders had predicted for the life of the high-rise.
P.J. Johnston, a spokesperson for Millennium Partners, lays blame on Transbay construction, telling Matier and Ross, "They built a half-mile tunnel 60 feet underground and next to our building, and they were supposed to (protect the Millennium) — and they didn’t."
The transit center, for their part, says they bear "no responsibility for the tilt and excessive settlement."
In fact, there stands several reasons why the Millennium is sinking—for starters, it's not steel-framed and instead uses a concrete design. Also, as the Chronicle points out, "the building is located on unstable mud-fill, just off the bay’s original shoreline."
And perhaps most damningly:
The Millennium’s engineers anchored the building over a thick concrete slab with piles driven roughly 80 feet into dense sand. "To cut costs, Millennium did not drill piles to bedrock," or 200 feet down, the transit center authority said in its statement. Had it done so, the agency said, "the tower would not be tilting today."
The Transbay Joint Powers Authority reportedly spent more than $58 million building "an underground buttressing system to shore up the Millennium before beginning excavation in 2010," hence why the new transit center’s costs are reaching upward of $2.4 billion.
While the Millennium Tower’s sinkage into the earth is reportedly not a safety issue for residents, it does pose a problem for investors. Buyers won’t be so keen to hand over down payments for a structure that’s tilting into the ground—not in an earthquake-prone city like San Francisco, anyway.
While sinkage is typical for many high-rises—the famed Petronas Twin Towers in Malaysia, for example, sank only a half inch since opening in 1998—the rapidity of 301 Mission’s plunge is cause for alarm.
As for fixing this frightening issue, not a lot can be done. Talk of pumping cement under the building is one Band-Aid measure being tossed around. Civil engineers are currently working on trying to remedy the issue. What is sure is that lawsuits galore should begin as a result of this snafu.
This could be one of the most pricey battles in San Francisco real estate history. Curbed SF will update as soon we know more.
- SF’s landmark tower for rich and famous is sinking and tilting [SF Chronicle]
- Millennium Tower [Cured SF]
- San Francisco's Most Expensive One-Bedroom Home for Sale is Asking $3.8 Million [Curbed SF]
- Hunter Pence Catches a $4.25M Millennium Tower Condo [Curbed SF]
- Transbay Transit Center [Curbed SF]