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Comment by Anechoic | Hacker News Reader

their soil stability test holes kept failing inspection

What do you mean by "stability test holes kept failing inspection"? If you're referring to geotechnical boreholes, there's nothing to inspect - it's a test of (among other things) soil strength. It's certainly possible to have soft/loose/low-strength soils (soft/loose solis frequently cause the borehole to collapse on itself, that's not unusual) but that doesn't speak toward safety. The building just has to be designed & constructed to account for that, usually by stiffening the soil and/or using a pile foundation.

I’ve always wondered how many other buildings are in the same state.

Given the loose soils and relatively high-water table in Seattle? Pretty much all of them. Structures can be built on soft ground, it just needs to be done right.

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No. The point was that the engineers should have fixed the design, but since the job was already started, it would cost too much to change or delay, so others decided to keep testing to find a result to Cherry pick.

Also, no, not referring to buildings on normal engineering. I’m talking about buildings built with corners being cut. This was also not in Seattle and wasn’t low lying, was on a hill.

A quote I often hear referred to in inspections: "It's not our job to catch you, it's your job to follow the law". If someone wants to deliberately avoid certain inspections, it's not that hard.

But your friend's story doesn't make a lot of sense. The foundation would have been engineered for the soil that was there, not designed, then tested to see if the soil matched. Even cutting corners, it doesn't make sense to do the steps out of order. So I imagine there's more to the story.

Lots of things on massive projects don’t make sense. And of course there is more to the story, I was summarizing.

Sometimes what is on site is not always what was in the report. And sometimes land nearby becomes unstable and retesting is required.

Also codes change on projects that take years. The current data center they are building gets changed to the prints almost daily.

>using a pile foundation

of course you need piles deep enough, and boreholes soil test results probably factor into the decision of how deep it should be. The $100M fix for the tilting and sinking 58-story SF tower built in 2009 with "floating" piles not reaching the bedrock :

https://www.sfgate.com/news/editorspicks/article/SF-s-sinkin...

"The solution, likened to putting a bumper jack next to a flat tire, will involve the installation of 52 piles along the north and west sides of the tower. The piles will be beneath the sidewalk, 250 feet into the bedrock of downtown San Francisco, and be tied with the original 60-90-feet-deep foundation piles."

A floating foundation can be safe. But not if you dig a giant hole next to it and pump out all the water. SF quietly settled and paid for most of the repairs.

Soil stability and it's ability to support a building depends a lot on water situation.

>A floating foundation

reminded - back at University i worked summers on construction mostly doing foundations in Siberia in permafrost zone. The most memorable part of the quick introduction to the profession there was when they showed us several buildings which didn't have piles deep enough - most of those you could easily spot from a distance by the building shape defects like tilting, bended roofline, etc... because if piles aren't deep enough the foundation pretty much becomes really "floating" during warm season after several cycles of freezing/thawing.

Related, at a bigger scale, global warming affecting foundations in the permafrost zone https://www.theguardian.com/cities/2016/oct/14/thawing-perma...

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