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Soil Analysis Planned At The Leaning Millennium Tower Of San Francisco

SAN FRANCISCO (CBS SF) -- A letter from management at San Francisco's Millennium Tower to the building's residents announced that they will begin installing below-ground measurement devices to collect data on the sinking, leaning luxury tower.

The letter states, "we will begin to install below-ground measurement devices in locations adjacent to the building…to monitor and collect data…regarding soil conditions, settlement and possible repair/mitigation options."

The work's set to last three weeks while the data collection is expected to run a few months.

The high-rise in the South of Market area has been sinking and tilting much more than anticipated.

UC Berkeley Professor of Engineering Nicholas Sitar said, "Settling is a very normal part of these very large structures, all of downtown San Francisco is actually settling."

Before anyone gets too alarmed by the Millennium Tower, Sitar wants you to know that towers were built to sink.

So what engineers really need to understand is why this building is sinking more than expected, and more importantly - what is it going to do in the future

"This is really the big question: what is going to happen next?" Sitar said. "There's a good scenario and there's a bad scenario, and the truth is probably someplace in between."

If it turns out that the building does need some kind of fix - the easiest solution would be reinforcing the foundation.

"Injecting material, it's called grouting, or adding additional support," Sitar explains.

More serious trouble would mean more radical answers like the suggestion floated in today's New York Times, making the structure lighter by actually taking 20 floors off the top of the building.

"In this case that would be the most extreme solution one would consider," says Sitar.

But with so many stakeholders involved, there could easily be disagreements over the severity of the problem, and any proposed fix.

Sitar points out, "The homeowners may have a different level of comfort than the design engineers."

A sinking, leaning luxury condo tower in the middle of San Francisco is a sexy story, people around the world are watching, and it's the kind of thing everyone wants an answer to - yesterday. But first, engineers need to figure out exactly what's happening under this sidewalk, and that won't happen any time soon."

The team that built the building insists it is safe. And there's no official word yet on when the city of San Francisco will offer its assessment of the tower.

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