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's the rule, but every so often you get something you don't see too often: a "smart' company. Hewlett-Packard in its day was one of those rarities IMO. I worked with them for a couple of years in the early 90's. This was after its heyday with Bill and Dave at the controls but I still I loved it. They processed and process-controlled everything and the results were sustained quantity. From what I could tell PM was not an issue at HP.
Thanx I don’t know a dam thing about it.
No doubt there’s “wear and tear” after 50 years, and even concrete is not indestructible. But I can’t get out of my mind the sidewall drains that weren’t operating in the area of the failure. That water was going somewhere. Underslab erosion? Slab jacking? No matter, it was an upset condition, and should have been addressed.
The operators knew it, yet took no action. If us novices can see the problem, then those “professionals” who we taxpayers pay to perform should have known.
My guess is underslab erosion. We can see now that the missing section of spillway was built on what I’d call lessor rock. All other issues appear to be secondary to that. In my opinion, of course.
Looks like they restarted the plant and are running it along with the spillway. That’s good to see.
http://www.water.ca.gov/news/newsreleases/2017/031817_dwr_news_elease.pdf
A beautiful image really. Sunset on the Orville Main Spillway!
+1. It is always the maintenance guys fault!
Note the cross-river observation lighting on roadway. Road lane closure to accommodate generator & lighting. Also note the ladder on the outer sidewall - next to path where workers/engineers would be able climb up to inspect the spillway while in operation.
we so far so good it seems....
the lake continues to drop and so far no problems that we know of from he damaged spillway
it looks like a wet week ahead starting tuesday
Thanks to you and all the other posters on the spill way going ons. I have a wee bit of construction background but nothing along this type of work.
Now in my younger days I might have been a bit of a wild and crazy guy but I don’t think I would have wanted to use that ladder with the spill way running at almost any rate:-)
Best Regards
alfa6 ;>}
Here's the Drone that zips by News Television video footage. The drone operator is a contractor for DWR to collect video for them and is the source to youtube postings.
What a job to have. Being paid to fly cool toys…. just don't fly into the high voltage power lines…
He looks bored, but I’d take that drone driving job! Especially at my age - I’m not quite finished, but I am no spring chicken.
A 1967 postcard image reveals a natural "Water Percolation Seam" at/near the Blowout Failure location. (note: the postcard was digitally enhanced to filter the "texture dots" to provide this clearer forensic image).
As this photograph was taken prior to the pour of the spillway concrete slabs, the image reveals the "grade" construction of which the slabs were to be emplaced upon. This forensic "seam" presence provides geologic insight, especially regarding the question of "Where's the Missing Water?" from the spillway drains in this pre-blowout failure location. The photograph also provides insight into how "un-captured" waterflow in the sub-par drain design could "wash" a void layer between the bedrock and the concrete slab pour. The spillway "chute" design has embankment fill. There were no signs of embankment erosion near this failure area. The only sign was a preference of large tree growth (roots + growth = subsurface water). The "Seam" answers the question of a "deeper" subsurface flow capability. Over time, the erosion of this flow could increase the underslab voiding.
Given these conditions, the deep waterflow + erosion could have created substantial voids (note: persistent spillway "missing water" at equal levels of the "working drains" observed flow rates = a high capacity deep flow "seam" likely was created in time; exploiting this location's natural formation). Each time the spillway was operated, it eroded and enlarged a void area. Until a higher structural stress condition was applied - such as a higher flow rate - did the right conditions of the voiding stress the failed slab to its limits. Part of this equation is the other dynamic stress condition of hydraulic jacking (one is up the other is down).
Subsurface Seam at Blowout Failure location. Photograph provides insight into how "un-captured" waterflow in the sub-par drain design could "wash" a void layer between the bedrock and the concrete slab pour.
Bottom line, a naturally weak sub-grade area, prior to construction.
Old time highway pavers have told me that the areas that give them the most long-term problem are natural streambeds (normally dry) and fence lines.
He then told me an interesting story of a recent "earthquake" drill that was conducted in concert with the states of Washington, Oregon, including counties and cities. Since part of the drill was to realistically test the communications & emergency response capacities - including emotions - some genius came up with a plan.
All of the engineers, inspectors, and other county participants were given a sealed envelope before the precise time of the planned "incident (earthquake)". ON the envelope was a specific location to go to prior to the event. He was beginning to think that his was a good idea; that he would learn quite a bit on what he would do, how the system reacts, the emotions, etc. When the "exercise test" time came & was at the specific deployed location - he then opened his sealed envelope... It said "your dead".
I guess the genius of this plan wanted to include this in a realistic simulation. But the engineer was mad. He learned nothing and wasn't able to participate in any communications, system response reactions, etc. All he could think about was "what idiot came up with this..."
Nice find!
Large bucket excavator carving into old dredge tailings. Note the leftover "grooves" on the surface - these match the satellite imagery of the "borrow fields".
Mobile swing conveyor machine. Transfers bucket excavation material to a fixed main conveyor line.
Note the trommel screen straddling the conveyor. They must have been classifying the aggregate prior to conveying to the dam site. Wonder how much gold is buried in the dam fill?
Ditto.
Maybe a book in the future...
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