Sinking tower under ‘stresses,’ ’14 report says
Private structural engineers who examined the sinking Millennium Tower in 2014 concluded that “some limited elements” of the building were under “significant stresses” as a result of the settlement and were “more susceptible to damage from an earthquake,” according to newly released public documents.
The assessment, included in a July 25 staff memo on the building, concluded that the tower could still survive a quake and that residents’ safety had not been “significantly affected.” But it said “a limited number of elements, such as the
outrigger coupling beams, and some locations of the foundation mat, are more susceptible to damage than would be the case had the settlement not occurred.”
The revelation is part of the latest batch of documents from the city’s Department of Building Inspection about the Millennium, a 58-story high-rise at 301 Mission St. that has sunk at least 16 inches and is tilting to the northeast.
The developer, Millennium Partners, blames the structural issues on the Transbay Joint Powers Authority, which is building the Transbay Transit Center next door. Millennium Partners says the joint powers authority has weakened the soil under its tower by pumping millions of gallons of groundwater from the area to create a dry construction site. The authority blames the sinking on the developer choosing a foundation with relatively short — 60 to 91 feet — piles rather than drilling 240 feet down to bedrock.
Officials with the Building Inspection Department have said they did not know about the Millennium issues until last summer, when Chronicle reporters started asking questions about the building.
Since then, the agency, which issues building permits and is responsible for enforcing codes, has been releasing public documents bit by bit, but has not released what many consider to be the most important piece of information — the engineering report by Ronald Hamburger of the engineering firm Simpson Gumpertz and Heger.
That report, which the Building Inspection Department referenced in its July memo, was commissioned by Millennium Partners “to examine whether the differentiated settlement of the building has compromised its structural earthquake resistance.”
Millennium Partners spokesman P.J. Johnston said that the report, a draft of which was completed in 2014, is still being finalized. He said the final version “will be issued soon, but that it is still being updated.” Millennium Partners is paying for the report.
Millennium Tower homeowner Jerry Dodson, an attorney who lives on the 42nd floor of the building, said that the city should release the Hamburger report immediately.
“It should be disclosed to homeowners and the public in general to reassure people that the building has been studied by a good engineer and found to be safe,” he said. He called the city memo summarizing what is in the Hamburger report “extremely superficial in light of the gravity of the situation.”
“It doesn’t provide you with any real information on the level of analysis being conducted,” said Dodson. “I think DBI and Millennium have way more information about this than they are letting on. There is a tremendous amount of gas lighting going on to make people believe the building is safe and everything is secure, when there is no proof one way or another.”
One person who has seen the draft version of the Hamburger report is Supervisor Aaron Peskin, who is holding a series of hearings on the Millennium. Peskin called the Hamburger report “inconclusive.”
He noted that all of the reports being prepared are being paid for by parties that have an interest in the high-stakes legal cases that are sure to ensue — the joint powers authority, Millennium Partners and the building’s homeowners groups — and he would be more comfortable if there were an analysis by an independent panel of experts.
“None of this is very satisfactory,” he said.
The latest report was made available Thursday. In it a geotechnical engineer hired by Millennium Partners once again blamed the sinking on the joint powers authority. The report acknowledges that the tower was sinking before the joint powers authority started construction — largely because of Millennium Tower’s own dewatering activities — but says “the rate of settlement was gradually decreasing.” It dropped from .022 inches per day in 2008 to .003 inches a day in 2009. The settlement picked up again after the joint powers authority broke ground on the new transit center in 2011.
“This isn’t about fingerpointing,” Johnston said. “This is about finding out what’s actually happening, and fixing it.”