(Saw 'David Leisure' listed as a cast member of an old movie last week and couldn't figure out where I knew the name from... Joe Izusu.)
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.
(Saw 'David Leisure' listed as a cast member of an old movie last week and couldn't figure out where I knew the name from... Joe Izusu.)
What about comparative safety?
I have done image processing where I've precisely overlayed images and using transparency setting fade methods I was able to look for any minute changes in the patterns (new channels, widening, deepening, etc). The evidence showed that the channels are forming over time.
Yes, the channels do look stark, but they remind me of a slow motion erosion version of seasonal dry creek beds - (formed by "large bursts of water" or "periodic gentle flows").
I agree that any type of a destructive erosion revelation should be swiftly addressed. But by then it is usually too late. DWR should investigate this situation to establish a risk factor. As far as putting a question to DWR on this issue, their past history of answering dam safety queries has been less than useful. I agree that it would take an outside independent expert (like the BOC panel) to hold someone's feet to the fire in getting an adequate response.
Looks like some of that shotcrete is still there. Maybe it did some good after all.
“David Leisure” - what a name!
About 35 years ago, I was a state inspector of things like
landfills, drinking water plants, and wastewater treatment plants.
We wrote up our observations in reports and passed them up the line.
We never knew what action was or was not taken until that site
popped up on the inspection to-do list again a few years later,
and we went back there to inspect it again.
He was a regular on “Empty Nest” on NBC where he played the playboy neighbor.
Personally, I feel better with a main dam being constructed of concrete. But, then there was the Francis Dam failure that had poor safety factor ratings and a faulty abutment zone (unknown geologic feature/structure).
The issue with the Oroville spillway was that the original design was flawed (the BOC report identified nearly everything we've uncovered in this long thread). I believe that DWR did not recognize clear sign of serious issues on the spillway. They should have raised the alarm on these issues and then realized they needed to replace the main spillway to modern standards.
But I firmly believe the design faced a potentially fatal worst case probable flood issue in needing to meet a 620,000 cfs then 646,000 cfs combined flow capacity. In DWR deciding to break the design into two structures has formed their destiny where they do not have many options today. Sometimes in projects you must recognize a significant design challenge (620,000 cfs flow hydraulics testing huge standing wave problem) and power through the problem even if it is hard politically, logistically, and engineering wise. There are no excuses in this high stakes engineering strata of dam designing.
That type of stuff drives me nuts.
Intuitively, so do I.
“... I feel better with a main dam being constructed of concrete ...”
-
I feel better with a design where the lake can be drained and
the river flow restored, and you can safely walk away from it.
A few new pictures have been posted (581 now).
Nothing of particular interest that I can see.
https://pixel-ca-dwr.photoshelter.com/galleries/C0000OxvlgXg3yfg/G00003YCcmDTx48Y/Oroville-Spillway-Damage
Well, guess there’s gonna be a dearth of news for a month or so...
http://www.orovillemr.com/general-news/20170327/independent-spillway-team-schedule-set-for-reviewing-oroville-dam
“ The state Department of Water Resources gave the overseeing federal agency of the Oroville Dam what it asked for last week — a schedule for the independent review team investigating the cause of the spillway failures
...
The schedule for the team is to review materials from March 23 to April 12, conduct site inspections and meetings with DWR from April 12-13, have team meetings April 13-14 and provide a list of potential causes for the spillway failure to be factored into the design of the “interim spillways” in the first week of May.
From April 14 to an undetermined time, the plan is for the team to continue to review materials, do evaluations, hold meetings and complete evaluations, according to the letter...”
Members and duties of review team:
https://www.ferc.gov/industries/hydropower/safety/projects/oroville/03-20-17.pdf
Now at 592 pictures ...
Whoever is posting these is fascinated with lubricating equipment,
and a deer wandering through the site...
https://pixel-ca-dwr.photoshelter.com/galleries/C0000OxvlgXg3yfg/G00003YCcmDTx48Y/Oroville-Spillway-Damage
Still no pictures that show potential slab movement, and no pictures that show the erosion from the latest release.
It would be easy to show pictures like this, and I’m sure they have been taken.
This may simply be a very poor job of keeping the public informed. But when obviously important information is withheld it is natural to assume the worst.
A contractor lubrcates his back hoe, while being observed by a doe.
Yo!
Water is looking to be "Escaping" the whole spillway chute and running up in elevation into the embankment & saturating hillsides. The curious line from a prior picture - when zoomed - revealed what this feature was. DWR emplaced a drain line in the hillside to re-route the saturated area via a perforated type of collection drain in the ground. Images reveal/confirm the original suspicion of the Hydro-seeding area "wet zones" as coming from the spillway. What is notable is that the hillside water level is much higher with respect to the water elevation at the adjacent spillway flow. This directly infers that the high saturation hillside water level is from further upslope on the spillway. This significant hillside waterflow is AFTER all of the recent meticulous repairs on all of the cracks and seams in the spillway concrete.
IF such a high "escape" water level exists even further up the spillway, then there may be concerns that there could be a "gate structure" level source of piping. The presence of such saturation of the hillside + the BOC concerns about "needing to investigate why" on the "extended release of waterflow" after the gates are closed is a valid issue. BOC's report commented to a potential causal source as "piping" (i.e. "channels" of waterflow paths underneath). The hillside saturation provides an answer to the "why" on the drains continuing to flow after the gates are closed. The "pooled" water into the hillside is re-entering the lowest point in the sub-slab drains.
If anything, this evidence demonstrates just how much water is not captured by the sub-spillway drain system. Prolonged waterflows in the hillside would erode small material ("fines") and could further introduce "voids" - including "voids" into the hillside.
Prior Post discussion link & larger image:
Suspected: Spillway is pooling water from upslope & saturating the spillway hillside (large photo)
DWR buried a linear water collection pipe to capture surface hillside water from the spillway chute. Infers Water is saturating the embankment further up the spillway - i.e. large areas of the spillway chute hillside. Waterflow from a broken longitudinal drain observable separate from green pipe "fix" outlet flow.
Buried linear water collection pipe "fill" line - pipe & fill designed to capture the volume of penetrating & saturating hillside via water escaping from the spillway chute. Saturated Hydro-seeding areas observable from the high water level(s) of the escaping spillway chute waterflow.
Strong waterflow from the buried linear pipe outlet demonstrates the significance of the escaping water into the hillside. Depth of the "collection pipe" inferred from the elevation differential of buried soil top surface to lower outlet of drain below.
You should be working there!
I’m thinking that there’s been some water moving through the soil for quite a while, but it has been invisible due to vegetation. The evidence you show certainly suggests that there is an issue with excess water, and it could possibly be from as high up as the gates. Maybe not the gates themselves (time will tell), but the first seam where the spillway butts up against the gate structure.
Oddly, I think that there might be more water seepage at that point when the gates are closed, because the water has minimal velocity and won’t “jump the gap” (if there is a gap) between the gate structure and the spillway deck.
Hopefully, no piping. But if there is, it needs to be dealt with this summer for certain. This is high up enough in the reservoir that the water will be lowered sufficiently to work on it. The possible seepage on the dam itself is much further down in elevation, I think.
Another observation - prior to running the spillway, the plant was flowing around 12,700 cfs. Since shutting off the spillway again, it’s been running at 11,700. I wonder if that’s because of the debris removal process or if it’s for some other reason.
This is interesting. Looks like it aligns with the spillway wall outlet location.
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