Emergency: California’s Oroville Dam Spillway Near Failure, Evacuations Ordered

Breitbart ^ | Feb 12, 2017 | Joel B. Pollak1

[janetjanet998]

The California Department of Water Resources issued a sudden evacuation order shortly before 5 p.m. Sunday for residents near the Oroville Dam in northern California, warning that the dam’s emergency spillway would fail in the next 60 minutes.

The Oroville Dam is the highest in the nation.

[Jim W N]

Thanks ER. Very interesting. I hope they’re getting closer to a solution for fusion in nuclear energy. I really don’t trust our fission nuclear plants at all.

[Jim W N]

I like Juan Brown but sometimes I feel like for some reason he’s wanting to downplay stuff. Maybe it’s to keep on the good side of DWR so he can have easier access to data, people, and environs in filming this stuff. Dunno. Complete guess.

[Repeal The 17th]

The “Main Spillway” has only been used a half-dozen times since the dam was built,
often with many years passing between it being used.
Yes, this was the first time ever for trying to use the “Emergency Spillway”,
and they would not have done that except for the failure of the “Main Spillway”.
Then, after the “Emergency Spillway” nearly collapsed,
they had no other option but to return to the broken “Main Spillway”.
Add to that the problems at the power plant,
the problems with the lower river drains,
the problems with the gates on the Main Spillway,
the possible leakage of the dam, itself...
...what a dam mess....

[Jim W N]

I guess worst-case scenario is nobody has to evacuate.

But especially with this leak, I really wondering what a reasonable worst-case scenario would be for the time required to fix this thing or residents to evacuation upon imminent collapse of dam.

I’m sure that is what these poor residents want to know and DWR won’t tell them.

ER, any educated, reasonable estimates of worst-case scenarios of time to fix or evacuate?

[EarthResearcher333]

Hi SteveH, If there are seepage seams or cracks in the clay/clayey core, there are methods to inject a mix of clay + Bentonite to seal these. However, this depends on the structural integrity of the surrounding cobbles, gravels, & clay. The "core" is sandwiched between zone 2 layers that have silts & sand which are intended to "self seal" any minor defects that may occur in the core.

They design these dams with redundancies in the Zone 1, 2, 3, & Drain Zone layers, including Factor of Safety margins. However, over time, seepage can find a weakness. Thus, very careful monitoring is required in observing wet spots + monitoring internal instruments inside of the dam. Another critical monitoring function is regular precision surveys of the 100 placed monument markers on the outer surface of the dam. Thus, any differential "settlement" (compaction) would give early warning to a potential developing internal problem. If maintenance is lax, and only a few monuments are surveyed sporadically, then the dam can sneak up on you - until it's too late.

Fixing the internal cracks with "probe" injection of the sealing mix may be done if the structural integrity is sound. However in extreme cases, some dams have come to the brink of failure from severe internal core cracks. The dams were saved by (1) lowering the reservoir below the cracks (2) excavating the top core layer down to the faulting area, then replacing with a new high tech mix of clay/clayey material & Bentonite (look up Bentonite for more info).

note: for any "core" repair work, for safety, the reservoir is lowered below the elevation of concern, even for minor "probe injection" - less invasive process.

A problem such as this leakage on the dam is challenging to determine the immediate risk as a full assessment must be performed. Dams have failed exactly from these identical "symptoms" at Oroville as it may reveal a slow motion failure (i.e. an internal erosion through the core scenario)- until it suddenly escalates. The conditions in 2017 seem to be pushing this seepage/leakage as revealed by the large vegetative growth. What is unfortunate is that there have been years of notes in reports stating - this should be monitored (besides just looking at grass). Nothing has been done. Guesses are being proffered in the form of "a natural spring" - but without hard physical evidence from a full investigation.

For those new to the long discussion on the Greening Wet area (more info):

Oroville Dam Showing Sign of a Differential Settlement Failure Mode? - Years of notable mid-slope seepage - Wet Area - Greening + soil medium (cracked core?)

[SteveH]

Many thanks for the information and clarifications.

Here is a link to sodium bentonite for groundwater barrier, which perhaps is what they could use:

https://en.wikipedia.org/wiki/Bentonite#Groundwater_barrier

[EarthResearcher333]

"ER, any educated, reasonable estimates of worst-case scenarios of time to fix or evacuate?

The immediate "crisis" is that DWR does not know the cause or magnitude of this leakage. Worse, one answer is given as "seepage" then another "its a natural spring". Yet, they drilled a test well just recently, in the early stages of trying to figure out the source to the leakage. It's a little bit late. 2017 has maxed the reservoir.

Until the issue is fully understood, the danger of "its been that way for years" is one of the classic "Lessons Learned" in Dam Failures. In other words, you can never be complacent regarding such a critical infrastructure.

If a "test" were to be conducted in "probing" the core, just this activity alone would be highly irresponsible without insuring the safety of this action - thus the reservoir elevation would need to be lowered below the Leaking elevation.

The Hyatt power plant (for now) is the only outlet that could lower the lake elevation below 650 to 600 ft. Then there is the time delay to allow for the internal water pore saturation (phreatic level) to drop. The snow melt runoff will likely prevent any type of internal analysis until late summer or fall - IF experts deem this issue should be investigated. I suspect action will only be taken when this issue is elevated outside of the existing engineering entities (i.e. forced to be dealt with).

AS for how long (time) in a worst-case scenario... Just look up the Teton Dam collapse. If it accelerates at a critical point, then it can take less than 1/2 a day.

[Jim W N]

So I guess worst-case scenario could be that from this point it could accelerate to a critical point within a days’ time.

My God, how would that make you feel if you lived below this dam? They should make these DWR officials live below the dam. Wonder what kind of changes we might be seeing if that happened.

[EarthResearcher333]

Hi Jim, this information may help in understanding the stages of "pre-failure", to the "critical acceleration", then to a full catastrophic failure. This information is from a FERC presentation, Federal Energy Regulatory Commission, Division of Dam Safety and Inspections, Feb 26 2013, Oregon Dam Safety Conference.

The presentation includes the sequence of the last days and hours of the Teton Dam. Each dam is different and an "internal erosion" failure could take years to develop to a "critical acceleration" state. However, because any "un-investigated" leak may be hiding the acceleration risk factors, the predictability of the stages should be considered unknown. Thus, any leak, should be treated as an immediate threat, as there is a high variability to the internal erosion stages that are "unobservable". Below is a link to an extensive slide presentation of the various complexities of how water finds ways of compromising earthen dams. The Teton Dam failure starts on page 69.

All major "leak" failures of a large earthen dam eventually work their way up to the dam crest. Upon breaching the crest, then this is the stage of the maximum onset or flow from the full reservoir (rather swift). The Teton Dam progressed from a pre-failure seepage condition that was observed at the bottom of the dam over by the spillway. This meant that a large portion of the spillway hillside, that forms the right abutment to Teton Dam, had been penetrated in a "piping" flow (leakage flow). This "flow" then developed at the bottom right abutment seam of the dam and worked its way upward. They lost 2 bulldozers, which fell into the escalating erosion cavity, as they were frantically trying to "fill in" the erosion progression. note: the operators were able to scramble out safely up the hillside.

IN the case of Oroville, the seepage of interest is in the mid-elevation of the dam. That's a different complexity in itself. However, Oroville has a much better design composition in its construction than Teton. Teton Dam lacked the balanced mixtures of Boulders, Cobbles, Gravels, Sands, Silts + the Clayey core that Oroville was constructed to. Teton had (1) poor dental grout sealing of the canyon abutment rock, (2) improperly balanced silts/sands in the transition zones, i.e. too high of "fines" ratio (note: transition zones are architected to work with and also protect the core), (3) an easier to erode core design (erodible) (4) usage of "silt" to fill in joints (the very fine grained, tiny particles -called "fines"- were able to migrate without adequate retention by the "filter" structure typical of higher grain sands, gravels, cobbles, & boulders working together).

Here are a series of slides from this FERC Dam Safety Presentation related to Teton Dam. See pages 78-84 for more information on the design related vulnerabilities & other photos.

Leading Cause of Failure - Internal Erosion during normal operations - Dam Failures - Teton Dam pg69

[EarthResearcher333]

Gallery Tunnels in Oroville Dam - & DWR's "natural spring" theory - Where's the water?

Carved in the rock in the canyon walls of Oroville dam are access tunnels referred to as "Galleries". They are encased in reinforced concrete and backset into grooves along the abutment rock wall. The Gallery tunnels along the left and right abutments of the dam are called "Grout Galleries" as they follow the grout sealed rock boundaries of the canyon.

Since DWR believes that "a natural spring" may be the cause of the green wet area dam face leakage, even though there are difficulties with the "uphill flow" physics :-) , DWR could investigate for any small moisture spots within the tunnels. A "natural spring" in the hillside could possibly create minor "wet spots" or "seepage" in the concrete, in the location of a purported "spring". The Grout Gallery Tunnel routes downward along the full hillside from 820ft in elevation to the bottom of the dam at the concrete core block. Any "seam" in the weathered rock of the hillside that is producing waterflow in a "natural spring" could elevate the water density surrounding the tunnel.

Dam Safety Inspection reports have documented areas of seepage within these tunnels, but not in the mid to upper elevations. The greatest "seepage" flow is deep in the core block at a seam of section joints 12-13 in the "bypass Gallery" (another connecting tunnel in the core block). This flow is significant, but normal under the high water pressures in the concrete block at the bottom of the reservoir lake level (but within the center of the dam). Sump pumps drain all of the "seepage" inside the concrete core block into a drain pipe that dumps it into one of the two outlet "diversion" tunnels the Hyatt power plant uses in exhausting turbine flow(s).

Yet the Safety Inspection reports do not mention any "seepage" of note in the upper elevations of the Grout Gallery Tunnel in the Left Hillside. Perhaps there is a "clue" if there were a "natural spring". Where's the water? AND- this has to be special water in that it may need an ability to "flow uphill" :-) .

Strong Seepage Water Flow deep inside the dam (normal) within the large concrete "core block" the main earthen clay core is built upon. Sump pumps drain this water into Diversion Tunnel 2 in the Hyatt outlet tunnels.

Original Archive document describing the Left and Right Grout Gallery Tunnels - re-inforced concrete tunnels along the rock abutment canyon walls of the dam. Entrance to the Left gallery tunnel is at/near 820ft.

Entrance to Left Grout Gallery Tunnel - goes 780ft down to the concrete core block at the base of the center of the dam - Fans at this entrance circulate fresh air to the lower tunnels below

[meyer]

Fascinating info, regarding the tunnels.

Incidentally, I’ve been through the “bowels” of the nearby Chickamauga dam, and there are areas way down below that are always wet. There’s a pumping system and a trough that runs through at least one of the galleries beneath the powerhouse at the south end of the dam. I’d be curious as to how that’s possibly changed over the years, but the guy that was taking us through was a former plant operator and said that it was like that 30 years ago when he worked there.

Incidentally, Chickamauga dam was built by TVA in the late 1930s. It is nowhere near as tall as Oroville, but it can spill about 470,000 gps (presently, 3 or 4 of the 18 spill gates are closed off because of a stalled lock improvement project that the federal government started a decade ago).

[janetjanet998]

lake ta 835

spillway to be shutoff in a couple of hours after a 17 day spill

[meyer]

Thanks, Janet. I was thinking that we’d be seeing that soon.

[WildHighlander57]

Here’s a post about oroville level betw the 14th & 28th (h/t paladin2 for info; thread is about heatwave & snowpack level...)

http://www.freerepublic.com/focus/f-chat/3549092/posts?page=6#6

[meyer]

In the meantime, at TVA’s Norris Dam.....

https://www.facebook.com/WBIRWeather/videos/10155105431982696/

We get excited in Tennessee over just a few thousand cfs!

[Paladin2]

Actually 12-30.

More info:

https://cdec.water.ca.gov/cgi-progs/plotDaily2?staid=ORO&end_date=17-Feb-2017+16:55

[KC Burke]

The tallest earthen dam in California before Oroville was finished was Trinity. Also in Norther CA.

Above are NASA JPL photos showing this dam and lake now at 97% capacity. The Sacramento Bee has an article of concern about this dam just because it is similar and subjected to the huge snow balance while at capacity. It has an internal spillway entry much different from Oroville.

Look up Trinity on the web and it has a lot of information.

Those of us that have been on FreeRepublic for a long time know our sites history of following geophysical events as well as geopolitical events all as they unfold. "Two-Thirds Vote Aye" and I did an armchair analysis of the volume of the twin tower debris needed to be removed the week that the towers came down. I was at a seminar give by the head of the Forensic team sixteen months later and found out we were within 5% as I recall.

JanetJanet may want to start a Reservoir/Dam/SnowMelt thread in general, as I think we are in for an interesting ride this next few months as Oroville serves as a public pointer to the weak points the public should watch for in the unfolding summer.

[Jim W N]

Thanks ER. Very interesting.

So the three stages (of “PFM” I assume) basically are
1) “pre-failure”
2) “critical acceleration”
3) “full catastrophic failure”

I think you said we are at stage one - “pre failure”. I’m also inferring from your comment that you can go from stage 1 to stage 2, “critical acceleration” pretty quickly (or it can take years apparently).

I still think they should move these DWR officials to Oroville and see how quickly they deal with this stuff.

I would also think the possibility of water coming from the reservoir through to the other side of the dam would make this the top priority issue over all others.

Imagine if you lived in Oroville right now. Would you bail now? I mean it seems like once “critical acceleration” began, you might save your life but probably not all of your possessions. If you didn’t leave now, what info or intermediate event before critical acceleration would get you outta there?

I feel for those poor residents below this dam.

[meyer]

“”So the three stages (of “PFM” I assume) basically are
1) “pre-failure”
2) “critical acceleration”
3) “full catastrophic failure” “”

Not unlike a major blackout event. The pre-event goes ever so slowly, until it reaches a critical stage, then accelerates. The acceleration at some point becomes so rapid that the cascading breaker operations are almost instantaneous.

It is during the “pre-failure” stage that things can be dealt with. Once acceleration begins to take place, the ability to prevent the failure becomes much, much more difficult.

Read the NERC report on the 2003 northeast blackout. I used to work for the “offending” utility, in their power system control room. The report is pretty accurate.

[Osage Orange]

The smartest, rational, realistic, informative guy....I've seen on this subject is Juan Browne.

Look him up....

He has some other cool videos....and just a guy..I'd like to be friends with.

FWIW-