
Oroville Dam: Feds and state officials ignored warnings 12 years ago - jdp23
http://www.mercurynews.com/2017/02/12/oroville-dam-feds-and-state-officials-ignored-warnings-12-years-ago/
======
krapht
“It is important to recognize that during a rare event with the emergency
spillway flowing at its design capacity, spillway operations would not affect
reservoir control or endanger the dam,” wrote John Onderdonk, a senior civil
engineer with FERC, in the Federal Energy Regulatory Commission’s San
Francisco Office, in a July 27, 2006, memo to his managers.

“The emergency spillway meets FERC’s engineering guidelines for an emergency
spillway,” he added. “The guidelines specify that during a rare flood event,
it is acceptable for the emergency spillway to sustain significant damage.”

tl;dr: in case of flood, anything goes so long as the main dam wall remains
functional?

~~~
rhizome
You can't just pave a lake, engineers _have_ to be calculating the dirt
spillways as ablative. Water is powerful stuff.

~~~
the_cap_theorem
what does ablative mean in this context?

~~~
Someone
[http://www.geography.learnontheinternet.co.uk/topics/river_e...](http://www.geography.learnontheinternet.co.uk/topics/river_erosion.html):

 _" Rivers erode in four ways:

Abrasion or corrasion - This is when large pieces of bedload material wear
away the river banks and bed.

Attrition - This is when the bed load itself is eroded when sediment particles
knock against the bed or each other and break, becoming more rounded and
smaller.

Hydraulic Action - This is when the force of water erodes softer rock.

Solution or corrosion - This is when acidic water erodes rock."_

So, there will be larger pieces of rock intake water that hit the bank of the
spillway, slowly destroying it.

When engineering the spillway, you have to take that into account.

That means we have to accept that it will need repairs after use, just as a
fire extinguisher needs it after use.

------
yread
I was just wondering about it the other day while researching the topic: why
are there so many dam failures in the states?

[https://en.wikipedia.org/wiki/Dam_failure#List_of_major_dam_...](https://en.wikipedia.org/wiki/Dam_failure#List_of_major_dam_failures)

Since 19th century US has the most (well, at least a lot) dam failures.

Is it because there are so many? Are they privately owned and the owners just
count on declaring bankruptcy if it fails? Is it the engineering, the geology,
the maintenance?

EDIT: Even such a major project like Hoover Dam was not done properly (it
seems grouting curtains were not often used elsewhere)
[http://web.mst.edu/~rogersda/hoover_dam/Grout%20Curtain%20Fa...](http://web.mst.edu/~rogersda/hoover_dam/Grout%20Curtain%20Failure-
Hoover%20Dam.pdf)

~~~
coldtea
> _I was just wondering about it the other day while researching the topic:
> why are there so many dam failures in the states?_

Given that, anybody want to bet on the safety of nuclear reactors?

~~~
xenophonf
I'll take that bet.

~~~
coldtea
Well, it's always "different this time", because "newer designs".

Meanwhile countless tones of toxic waster from said reactors are also
transported through regular highways and roads en route to disposal and/or are
dumped in the sea by governments and "cheapest offer" subcontractors
(including the mafia [3]).

[1] [http://www.independent.co.uk/news/ministers-admit-nuclear-
wa...](http://www.independent.co.uk/news/ministers-admit-nuclear-waste-was-
dumped-in-sea-1248343.html)

[2]
[https://www.wsj.com/articles/SB10001424052702304773104579268...](https://www.wsj.com/articles/SB10001424052702304773104579268563658319196)

[3]
[https://en.wikipedia.org/wiki/Toxic_waste_dumping_by_the_'Nd...](https://en.wikipedia.org/wiki/Toxic_waste_dumping_by_the_'Ndrangheta)

~~~
xenophonf
As I understand it, coal-fired power plants emit more radiation than nuclear
power plants:

[https://www.scientificamerican.com/article/coal-ash-is-
more-...](https://www.scientificamerican.com/article/coal-ash-is-more-
radioactive-than-nuclear-waste/)

Until sufficient solar and wind power generation comes online, I would rather
we use nuclear and gas-fired power plants, and in that order. I think that on
the balance nuclear power is cleaner. The sooner we get off fossil fuels, the
better.

------
Animats
As of midnight, the reservoir level was at 899.77 feet, and flow over the
emergency spillway has stopped. If the level is above about 900 feet, the
excess goes over the emergency spillway. Peak was around 902 feet. Data feed
from dam sensors here: [1] Google Maps view of emergency spillway under normal
conditions here: [2] Compare with drone footage from yesterday.[3] Main
spillway (which has gates) is back in use.

Things look a bit better than a few hours ago.

[1]
[http://rdcfeeds.redding.com/lakelevels/oro.cfm](http://rdcfeeds.redding.com/lakelevels/oro.cfm)
[2] [https://goo.gl/maps/mzwyXvRvZAv](https://goo.gl/maps/mzwyXvRvZAv) [3]
[http://www.sacbee.com/news/local/article132154774.html](http://www.sacbee.com/news/local/article132154774.html)

~~~
jnsaff2
The outflow hasn't changed so I'm not convinced that the flow over the lip has
stopped. #armchairanalysis

~~~
wtallis
The outflow seems to be the ~100000 cfs from the main spillway draining at
full capacity, which they opened to 100% early in the evening to relieve the
emergency spillway, in spite of the existing damage to the main spillway.

~~~
jnsaff2
Thank you.

By the way there's an amazing book that has a very gripping account of the
Glen Canyon Dam incident and Grand Canyon in general.

[http://www.goodreads.com/book/show/15803144-the-emerald-
mile](http://www.goodreads.com/book/show/15803144-the-emerald-mile)

------
orthoganol
From what I gathered the main spillway is quite damaged with a ~ 200' x 30'
eroded hole in the center, potentially eroding into the supporting hill. It
was a problem even before they doubled the outflow to 100,000cfs yesterday
which I believe is still the current flow.

They want to get the lake down 50' to shutoff the spillway and assess repairs,
but even at the current (high) release rate it appears they can only lower max
~8'/day, which is a problem because heavy rains return on Wednesday.

Let alone the emergency spillway, the main one's at risk too.

~~~
throwawaydbfif
I get the feeling the dam is likely doomed and they're trying to drain the
lake as much as possible to decrease the force of a break

~~~
tajen
Indeed, 13 times more dams than France (who prides itself for 12%
hydroelectricity), while USA is only 5 times bigger in population. China has
the most number of large dams in the world: More than twice the USA, for 4x
population.

[http://www.icold-
cigb.org/article/GB/world_register/general_...](http://www.icold-
cigb.org/article/GB/world_register/general_synthesis/number-of-dams-by-
country-members)

~~~
Bombthecat
That's... Quite impressive...

------
beatpanda
This is what California always does. We forget about what happens in a drought
as soon as the rain comes, and as soon as the rain comes, we realize we forgot
about what happened the last time it flooded. After the catastrophe is already
upon us, recriminations fly, trillions of pixels are wasted on heavy-handed
think pieces, and we forget again, only to wonder why an entirely preventable
tragedy managed to find us the next time one comes.

~~~
hueving
Outrage and complaining is much easier than action.

During the drought, the best thing we got for legislation to 'fix' it, was
preventing people from getting water without explicitly asking at restaurants.
As idiotic at this was (this accounts for approximately 0.0% of water use in
California), activists rejoiced over how they were fixing the problem by
having everyone 'chip in'. Meanwhile farmers continued on not even paying for
the water they use (farming is >50% of water usage).

~~~
x0x0
One almond requires over a gallon of water, and you can buy a pound of raw
almonds for $8 or so at my grocery store. But that 1/16 gallon glass of water
is gonna save the day.

Meanwhile, our state capital is -- wait for it! -- building out water meters
so they can tell how much each house is using. They're trying to get 80% of
households by 2025.

------
Freestyler_3
It reads like they designed the spillway to withstand this much water,
provided that the ground it rests on doesn't move. Was it a sink-hole under
the spillway or the force of water broke the concrete and then created the
hole?

~~~
nraynaud
My understanding from this accident and the Glen canyon dam accident, is that
they are not very good at concrete in contact with rushing water.

In this last instance, the rushing water is eroding the dirt under the
emergency spillway so it will end up forming a bridge. the emergency spillway
is a mini-dam, it will just fall if it's not supported. And if it falls, the
rushing water will erode the rest of the dirt, lower and lower. The worst case
scenario is a complete dam accident (uncontrolled drainage of the lake) that
would not even involve the actual dam.

~~~
Freestyler_3
Ah thank you, makes it much clearer.

They were dropping rocks with helicopters to slow down the eroding I heard.

------
themodelplumber
Do we know if this has the potential to flood the old ICBM complex at Sutter
Buttes?

~~~
Gargoyle
Sutter Buttes are a couple thousand feet in elevation, well out of danger even
if the whole dam collapsed.

------
rodionos
Current Storage vs Capacity Levels:

[https://apps.axibase.com/chartlab/dee79515](https://apps.axibase.com/chartlab/dee79515)

The overflow lasted for 45 hours.

------
lucaspiller
> with flows of only 6,000 to 12,000 cubic feet per second

In case anyone needs something to put that into perspective, an Olympic-size
swimming pool holds around 35,000 cubic feet (1 megalitre) of water.

~~~
wiredfool
And the 100000cfs on the main spillway is 5 million lbs/sec.

Edit: oops. Off an order of magnitude.

------
TwoBit
Does this mean that a lawsuit after a catastrophe would much more likely
succeed?

~~~
dorianm
[https://en.wikipedia.org/wiki/Act_of_God](https://en.wikipedia.org/wiki/Act_of_God)

------
yellowapple
It's rather surreal that Yuba City (where much of my family lives) is making
national news. Not sure how to process it.

------
throwawaydbfif
Holy shit look at the pictures. Both the regular and emergency spillway are
heavily damaged and even more rain is expected Tuesday and in the coming
weeks.

They shut the main spillway off because of damage and now they're running it
at maximum flow because the emergency spillway is even more damaged. This
feels every bit like a hail Mary pass to drain the lake as much as possible
before the dam breaks. In another day or two they won't have any spillway
left.

This dam is doomed, it seems like one of the rare times media is downplaying
the risk... Probably because a lot of people are going to die :(

~~~
the_mitsuhiko
Why does the damage on the spillway matter? Is it fear of erosion if it does
not go down the spillway?

Twitter says it's below the emergency spillway level now anyways so that
damage shoukd not matter from what i understand.

~~~
Gargoyle
If the emergency spillway goes, that's 30ish lake-feet of water that would
drain uncontrolled. That would likely wipe out a few towns down the river.

I think gp was getting to the fact that the main spillway is eroding as well,
and it could reach a point where it was unusable. In that case, with
significant rainfall expected in the next week and a good deal of snow melt to
follow, there could be huge amount of water coming into the basin with no way
to control the outflow, which could result in much worse flooding.

Hopefully that all can still be avoided. It's a bit dramatic to say it's
inevitable. It's a possible scenario, but it's also possible the right plan
avoids it.

------
guelo
This whole emergency evacuation makes no sense to me. They cut the flow on the
main spillway from 100,000 to 50,000 cubic feet per second to push water to
the emergency spillway and it immediately started dangerously eroding at only
6,000 to 12,000 cfps. So they cranked the main spillway back up to 100,000
cfps and as I type this the water level has dropped back down well below the
top and the erosion danger has passed. The damage on the main spillway looks
severe but not at immediate emergency levels. But in the mean time they have
unnecessarily caused panic among 180,000 people with no warning and generated
national headlines. It just seems like a lot of overreaction.

~~~
throwawaydbfif
The damage to the main spillway is extreme. Look at the pictures, it's more of
a semi controlled waterfall at this point. If erosion moves upstream on the
spillway, which it eventually will, once it reaches the gates they will need
to stop the spillway or risk the dam itself.

Their emergency spillway is already unusable, so this means just get everyone
out and wait for the dam to blow once the main spillway erodes too far back

