DWR May 20, 2017 Youtube:
https://www.youtube.com/watch?v=DIuNfw5Vxsk
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.
I didn't see anything in the report about being unable to get "good" measurements, nor about "not returning believable data".
The one challenge they had was that the prior unsuccessful Lawrence Livermore National Laboratories (LLNL) low frequency ultrasonic test project required drilling a hole in the end of the tendon. These drilled holes could "amplify" echoes of cracks in the later used Higher Frequency Ultrasonic testing. So they had to develop a compensation/verification in getting around this effect (see technical info below).
They had a careful calibration process & testing verification method to establish a quality control to the data (see Technical info below).
They could detect multiple cracks at different depths in the same tendon, so it wasn't a "one and done" and can't see anymore. What I did find interesting is that they had a total of 43 tendons indicating flaws between 1/32 and 1/8 inch, yet only 28 were officially identified in the report. There is NO explanation why the other 15 were left out of the report.
Overall, the testing was a decent quality control based methodology. What was clear is that if there were NO cracks, the echo would be clean (i.e. no echo). What is disturbing is that DWR has had 17 years to replace these cracked tendons and have done nothing about it.
Keep in mind, tendons may have experienced concrete creep or tendon relaxation to where post-tensioned strength could greatly be lost. Ultrasonic testing does not measure the remaining tension in the tendon steel. That is what the new Dispersal Wave Testing is designed for (like detecting the ring frequency of a ping on a guitar string - except the tendon is encased in a high attenuation grout environment - thus dampening the detectable ring significantly).
Technical info:
The cracked tendons are from their process of a baseline of data integrity involving (1) Repeatability (Single Operator) (2) Consistency (Multiple Operators) (3) Geometry Effects (Drilled hole in end of tendon).
The 28 identified tendons in this graphic were from the officially reported tendons in this developed process. Whenever a crack was detected (acoustic reflection), they would carefully manipulate the transducer to optimize the reflection (zero in on it).
They calibrated the system using different gain settings of 30 dB, 74 dB, and 80 dB, on a pre-crack (small saw cuts) at 5, 8, 9 and 10 inches on a 48 inch ASTM 322- Grade 5160 rod. A second rod of 1.417 inches provided a baseline for the acoustic velocity of the tendon steel. At least 74 dB was required to adequately identify a 1/32 inch flaw at a distance of 10 inches from the rod end.
Testing requires a knowledgable and skilled operator. Fatigue was noted as a factor as the operator had to hold the transducer stable during a 10 second acquisition interval.
What was clear is that if there were NO cracks, the echo would be clean (i.e. no echo). Thus the operator to operator and the repeatability was in getting a precise measurement to the cracks that ARE present in the tendons.
The report provided measurement crack sizes to fractions of a thousandths. The variability of the factors of repeatability were found to be within either identical or within 15 percent.
To compensate for the "drilled" end tendons, lab testing was done on identical "drilled end" samples to confirm the amplification factor - to be thus adjusted or accounted for in those particular tendons.
IIRC, this same scenario played out in the Katrina disaster.....corrupt and lazy overseers let needed repairs go undone...
Not only that, but they used federal funds designated for levee repair/maintenance and spent them elsewhere.
The problem is that CEII has allowed DWR to weaponize the process of hiding secrets. To ferret out solid information that penetrates the DWR PR games & CEII "hiding" of information requires an extraordinary effort & skillset that the press doesn't have. The Press requires getting credentialed Engineers on the record where the engineers have real data to evaluate in order to do a story. DWR can say anything they want to spin but if there is no real data out there for independent analysis from engineering peers, the press is effectively muted.
That is what is so frustrating about this. From what I've seen in the piles of FERC/DWR communications, the comments, the mis-leading info DWR gives to FERC, the outright contradictions given to FERC, the intentional absence of critical facts to FERC, the proof of effective "incompetency" in realizing the level of what high reliability "safety and risk" really mean... DWR shouldn't be allowed to operate this dam. It should be immediately taken control of by another entity who KNOWS what it takes.
But the press cannot say this as they have been hamstrung by the games being played.
You comment about transmission power reliability affected by stretched infrastructure & decisions, yet the consumer has the ability to install backup systems in critical operations such as Hospitals. Where is the "backup" to a failed dam? There is none. The outcome is unthinkable. There cannot be a scintilla of acceptance of compromise on a high-reliability system operation as a dam when it directly risks hundreds of thousands of lives, plus critical infrastructure, levees, agriculture, and the water delivery system to the state.
Because the press is hampered with DWR's games, is partly (or mainly) why I continue to try to get information out there. Yes, there are some I help with information to get items out there besides the forum. But this is taking a toll. I was in the Emergency Room for 5 hours yesterday getting a heart cardioversion (anesthesia then shock paddles). I wish there were more brave souls digging on this, but forums are only as good as the "safe cracker" that can get beyond DWR's games of hiding via CEII and "telling stories".
I am very thankful for those who contribute on forums, postings, and in any way they can, especially the brave souls such as Professor Robert Bea (and other engineers that have come forward).
But the pressure on DWR is only as good as the "safe cracking" in getting actionable information out there.... I better stop or I'll end up in the ER again.
Thanks! I was thinking about the LLNL report.
A yearly maintenance program could easily have been put in place to replace the anchors at say 10 per season. The cost would of been reasonable and the work completed by now - hopefully with better materials involved. I would really enjoy watching the coring and removal process.
Don’t put yourself in the ER, ER333. :)
DWR May 20, 2017 Youtube:
https://www.youtube.com/watch?v=DIuNfw5Vxsk
ER333:
Hope your ticker is doing OK. Please don’t get too stressed out. The world needs your experienced perspective and insight.
I have a couple of questions regarding your recent posts.
The painted red crack shown in post 3671 is from a Feb 2015 DSOD report, isn’t it?
If so, at that time the FCO gates hadn’t been used for years, and the reservoir was below the FCO inlet, so there was no head pressure at all on the gates or structure. If the crack was growing then, it had to be from concrete shrinkage or settlement and drying of the foundation. I think I recall Scott Cahill saying that he thought the back side of the FCO foundation was partially built on fill, so perhaps that could have something to do with it.
If the FCO structure was cracking in 2015, one can only wonder how it’s working now. The gates were recently under greater static head pressure loading then ever before, and they’ve been dynamically opened and closed more times this year than in the last decade. Also, that heavy truck traffic no doubt stressed the structure way more than the pickups with speed boat trailers that it was designed to carry.
Question: if 2 of the 384 anchor tendons “failed” in 2010, how did they determine that? Did they get no ultrasonic reflection at all? Were these rods completely fractured? Or did they rate 1/8” rather than just 1/16” on the ultrasonic test?
I too would very much like to see how they went about coring and replacing them.
It seems strange that 2 rods failed to the point that they needed to be replaced a decade or so ago, but none of the other 382 have structurally failed since then. Was there a QA issue with just those 2 rods, or were they somehow tweaked due to their position relative to the cracks in the FCO structure? Were they both adjacent rods from the same gate? One might think that other adjacent rods would have failed by now with all the recent high stress dynamic loading on the FCO.
There are many questions to be raised if and when DWR becomes more accountable. With Oroville’s DSOD “regulators” just being just another internal division of DWR, it appears that this accountability will have to come from outside independent scrutiny. Please keep up the good work as you are able, and the scrutiny will be applied.
"The painted red crack shown in post 3671 is from a Feb 2015 DSOD report, isn’t it?"
Yes, the crack image is from Feb 3, 2015 DSOD inspection report. A key point in this image is the dashed red arrow the inspector placed in the photo. This dashed red arrow was where the crack "was" before it "extended" downward 2+ feet. The date is not revealed, in this report, when the crack was at the tip of the dashed red arrow.
Your question is insightful regarding bridge loading, foundation stability (seasonal rains & water table flow to the "lowest point"), and operational loading from recent spills.
You are a bit ahead of me in questions as I've been doing more research to get further documentation to possibly get better data. One aspect that should be noted is that the higher column section is more massive in its relationship to the lower column section. In addition, the 5 foot thick column abuts the massive 40 foot thick monolith #27 in the headworks.
The crack may be a result of the construction of anchorage (or not) between monolith #27, Gate 8 pier, and the spillway bridge.
A 1998 DSOD inspection report noted that there are "shear cracks" at each end of the spillway bridge junctions in the gate columns. Quote: "Shear cracking was noted in the first and last bay of the headworks structure. The cracking occurred through two lifts at the reentrant corner below Elevation 868.5 (the spillway road bridge elevation). The cracking is cited in past inspections and evaluations and is noted here, for completeness."
To me, this indicates that the Monoliths at the ends of the FCO structure are not secured to the FCO piers with reinforced anchorage (rebar). (the Finite Element Analysis simulation of the FCO affirms this too). This creates a fulcrum point at the extension of concrete that supports the ends of the spillway bridge. This extension of concrete is noted in blueprints to be part of the monolith profile, but not noted whether there were isolated sections to "float" with the bridge & FCO pier columns. The bridge is structurally part of the FCO pier columns.
Because of this, the bridge abutment concrete supports may be torsioning the end 5 ft thick piers by settlement (and/or in addition to heavy load crossings), causing the shear cracks. This is a serious design flaw if so.
"Question: if 2 of the 384 anchor tendons “failed” in 2010, how did they determine that?"
The 2 failed tendons were first noted in a 1999 FERC/DWR communications. At Pyramid dam, finding the failed tendon was easy, the whole end assembly fell off the bearing plate. Stood out like a missing tooth. At Oroville, it was not stated how the failed units were identified, but my guess is that they were found to be loose since the tendon failure shear was within inches of the bearing plate. Post failure analysis of the face of the shear would reveal the corrosion progression to "critical crack size failure" via the distinction line to uncorroded or less corroded surface indicators.
"..but none of the other 382 have structurally failed since then."
DWR doesn't know how many have failed as they cannot accurately test beyond 10 inches. Thus, DWR is only testing 2.1% of the total tendon length. When a tendon "fails" it removes the tensile stress that assists in corrosion crack growth. Even if they don't detect a growth in a crack, the tendon may already be useless. P.S. The only reason why so much information is available is due to the CEII secrecy enactment process was enabled in 2001. The detailed Ultrasonic test report was filed with FERC in 2000 (before the CEII lockup of information). So, DWR can keep "failures" bottled up in CEII secrecy.
DWR may be operating with less functional tendons today. Even they admit they don't know as they have turned to a new method tryout of Dispersal Wave Testing. They will not have the results of this testing (accurate results) until Sept 1, 2017. Sort of late to find out if your FCO is going to "work" for the new repair spec of 100,000cfs....
Stunning. When you take government, you take away reason and accountability just like Melvin Udhall said.
Amen.
Generally isn’t that the way big government bureaucracies operate? If they waste money and fail to accomplish the objective, it’s an opportunity to ask for more money next year. In government, waste and failure are the road to growth and success.
Bingo. If big government bureaucracies waste money and fail to accomplish the objective, it’s an opportunity to ask for more money next year. In government, waste and failure are the road to growth and success.
I feel for those poor folks below the dam. It would seem they are in peril because who knows when and what it will take to go from “pre-failure” to “acceleration”. And from what I can tell, those folks aren’t being told the truth. If they were, I wonder what kind of mass exodus we’d be seeing.
Don’t get me started. I’ve spent five hours today listening to the “Clinton Cash” audio book for a refresher.
Here is an interesting tidbit.
April 25, 2014 - After nearly 30 years, the Nuclear Science Division has moved its Low Background Counting Facility from Lake Oroville to the Sanford Underground Research Facility (SURF) in South Dakota. The facility, which was housed 300 feet below ground in the Oroville dam power house, consisted of an array of eight Germanium detectors shielded by copper and lead bricks. It was designed to search for neutrinoless double-beta decay, a rare decay mode whose observation would provide evidence that the neutrino is its own antiparticle. It was also used to search for dark matter. At SURF, the facility will be located more than a mile underground. A delegation from the Lab went to Oroville on April 21 for an appreciation ceremony.
Interesting indeed.....
300 feet below the power house. Probably a safer location than the city of Oroville. :)
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