three foot thick Underground Wall Could Be Hitch for SF's Millennium Tower Fix Plan
“Although the building remains safe, we believe the project needs to resume construction and complete this construction quickly,” Hamburger said at the January meeting of the Audit & Government Oversight committee. “To allow us recovery of the tilt as originally planned.”
But some experts say there could be a hitch – a big one – to that plan. It’s a three foot thick, 90-foot high steel and concrete wall built directly under the eastern edge of the ten-foot thick slab foundation.
“It just creates a huge amount more uncertainty about how it will respond when you implement …the fix,” said deep foundation expert David Williams.
The wall was put in place early on in the project to serve as a buffer between the tower’s foundation and the five level deep parking garage being built next door on the tower’s east side.
That’s the side, under Hamburger’s plan, that needs to settle and sink once weight is shifted so as to straighten the leaning tower. The wall is depicted in early construction photos, which also show that just above the wall is a gap filled with about a foot of soil. The gap was designed to allow the building to settle the six inches that engineers estimated would occur after construction. But the building has sunk so much that surveys done back in 2018 indicate it is now nearly on top of that wall. Williams says the wall could prop up that side of the building indefinitely, and in the process, doom any chance of reversing the tilt.
“So there's a lot of concerns about the fact that it may be hung up on the shoring wall,” Williams said.
https://www.nbcbayarea.com/investigations/series/millennium-tower/underground-wall-could-be-hitch-for-sfs-millennium-tower-fix-plan/2888365/
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