Plans submitted to re-center San Francisco's sinking, tilting Millennium Tower
SAN FRANCISCO (KTVU) - Engineers submitted plans to fix San Francisco's sinking and tilting Millennium Tower.
KTVU spoke with an engineer who says this will be the permanent fix and will go deep underground here on the North and West sides of the tower. The hope is that the fix will not only stop the tilting. But, will eventually bring the building back on center.
Millennium Tower opened to rave reviews in 2009-- but by 2016 engineers confirmed the building was sinking and leaning-- the latest reports showing the building has now sunk a foot and a half and is tilted 14 inches.
Now an engineering firm hired by the Millennium Tower homeowners association have filed the proposed fix.
"I have done more extensive analysis on this building than any building I've ever designed or retrofitted before," said Ronald Hamburger from Simpson Gumpertz & Heger Engineering who came up with the proposed fix called a perimeter pile upgrade.
The plans call for extending an underground concrete mat under the tower, then drilling 52 new pilings underground along the Mission and Fremont Street sides of the foundation.
Those piles will drill through 250 feet through clay and mud and into bedrock, the plan is then jack the building up on those new pilings redistributing the buildings weight.
It's a commonly used fix, albeit on a larger scale with the Millennium Tower.
"The most challenging part of the design was basically trying to understand the nature of the soils beneath the building and why the building was settling and tilting in the way it was. Once we figured that out the fix was relatively straightforward," said Hamburger.
The work is expected to take close down one lane of traffic on mission and fremont as crews drill the piles into place.
The cost: approximately $100 million.
As for who will foot that bill, "It's a matter of litigation, and I don't know," said Hamburger.
The plans for the fix were delivered to the Department of Building Inspection Tuesday and will go through departmental and peer reviews.
Work expected to get underway in the spring, and is expected to take 18 months.