What Really Happened at the Millennium Tower?

The Millennium Tower at 301 Mission Street in San Francisco is famously tilting and sinking into the ground. How does geology affect the design of skyscraper foundations, and what is being done to fix this structure?

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This is not engineering advice. Everything here is for informational and entertainment purposes only. Contact an engineer licensed to practice in your area if you need professional advice or services. All non-licensed clips used for fair use commentary, criticism, and educational purposes.

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Producer/Writer/Host: Grady Hillhouse
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[vizionthing]

At least they didn't build it in an area prone to earthquakes and liquefaction.

[ricos]

Why didn't they just get the residents to put all their stuff at one side?

[nickbono]

I did some geotechnical drilling in the Bay Area for a couple years and I hated that bay clay. We called it bay mud as it was super dense, very sticky, and stinky. Fun job though as it was very interesting to literally see the different layers of soil beneath you as you pull out sections of soil and rock. Bedrock coring was my favorite because we would drill and pull out a cylindrical tube of solid rock and we could see all the layering of millions of years of rock formations.

[cayrick]

This video was made 7 mos. ago and Hamburger has made more mods to his proposed repair by reducing the number of piles from as I recall, 52 down to 18. This will produce less vibration during installation but pile loading will increase. The fact that they keep tweaking and tweaking the design suggests to me that ultimately this bldg will be torn down or at minimum some number of floors will be removed. All of these measures are stop gap to forestall the inevitable.

[STEMforlife]

Speaking as a geotechnical engineer, this is the best project I’m glad I never worked on.

[ariochiv]

I've probably said this before, but I'll say it again: I'm pleasantly surprised and gratified that such technical videos appear to be so popular. I'm sure that a lot of it has to do with how well they are assembled and presented, but I think it also says a lot about people's interest in technical subjects. People are smarter than they're often given credit for, and subjects can be highly technical as long as they are also clearly explained. Thanks for what you do and how well that you do it.

[rmTheWalrus]

As an engineer (albeit in a rather different field) I can say that one of the most demoralizing things in my life have been situations where you discover “yet another problem” that threatens to unhinge the entire project. I have no idea whether and where the mistakes may have been made, but I empathize with what the various engineers in this story must have (and are likely still) gone/going through…

[bobv]

I was working on the new construction as a drywall, metal stud framer. The year was winter of 2008 . The windows weren’t installed on many floors and wind would come in and take out anything that wasn’t tied down. The fog would be so thick inside that you couldn’t see but 20’ and the cold temperatures coupled with wind was a challenge. I have some great memories of this project. I was 44 at the time, now 58 and retired from local 152 Martinez Ca. 36 years of framing in the city. The company was Anning Johnson Co. and the foreman’s name Jim Hayden (Retired) and Ted both long time employees of AJ. Thank you for sharing.

[MikeBaxterABC]

When The excavator was digging the basement for my new house we found bedrock just a few feet deeper than the original depth planned ... I paid extra to dig down to bedrock. The footings are drilled and pinned to that bedrock, and the ten foot ceilings in the basement make it a unique living space.

[sicksock]

There's something uniquely unsettling about such a large building tilting.

[unvergebeneid]

The YouTube channel "Building Integrity" had an interesting update on this a couple days ago where he predicted that the steel plates transferring the hydraulic load into the concrete are way too small.
Now I'm the wrong kind of engineer to have an opinion on this but there might be a chance for an update video if this whole rescue plan fails spectacularly 😄

[kk_bricks]

So my understand was that not only was it the piles not reaching through the old bay mud to the dense bedrock, but that the structural system was also changed. Originally the plan was for the building to be constructed with steel girders and columns and thus the engineers understood that the old bay mud should be enough for the structure as it was designed. The developer however in a bid to save cost on the structure proposed with the contractor to replace the structural system with a reinforced concrete design, not taking into account the design for the sub-structure that was going into the ground. This also contributed on top of the issues outlined in this video about why the building sunk faster, but the added weight of the concrete instead of steel was also not taken into account thus exacerbated the sinking.

[MasterMayhem]

“This structure is incomplete and already tilting”

“No worries, just keep building”

[andrewday]

“But the estimated cost for the repair was as much as $500 million, more than the original cost of the entire building. Turns out it’s a lot easier to drill foundation piles before the building’s built than afterwards.”.
Great quote, you win this one

[giuseppeworthington]

After what happened in Miami, you'd have to be crazy to trust a building with a history of problems like this.

[KillerArcadeGames]

Jeez, this channel is addicting. I love knowing how things work and am especially interested in infrastructure stuff you can't always see. It also helps that I'm in San Antonio so I see local stuff I've wondered about.

[JeffGeerling]

6:41 - a comprehensive settlement... (of the legal kind) 😆

[theeota]

Channels like this are literally all I wanted as a kid while watching shows like modern marvels. Its so fun and the content is informative.

[bradlevantis]

A follow up on this would be great. From what I saw in December 2023 significant issues were still ongoing

[khughes]

I happened upon this video and am I glad a did. What a serendipitous find it was. Your explanation of what is going on at Millennium Tower is, perhaps, the best comprehensive overview I have ever heard...from the beginning of this ordeal back in 2016. The manner with which you explain the engineering situation even as you allow the listener to remain interested in the topic...is outstanding. I am not an engineer but you kept my interest for the entire video. You remind me of the professors I had as an undergrad who explained things so well, you actually didn't want the class to come to an end each day. Great job!