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.

[Repeal The 17th]

By those definitions, it sounds like
what we have been calling the “Main Spillway” is an “Auxiliary Spillway” and
what we have been calling the “Emergency Spillway” is the correct term.

[Repeal The 17th]

I think it would be wise for a dam this large to have a way to drain the lake.

[Jim W N]

the 1960's political engineering decision...the [ES] apron does not protect the full hillside down to the Feather River.

It would be interesting to see the relevant minutes (if there were any and if they haven't been destroyed by now) of meetings where this was being debated (?) and decided. Can't you just picture at least one person in the proceedings objecting to compromising the exceptionally critical dam by not armoring the ES?

[Jim W N]

Any legitimate concern for blasting vibrations further compromising the safety of the already leaky/seeping dam itself?

[EarthResearcher333]

"An auxiliary spillway is infrequently used and may be a secondary spillway (augmenting a service spillway discharge capacity). During operation there could be some degree of structural damage or erosion to the auxiliary spillway due to releases up to and including the maximum design discharge."

(1) Oroville's design is stuck with the 1,730 ft long 901ft elevation crest for the original 350,000 cfs "Emergency Spillway" requirement for PMF (now bumped up to 369,000 cfs by the BOC). DWR has played PR "name games" switching auxiliary spillway with the original design stated "emergency spillway". Oroville's design is 100% accurate to "emergency spillway" per definition of 3.2.1.3 above.

(2) It is physically impossible to have an "auxiliary spillway" function (as stated in 3.2.1.2) unless a linear section of the 1,730 ft is rebuilt to a lower elevation, thus preventing the 901 ft elevation "emergency spillway weir" from self-activating.

However, IF cash were flowing in heaps, and there was a luxury of time, a redundant "less sophisticated non-radial gate" chute lined w/ sidewalls parallel structure could theoretically serve as an "augmenting to a service spillway discharge capacity" (i.e. augmenting the main spillway). This would kick in at a lower elevation than 901ft with perhaps a simple release mechanism (other engineering technicalities arise due to the fixed main spillway head gate structure & Head requirement for flow, but ignoring these complications just for discussion sake).

(3) However, the sharp elevation drop to the Feather River, due to the tremendous height of this dam, creates a "solution killer" in that erosion must not dam the Feather river. Severe damming of the Feather river causes a backflow to the toe of the dam. This can flood the power plant, thus *failing* the turbine infrastructure & losing the ability to drain the reservoir below 813.6ft.

So - (1) without full hillside armor will cause (3), (2) will prevent (1) from fulfilling the spec requirement of rated 369,000 cfs, but (2) will still cause (3) without full hillside armor or a "walled chute". (2) will require big cash & time on top of nearly an impossible window. (2) cannot handle a PMF flow, thus (1) has to kick in and you have (3) again (unless there is full hillside armoring). Also, (2) cannot fail in concert with (1) as it must handle a PMF flow.

No matter how you look at it, the only solution with time & wise spending is to fully armor the hillside (& buttress the concrete weir to secure its anchoring). Only this solution will protect the main dam in a full "safe" redundancy.

[EarthResearcher333]

that would be humorous if it weren’t so true....

[EarthResearcher333]

I've witnessed these discussions internal to corporations when millions were on the line. Essentially, the discussion was the "human" factor of facing a tremendously difficult problem and feeling the pull of temptation to use a "technicality" or a method to say "this won't happen because of xyz circumstances". Fortunately, they made the right choices. However, in the midst of finding solutions to these extremely difficult problems, I've spent time consoling a top director who knew he was going to lose is whole career if we didn't come up with a minor miracle (we did).

I've seen these "politics of engineering decisions" occur too frequently with other engineers in lesser matters. This is what kept me in business doing consulting to stave off major crisis (but, sometimes the crisis is too big and the result is that "sometimes the dragon wins").

[EarthResearcher333]

No. Not unless they are using a MOAB, then maybe. :-)

[Jim W N]

Who knows, maybe there’s an Islamic terrorist hiding in there somewhere...all those “cavities” in the rocks... :-)

[janetjanet998]

don’t know but I assume there is already vibrations coming from the force of the water.......also I assume the cliff will collapse into the canyon then the debris will be washed into the diversion pool from the flow..more dredging needed

the NWS service forecast from this morning still doesn’t have the flow increasing on the Feather at Gridley...in the past they had changes About 48 hours ahead if any panned outflow changes occurred at the DAM

the plan on the 14th was with have the power plant and 7,000 bfs of outflow back on Saturday the 22nd..

[EarthResearcher333]

"It would be interesting to see the relevant minutes (if there were any and if they haven't been destroyed by now) of meetings where this was being debated (?) and decided."

Actually, you don't need minutes. There is so much evidence that a "political engineering" decision was made, so much so, you could say it is overwhelming evidence - IF you know what documents to put together & what you are looking at. I've seen this so many times.

However, before casting stones whilst in a glass house, a person has to be fearless to do the right thing. Even to the point of losing much (career, job, etc). There are times you have no choice but in making a hard decision & driving for what is right - at a great cost.

I've been asked more than once to write books in my years...

[janetjanet998]

outflow now 36,200 an increase of 1200, it has been tardy around 35000.. I wonder if one of the plants is back on or just a glitch

time will tell

[Ray76]

I think a potential problem with full hillside armoring is that in summer it will BAKE, and suffer the freeze/thaw cycle the rest the year. It might lead to durability issues. I suppose an armored area could funnel the water into a lined channel, maybe decrease the armored area subjected to sun etc.

Completely outside the box - another spillway could be in a different location, perhaps in the Bidwell Canyon area to the left of the dam. A canal or canal/aqueduct could convey water south then west to join the Feather River. Or perhaps the water could stop off in a newly constructed storage area before returning to the river, perhaps with power generation at the outflow - a mirror of the Thermalito setup. The elevation near the head of the canyon is higher than the MS and lower than the ES. Possible benefits would be improved flood protection, increased storage capacity, and increased power generation. Depending on the design of the storage area there could be improved recreation attractions, fishing for example. Of course, dollars are always an issue. Costs over time might be offset by additional storage and power. Repairing the existing design offers no improved storage or power. Just an idea.

[Ray76]

A canal vs spillway might mitigate the “weathered rock” issue.

[janetjanet998]

outflow 37100

I’m going to assume the power plants are coming back online....but remember 1/2 will be down for a month

[meyer]

I lean towards agreement - I hope that it is the power plant that is starting up. That implies that the use of the spillway is not depositing a large amount of sediment into the river below, which I would think is true given that they’re flowing the spillway enough to throw beyond the “incompetent” rock.

I hope that they’re running some generation.

[EarthResearcher333]

Yes there are always engineering considerations, including the costs.

[EarthResearcher333]

Projected Reservoir Graph - Based on 8 days of Spillway flow - Visual on "projection rate" to Feet & Days

Hi janetjanet998, Yes, at the current rate of discharge and inflow, the reservoir spill could take a number of days longer than the originally estimated 10-14 days stated by DWR. Assuming that this slope follows, of the last 8 days, it could take close to 30 days to get to the last "turn-off" elevation at 836.28 ft. This would push the date to May 14.

note: this graph projection will vary based on Hyatt power plant discharge augmentation & future precipitation inflow (including snowmelt).

Another point of interest: Note the slope angle change in the last "run off". DWR started the spillway at 50,000 cfs, back then, and later reduced the rate to 40,000 cfs. This is reflected in the slope angle change. Again, it could have been related to a noticing of a "shift" in the optical targets, initiating a "slowing" to try to stabilize the movement of the damaged section. DWR has not revealed any information regarding this matter. IT may be the reason why DWR is limiting the outflow to 35,000 cfs in this current spill. Perhaps, because of a "time squeeze", DWR may take a risk and up the spillway flow?

At the current rate of discharge, the reservoir spill could require 30 days to reach 836.29 ft, placing a "turn-off" date at May 14.

[janetjanet998]

with part of the power plant online and less rain the pace(and slope of your graph) of should indicated faster rate drop...

IMO the updated target of May 6th(aka through the last week of May) looks decent for the next stop

looks like a weak-moderate system mon-weds with 1/3 inch of rain at the DAM and 1-2 in the mts at this point

after that the pattern look drier as high pressure builds in....which is typical for this time of year as the dry season looms

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I assume that there is still some slippage of that wall even at these lower levels...the longer it runs the more it slips.

[mad_as_he$$]

Congrats on a great thread!

It occurs to me that we could start a pool to guess when the “loose” piece of the spillway tumbles into Moonbeam Canyon. I’ll start with May 5, before 5 pm Pacific.