Jeez. I just checked out the Google Earth view of the dam and even to my untrained eyes, zooming in on my phone, into a photo taken from a satellite, I can see cracks and irregularities in the concrete spillway. The current photo is from when the spillway was dry- so the cracks and such seem quite obvious.

Using the s-bend in the road in the photos of the hole previously posted as a reference...



Zoomed in, looks pretty uneven and cracked:



and then, rotating the view to look down the spillway (with flow):



Seems a little scary if nobody figured they should fix it better, if the un-evenness really is as bad as it looks to me.


ETA: saw f2's post after I got mine up- holy hell it looks like the entire bottom part of that spillway's going to be undermined by the world's largest water-jet cutter.

dailymail is showing what is really going on.

Another pic of the spillway erosion:

full resolution

The course of the Colorado River was almost permanently altered a century ago. An irrigation plan turned into a cutback, effectively rerouting the river. "While passing Calexico the New River was cutting back at the rate of one foot per minute. http://www.sandiegohistory.org...uary/imperialimages/

From the images, if I was in the path, I'd be gone last week.

quote:

Originally posted by f2:
Isn't this the spillway erosion? HELL, it looks like a separate spillway carved out from near center off to the left facing downstream.

Is that "new spillway" just water being thrown off and to the left by smacking into the hole that's eroded into the real spillway, or has there been some kind of breach in the spillway walls? Even down in the channel, that is some frothy-lookin' water.

quote:

Originally posted by Il Cattivo:

quote:

Originally posted by f2:
Isn't this the spillway erosion? HELL, it looks like a separate spillway carved out from near center off to the left facing downstream.

Is that "new spillway" just water being thrown off and to the left by smacking into the hole that's eroded into the real spillway, or has there been some kind of breach in the spillway walls? Even down in the channel, that is some frothy-lookin' water.

Both.

That part of CA is looking at seven straight days of rain starting Wednesday.

quote:

Originally posted by BBMW:
That part of CA is looking at seven straight days of rain starting Wednesday.

Uh oh.

quote:

Originally posted by ulsterman:

quote:

Originally posted by BBMW:
That part of CA is looking at seven straight days of rain starting Wednesday.

Uh oh.

That is why they are trying (!) to lower the lake level by at least 50 feet.

flashguy

Down in the southern end here we are expecting 3 day of rain starting Friday.
My heart goes out to them.
About the only reservoir not full here is the one by me in north county inland.

Long past time for CA to drain the swamp

The water level is now down approximately 10 feet from the high last weekend.

It appears that the water going over the emergency spillway, when it got to the bottom, started gouging out the dirt a little bit away from the face, then the gouge started moving towards the face. If it were to fail, water would go under the spillway, and probably take the spillway with it.

The normal spillway, while damaged, appears to be holding up to the task at this time. Getting the water level below the level of the emergency spillway base is the first task - they still want to get it down further in case the storms that are coming are warmer. If they are cold, some will stay in the mountains as snow for a while - if not, then they need the space that is being freed up now.

I'm far enough away, and on high enough ground, to be safe. Sacramento, while portions are low, still has several ways to disperse the water coming down now - through the Fremont and Sacramento weirs, and natural flow through the Delta. Some low-lying areas in the Delta are being advised to evacuate due to potential levee issues, but they are small areas.

I'm not on the ground at the site of the issue, but belong to a few volunteer groups (CAP being one) that could be called on to assist with assessment and communications should the need arise. We have aircraft with cameras with GPS that can detail any areas affected - images can be stitched together for wide area views.

I believe that the local sheriff there is doing a VERY good job - he didn't hesitate to start the evacuation with limited information, and he is not going to be hassled into allowing people back in until he has enough information to be sure that he won't have problems.

Water is your friend or is it? Do a google (search) for "cavitation Glen Canyon Dam" and look at some of the videos. Remember this was in 1983! What is it said about History?

I also looked at it on Google Earth.
Question:
The down stream dam? What will be the effect on this dam if the upstream dam fails?

quote:

Originally posted by YooperSigs:
I also looked at it on Google Earth.
Question:
The down stream dam? What will be the effect on this dam if the upstream dam fails?

I was looking at that too, the Thermalito Afterbay.

http://www.norcalwater.org/water-maps/oroville/

quote:

It appears that the water going over the emergency spillway, when it got to the bottom, started gouging out the dirt a little bit away from the face, then the gouge started moving towards the face. If it were to fail, water would go under the spillway, and probably take the spillway with it.

This is the flaw that amazes me. How this design element was allowed to be incorporated is a real head scratcher. It's almost designed to fail, given the loose nature of that hillside. No apparent bedrock. It almost seems that they threw in the emergency spillway assuming it would never carry a significant flow. Or maybe they didn't envision a situation where the lake water level and dam management would get to this critical point. Makes little sense.

How much has dam and spillway construction changed in the past 50 years?

Are we building them the same as we did then are has there been improvements in design and construction?

quote:

Originally posted by Sigmanic:

quote:

It appears that the water going over the emergency spillway, when it got to the bottom, started gouging out the dirt a little bit away from the face, then the gouge started moving towards the face. If it were to fail, water would go under the spillway, and probably take the spillway with it.

This is the flaw that amazes me. How this design element was allowed to be incorporated is a real head scratcher. It's almost designed to fail, given the loose nature of that hillside. No apparent bedrock. It almost seems that they threw in the emergency spillway assuming it would never carry a significant flow. Or maybe they didn't envision a situation where the lake water level and dam management would get to this critical point. Makes little sense.

Agreed, as I said just earlier though not quite as nicely. The pieced together photos of individual spots give some idea of what seems to be an absence of thought, but as pointed out the view in total really illustrates it.

From Google Earth, though obviously while water levels still low.



At the risk of continuing the unintended puns, the issues they have and the design seems to have resulted in a cascading effect of issues that is nowhere near complete.

The generating pathway got jammed by debris, apparently up and down stream.

Having to divert to main spillway wasn't able to keep up with water levels (this is where they really screwed the pooch. You never want to be in a catch-up scenario on a controlled reservoir)

Using this spillway at increased flow rates reveals its apparent and rapidly worsening issues.

Water overtopped the emergency spillway, showing the design failures there. No other word.

Trying to control that, and with generating pathway still jacked up they really turn up the stream on the regular spillway, creating phenomenal but disturbing photos for us all.

As someone pointed out above, that created the biggest water jet ever and the damage seems to bear that out. At first it seems to just be chewing away "down-chute" from the damage, but it now seems to be working its way back and may well wash off enough rock and dirt to put the main spillway genuinely at risk, far uphill from the original hole. All the while piling up more debris at base, exacerbating the original flow issues in generation plant.

So, now they are simultaneously trying to fix three issues that would each individually be huge undertakings and likely require the other two areas to be functional.

Clear out the debris at intake and discharge of generating areas, which seems impossible while the main spillway is jettisoning mountains of debris into the downstream area.

"Fix" the emergency spillway by dropping in bags of "large rocks to stabilize the area." Call me a pessimist, but in the face of any meaningful flow those are just pebbles in the river. And to be possible require the relief of current pressure and near-term rain by the other two failing systems.

Repair the main spillway before it collapses and slides off the mountainside. Obviously nothing they can do there since that's the only area they can divert water.

It may not be named Fukishima, and it may not be nuclear, but it sure seems like just as much of an slow-motion catastrophe as we saw there.

I feel really badly for the 200K folks who they've had to evacuate for a problem that seems to have been right in front of folks for some time.

quote:

Originally posted by ulsterman:
How much has dam and spillway construction changed in the past 50 years?

Are we building them the same as we did then are has there been improvements in design and construction?

I have to think that the engineering would have advanced on multiple levels, but I don't think they've been building many dams in the last few decades. Environmentalists have largely shut down these sorts of activities. Part of California's water issues the last few years have been lack of storage given the drought and how the state's population and water needs have outstripped supply. The environmentalists have even gone so far as to advance the removal of the Hetch Hetchy dam above San Francisco.

quote:

Originally posted by MooneyP226:
There's probably 2,000,000 plus other ways for the water to be diverted.

The more I look at the pictures, the more I think this isn't true - no matter how you take it out, there's just nowhere to send the water in any quanitity except via the riverbed.

quote:

It may not be named Fukishima, and it may not be nuclear, but it sure seems like just as much of an slow-motion catastrophe as we saw there.

Multiple failures across the board! Add to it the somewhat unforeseeable aspect that mother nature has thrown in the mix, with first a prolonged drought which may have had a loosening and shrinking effect on the dam soils and structure, followed by extensive and prolonged rainfall that hyper-saturated the materials thus causing movement and spot failures underneath the main spillway. Mountains make great dams, but they're not "engineered" and are more subject to the ebbs and flows of environmental forces. Perfect storm, really.