Oroville Dam Main Spillway Waterfall Erosion Watch

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But again this is very likely irrelevant to future erosion which causes main spillway damage in a direction towards the dam? Unless the edge of the exposed spillway collapses some more then there must be a boundary to the maximum possible extent of the erosion?

I am visualising a triangular fan-shape zone of erosion downstream of the spillway lip (the highest extent of the structural failure)...

Thanks. I agree, not really relevant to the integrity of the spillways (lower portions) and to the dam, but more debris in the river (worst known case is bounded by the new left hand side ravine discovered a few days ago) means more risk of flooding the power plant.
 

David T

New Member
Does anybody have any up to date shots of the original main spillway failure?

It seems to me the latest shots of the lower spillway failure to the RHS are obscuring the original failure due to the spray.

It would seem to me to be important to get a handle on the extent (if any) of the potentially ongoing undercut back towards the power lines.

It is also somewhat disturbing to see that the extended outflow of water down the main spillway has caused it to also fail much lower down.

On the plus side, 'Oroville Falls' could become a new tourist attraction ;-)
 
Fox News is currently sharing live video of the spillway flow on their Facebook page. I hope Facebook is an acceptable link, I didn't not see a mention otherwise in posting guidelines but please delete if not.

Live video link (mobile): https://m.facebook.com/story.php?story_fbid=10155128737211336&id=15704546335

Desktop: https://www.facebook.com/FoxNews/videos/10155128592566336/

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Thanks for the link Anna. I noticed something on the live video that I hadn't seen or appreciated before in the static pictures. There is a large "nose" in the cliffs on the right stream that is currently taking a real pounding. This could be an area that breaks off, unless there is a lot of stable bedrock underneath. It looks like today's flow wants to take the uphill path to the river...
 

Ln X

New Member
Thanks. I agree, not really relevant to the integrity of the spillways (lower portions) and to the dam, but more debris in the river (worst known case is bounded by the new left hand side ravine discovered a few days ago) means more risk of flooding the power plant.

The area you highlighted does have high cliffs of about what... a minimum of a 100 feet? My concern is landslides since the dull orange rock has little resistance to high flows of water. Above the area you highlighted -- with those two red lines -- is surely vulnerable to small-scale landslides... ? Any rock type needs lateral and vertical support, so my argument is that landslides are more likely since the water is eroding away one side of the lateral support.

And given how this part of the hill rises up a bit above the main spillway, the damaged top-left (downstream left) section of the main spillway could retreat even further upstream due to either the landslide knocking out part of the side walls, or the side walls over-hang and eventually collapse when the water does its work on the rock areas exposed by a landslide(s).

What I hope for is that the dull orange rock stops along the line where the main spillway's gradient begins curving, if there is igneous and/or metamorphic rock the water will make very slow progress eroding it away.
 
Thanks for the link Anna. I noticed something on the live video that I hadn't seen or appreciated before in the static pictures. There is a large "nose" in the cliffs on the right stream that is currently taking a real pounding. This could be an area that breaks off, unless there is a lot of stable bedrock underneath. It looks like today's flow wants to take the uphill path to the river...
I have annotated a photo showing the "nose" that I was referring to.
nose_Ink_LI annotated.jpg
 
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Charlie P

New Member
The following is an amateur question. It is based on the big hole in the main spillway, with the waterfall going sideways onto the wooded hillside between the damaged spillway and the dam.

Will that water dig out trees by their rootballs, thereby causing erosion of that hillside, and endangering the dam itself?
 
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My thoughts are that would depend on when they ramp it up and whats in the hole. Meaning how much deeper will the hole get. If the hole stays about the same depth as it is now then a heavier release (100,000cfs ex) should jump (bounce out of) the hole the same way it did before.

add: right now, i think, the only reason most of it is going out the hole in the spillway side is because the floor hole isnt filled to the rim with water, due to decreased flow. once the water coming down the spillway fills the floor hole faster than the side broken spillway can release it, the remaining water will skid across the top of the full floor hole.

a sketch would probably help. i'll think about how i can demonstrate my point with household items...

add:
Source: https://youtu.be/M-bMv0C2G5U
Thanks for your response and for the video. Looking again at the live facebook feed, the left hand deck is almost gone adjacent to the "hole" at the bottom of the chute. Effectively, as far as directing flow, the deck is already gone. To me it will take an extremely large flow to ever really make it to the original discharge. The void in the original deck is now too large for the stream to "jump". For the foreseeable future (ie, until the next surprise), the vast majority of the flow has to go to the right hand side.
 
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yellowsubmarine

New Member
Thanks for your response and for the video. Looking again at the live facebook feed, the left hand deck is almost gone adjacent to the "hole" at the bottom of the chute. Effectively, as far as directing flow, the deck is already gone. To me it will take an extremely large flow to ever really make it to the original discharge. The void in the original deck is now too large for the stream to "jump". For the foreseeable future (ie, until the next surprise), the vast majority of the flow has to go to the right hand side.
it is quite a change in the flow pattern, but it makes sense the way you describe it. Interesting to see the blocks of asphalt down by the teeth at the bottom of the spillway. The good news is the storm seems to be heading more south so probably we won't see much change in outflows for a couple of days at least.
 
Fox News is currently sharing live video of the spillway flow on their Facebook page. I hope Facebook is an acceptable link, I didn't not see a mention otherwise in posting guidelines but please delete if not.

Live video link (mobile): https://m.facebook.com/story.php?story_fbid=10155128737211336&id=15704546335

Desktop: https://www.facebook.com/FoxNews/videos/10155128592566336/

20170219-112724-ccdff.jpg
I don't think the live feed is "live" anymore. It seems to be just replaying what was "live" earlier.
 
From an update by County Supervisor William Connelly:

https://m.facebook.com/story.php?story_fbid=1683579861668957&id=100000508772678

Relevant excerpt:
"
o removal taking place in multiple locations from land to build what DWR is
referring to as the “low flow channel” to get water around the large debris piles at the
bottom of the primary spillway.
o Elevation of water at the Hyatt power plant has been lowering so that water is not going
into the plant – once the “low flow channel” is in, that level will continue to decrease.
 Construction and repairs continue on the emergency/auxiliary spillway. The weather is not
stopping the progress, though it may be slowed down periodically.
 No further erosion has been seen on or near the primary spillway. It is being monitored and
evaluated 24/7.
 PG&E continues to relocate lines below the spillway. Anticipate being completed by Tuesday.
 Lake elevation at 9 AM was 852.30 feet. Only two feet from the 850 goal.
 Current inflow approximately 45,000 cfs. DWR anticipates it will peak on Tuesday morning at flows
that could exceed over 100,000 cfs. The average inflow over the next several days could be around
68,000 on Monday and Tuesday. Outflows are expected to stay at 55,000, but could be adjusted
upwards as necessary. DWR is extremely confident that the lake can easily hold the expected
precipitation through the Tuesday storms. The lake may get above the 850 level, but they expect
nothing even resembling a problem...
Content from External Source
"


Looks like the heavy equiptment work we were seeing on the banks of the pool in earlier photos may have been in preparation for this new "low flow channel"

Also looks like they are ramping up outflow to 60,000cfs, per the Butterly County Sheriff's office:
https://m.facebook.com/story.php?story_fbid=785455638271383&substory_index=0&id=119221578228129

Thanks for this. The new low flow channel makes sense, although it might be difficult to implement if the debris comes in faster than they can dig it out. Also ramping the main spillway back up to "exceed" 100,000 cfs could prove interesting. This animal is not the same animal it was a few days ago. "Easy" doesn't come to mind at all. Also, looking at the current "live" video, it is clear that they are currently ramping up the flow as we speak. It is quite dramatic, but I am not sure how significant the change is. There are some large low frequency hydraulic pulsations going on, on the left hand side of the deck, but the vast majority of the flow is turning south... (right hand side)
 
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David T

New Member
Thanks for this. The new low flow channel makes sense, although it might be difficult to implement if the debris comes in faster than they can dig it out. Also ramping the main spillway back up to "exceed" 100,000 cfs could prove interesting. This animal is not the same animal it was a few days ago. "Easy" doesn't come to mind at all. Also, looking at the current "live" video, it is clear that they are currently ramping up the flow as we speak. It is quite dramatic, but I am not sure how significant the change is. There are some large low frequency hydraulic pulsations going on, on the left hand side of the deck, but the vast majority of the flow is turning south... (right hand side)


Is it clear what they mean by the 'low flow channel'?

Is it

a) The RHS channel that is taking more 'dirty' water closer to the dam wall and power station? Visually from the photos and Fox feed it looks like this channel is taking ~90% of the flow, so can hardly be called low flow. Moreover the contrast enhanced images further up the thread indicate this channel is continuing to erode the weathered orange coloured rock.

Or

b) The LHS channel that doesn't appear to be taking any significant flow at the present time.

I don't really see how they can control the direction of the flow in the lower part of the spillway at the present time. Nor is it easy to see how they can do effective work to put in controls with so much water flowing.
 
Is it clear what they mean by the 'low flow channel'?

Is it

a) The RHS channel that is taking more 'dirty' water closer to the dam wall and power station? Visually from the photos and Fox feed it looks like this channel is taking ~90% of the flow, so can hardly be called low flow. Moreover the contrast enhanced images further up the thread indicate this channel is continuing to erode the weathered orange coloured rock.

Or

b) The LHS channel that doesn't appear to be taking any significant flow at the present time.

I don't really see how they can control the direction of the flow in the lower part of the spillway at the present time. Nor is it easy to see how they can do effective work to put in controls with so much water flowing.

I didn't listen to the press conference, but I suspect they call it "low flow" because the design flow thru the power station is much lower than that over the spillways. I don't have the number handy. They want to clear a trench to bypass the debris and drain the pool, but as you allude to above, there is a lot of "splashing" going on.
 

EricL

Member
If it wasn't reinforced then it's just aggregate and as as the water de-grouts the concrete the resistance over the area will increase relative to the rest of the structure.
This doesn't have to be the rapid process that you make it out to be. There are plenty of spillway "deflectors" exposed to the constant and direct impact of water dropping nearly vertically off smaller dams that have been in place for 100 years or more, and though the concrete in such cases has inevitably been worn, it is by no means failing in cases where the concrete was of good quality to start with. The same goes for concrete rubble that's often found in swift tail-race areas to disperse energy. There is a tremendous range in the durability of what you are calling "grout", the sand/cement matrix in concrete, and one-size-fits-all statements are not likely to be correct, in my opinion.
When high volume fluid, water in this case, scours a disturbance like that for 24 or 36 hours one of two things happens. Either it creates a nice smooth channel or it rips away material looking for a place to create a smooth channel. Concrete isn't that strong when put up against lateral loads and scouring action like that. Great compression strength along the long axis but not so robust at lateral forces (why some buildings have problems during earthquakes).
The problem with this statement is that it's not the concrete slab above the waterfall that will dictate whether or not significant headward erosion takes place. It's more a matter of how durable the bedrock is. The concrete could even be stripped right off the top, but if the bedrock below is sound, there should be little to worry about. The quality of the bedrock is highly variable within this area, as has been talked about ad infinitum on the main thread, but so far (also re-hashed many times) much stronger rock seems to be taking the brunt of the water's force at this time, now that the highly-weathered rock is mostly gone from the area of concern. As far as the water ripping away material looking for a place to create a smooth channel, I have seen lots of powerful whitewater runs on rivers which show no sign of the jagged bedrock rock of the riverbed becoming smooth, and no indication of perceptible wear, and they've been running for thousands of years. It seems to me that reasonably durable rock (even if it's not as durable as the rock exposed on the kinds of river beds I mentioned) could be expected to tolerate the present stress for the relatively short time that is necessary here, which is until the dry season, when repairs can begin.

I wish I could provide proper links regarding the durability of rock or concrete when subject to such erosive forces, but that would be of little use to me since I don't have the ability to quantify either those forces or the durability of the materials at this site. But then, you are not presenting your ideas in that kind of context either, so I'm just saying there are plenty of places where the condition of existing dams of great age, or significant drops on natural river beds show that what you say here is not universally true.
 
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Keith Beachy

Senior Member
Good news, after May it will stop raining, and we have till November in CA to fix it... okay, it might rain in August and be cool and foggy (but this only happens when you brag about not raining from May to November), but that is once every 7 to 10 years. The USAF weather men at Beale AFB, CA use to have a betting pool for the first rain after summer (albeit in the valley), with date in November popular.
 
I provided this update on the man thread as well, but since the "low flow channel" made it's way here as well:

I spoke earlier with City Admin of Biggs, Mark Sorensen, who has attended all of the DWR breifings. He said that William Connelly's update is quoting the DWR press release that is given to local officials about the work the DWR is doing, but Mr. Connelly himself has not actually been at the breifings. Mr. Connelly is not misquoting, but at the in person breifings the DWR representatives have made it more clear with maps and clarification that the "low flow channel" is how they (DWR employees, etc) refer to the section of the pool that currently has low flow due to debris build up. The section of the pool between the dam and spillway is termed the "low flow channel." They are removing debris from it, but it does not sound like they are creating any new channels at they his time.

Thanks for this. The new low flow channel makes sense, although it might be difficult to implement if the debris comes in faster than they can dig it out. Also ramping the main spillway back up to "exceed" 100,000 cfs could prove interesting. This animal is not the same animal it was a few days ago. "Easy" doesn't come to mind at all. Also, looking at the current "live" video, it is clear that they are currently ramping up the flow as we speak. It is quite dramatic, but I am not sure how significant the change is. There are some large low frequency hydraulic pulsations going on, on the left hand side of the deck, but the vast majority of the flow is turning south... (right hand side)
 

whoosh

Member
The main spillway withstood a week (so far) being damaged.

To clarify, the primary spillway has "withstood" only above the initial break. Downstream has been steadily destroyed; and the terrain well scoured down to pretty sturdy surfaces, we can suppose, but won't know for sure until it is shut down and inspected.
 
Is it clear what they mean by the 'low flow channel'?

Is it

a) The RHS channel that is taking more 'dirty' water closer to the dam wall and power station? Visually from the photos and Fox feed it looks like this channel is taking ~90% of the flow, so can hardly be called low flow. Moreover the contrast enhanced images further up the thread indicate this channel is continuing to erode the weathered orange coloured rock.

Or

b) The LHS channel that doesn't appear to be taking any significant flow at the present time.

I don't really see how they can control the direction of the flow in the lower part of the spillway at the present time. Nor is it easy to see how they can do effective work to put in controls with so much water flowing.
Here's a video from this morning https://www.facebook.com/AccuWeather/videos/10154965453052889 there doesn't appear to be much additional erosion.

Thanks Sean. I agree that the water in the gorge doesn't appear to be carrying much sediment today (perhaps we are down to stable bedrock?). I wonder what the flow is in the spillway? I am a bit puzzled though on the extent of the erosion on the gorge (right hand fan). To me, the gorge likely grew a lot larger when the flow decided to go primarily to the right (yesterday). The cliff, adjacent to the spill appears to not have moved uphill, per Mick's side-by-side comparison yesterday. So is it possible that the gorge is now just wider and deeper downstream of this point? There seems to be a lot more debris in the river, based on yesterday's video post #1210. It is probably difficult to do a decent comparison of gorge width/depth using photos, as this area has been obscured with spray until just recently.
 

Mick West

Administrator
Staff member
Thanks Sean. I agree that the water in the gorge doesn't appear to be carrying much sediment today (perhaps we are down to stable bedrock?). I wonder what the flow is in the spillway? I am a bit puzzled though on the extent of the erosion on the gorge (right hand fan). To me, the gorge likely grew a lot larger when the flow decided to go primarily to the right (yesterday). The cliff, adjacent to the spill appears to not have moved uphill, per Mick's side-by-side comparison yesterday. So is it possible that the gorge is now just wider and deeper downstream of this point? There seems to be a lot more debris in the river, based on yesterday's video post #1210. It is probably difficult to do a decent comparison of gorge width/depth using photos, as this area has been obscured with spray until just recently.

Well, it's not getting any wider at the big road. Note the debris pile in the red rectangle. I think there's solid rock holding that up, shown in blue. (photos are at different angles, compare with care)
20170220-095646-gz7ai.jpg
 
Well, it's not getting any wider at the big road. Note the debris pile in the red rectangle. I think there's solid rock holding that up, shown in blue. (photos are at different angles, compare with care)
20170220-095646-gz7ai.jpg
Thanks. Those are good photos. Agreed the ridge is holding at the road. But, unless my eyes are playing tricks with me, it looks like the gorge is now much deeper in the areas annotated green and further downstream. The photo on the right shows much more flow, yet more rock is exposed to the left, implying lower water level in the gorge at that point.
gorge_Ink_LI.jpg
 

SeanT

Member
Thanks. Those are good photos. Agreed the ridge is holding at the road. But, unless my eyes are playing tricks with me, it looks like the gorge is now much deeper in the areas annotated green and further downstream. The photo on the right shows much more flow, yet more rock is exposed to the left, implying lower water level in the gorge at that point.

I think that might just be the angle, it's hard to tell, though.
 

Mick West

Administrator
Staff member
Thanks. Those are good photos. Agreed the ridge is holding at the road. But, unless my eyes are playing tricks with me, it looks like the gorge is now much deeper in the areas annotated green and further downstream. The photo on the right shows much more flow, yet more rock is exposed to the left, implying lower water level in the gorge at that point.
gorge_Ink_LI.jpg

No, it's a radically different perspective ("compare with care"). Look at the cliff on the right. It's actually pretty much unchanged, but looks a lot bigger.

20170220-101854-ydi9i.jpg
 
No, it's a radically different perspective ("compare with care"). Look at the cliff on the right. It's actually pretty much unchanged, but looks a lot bigger.

20170220-101854-ydi9i.jpg

oroville dam - Facebook Search - Google Chrome 2017-02-20 1_55_57 PM.png Another facebook live stream was recorded today. Some good shots of the debris island and of the gorge. See screenshot and link. I know I need to get my eyeglass prescription checked, but that gorge is looking pretty deep to me, and the debris has to be coming from somewhere. **cleaned up formatting and fixed the link**
https://www.facebook.com/AccuWeather/videos/10154965702387889/
 
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Mick West

Administrator
Staff member
oroville dam - Facebook Search - Google Chrome 2017-02-20 1_55_57 PM.png Another facebook live stream was recorded today. Some good shots of the debris island and of the gorge. See screenshot and link. I know I need to get my eyeglass prescription checked, but that gorge is looking pretty deep to me, and the debris has to be coming from somewhere. **cleaned up formatting and fixed the link**
https://www.facebook.com/AccuWeather/videos/10154965702387889/

Sure, I just don't think it's changed much in the last few days. Croyle said there was continued erosion (as you would expect) just nothing to worry about.

Mind you he also said the emergency spillway was solid rock.
 

Jody Bourgeois

New Member
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Mick West

Administrator
Staff member
Outflow has been increased to 59,000 CFS and per linked live feed above there's a bit more water coming out the left side of the spillway than before.

http://cdec.water.ca.gov/cgi-progs/queryF?s=ORO

Edit: live stream just died, took a screencap of it before it went down.
Fox10 now covering here https://www.facebook.com/FOX10Phoenix/videos/1281404491908095/

Another live stream this morning, just now (7:40AM Feb 21)
https://www.facebook.com/AccuWeathe...&notif_t=live_video&notif_id=1487691424178596
20170221-073739-5rs6o.jpg

20170221-074407-h9ajv.jpg

Seems like quite a bit more coming down the right side of the actual spillway. Outflows are apparently unchanged at 60K, so this might indicate some additional erosion. Water looks perhaps slightly brown.
 

sushi

Member
The post
https://www.metabunk.org/oroville-dam-spillway-failure.t8381/page-33#post-202055
contains another of Alan Kuertz' videos of the FCS spillway.
Source: https://www.youtube.com/watch?v=JB8ssAI6lF8


Just around the 11:40 mark when Alan begins to talk about the wild turkeys, he pans the camera left and also lowers it. As the camera movement begins there is a brief view of the tower base. Erosion has eaten away to the base of the nearest tower footing. There is water vapor in the air but there is a clear change in colour. The image below has had the color manipulated to "cut through" some of the obscuring water mist which greatly reduces contrast.

If correct, this suggests the erosion is cutting back the damaged spillway face. It also suggests that the report of an altered plume on the spillway may be further evidence of increased erosion in the direction of the spillway gates.

[Image removed from post to avoid misleading, see below]
 

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deirdre

Senior Member.
It also suggests that the report of an altered plume on the spillway may be further evidence of increased erosion in the direction of the spillway gates.
what report?

If correct, this suggests the erosion is cutting back the damaged spillway face
i dont want to get into a big tutorial about perspective, angles, focal length, zoom..you can find information about that in other MB threads... so i'll just give you this visual. Let's not start speculating all over the place.
xx.jpg

20170213-090626-ksyaf.jpg
 

Mick West

Administrator
Staff member
Just around the 11:40 mark when Alan begins to talk about the wild turkeys, he pans the camera left and also lowers it. As the camera movement begins there is a brief view of the tower base. Erosion has eaten away to the base of the nearest tower footing. There is water vapor in the air but there is a clear change in colour. The image below has had the color manipulated to "cut through" some of the obscuring water mist which greatly reduces contrast.

If correct, this suggests the erosion is cutting back the damaged spillway face. It also suggests that the report of an altered plume on the spillway may be further evidence of increased erosion in the direction of the spillway gates.

Here's a better extraction from the video:
20170221-153702-rrbo8.jpg

There's significant perspective foreshortening there. It does not really look any closer than other shots would indicate. Unless you can compare like with like then you should not be announcing a change.

And from his 2-15 video
Source: https://www.youtube.com/watch?v=E0Rzi8kELM4

20170221-155008-3flfg.jpg

Other than the viewpoint being slightly to the side, it's exactly the same.

Please do actual comparisons in the future.
 
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Paul Bogdanich

New Member
It's funny how one can't find even one good picture of where the trailing edge of the breach is past about 02-15-17. It looks like it's still below the power poles so it hasn't moved that much as it was within 100 feet of the poles a week ago now. All the action below the trailing edge of the breach is interesting but that whole area is toast anyway. The water is going to cut away all the soft material and dig its own channels. I notice they increased the outflows back to 60,000 cfs. I also went to the Department of Water Resources website and they have redone the website so you now have to find the "Spillway Incident" tab and the last pictures are dated today, 02-21-17, but the last pictures of the breach are still the reference shots of 02-15-17. All indications are that they put the kabash on the detailed pictures of the breach. Just what one would expect. Reporters go to a designated areas to low to see and the helicopters follow orders. If anyone has a Geomet or other satellite service they can share please do so.
 
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aczlan

Member
how are you supposed to get detailed pictures of the breach with all that spray going on?
It is not like they have been able to get close without risking getting washed downstream or sliding down the hill.
Now that they have a road cut to the RH side of the main spillway (as evidenced by the backhoe up there on the pictures posted today), perhaps they will add some pictures there. The problem is until now, to see what is happening, you need to be below it and to the right (toward the emergency spillway) and its an active construction site with possible hazards (water+dirt+slope=mudslides) and pictures aren't worth someone sliding down into the spillway to get.

Aaron Z
 
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