The word of the day is "dewatering." That’s supposedly what’s behind the dramatic sinking of the Millennium Tower, Millennium Partners founders told reporters at a press conference this morning.
Dewatering (as explained in this 1,600 page Caltrans field manual) is simply the process of pumping water out of the ground under and around a construction site. Naturally, this sinks the water table and compresses the earth. That’s the whole reason you do it,.
But Millennium Partners founders Chris Jeffries and Phil Aaron claim that the ground beneath Millennium Tower has been continually dewatered for years, dropping the water table a "reckless" 20 feet since 2011 and sinking the building with it via the old French press mechanic.
The culprit? The nearby Transbay Center site, which MP says has been drinking their milkshake all along.
No surprises on that front. Although Millennium Partners has not said much publicly about their building woes before today, what they have said almost always involved implicating the Transbay Joint Powers for undermining them (literally).
Jeffries alleges that Transbay neglected to create a watertight seal around their project, that they turned off water monitoring devices in early 2015 for seemingly no reason, and that Transbay has (pardon the phrase) stonewalled Millennium for years, even as the waters receded.
"The problem is not our foundation," Jeffries said. "The state of the art is not to drill to bedrock," he added, again presenting a laundry list of buildings MP says have similar sandy foundations as Millennium Tower.
(For more on the engineering principles that are supposed to keep a foundation like this stable, see our simplest possible technical explanation.)
Transbay Joint Powers have not yet responded to our requests for a comment. Previously, Transbay claimed that it anticipated the building’s descent years ago and warned Millennium well in advance.
Jeffries does admit that most of the building’s settlement (as much as 12 inches) is the doing of Millennium Partners. They themselves dewatered the area significantly more than originally planned.
But he was also quick to claim that the the building is designed to settle that far without incident, and that it’s the additional quagmire next door that’s to blame any problems.
"We are appalled that this situation has become one of finger pointing," Jeffries added, despite just wrapping up a half hour address comprised largely of a finger pointed straight at the folks across the street.
Lest anyone think we’re to accept this all on the authority of a pinky swear, the company promises to turn over corroborating documents (along with an independent report illustrating that the building it still safe to inhabit) to the Department of Building Inspection.
Meanwhile, a City Hall hearing on the tilting tower is set for Thursday. City Attorney Dennis Herrera is presently issuing relevant subpoenas, including to Millennium Partners.
- Field Guide to Dewatering [Caltrans]
- Dozens of High-Rises Built On Sand [Curbed SF]
- Don’t Blame Us For Tower, Transbay Says [Curbed SF]
- Engineer’s Simple Explanation of Millennium [Curbed SF]
- Millennium Investigation Begins [Curbed SF]