Is there a cheaper solution to stop Millennium Tower from sinking and tilting?
Independent American Communities
Deborah Goonan
15 September 2018
San Francisco’s Millennium Tower has gained notoriety for sinking
18-inches into the soil beneath the mammoth structure, causing the
building to tilt to one side.
For several years, condo owners and the homeowners association have
been engaged in legal battles with the developer. Both sides conducted
various invasive tests of the site and the building, and the City’s
Department of Building Inspection (DBI) was supposed to be kept in the
loop by Millennium’s mangement team.
But after a window cracked on the 36th floor of the tower over Labor
Day weekend, DBI found out about the problem from local media reports
(see video about the drone accident, below), not from the HOA or its
manager.
Earlier this week, that communication breakdown prompted DBI to
threaten to “yellow-tag” the building if certain safety measures and
inspections were not completed by Friday, September 14. DBI later
backed off of its threat, allowing Millennium Tower’s management team a
bit more time to arrange for DBI inspections of some 400 units in the
building, as well as repair of its window washing crane.
The cracked window has been taped from the inside, and the HOA says its
engineers have not yet determined the cause of the cracking. The HOA
has begun the process of erecting scaffolding around the tower,
in order to protect pedestrians, vehicles, and neighboring buildings
from potential damage due to falling debris.
Earlier this week, the HOA hired a drone operator to attempt to get
photographs of the exterior of the window, to help determine the cause
of the cracking. But, as bad luck would have it, the drone lost its
satellite signal and came crashing down to the ground, nearly hitting a
young boy.
Amidst all of this chaos, NBC Bay Area reports that there may be a
solution in the works. The proposed $80 million fix would be far less
expensive than the $400-$500 million proposal to drive dozens of piles
through the building’s foundation and down 200 feet into bedrock.
Instead, the developer is reportedly proposing to drive fewer but
larger piles into the sidewalks along the northwest corner of the
building, then attach these supports to the building’s foundation.
However, an engineer interviewed by NBC Bay Area, Joe Maffei, expresses
some skepticism about this cheaper solution. What if driving piles on
one side of the tower allows the building to continue sinking on the
other side, causing it to tilt in the opposite direction?
But anyone following this story is apt to wonder if cheaping out on an
after-the-fact foundation support system is a good idea, especially
since Millennium Tower’s sinking and leaning appears to have been
caused by cutting corners on the original foundation’s support system.
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