post#2393
How many slabs per side drain?
Looks to me like only 1 side drain for every 2 slabs?
Not sure...
(also note at least one on each side with no flow,
I suspect these indicate complete drain failure)
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.
Someone suggested the possibility of just starting over on a new spillway next to this one which would be used until the new one is finished. At some point, maybe the cost and possible further risk of properly fixing the damage/design/construction errors on this spillway may justify spending resources on a new one altogether.
Starting over on a new one makes sense to me.
Even if repairing the existing spillway is feasible, which I doubt, there’s a good chance they’d end up behind schedule.
Anybody want to take that chance?
Ha! "..an unstable feedback loop.."
Heard from a Boeing electrical engineer (worked on designing amplifiers in Radar systems): "You design an amplifier you get an oscillator. You design an oscillator you get an amplifier."
I believe in the next few weeks, DWR is planning on announcing details in the Main Spillway reconstruction mitigation (in phases). This should tip their hand in what they may be thinking for the future.
btw- They will need Nature/God to cooperate. But they already have this covered: :-)
== clip:
Phase I is DWR’s Greenhouse Gas Emissions Reduction Plan (GGERP),...
== end clip
It worked for fifty years without a problem, so the system was relatively sound. Something changed in the last few years. If the system deteriorated, that means maintenance was neglected.
B-52’s are still flying 60 years on. I can’t believe a concrete structure, properly maintained, won’t last at least as long.
If I recall, the main spillway has not seen a great deal of use overall.
If I recall, the main spillway has not seen a great deal of use overall.
Appar ntly, that bears repeating!
Sorry about the double post. I blame Siri - always!
Bid dams had been built for many decades prior. Sure, it was tall. The spillway length and slop was and is very massive but many dams like Hoover Dam had been built in the 30s and after prior to this structure.
The 1880s Johnstown dam failure was a spillway event but I don’t know how similar the spillway was so knowledge of this being a critical feature was not new ground.
I still think that a junior engineer was detailed to show a french drain under the slab and as he started to detail it out in a normal manner someone stopped him and said, the bulk of the spillway slab is going to be on rock and we don’t want to have them cut individual channels in the solid rock. He drew something else and no supervising threw it out.
Abb's drawings of drain system..
Quick answer: 1 wall drain per 4 slabs & wall drains spaced 200ft apart.
Evidence: The image at the FRpost below clearly reveals the drain system design & spacing per slabs. You can see 10 drain cracks for every 4 slabs. If the slabs were exactly 50 ft long (ignoring any radius factor at the spillway curvature transition), this would be 10 drains for 4 slabs with an sidewall outlet every 200ft. Note: these drains are mirrored & aligned on the other half of the spillway (cracks verify this alignment). Thus you see sidewall outlet drains aligned down the spillway.
HerringBone Drain Pipe - Fracture pattern in Main Spillway...
This FRpost image set shows the "missing water" issue going back to 2009. There are other images that show this same issue in 2007. So for 10 years they had advance warning that there could be a problem (besides the constant repairs in the "missing water" area).
Years of Warnings at Blowout Area? Missing drain water/slabs being repeatedly repaired at leakage..
= = = Regarding Post 2,393 ("The Mercury News" Chico-Enterprise Record - photo w/ spillway defect asking DWR for comment).
Something Interesting... The base photograph in "The Mercury News" article states 2 photos were taken by their news photographers Jan 13 and Jan 27. The image in the article is the Jan 27 photo. This Jan 27 photo was placed on SmugMug by ChicoER where you can sell photos online. I purchased an electronic copy of this photo from SmugMug to get the best forensic investigative evidence (in pixel resolution analysis). This same base photo started making the rounds on discussion/engineering forums in failure analysis. Many different markups made on each photo. (note: FRpost 2,092 image was from a purchased copy & specific graphics added for failure analysis & discussion for our FR thread).
As groups progressed (including the forensic discussions in FR) the mounting evidence was becoming strong on the failure mechanisms at play regarding the spillway "blowout".
Then a news story where DWR is asked about this photo & the "hole in the concrete" (the defect) comes out March 11.
Word must be getting around to where the news people are picking it up. OR they are perusing forensic discussion websites/forums.
Identical base image in FRpost 2,092, March 1, 2017:
Same missing waterflow in drain near pre-failure blowout area. notice the defect in the concrete slab seam at/near the pre-failure blowout area.
http://www.krcrtv.com/news/local/butte/paradise-prospector-a-golden-opportunity-at-the-damaged-spillway/370298858
(snip)
"I see a lot of gold potential there," said Van Camp, estimating that there could be "pounds and pounds" of gold just at or near the surface.
"Because gold is so heavy it always seeks the lowest area," he said. "It constantly wants to go down."
"This dirt came off the hillside and is full of gold," he added, pointing to the video.
The main dam itself is constructed of tailings from earlier hydraulic gold mining operations.
https://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=MT19660421.2.33
“The dredge tailings, once considered as unsightly and almost worthless mess, have proved excellent material for dam building.”
3-12 update
explains the river valve system and why they are not in use(can move 4000 bfs)
https://www.youtube.com/watch?v=_q0g43iI9kA
This google earth view along the river south of town shows evidence of dredging in the past. Must be the area where the dam borrow was obtained.
A few new pictures are up (currently 456 images)
https://pixel-ca-dwr.photoshelter.com/galleries/C0000OxvlgXg3yfg/G00003YCcmDTx48Y/Oroville-Spillway-Damage
Installing new sets of power poles to re-route power lines.
Did you notice the letters "O" "I" "L" carved in water ponds in the tailings area? (just east of the airport - note: the "O" is 582 ft by 306 ft)
Olive Trees in Oroville are well known for producing outstanding Olive Oil. Farms go back 100+ years.
These little pond/lakes must have been around for a while. Curious if dam construction crews left these letters as part of a promotion to this industry -or- if the dredgers created them & the construction crews left them undisturbed. btw- You can't carve this in the middle of a wildlife refuge nowadays.
Maybe a FReeper who has some history on this at Oroville could chime in..
1998 image:
2016 image:
Potential Concerns or Precautionary measures from further Upper Main Spillway Damage/Erosion: An Electrical Tower closest to the Broken upper section of the Main Spillway has been removed.
+A full compliment of high tension power lines are observable on the upslope adjacent upper Tower.
+Subsurface drilling/repair work of the Main Spillway concrete continues. Drill equipment in the slabs just upslope from the "shifted/rotated" sidewall & main spillway slab section.
+A large stairway system built using scaffolding.
+Excavation work being conducted (2 excavators) at the foundation of the removed electrical tower.
lake level now at 861.43 rising about 5 inches per day
inflows 15-19cfs outflows 13K
the plan is to turn the damaged spillway back on around 40-50K cfs around friday....when combined with the power plant outflows of 50-60K..
they don’t want to run the main spillway lower(ie 20-30cfs) because of eroding the head..but on the other hand they don’t want to run it too fast or more debris may get washed back into the channel and shutting down the power plant
even modest snowmelt has the inflow higher then the power plant outflow...
so I suspect the plan is to turn the main spillway on again..drop the lake level down to 840 feet or so like last time, shut the main spillway off, shut down or reduce the power plant outflow, dredge out anything they have too to get the power plant back up to 13,000cfs..let the lake rise..and repeat
the big wildcard is the weather..most models agree a wetter period 8-14 days out
This is assuming the main spillway can hold up the next couple of months
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