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Will It or Won't It? The Oroville Dam's Potential Collapse

Posted February 16, 2017 10:25 AM by HUSH
Pathfinder Tags: dam infrastructure Oroville weather

It isn’t too hard to argue that here in the United States we take our infrastructure for granted. Next month, the American Society of Civil Engineers will release its 2017 report card on the state of American infrastructure. ASCE updates the report card every four years. In 2013, the cumulative GPA for the U.S. was a D+, up from a D in 2009. No one is expecting the U.S. to make Honor Roll this year.

One of the lowlights from 2013 was the country’s grades on dams, also a D. It noted that the average age of the 84,000 dams in the U.S. was 52 years old. The number of high-hazard dams—those whose failure may cause loss of life—has steadily risen over the years, all the way up to 14,000. The reasons for this are twofold. Dam construction techniques have improved and old dams just don’t stack up to new evaluations. Also, more people have moved into the low-lying areas that are shielded by dam walls, some of which were built to poorer standards as formerly the area was undeveloped and less important.

Today, one of the most pressing U.S. infrastructure challenges in recent memory continues and the threat of a partial dam collapse persists even as workers attempt to reinforce the dam at this very moment.

After days of rain, on February 7 Oroville Dam officials opened the dam’s spillway so excess water could begin to drain from Lake Oroville, which is at its highest February water level in more than 30 years. The spillway routes water past the dam’s hydroelectric plant as well as bypass valves that had been broken since 2009.

Despite the flushing being well within the spillway’s design limits, operators noticed a hole developing in the spillway. With the lake’s water level rising up to 20 feet per day the spillway had to continue to be used, and gradually the hole grew into a crater. Eventually the debris carried from the 500 ft. x 300 ft. by 50 ft. crater fell into the river below, blocking the outlet of the hydroelectric plant.

State engineers determined that they would need to use the dam’s last resort, its emergency spillway. While it’s not made of concrete like the main spillway, the emergency spillway is a nearby embankment that sits 20 ft. lower than the lip of the dam. On February 11, water crested the edge of the auxiliary spillway. Slowly but surely the water eroded this hillside too, and finally on February 12 an evacuation order was given to 188,000 residents of the Feather River valley. Engineers became less confident in the spillway’s ability to hold as snowpack that is 50% above normal combined with excessive rain. With more rain in the forecast for this week, there is no shortage of wet stuff.

It’s arguable that this disaster-in-the-making could have been prevented. It is well-known that California is in the midst of an epic seesaw drought. Perhaps that is why in 2005, state and federal officials decided not to reinforce the emergency spillway, despite requests from environmental groups including the Sierra Club. What’s notable is that the auxiliary spillway began to erode with water flows of 12,600 ft.³/s, a volume much lower than its specified capacity of 350,000 ft.³/s.

Water flow has finally receded to the point where crews are airlifting and excavating boulders and sandbags into place in the gulley of the auxiliary spillway.

As of Valentine’s Day evening, locals were allowed to return home but were prompted to remain ready for another potential evacuation. The situation at Lake Oroville is tenuous, but appears to be in control for now. The same cannot be said for thousands of other risky dams around the country.

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#1

Re: Will It or Won't It? The Oroville Dam's Potential Collapse

02/16/2017 10:53 PM

Some clever administrator just needs to tell DT that he needs a few Billion$ to build walls, employing 1000's of people.

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Re: Will It or Won't It? The Oroville Dam's Potential Collapse

02/17/2017 2:18 AM

..........or is that DD - (Donald Duck)

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#3

Re: Will It or Won't It? The Oroville Dam's Potential Collapse

02/17/2017 8:22 AM

Seems like I read somewhere that the federal government had given California money to upgrade this dam but the governor spent it on other things. Can't remember the source. Kind of like New Orleans that had moneys to upgrade the leveys but party time was more important.

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Re: Will It or Won't It? The Oroville Dam's Potential Collapse

02/20/2017 6:09 PM

Since time immemorial, transient political convenience, and bean-counters, continue to be the bane of civilization becoming any more civilized...

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Re: Will It or Won't It? The Oroville Dam's Potential Collapse

02/17/2017 9:24 AM

All of the public disclosures on this dam state that the dam itself is sound and not at risk for a collapse. The problem is in the design of the spillways used to prevent the dam from being over topped. An over top could create a cascade of problems leading to a dam collapse but that is not imminent. What is critical in this article is that the spillway failed with less than 5% of the water flow it was originally intended to handle. Unless some earlier incident (quake?) weakened the concrete spillway before it was needed then the soundness of the dam construction is in question. The previous dam collapses in California of St. Francis, Baldwin Hills and Mulholland point out that this can and most likely will happen again one day.

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Re: Will It or Won't It? The Oroville Dam's Potential Collapse

02/17/2017 10:15 AM

That collapsed in 1928. I've seen the debris left behind by that dam when hiking in that area in the 1970's, with a guy that was alive and lived near that area when it happened.

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Re: Will It or Won't It? The Oroville Dam's Potential Collapse

02/17/2017 1:33 PM

From the photo, it appears that the dam, itself, is relatively safe for now, but that the emergency (triangular-weir) spillway (see photo, upper-left), is suffering dangerous erosion of it's unprotected hillside, so much as to be in danger of imminent progressive failure...

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Re: Will It or Won't It? The Oroville Dam's Potential Collapse

02/17/2017 11:22 AM

I think one of the main problems with infrastructure (this dam included) is that it is the individual state's responsibility and they let it go to hell. Then when it is in imminent failure or failed they cry for Federal emergency aid...and get it! This allows the state governments off the hook for spending the maintenance $$ on other pet projects or programs. Then other taxpayers from other states get to pick up the tab.

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Re: Will It or Won't It? The Oroville Dam's Potential Collapse

02/17/2017 4:40 PM

Well I wouldn't wait for the next evacuation alert/traffic jam fiasco, I'd get out of Dodge now, while the gettin's good....and wait for the repairs to be completed properly...

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Re: Will It or Won't It? The Oroville Dam's Potential Collapse

02/17/2017 11:44 PM

A. Report cards (?) How silly. How about using the energy to grade infrastructure to come up with a plan of action.

Since the " Operators " of the dam can't fix a little hole before it develops into a major cluster____, maybe they ought to put these guys to work on it,,

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Re: Will It or Won't It? The Oroville Dam's Potential Collapse

02/20/2017 1:12 PM

The good news is that they use experienced engineers to do the periodic inspections so they have a better understanding of what they are seeing...

The bad news is that those engineers still don't have xray vision...

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Re: Will It or Won't It? The Oroville Dam's Potential Collapse

02/20/2017 1:37 PM

Why don't they have x-ray vision.

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Re: Will It or Won't It? The Oroville Dam's Potential Collapse

02/20/2017 5:32 PM

Because, Superman, the only guy that did have xray vision, eventually became so fed-up with humanities' inability to solve it's own problems, that he simply threw up his hands one day , and left in disgust... (so I think I heard somewhere...)

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Re: Will It or Won't It? The Oroville Dam's Potential Collapse

02/20/2017 9:35 PM

Concrete can be x-rayed and ground penetrating radar can also be performed.

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Re: Will It or Won't It? The Oroville Dam's Potential Collapse

02/21/2017 1:17 AM

........Oh! Dam(n)!!!

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Re: Will It or Won't It? The Oroville Dam's Potential Collapse

02/20/2017 10:23 PM

From my readings about the Oroville dam's problems, it seems they use "emergency" and "auxiliary" spillway interchangeably; this is the far left one in the above graphic. What is the "proper" name; I assume "emergency" since that is on the graphic. The middle one is the main spillway, but what to they call the one directly under the dam which hasn't been mentioned in the news except to say it is safe and of no concern?

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#17

Re: Will It or Won't It? The Oroville Dam's Potential Collapse

02/21/2017 5:34 PM

Jerry Brown is a clueless governor, happy to spend California's money on aliens and bullet trains instead of existing infrastructure. Brown's legacy is a dam failure.
/For shame

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