https://pixel-ca-dwr.photoshelter.com/galleries/C0000OxvlgXg3yfg/G00003YCcmDTx48Y/Oroville-Spillway-Incident
Posted on 02/12/2017 4:26:47 PM PST by janetjanet998
Edited on 02/12/2017 9:33:58 PM PST by Admin Moderator. [history]
The Oroville Dam is the highest in the nation.
That still holds true today to varying degrees. I've seen it a lot in the power industry over the years. And with Obama's war on coal, even more so as utilities forego maintenance to keep units on line while decommissioning functionally sound plants. For no good reason, I'll add.
Coal is so un-pc. But it can’t be beat as a fuel. It really bothers me to drive out through the Great Plains and see all those stupid windmills. Without huge taxpayer funded subsidies, they wouldn’t be viable. The same with solar. Plus, you have to keep conventional capacity on standby for when the wind isn’t blowing or the sun isn’t shining.
I have access to wind generation data for the Midwest plains area - total numbers. It varies from around 2000 MW to around 12,000 MW. That’s a 6:1 difference. And when the wind isn’t blowing, as you noted, fossil fuels have to make up the difference. So, you have to build a significant amount of redundant generation to back up any wind generation you have.
Not very cost effective in most areas.
dry but warmer then normal conditions will need to some snowmelt in the mountains...
the forecast for the middle feather river upstream seems to show minor rises expected in a couple of days...and since it should be dry that has got to be from predicted snowmelt
the lake just passed 959 feet and is still rising .05 feet per hour
good news is that high pressure will push the storm track more north and the rain with it into next week.... not so good news is that that same high will cause warmer then normal temps and some snowmelt
I just noticed temps in the mountains are running 5-15 degrees above the predicted highs for today (elevations 3,000-5200 ft)
Higher temperatures - not good. The longer it stays cold, the better. Keep the snow up there long enough for them to get ready for increased flows.
If the plant had been running at full output, the lake level would have been falling at least the last 7 hours. But they’re proceeding with caution on that, which is OK. I’m certain that they are cognizant of the whole situation.
do you, or anyone. know exactly how they calculate inflow?
I’m taking a shot in the dark and assuming it’s known outflow versus the lake elevation change that hour.....
it seems whenever outflow changes the inflow numbers get screwy
outflow jumped from 7000 To 7300 last hour.....they may have just started/increased a turbine we should find out here soon
also lake level up .08 last hour ...if previous patterns hold up the next hrs increase should be very small(i.e. .02ish)
The inflow number increased last hour too, but I don’t know how they measure or calculate it. I saw the 300 rise, and I think they might be bringing on the 5th unit. That will help.
Keep in mind that there are generators at some of the dams upstream so they might be releasing water through the generators up there based on loading. We schedule our hydro units to coincide with peaks in system loads, unless we need to move more or less water.
outflow jumped to 8800 last hr
Oroville Dam: Damaged main spillway to reopen next week
Oroville Dam’s heavily damaged main spillway is expected to resume releasing water a little more than a week from now as water levels continue to rise in the reservoir.
The state Department of Water Resources announced Wednesday that the battered concrete spillway is likely to begin water releases around March 17. At that point, the water level in Lake Oroville is expected to have risen to 865 feet. That’s well below the point at which water would go over the adjacent emergency spillway, but several feet above the comfort level established by Acting DWR Director Bill Croyle.
The lake was sitting at just below 860 feet Wednesday evening.
Read more here: http://www.sacbee.com/news/state/california/water-and-drought/article137330683.html#storylink=cpy
That sounds about right, if my old memory serves...
I think shot-crete needs about a week to “cure”.
what are those tubes sticking out from under the main spillway?
also notice how thin the bottom is in the middle compared to the edge
I guess those are drains for water on the backside of the shot-crete.
The scaffolding has been removed, so they are “done” with this.
It looks like little more than a band-aid to me.
All the smaller reservoirs above are pretty full. They run the gamut from flood control, water storage to hydro-electric for the rural mountain and foothill area. When they release that will be a quick bump factor to the inflow numbers as they see the lake surface of the big lake jump from the release.
These "chipping" holes occurred recently in 2017. This evidence means that other slab areas may "chip" in re-activiation of the spillway. Cavitation erosion may accelerate damage to a spontaneous "chip". Thus another important reason for "eyes on the upper spillway" during its operation. There is no time to address this design weakness as only a full reconstruction of the spillway is required to eliminate these design weakness/flaws. (note that water was redirected to allow "dry" access to these TWO spalling "chipping" failures. A "THIRD" "chipping" failure is present in another image (not shown here) very close to a seam close to the Main Spillway Chute Gate.)
IMPORTANT: A similar "chipping" failure defect was observed in the area at/near the "blowout" failure location, prior to the catastrophic Main Spillway blowout. See post 2,092 or the second link below. This "chipping" defect failure was captured in a picture taken in the last week of Jan 2017 - just before the blowout failure in February.
Oroville Slab Design - 6" Drain Pipe causes drastic thinning from O.D. & Bell Joint dimensions..
Clip from FRPost link: This means that the actual thickness of the outer dimensions of the pipe need to be factored for a net slab thinning. Thus, shifting to the catalog 6" drain pipe specs (6" I.D. was used in the Oroville slab design) the thinning results were stark. Unless there was a cutting into the foundation layer to compensate for the larger diameter pipe, there was not much spacing in the thin zones for rebar (~2.5" down - centered) at the "bell coupling" areas. Worse, penetration of water into such thin region(s) could cause persistent cracking, and even spalling (chipping) of the slab concrete surface from Stagnation Pressure ("hydraulic jacking").
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Years of Warnings at Blowout Area? Missing drain water/slabs being repeatedly repaired at leakage..
Clip from FRPost link: Having this defect present would have likely initiated very damaging cavitation erosion from spillway flow (jackhammer effect on the concrete)….. = = reference notes: 1. Stagnation Pressure' as described by the Bureau of Reclamation: "Stagnation pressure refers to two conditions that can result in damage and/or failure of the spillway: (1) High velocity, high pressure flows enter cracks or open joints in the spillway flow surface (such as a chute), which results in uplift pressure that lifts (displaces) portions of the spillway conveyance feature; and (2) High velocity, high pressure flows enter the foundation through cracks or open joints in the spillway flow surface, which results in internal erosion of the foundation and loss of support of portions of the spillway conveyance feature [26]."
… end clip
Spontaneous Stress Induced "chipping" failures in the Upper Main Spillway (from spillway use 2017). Third "chipping" failure not shown (in another DWR image) in slab close to Main Gates.
Please remove me from the spillway pings. Thanks.
Got it.... thanks for notifying.
Years of Warnings at Blowout Area? Missing drain water/slabs being repeatedly repaired at leakage..
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