Oroville Spillway Repairs

[Birken Vogt]

No conspiracy theories please. I believe this is mostly a case of "stuff happens". Nobody died or got seriously injured and that is good. But I bet the price tag approaches a billion dollars.

They shut off the water yesterday since the lake is low enough. I wonder how you all would go about digging out this pile of rock. From a distance it looks like a pile of washed gravel. But there are a few shots with a Cat in it that shows there are lots of these blue rocks about the size of a small car.

I saw in another place they had built a road out onto the pile of dirt from the downstream side. Presumably to make it easier for the less nimble equipment to get farther out there. They have barges floating on both sides and even a tug boat. I don't know how they got the tug boat down there. This is a pretty steep canyon with not great roads. I guess the power plant must have a pretty good road.

How would you go about cleaning this channel? Start pushing to the south side where the roads are and haul it off one dump truck at a time? What about getting some water back in the channel? Sounds like they want to start flowing several thousand CFS as early as Thursday.

 

[51kw]

There is a lot of material to get placed back. The equiptment looks like matchbox toys.

 

[Birken Vogt]

Long distance shot of rock trucks. I guess they are just going to stock pile this stuff on this less steep hillside. Maybe they have plans to use it for the thousands of yards of concrete they will be making this summer.

 

[td25c]

Thanks for sharing Birkin , those videos give some of the best footage I've seen yet .
Not sure how the concrete spillway was constructed , some precast / tilt up ?
I see allot of square edges & corners left around the floor & walls .
Not seeing much rebar hanging out around the damage ???
I would think a project like this would have used allot of rebar in the concrete & pins between section pours /cold joints ?

 

[Birken Vogt]

I saw some close up pictures and there was plenty of rebar in it. Also some real long bolts that used to go into the rock from the walls down. Can't find where it was I got the pictures though.

The rock bolts were hanging in midair 20 or 50 feet away from the nearest rock. A lot of crummy rock in this area. They laid that structure over the crummy and the good. They did not expect this to happen. They expected it to stay inside the channel.

There is a lot of rebar but it sort of disappears with the scale of this thing like everything else.

I'm pretty sure it was all cast in place.

 

[Birken Vogt]

The good news in the paper I was just reading that they got some biologist type people who are running up and down the now dry riverbank and saving any poor fishes that got caught in little pools.

 

[rsherril]

When the BoR tried to top off Lake Powell in 1983, there was an unexpected snow dump in May that caused all the drainages flowing into it to flood. The extra flow of water resulted in the opening of the spillway tube to prevent water going over the dam. The resulting cavitation damage of 100 tonnes/sec. of water flowing over 100+mph was incredible. Several videos documented the event and subsequent repairs in 83-84. Lessons learned included putting an air cushion under the flowing water to slow down cavitation damage and leaving room in the reservoir for the unexpected.

 

[Birken Vogt]

The interesting thing is that Oroville has seen many of those type floods over this spillway since the early 1970s and many since the Powell event in 1983 which I am sure made them recheck the facility. When it broke up this time it was way below what it has been tested with in the past. I just hope the short inspection they got in there and did at the beginning of this whole thing, plus the records allows them to determine a cause because all evidence has been washed away and ground to powder at this point.

 

[hvy 1ton]

Here is a video i stumbled on this morning.

 

[Birken Vogt]

That is the best one yet. Must be brand new because I see more activity in that one than any of the others.

Trying to figure out where the long reach excavator on the barge has put the rock it dug out of that hole.

I guess if they get the channel opened up they can run the powerhouse and then work on the rest of the rock pile into summer rather than moving a whole fleet of machines in there to do it in a short time.

 

[lantraxco]

They knew it needed upgrading over ten years ago, but complacency and money-grubbing vetoed that. Everybody figured with the drought it was no worry and if it did start to rain it would take years to fill the reservoir, right? Right fellas, nothing to worry about huh? Hello? Hmmm... people SHOULD get fired or recalled over this, but no, anyone responsible will get promoted/reassigned/retired. And now we know that the 50 year old emergency spill wall was only designed to give some people enough time to run like hell to higher ground before the whole mess breached catastrophically. Truly the term "Emergency" was aptly applied, a bit like putting a tube of sunscreen in a nuclear blast survival kit.

 

[hvy 1ton]

Looks like the long reach is loading the barge to it's left. I don't know what they are gonna do with it after that, b/c that's the upriver side of the rock. They had a couple long reaches trying to deslit around the powerhouse before things went completely sideways.

 

[crane operator]

I worked with some guys dredging here in town this past summer, and a few summers ago also after some flooding. They would load the barge, then float to the side, and unload to a conveyor taking the rock up the bank to trucks. I suspect they're doing that with those barges also, loading in one spot, then swapping to a empty while they float the full one over to shore to unload it.

 

[Birken Vogt]

I saw a tug boat in what I think was the upriver side so maybe they are using that to shove the rock barges around.

 

[hvy 1ton]

Birken, there are at least 2 tugs stuck on the upriver side. I don't know how or where they are gonna unload the barges.

 

[Birken Vogt]

Here is a good photo sequence

http://www.sacbee.com/news/state/california/water-and-drought/article135860663.html

 

[Birken Vogt]

Here are some videos that just appeared of unloading barges, and also building "pads" which I think may just be stock piles.

 

[Birken Vogt]

Explanation and more pictures of work

 

[Graham1]

I saw the evacuation etc on the news. They kept on about a thirty foot wall of water could come down the river. The spill way had broken up and the spill water was making its own way down. How would this translate in to a thirty foot wall of water if the main dam was was in no danger?
Graham

 

[lantraxco]

I saw the evacuation etc on the news. They kept on about a thirty foot wall of water could come down the river. The spill way had broken up and the spill water was making its own way down. How would this translate in to a thirty foot wall of water if the main dam was was in no danger?
Graham

They had shut off the damaged control spillway with the gates and let the lake level rise until it topped a concrete wall which is the emergency spillway built at a level lower than the actual dam top. It's to the left of the damaged spillway. This had never been used and to apparently everyone's horror the immediate effect of the water blasting over the top of the concrete structure was to begin eroding away the outboard toe of this emergency wall. The assumption was, probably correctly, that the continued flow of water would soon destabilize the whole concrete wall and when it failed the top twenty to thirty feet of the reservoir would be released. God only knows if the rest of that whole slope would have slowly been destroyed or been subject to a cascade failure creating maybe a 200 foot wall of water headed for Sacramento. The short period of time the water ran over the top of the emergency structure it wiped out the access road below it and the power lines connecting the power station with the grid I believe. The only choice left was to open the spillway gates wide and watch as the water carried most of the hillside down into the channel below but they avoided a much more catastrophic failure. Only just, and by luck and the grace of God moreso than any rational decision making.