Oroville Dam in danger of failing

[CardsFan]

And yet, with all this water, CA will suffer a water shortage soon, because there is not enough storage capacity, no matter what the precipitation.

 

[samclem]

The sad fact is that for this not-unprecedented high-precipitation event, the dam design was a failure. The main spillway could not handle outflows well within range. The emergency spillway basically couldn't handle anything.

Before calling the design of the main spillway a failure, let's see why it failed (despite having handled higher flow rates in the past). It sounds like maintenance, rather than design, may very well be the issue with that.

I do agree that the emergency spillway appears to have been "insufficiently robust." In 2005 several groups requested federal funds ($100 million) to line the emergency spillway with concrete, but that was rejected by federal regulators.

 

[JoeWras]

Before calling the design of the main spillway a failure, let's see why it failed (despite having handled higher flow rates in the past). It sounds like maintenance, rather than design, may very well be the issue with that.

I do agree that the emergency spillway appears to have been "insufficiently robust." In 2005 several groups requested federal funds ($100 million) to line the emergency spillway with concrete, but that was rejected by federal regulators.

Very good point. My emotions got the best of me. You are absolutely right.

I was wasting time today reading about Hoover dam because I remember in 1983, it went into spillway mode. I thought: "Man, they really designed that thing well. It had no problems."

But I was wrong. Turns out Hoover dam had some very serious issues with the spillway tunnels in that 1983 event. Huge erosion of the concrete liner. And this was after they discovered the flaw in a 1941 test, where the same erosion occurred. From that, they polished the concrete and tried some other things. The current thought is aeration may be the solution.

Point is, if the Oroville spillway was not being watched, and if any cracks, fissures, undulations, concrete erosion and roughness has been occurring, it may have resulted in cavitation or other problems. Clearly the spillway can handle 100k cfm. Why couldn't it now? Could very well be maintenance. Maybe that will go down in the books for the future. These things need to be watched.

 

[jazz4cash]

I read the wiki for Oroville. It was nicknamed "the dam that talks" due to the embedded sensors that are supposed to provide feedback on the structure but I guess they didn't include the spillway in the feedback loop. I agree it's way too soon to say what caused this problem but I'll bet it's a combination of things. Kudos to the design of the main structure (AFIK).

 

[Ronstar]

I read the wiki for Oroville. It was nicknamed "the dam that talks" due to the embedded sensors that are supposed to provide feedback on the structure but I guess they didn't include the spillway in the feedback loop. I agree it's way too soon to say what caused this problem but I'll bet it's a combination of things. Kudos to the design of the main structure (AFIK).

I don't know if the embedded sensors are part of the dam deformation system, but they could be. Deformation analyses are performed on dams, bridges, buildings, etc to determine structure movement due to earthquakes, crustal motion, etc. A series of survey monuments are generally built into structures for this purpose. Horizontal and vertical measurements are taken periodically at the monuments and compared to historical data to determine movement.

Deformation analyses have been performed for several decades, using whatever the most advance surveying technology was available at the time. I wouldn't be surprised if dam deformation control monuments today are attached to continuously operating GPS receivers that would publish deformation realtime.

That said, I doubt that they had deformation set up for the Oroville spillways prior to this incident. But I assume that they have set up some sophisticated temporary deformation system for the emergency spillway within the last week or so.

 

[imoldernu]

For anyone interested in the California situation, this article may be of interest.

It goes into the broader picture of how the water situations have changed over the past 50+ years, and deals with drought, the construction of the 1500 dams,(most built before 1970) , the current state of the dams, the use of snowpack runoff, and very important, the effect on the groundwater.

In addition, the studies that are underway to repair, and predict the future of water in California.

http://www.theverge.com/2017/2/22/14700460/california-water-system-infrastructure-dams-oroville-don-pedro-flooding-drought

 

[Chuckanut]

I heard that the Oroville dam is supposed to be part of a overall project that included another dam down stream from it. The one dam was never meant to be the only dam controlling the river. However the other dam was never built for money and environmental reasons.

Any truth to that?

 

[Brat]

It is very difficult to build dams today because of the impact on the fishery.

 

[Ronstar]

I heard that the Oroville dam is supposed to be part of a overall project that included another dam down stream from it. The one dam was never meant to be the only dam controlling the river. However the other dam was never built for money and environmental reasons.

Any truth to that?

I don't know of any proposed dam that wasn't built, but there are 2 small dams downstream of the Oroville dam just north of the city of Oroville. These 2 probably help to control the river level through the city of Oroville.

 

[imoldernu]

Aftermath... video:

Following this is a 40 minute video of the press conference over the future of the dams.

 

[2017ish]

article with some stills; maybe excerpted from the same video? Dramatic new images show scale of damage to Oroville Dam spillway - SFGate

 

[Texas Proud]

Looks to me that either the engineers were bad or the construction company....

There should be no reason for this much damage to happen without incompetence ......