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Oroville Dam

6K views 23 replies 8 participants last post by  zylon 
#1 ·
"Scott explains to Chris how this crisis is indicative of the neglect of the entire US national dam system. Oroville is one of the best-managed and maintained dams in the country. If it still suffered from too much deferred maintenance, imagine how vulnerable the country's thousands and thousands of smaller dams are. Trillions of dollars are needed to bring our national dams up to satisfactory status. How much else is needed for the country's roads, railsystems, waterworks, power grids, etc?"

After intro, etc, interview starts at 3 minutes.

 
#2 ·
That was fascinating, thanks for posting. This engineer was so well informed and articulate. Why do governments always emphasize big capital projects, then skimp on the maintenance? Short term thinking, and fear of losing votes. There are countless examples in Canada too. Like 24 Sussex, which was allowed to deteriorate to the point of being uninhabitable for want of maintenance. In health care, I have seen a provincial government announce capital funding for a new MRI but completely ignore the need to fund its operation, including staff. They like to have their name on a plaque.
 
#6 ·
Did you listen right to the end? They discussed how much it would cost to bring the dams up to code in the US. They are mostly 50-100 years old. The speaker said he had done that analysis, and it would cost about $2 trillion. Trump has promised $500 billion, for everything.
 
#9 ·
The bag of apples I bought last week came from Algoma Orchards, Newcastle, Ontario Canada; however, a lot of produce in my neck of the prairie comes from California.

On another forum I see this:

>"25% of California Food Production is within 1 hr. of this Lake.
If the concrete spillway is washed out, a 30 Ft wall of water will rush down the hillside. The problem won’t be the flood, or the 200,000 people displaced from farms, homes etc. it will be what comes after, the effect of the loss of the essential water for running the 25% of the food production will cause a economic hardship on California that there is no precedent for."<

I'm not sure about the "25%" bit, but it got me thinking that this is reason enough why Canadians might want to pay attention to the Dam issue. If this turns into a worst case scenario, leafy greens in winter going to be dear, Dear.

Wiki says this about irrigation:

>"Water and power from the dam contributes to the irrigation of 755,000 acres (306,000 ha) in the arid San Joaquin Valley Westside and municipal supplies to some 25 million people."<

Then there's this credible sounding comment below the article found here:
http://heavy.com/news/2017/02/orovi...fornia-watch-pictures-video-videos-emergency/

>John Love · Marysville, California "What both of the people correcting the writer of this article are missing is that although the dam and the main spillway are not currently in danger of failing a failure of the emergency spillway could be a catastrophic event releasing a massive amount of water within a short period of time and could result in a wall of water near the break and very deep flooding for many miles to the south of the lake. In Item #1 of things to know this article refers clearly time and again that the current problem is confined to a "Hole In the Emergency Spillway." If this hole erodes the earth below the emergency spillway a possible massive washout of the emergency spillway could be catastrophic."<


 
#12 ·
@heyjude

Thanks for posting that video - very good.

I've seen a couple other videos on the topic, but they try to sensationalize an already bad situation, and I won't link to what seems to be garbage info - fake news.
 
#13 ·
The biggest flood in recent (known?) Canadian history was caused by poorly maintained dams

The department has not succeeded in ensuring that the law on inspecting dams has been respected. The law was adopted in 2002 responding to the aftermath of the Saguenay floods in 1996... commission investigating the floods found that there was poor co-ordination and management of the 2,000 dams in the area.
source
 
#14 ·
It is a good reminder that when politicians start talking about eliminating regulations or reducing the number of people working in the public service, that the people ask exactly where those cuts will be made.

Cutting costs is great, but I think most people still would like to know their infrastructure is getting inspected and maintained, or the meat they are eating meets a high standard of regulatory standard, or if they call in an emergency someone is going to respond.
 
#15 ·
This is certainly an issue going into the future. Dams, and especially dam components like spillways, are not design to last forever. 50 years is pretty good, 100 tops. Certainly not multiple hundreds, though earthfill structures like Oroville might last hundreds if well maintained.

Doesn't seem like a maintenance problem though (on emergency) from all these links, but a lack of sufficient spillway construction/design robustness and armouring. Some probably don't need it, but look at (google earth) the slope downstream of the emergency spillway, it's about 10H:1V, a very steep hill.

The big concern as I see it is that they are now worried about any water being up against the concrete face of the emergency spillway, hence the call to lower the pond elevation by 50' (the emergency dam is 59' tall by my google estimate). There has been severe erosion downstream, which has saturated the ground that has never been saturated like that before, and a significant weight of soil has been removed from the downstream toe of the concrete structure as well. The major risk now is the footing of the emergency spillway might slide, causing the concrete to fracture and the emergency spillway to literally "split open".

The good news is it looks like there is significant fill (beach) on the upstream side of the emergency spillway, it is only 25' high on this side, and they said yesterday that the water is already brought down 20 feet from max. So likely there is no water against the concrete of the spillway at this point.

It will be interesting if they slow the rates of the main spillway now, once the emergency spillway is not in a critical state, to stave off the "head cutting" up the main spillway.

The main spillway eroding is the primary concern here, both from a protecting the Oroville dam, and a "how the hell did this happen" perspective. It is not surprising the emergency spillway had severe downstream erosion when used. It IS surprising that the main spillway failed due to full bore flow through it. That may have been a maintenance issue, and really shouldn't have happened.

With its location next the dam, if the main spillway is lost the dam could very well go too, if the emergency spillway breaks, it may not make its way to the Oroville dam and take it out. You'd be looking at only partial drainage of the reservoir instead of full, and at flow rates a small fraction of a Main spillway/dam failure. Of course it may progressively take out the main spillway and then dam, but the chances of that are lower than a direct main spillway failure. Likely (hopefully) there is enough distance and elevation built into the main spillway so if it fails and flows uncontrolled it will not affect the O Dam. From google earth again, it appears there is some significant material between the two, though whether it is constructed fill or bedrock I'm not sure, but it is slightly reassuring.

Anyways - back to my breakfast mimosas on the beach (Cancun) :) But I couldn't resist following this story even on vacation.
 
#17 ·
Wow...........that dam is massive and it is gradually eroding away. almost 900 feet of water held behind it ? Yikes, how do they fix that ?

I am not an engineer, but would it not have been better to have a series of step down dams with spillways, rather than one monstrous dam?
 
#18 ·
Fortunately, the eight inches of rain predicted by some fear mongers has not materialized. Rain is in the forecast until Wed, but doesn't look too serious.

Inflow column fluctuates mostly because of temperature changes which affects the amount of snow melt.

The plan was to reduce water level by 50 feet before heavy rains come so that water won't go over the emergency spillway again. They have another nine feet to go, and it's slow going.

This table updates every hour:
https://cdec.water.ca.gov/cgi-progs/queryF?ORO

Screen shot 02/17/2017 14:00



uploading images
 
#19 ·
Excellent update from Juan Browne.



Note on the height of the dam:
- maximum water level in the reservoir is 900 feet above sea level
- the dam itself is 770 feet high (see Wiki)

For dam enthusiasts, there's an interesting 3-part docu about spillway repair at Glen Canyon Dam after the flood of June 1983.

The link to part one:
https://www.youtube.com/watch?v=dHpKvQ9XHV4
 
#20 ·
http://www.thegoldenstar.net/

"Can Oroville Dam situation happen in Revelstoke?"
By ALEX COOPER
February 23, 2017

http://www.thegoldenstar.net/news/414630404.html?mobile=true

Snip:

"Some of our major spillways haven't been used in the last 4.5 years now. After those spills, we closely inspected them and have effected repairs, but we've also done a lot more. If we see something we think could turn serious in future spills, we get on it and we do major rehabilitation work. At (W.A.C. Bennett Dam), we spent $64 million to replace areas of damaged concrete in the spillway chute, and to provide safe access for that work, and to make sure we can get in quickly to do any future repairs. We look really closely at our spillways after a major spill and spend money when and as required."



Maintaining spillways, like the one at Mica Dam, is key to dam safety, says Stephen Rigbey, BC Hydro's head of dam safety.
/ BC HYDRO
 
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