
After near-disaster, Oroville Dam spillway about to face its first big test - bryanrasmussen
https://www.latimes.com/local/lanow/la-me-ln-oroville-dam-spillway-20190329-story.html
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_ph_
As the article is already 2 weeks old, in the meantime the test has been
performed successfully. The problem with the old spillway was, that it was
just put on top of the soil. Over the decades, the soil got eroded away by
water in some places, destabilizing the spillway. The other part of the
disaster, after the main spillway failed, was, that the emergency spillway
basically didn't work, so they had to use the main spillway even if it was
completely destroyed.

Rebuilding the main spillway was very thorough work, they removed all soil
completely from the bedrock and filled the space up with concrete. On top of
that they built the new spillway, up to modern standards and much thicker than
the original one. There is all reason to assume that this new spillway will
hold up much longer than the old one, which did work for 50 years. Also, they
are completely rebuilding the emergency spillway so it can be used by adding
massive amounts of concrete.

A great source for in-depth information about the failure of the old and the
rebuilding effort is the blancolirio-channel on youtube
([https://www.youtube.com/user/blancolirio/videos](https://www.youtube.com/user/blancolirio/videos))

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martyvis
And Juan, the man behind the blancolirio channel, has to be the best citizen
reporter out there. He sought many of the real facts and avoided the
mainstream media trap of looking for blame purely to sensationalize the issue.
He seems to have sound engineering knowledge, even though he is an aircraft
pilot by trade. And he was able to put his plane to good use as a great
viewpoint during the construction.

He has also provided wonderful interpretation on recent air incidents
including the 737MAX ( he flies 777 commercially)

~~~
moocowtruck
I'll have to check that out, I do have one question tho (maybe someone asnwerd
it already somewhere?)..if everyone knew soil was underneath then wasn't this
preventable ? or was it one of those..well we can't get the money to fix it
until after something bad happens? I'd say it's pretty obvious soil erodes by
now, and that having it underneath large structures alone is not a great idea.

~~~
Kadin
It's not that straightforward; there was concrete on top of the soil, it had
functioned as designed for many years.

There are problems with infrastructure maintenance at a national level, and
lots of deferred maintenance/upgrades. Given that, there's no reason to
suspect that upgrading the spillway prior to failure would have seemed like a
higher priority than many other remediation projects. There was not an a
priori way of knowing it was going to fail, instead of a bridge abutment or
whatever else was presumably repaired first, and would have had to wait if the
spillway work had happened first instead.

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shereadsthenews
That’s right. If they’d cut down that one tree in time we probably would still
have the original spillway.

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dogsgobork
Video of the new spillway being used
[https://www.youtube.com/watch?v=EFZNUyS89fg](https://www.youtube.com/watch?v=EFZNUyS89fg)

~~~
droithomme
The end of the spillway with the enormous waterfall makes me uncomfortable
since erosion back from that point working backwards along fissures to
undermine the spillway basin seemed to be an aspect of design contributing to
the previous failure. But presumably they have accounted for all that. It
would be interesting to read the post-mortem of the previous failure and the
challenging new engineering decisions behind the new design.

Fortunately the article contains such a source:
[https://issuu.com/asdso/docs/independent_forensic_team_repor...](https://issuu.com/asdso/docs/independent_forensic_team_report_fi?e=16355058/57087615)

~~~
athenot
At the end of the spillway the water is send upward. This is a way to
dissipate the energy of the water coming down and avoid digging a hole or
eroding the river itself. This appears to be a common feature in most
spillways.

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wgrover
Here's a (pre-repair) photo of those energy dissipator blocks at the bottom of
the spillway, including people for scale:

[http://media.fishreports.com/reports/img-20170303-78a7bb40.j...](http://media.fishreports.com/reports/img-20170303-78a7bb40.jpg)

Hard to comprehend how massive those blocks are...

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pdkl95
Yah, it's kind of hard to show the magnitude of the spillway and the repair
work in a few pictures.

Juan (blancolirio) posed a very good time-lapse/montage (including footage
from the DWR) that shows the entire repair project. The audio has comments
from Keiwit's executive project director of the repair project about the
insane amount of material and work that was needed.

[https://www.youtube.com/watch?v=v6lus-
PXS4k](https://www.youtube.com/watch?v=v6lus-PXS4k)

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olliej
Does anyone have the numbers on how much money was “saved” by not doing
maintenance? Was it more or less than the $1 billion required to rebuild it?

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throwaway5752
I think in someone else's link there was a figure about the rejected 2005
improvements to the emergency spillway being $100M. I don't know if that's
correct, if there would have been overruns in cost, if that's inflation
adjusted, or if that would have even prevented the 2017 crisis.

I briefly looked it up, and found some information correlating this under
[https://en.wikipedia.org/wiki/Oroville_Dam_crisis#Timeline_o...](https://en.wikipedia.org/wiki/Oroville_Dam_crisis#Timeline_of_crisis)

