Emergency: California’s Oroville Dam Spillway Near Failure, Evacuations Ordered

Breitbart ^ | Feb 12, 2017 | Joel B. Pollak1

[janetjanet998]

The California Department of Water Resources issued a sudden evacuation order shortly before 5 p.m. Sunday for residents near the Oroville Dam in northern California, warning that the dam’s emergency spillway would fail in the next 60 minutes.

The Oroville Dam is the highest in the nation.

[EarthResearcher333]

You be the judge - Failure of the consultants in 2014 FERC Part 12D process

Here is the supporting evidence of the problem of a "consensus" vote in a panel. Investigative reporter Dan Brekke uncovered confidential information through a California Public Records Act (CPRA) request.

With the evidence staring the consultants in the face, they still decided (panel outcome), that the failure mode that Oroville displayed to the world Feb 2017 was "Highly Unlikely".

Yet what is not revealed is any internal discussion on the "dissent" in this FERC Part 12D analysis. This is where there is a critical weakness in this process.

It is highly revealing that ALL of the consultants did not respond for comment. Yet, when presented with evidence to an outside independent engineer, he was "startled" at their Part 12D conclusion.

So how could four engineering consulting experts "miss" such stark evidence? This leaves the question open to the "consensus" process of analysis (i.e. dissenting views vs a "vote").

The recent Independent Forensic Team (IFT) interim report has cast a dark shadow on the original assessment of this FERC Part 12D analysis as the IFT team stated that the historical evidence to the failure mode(s) was known and documented. Yet this historical data was seemingly ignored.

The subsequent IFT interim report turned into a public embarrassment to DWR in Erin Mellon's prior "on-the-record" statement "the information gathered showed the spillway was in good condition and the rock beneath it was extremely competent."

----- Investigative Reporter Dan Brekke Article clip:

The four outside consultants hired to conduct the 2014 Part 12D safety review, including the PFMA process, did not respond to emailed requests for comment.

Department of Water Resources spokeswoman Erin Mellon said in an email Monday the evidence presented for the potential failure mode analysis included a site inspection and historical documents including past geologic studies of the area.

While not offering specifics about the data considered, Mellon said “the information gathered showed the spillway was in good condition and the rock beneath it was extremely competent.”

---- end clip more at link

Panel Weighed Oroville Spillway Failure in 2014 - and Called it 'Highly Unlikely'

[EarthResearcher333]

Joining of Old to New Sidewalls & Spillway Slab concrete - Lower Transition Slab (RCC to Construction Concrete)

Getting the last sections completed. An interesting RCC design modification. Power jackhammer mini-excavators have been used to cut grooves across the RCC spillway surface. No particular pattern to these cut grooves. In addition, the large flat surface area of the RCC is being air blasted and hydro blasted in what seems to be a "roughing up" or cleaning up of the top aggregate of the RCC. Power washers are then used to move the dislodged material downslope.

The mini-tracked dump units are able to rotate 360 degrees on the central axis over the tracks. This allows "dumping" material over the side of the sloped RCC areas by the sidewalls without having to skid rotate turn the tracks.

Old original Sidewall and New taller Sidewall being joined in a final stage concrete pour. Same for the Old spillway slabs to the New spillway slab area.

Lower transition section of construction concrete has been poured. Water fills a "V" ditch to where the other half of the transition will be likely filled with RCC in the final top surfacing phase.

[EternalHope]

It’s been interesting to follow along with this. Thanks for your work, and the work of others, keeping us up to date.

This thread needs to be preserved. Without it a lot of what has happened will vanish down the memory hole. The politicians and California DWR will do everything they can to make sure that happens. They MUST ensure they are not held accountable for what happens in the future.

The spillway is the most visible problem and is getting all the attention. But catastrophic failure of the dam could happen in many other ways.

They MAY be working on finding the cause of the “green spot” behind the scenes. Let’s hope so. (As clearly documented on this thread, it’s not rain.) If you don’t know what has caused it you can’t fix it.

The turbines and “drain” at the bottom of the dam may have been “fixed”. They claim all is now well. If everything is now working fine inside the dam, but the spillway must be used again, will water back up so high, again, that the “innards” of the dam are again in danger?

The most serious problem may be the gates, tendons, etc. This could be the weakest link, and lead to failure of the whole dam.

If they are concerned about this they certainly won’t admit it. Whatever work they are doing on it, they are certainly doing a good job keeping the details out of the public eye. As far as I can tell, they are merely “studying” it.

Personally, I think even the incompetent ones among them (they are not ALL incompetent) must know about ALL of these issues by now, and more. Most of them are decent enough people to want to fix it.

However, they live in a political fishbowl and MUST keep their personal concerns away from the public. In their view they MUST put as optimistic a public face on it as possible. The spillway is the most visible problem by far, so fixing it is what they focus the public eye on.

But all of these issues MUST be fixed if the dam is to be safe. There are so many they simply cannot get to all of it at once. For PR and political reasons (and CYA), everything they cannot get to must be downplayed.

To sum up, they know a catastrophic failure of the dam would be the worst disaster in California history. They are not vile enough to want this to happen, and they are trying to prevent it.

But they also know that if the public were made aware of the very real possibility of catastrophic failure, and that the DWR negligently allowed the problem to fester for years, their heads would role. So would the heads of the politicians who let it happen. THAT must be avoided at all costs!

[marmaly]

Curious as to how do you know about the meeting if it is ‘secret’?

While this issue needs immediate attention, I cannot imagine how a single or multiple gate failure (stuck open or closed) could cause dam failure at Oroville. Perhaps in a location where there were fewer gates and they were stuck closed, but not in a structure with 8 gates. Water could still be released.

[EarthResearcher333]

"Curious as to how do you know about the meeting if it is ‘secret’?"

If you search the FERC federal database on project P2100 (Oroville, Pyramid Dam, et al) there is a notice of this Workshop. The information to "assess" is classified as CEII secret via another FERC database filing from DWR on the NDE (Non-Destructive Examination) testing, lab tests, and finite element analysis modeling.

When Professor Robert Bea approached DWR for original blueprints and information on the Spillway, back in the early days of investigation of potential failure causal mechanisms, DWR actually said to him "you might be a terrorist" - in a rather outright discourteous manner.

Professor Robert Bea has been recognized with Honors by the U.S. Senate in his excellent analysis work on the Deep Water Horizon Disaster. He has been involved in 600 engineering failure analyses including Katrina Levees, Space Shuttle Columbia explosion, Exxon Valdez (see reference links below for all background expertise & work)**.

DWR has a long history of abusing the CEII classification to keep information from public scrutiny. In contrast, the Army Corps of Engineers freely published their findings on Anchor Tendon NDE studies at multiple Dams - FROM THE SAME outfit DWR has hooked up with (FDH-Velocitel).

DWR has been caught "number fudging" on the Anchor tendon "corrosion crack" dimensions to tendon "failure" in communications to FERC. When this information became public in articles, it made DWR look bad. Then, through DWR's request, the FERC documents suddenly became switched to CEII status making the information "secret" (inaccessible and stated as CEII secret).

"..I cannot imagine how a single or multiple gate failure (stuck open or closed) could cause dam failure..."

There is a failure mode from a "stuck open" gate. The Spillway inlet is not designed for inlet flows that are near the inlet apron elevation. This would cause turbulent scouring of the aggregate & riprap. That is why the Radial Gates must be all closed at a buffer height above 813.6 ft MSL.

The failure sequence involves turbulent scouring erosion to the apron base and thus the risk to the headworks foundation (erosion forces via non-laminar flow). If there is any compromise to the Headworks' foundation from turbulent hydraulic flows, this could lead to a "V" breach condition. If this "V" breach condition escapes the normal spillway flow (i.e. contained within the chute", the earthen "buffer" between the Headworks and the Main Dam is at risk of an escalating breach to the Main Dam.

So the "Water could still be released" becomes the failure mode. The Headworks design must stop water from being released to protect against this design condition (inlet apron compromise).

btw- much of what you've asked has been covered in prior posts.

**More: http://www.mensjournal.com/magazine/bob-bea-the-master-of-disaster-20130225

And:

https://drive.google.com/file/d/0Bz1I1mIutSEnd05fWUNlVXcyWFk/view

[EarthResearcher333]

Hi EternalHope,

With your background in mathematics, you would appreciate this...

High Risk Structures, such as the Oroville Dam & complex, are required to be "Risk managed" such that ANY risk is kept As Low as Reasonably Practical. The higher the risk to life, property, et al. the greater the ALARP factor must be (lower ALARP coefficient).

How this is translated into engineering is providing demonstrate-able proof that each critical component has a KNOWN operational safety margin with an additional factor of safety (FOS) on top of this.

What was so alarming in the initial press statements by DWR - during the Feb crisis - of "sometimes you get a flat tire" and "you run out of oil (engine)".. This reveals a cultural pattern in thinking whereby it is accepted that sometimes you have to "fix it when it breaks". (Prior thread posts reveal DSOD documents where this was actually stated regarding "drummy patches" on the spillway (i.e. "we'll fix it when it breaks")).

This clearly goes against FERC's and other Federal Government Dam Safety Risk Management Guidelines mandate of Dam operation of RIMS (Real-Time, Interactive Risk Management)*.

DWR has zero working piezometers inside the dam - they cannot determine the internal phreatic level (risk to a potential collapse) inside the earthen dam. Piezometers are deemed critical in immediate assessment of dams during and after an earthquake.

DWR built the original spillway on highly erodible material (clay) (and other design defects). The spillway blew up from Stagnation Pressure & Hydraulic forces at 18% of its rated design. Yet their own Final Geology Report clearly revealed these wide swaths of clay - but were ignored for evidence of cost reasons (schedule and cost impact if excavated to the original engineer's requirements to competent rock).

DWR fought having to cover the Emergency Spillway with an Apron - they said that the destructive erosion is within the parameters of the definition of an "Emergency Spillway". DWR also reasoned that the use of the Emergency Spillway would have been extremely rare. Even when asked directly (via 2014 FERC Part 12D analyses and FOR's filing to FERC on the dangers of the ES spillway erosion), DWR engineers stated that the bedrock was competent on the hillside. Yet it failed at 3% of its design rating.

DWR was told not to operate the River Valve without the Baffle ring by UC Davis scientists/engineers - DWR ignored this and operated it anyway, leading to near death of one individual and severe injuries to multiple others from the vacuum effects created due to the baffle ring issue. DWR hid this information from the press for years until OSHA fines and reports exposed what really happened.

DWR has known for nearly two decades about the "end of life" and "cracking" and failures of the anchor tendons. Yet they continue to "calculate", "fudge numbers", and "calculate" scenarios where they can operate the Radial Gates even with losses of more anchor tendons. The gates have exhibited chronic alignment, leaking, and jamming issues.

DWR has been ignoring, but painting with orange paint, a now 16+ foot long crack in a 5 foot thick pier that holds secure one of the trunnion pins to Gate 8. Water has been seeping through this large crack (leaving mineral deposits), likely causing decades of moisture exposure to the trans-secting reinforcement steel (rebar). This rebar is critical to maintain the max 0.017" torsional movement to keep Gate 8 (and Gate 7 by anchor block association) from jamming the gate. Yet DWR just keeps adding orange paint when the crack grows.

There is more evidence that goes on and on in this environment of the opposite of ALARP & RIMS. That is why the "Patch and Pray" moniker evolved. DWR has managed the failure of two spillways (Main and Emergency). What's next?

*Safety Risk Management Guidelines require continuing formal data gathering and analyses that allow future hazard developments to be properly detected, analyzed, and corrected - mitigated when necessary ('Real-Time', Interactive Risk Management).

[EternalHope]

Long rant coming. Sorry ‘bout that..

Yes, this is a situation that might be modeled mathematically. Plenty of people know how to do this. I’ve even done a little bit of that myself.

It would most likely involve many variables, and thousands of simulations run with separate probability distributions and cross correlations on each of the variables. You would most likely want to make multiple runs using different underlying assumptions as a way of testing the sensitivity of the results to the various estimates used. The final result would be a sensitivity analysis and an outcome probability distribution.

Caveat: The outcome would certainly look “scientific,” but the “garbage in, garbage out” rule would still apply. Anyone who knows how to do this could skew the result if they were so inclined. Spotting what they did would require knowledge of the underlying engineering issues plus knowledge of the model specifics.

I hope someone is actually doing this type of analysis, and the data they use is unbiased. If they are, there seem to be enough things that might go wrong, and a high enough probability associated with each, that the combined risk profile an analysis like this would generate might not look so good... The public would never see it.

HOWEVER...

You don’t need advanced math and a computer to know that the more things that MIGHT go wrong, the higher the odds are that at least one of them WILL go wrong.

You don’t need advanced math and a computer to figure out that if you don’t fix something it is likely to get worse.

You don’t need advanced math and a computer to know that if a dam is leaking enough to create a large green spot you should dam sure figure out why.

The giant underlying exogenous variable is the weather. If this winter is as wet as last winter, then the spillway will again be needed, and the gates/tendons/pillars will again be put to the test. Absent repairs, sooner or later they will fail that test.

Even if the spillway is not used this winter, the green spot will be an issue whenever the lake rises to a level high enough for more water to leak out. This does NOT seem to be a self-sealing leak..

[EarthResearcher333]

Actually, your first part of your post is what I've found to be an engineering temptation that can be abused in a failure analysis/risk analysis assessment. The temptation comes into play by using a "probability" assessment similar to "Monte Carlo" application of sub-failures aligning.

In a complex system, any single point of failure must be considered a failure if there is no "redundancy" as a backup. In true "worst case analysis" of High Risk Systems there is no "Monte Carlo" applied.

DWR is required to do FERC Part 12D Potential Failure Mode Analysis (PFMA) exercises but the problem has been they have been effectively using "assumed" data rather than KNOWN* data. Worse yet, the Dam industry has been warning for years of the potential of blowouts of spillways from Stagnation Pressure. The Main spillway had all of the classic sign and symptoms but this was overlooked or not understood. So yes, it became a GIGO (garbage in - garbage out) analysis scenario.

From what has been uncovered in FERC database documentation (before it became "hidden") on the Anchor Tendon crack analysis, DWR revealed that they were playing "number games" and fudging (changing over time) what was a critical verses a minor steel tendon crack in a failure risk.

So this Safety Risk Analysis of the Dam & complex becomes an issue that should concern the public. What is needed is an outside independent analysis of the real information (that DWR may or may not have but is keeping ALL critical documents CEII secret where you cannot distinguish either).

Bottom line, a Safe system can be proven in every piece of the system by worst case analysis showing margin with a factor of safety margin above.

(btw- I prefer straight numbers rather than the translation into probability coefficients. This allows identifying any assumptions or critical analysis issues much quicker rather than having it condensed into a final number or numbers).

*(proven, tested, verified, data with known industry time tested methods)

[EternalHope]

You’re describing a situation where ANY chance of failure is completely and literally unacceptable.

However, it’s hard to imagine anything complicated with a literally zero probability of failure. A complex system with multiple redundancies can still fail.

In a complex system the odds of a single point failure of at least one of the points are always higher than the odds of failure at a specific point. A cascade effect can occur if something causing failure of one part can also cause failure of others. Multiple related failures, even if each is minor, can lead to failure of the entire system.

The gate tendons at Oroville are a potential example of this. If one tendon fails due to corrosion, the odds that other tendons will also fail due to corrosion go up. If one tendon fails the load on the others will rise, increasing the chance that one of them will also fail. Tendons that have already been weakened by corrosion are especially vulnerable to this effect.

Failure of enough tendons will cause gate failure. Failure of even a single gate at high flow rates might cause enough turbulence to cause the spillway to fail, potentially destroying the entire gate system. This could, in turn, lead to rapid “V” erosion and subsequent failure of the whole dam.

This is an example of a failure of one thing can increase the odds of other similar things failing, leading eventually to failure of the entire system.

[EarthResearcher333]

"The Blue Screen of Death"

HA! You would be good at chess...-or- an expert witness as you explain well… :-)

"You’re describing a situation where ANY chance of failure is completely and literally unacceptable."

Here is an example of an unacceptable "single point of failure": - Ever hear of "The Blue Screen of Death" (TBOD) in computers?.

This is a perfect example of a single point of failure that kills the entire system operation (a hardware fault) resulting in a Non Maskable Interrupt (NMI) and a "Blue Screen" computer display.

I'm sure many people remember these…..Great fear an anguish result from TBOD's.

With 4 Gigabytes of system DRAM memory, with a parity bit for each 16 bits (2 bytes) becomes 4,294,967,296 individual data bits with 268,435,456 more individual data bits for parity check. So any single failure of one of (4,563,402,752) four billion five hundred sixty three million four hundred two thousand seven fifty two individual DRAM cells will cause a TBOD - if the Central Processing Unit (via memory controller) reads a memory location with a faulty single bit.

When the U.S. Courts found in favor of Micron Semiconductor (Idaho USA) vs Japan and South Korea DRAM manufacturers (that were "dumping" cheaper price than actual R&D cost developed DRAM memory to corner this originally dominated U.S. manufacturer market) the court's ruling forced these Asian Companies to recoup R&D costs by limiting future R&D to DRAM product profits. What resulted was some Asian companies (name withheld) released new DRAM bigger-faster memory that was marginal and susceptible to single bit errors (loss of charge in bit "cell" due to an imbalance in the substrate bias) just to get early profits coming in.

This Asian manufacturer took advantage of the "CTRL-ALT-DEL" mentality that PC systems lock up every once and a while, so the consumer resets and starts over. So they dumped marginal product on the market to get profits until they could "fix" it in the next spin or "stepping" of the DRAM design. But in Massively Parallel Supercomputer Systems (such as Intel's Paragon System in the 90's) this was intolerable when your system is designed for Parity only data integrity checking on memory. I would get calls from inside development engineers (from Intel) asking about these elusive and frustrating DRAM memory errors. After many months, and with very expensive Tek Logic Analyzers, I had already identified** the extremely complex interaction(s) that caused the loss of bit charge from the imbalanced substrate bias. I worked in R&D at another Massively Parallel Supercomputer company that used ECC instead of Parity (Error Check and Correct).

Computers eventually migrated to ECC memory today as this failure was intolerable. Any minor defect in billions of cells could render the computer useless (loss of computation and/or results) at any moment. ECC memory is a backup "redundancy" that (1) allows for a minor manufacturing (process QC) defect to exist but not bring the system down (2) allows for longevity in safe margin performance even when "wear out" approaches in the end of the life time bathtub curve.

---- Oroville Dam is like Parity Error & "The Blue Screen Of Death" (i.e. single points of failure)

Due to historic design decisions that eliminated the redundant "Delta Shaped" Headworks structure, DWR's choice to eliminate this increasingly costly approach forced the current design into a "single point of failure" Dam. How? DWR chose not to armor the Emergency Spillway hillside, even though it is rated at an enormous 350,000 cfs flow capacity. It failed at 3%. The Main Spillway was rated at 296,000 cfs. It failed at 18% after so many uses that progressively damaged itself.

When the "single point of failure" of the Main Spillway occurred, the Emergency Spillway should have operated as a "redundant" backup. It did not. IF DWR had done the proper research, they would have known that the Emergency Spillway would have failed miserably from the blocky type hydraulic turbulence effects in swift erosion of the highly weathered rock. They then would have armored the Emergency Spillway (similar to what is being done now - or more so back then: the full armoring of the hillside).

The Main Dam is a "single point of failure" in that there is no high volume flow path to empty the reservoir if an unexpected anomaly (leak) is detected in the dam. In essence, there is no way to diffuse the "bomb". The Main Spillway can only release water down to ~830 ft MSL so as to not turbulently erode the inlet apron. So in an emergency condition (leak in the dam), the max outflow of the power house plus the river outlet won't be able to draw down the lake fast enough. This issue has been brought up as a long term problem to address as noted in DSOD reports. So DWR recognizes this problem. Yet they are stuck in these "single point of failure" conditions.

That is why they must make D*A*M sure that there is no "through the dam" leak in the Dam. The "rainfall only" recent report was more for Public Relations. DWR (Joel Ledesma) recently stated that they will be looking at the green wet area the first of the year at recent Butte County Meeting a few days ago. If this is the case, then why did they publish the "rainfall only" report? Joel (DWR/SWP director) stated that this will be re-visited.*

Your analysis of the ripple effect in stress transfer to adjacent anchor tendons is accurate. All of the components to the Dam and the complex can be analyzed appropriately. The use of "single point of failure" has duality. Unacceptable composition by the steel manufacturer and/or QC of the high strength steel used for the Anchor Tendons can be considered an unacceptable condition akin to using poor quality bolts on a bridge (i.e. the bolts are a "single point" usage in design that is a failure source mechanism to the overall bridge's Factor of Safety). The failure analysis just carries out from the implications from this "single point". There are a myriad of "single points" in a design that carry out in their effects. My point was to not use "probability" as a method of partial acceptance of poor quality conditions. All components must be treated as KNOWN in their quality and KNOWN in their performance over time.

*Butte County Supervisor tells DWR it needs to restore trust with Oroville

http://www.krcrtv.com/news/butte-county-supervisor-tells-dwr-it-needs-to-restore-trust-with-oroville/644622156

--- Article clip: (emphasis mine)

In response, Butte County Chairman Bill Connelly made it known that Oroville has some major trust issues with the Department of Water Resources. He fired concerns at DWR's Deputy Director of the State Water Project, Joel Ledesma.

"I'm just personally leery of a situation where the same people who told us everything was okay are doing the inspections now," Conelly said to Ledesma in the meeting.

The vocal board member has been pushing for an independent team to oversee the repairs and asked Ledesma what will be done about allegations of cracks near the gates of the spillway.

"The gates are cracked, one crack is 15 feet long," said Connelly. "They leak, there are problems, they need to be addressed. [Ledesma] promised that it would be addressed in the near future, and that they would look at the river valve and the green spot on the dam in the near future. But again, that's somewhat hollow when it comes from DWR. I believe we need an outside, independent forensics analysis of the entire dam." --- end clip more at url link.

**Our Massively Parallel Supercomputer system was showing an "out of spec" soft error rate that didn't match the specs in the datasheet, even though the computer would safely continue as the ECC performed the rare bit failure correction on-the-fly.

The feared "Blue Screen of Death" - single point of failure hardware malfunction in computers (Parity Error)

Intel iPSC/2 16-node Supercomputer - 1995

[EarthResearcher333]

KRCA Copter Photo - RCC spillway completed to Construction Concrete

Oct 27, 2017 photo from KRCA news helicopter shows the RCC spillway slope is completed at the Upper Spillway Construction concrete transition slab. The vertical "drop" from the transition slab is the "Aerator" mechanism to introduce* air bubbles into the spillway flow.

The Transition slab has a coating of white sealant to assist in a moisture controlled curing of the concrete. Work is underway in finishing the RCC sidewall inner wall concrete finish at the junction of the Construction concrete sidewall. A bulk pour of concrete reveals a square type of mass concrete column that looks to be placed upon a concrete footing block as per prior photos. Thus concrete column is "sandwiched" by RCC on 3 sides and abutted to the transition wall face on the 4th side.

Now it is time to "see" the RCC machines that will place the 1 ft top RCC "hardened" layer on the full RCC spillway section.

*Sudden drop in atmospheric pressure levels inject a froth of bubbles within the water flow. Injected bubbles help prevent Cavitation Erosion effects in the downslope RCC surface(s) as the water flow velocity becomes higher.

Oct 27, 2017 photo from KRCA news helicopter shows the RCC spillway slope is completed at the Upper Spillway Construction concrete transition slab.

[EarthResearcher333]

Side note: The vertical concrete columns look to be hollow. This may be to facilitate an upward routing of piping from the lower "open drain" flows on the outside footings of the sidewalls ("fill concrete" level).

The size of the box like concrete column projects outward enough such that coring of pipe access would be available as the outward width sizing is within the construction concrete spillway wall footing "open drain" space.

[EarthResearcher333]

Hollow Concrete Columns - Look prefabricated & stackable - Equipment left in RCC spillway

Series of photos from DWR drone footage gives a clear view that the vertical box like concrete columns are indeed hollow. These columns look to be made from prefabricated blocks that were stacked as evidenced from the interlocking lip at the top.

Vertical view in one of the photos shows a small "catch basin" in the open drain area outside of the footings of the spillway walls.

Another puzzle & question: How are they going to get the two bulldozers and the two excavators out of the spillway? Do you think these were left there to assist in the application of the upcoming final RCC "hardened" layer?

[EarthResearcher333]

Dozers, Mini-Excavators, Roller Compactors Gone - No Track Marks - Craned Lifted Out

KRCA helicopter flyover Oct 27 shows all of the equipment missing from the RCC spillway. Since there are no tracks from the steel crawler tracks of the dozers on the RCC, this indicates all of these pieces of equipment were "lifted" out by crane. The heaviest piece would have been the larger Cat dozer which is just under 37,000 lbs (If I've pegged the Cat model correctly).

We'll see soon what equipment will be used to place the 1ft "hardened" RCC top layer to finish the RCC spillway section.

Dozers, Mini-Excavators, Roller Compactors …. Now you see 'em…. Oct 26..

… Now you don't….Oct 27

[mad_as_he$$]

Interesting update, thanks. I am impressed by the progress in the last week. Yes the area of work got smaller but the activity there is significant. The walls are really coming along.

Weather change at the end of the week with the warm atmospheric river in place.

[EarthResearcher333]

Final Enriched RCC Layer Application - Dozers, Small Excavators, Roller Compactors, Interactive GPS survey process

The Final Enriched RCC layer application is underway. No special application equipment other than the original process using bulldozers and Roller Compactors. Rubber tracked small dump trucks deliver the RCC loads.

Wood Sheets keep the small excavator tracks isolated from the RCC layer. The excavator head is being operated similar to a "trowel" with the addition of pressure controlled finishing. Wood sheets and other actions are leaving indentations and irregularity "edges" estimated up to 3/4 of an inch on the finish surface. With near 90+ feet per second flow velocity in the lower spillway cavitation effects become a factor. Unless these "edges" are finished to a smoother transition later there could be a some risk of cavitation damage to the top RCC surface at these edges from straight water flow alone. The upslope "drop-off" Aerator bubble injection process would help mitigate the risk exposure to cavitation damage. We'll see if further finishing is performed to smooth these "edges" & gouges or if they will leave it "as is".

The bulldozers are kept on the rough applied RCC - mostly - to keep the steel tracks from indenting the base RCC layer.

Careful survey & markings denote the final small excavator finish work (likely "vibrator head) to tune the elevation finish.

Note: Normal GPS readings alone are not accurate nor fast enough for high accuracy "real-time" readings. There needs to be a reference signal to give "real-time" compensation to achieve survey-grade accuracy. This requires a type of CORS, continuously operated reference station, that transmits to the receiver to get readings down to the centimeter in real time (0.8 cm horizontal, 1.5 cm vertical - reading in 8 seconds). Otherwise, the process would require "post-processing" 24 hours later after the Satellite Orbits are daily compiled so that their slight variations above the Earth's orbit may be taken into account for adjustment. They may have updated this CORS RTK* system to have further distributed localized base station(s) (WiFi & UHF linked) to provide this critical "real-time correction" information. See: https://construction.trimble.com/products-and-solutions/gnss-correction-sources for "Correction Sources".

Note2: This final RCC "lift" looks to be higher than the described 1ft final layer height (closer to 2 ft). See Photo 2.

*Real Time Kinematic (RTK).

Photo 1 - Final Enriched RCC Layer Application - Dozers, Small Excavators, Roller Compactors, Interactive GPS survey process

Photo 2 - Final Enriched RCC Layer Application - Dozers, Small Excavators, Roller Compactors, Interactive GPS survey process

Photo 3 - Final Enriched RCC Layer Application - Dozers, Small Excavators, Roller Compactors, Interactive GPS survey process

[EarthResearcher333]

Surprise! Big Crane Trapped In Upper Spillway - Will need Disassembly - Old Upper Spillway Extensive Patching & Repairs

One of the Large Cranes is found to be back in the Upper Spillway. This is a surprise as the spillway seemed to already be "walled" in by the sidewalls. The crane is positioned at the last "joining" section from the Old Original Upper spillway to the New Upper Spillway. This section and the sidewalls were poured just a few days ago.

The only way out for this crane is to be disassembled and the pieces lifted out by another crane.

Second photo shows the extensive concrete work patching of the original upper spillway section. Some of the protective covering is angled in matching the diagonal orientation of the original drains. Kiewit emplaced near 3,000 new anchor bolts in the old upper spillway's 730 ft section. These patchwork sections are likely slab related repairs, including void repair, rebar repairs, & drain line repairs, and not from the extensive anchor bolt emplacement operation. The prior anchor bolt repairs would be best if they had curing time prior to these other repairs due to the extensively drain line fractured slabs. Thus these "section repairs" would have a stabilized reference of surrounding slab integrity - from the anchor bolts - in which the grouting reached a prior nominal 28+ day curing strength.

Unexpected surprise. A Big Crane found in Upper Spillway. It will need disassembly to get it out - likely from another crane lifting the pieces. Oct 30, 2017

Extensive concrete repair work in old upper Main Spillway (730 ft section). Likely slab repairs, void repair, rebar & steel bar repairs, & drain line repairs. 3,000 anchor bolts placed prior to this work.

[marmaly]

The crane will be able to drive out through the gate once the boom is removed.

[EarthResearcher333]

"The crane will be able to drive out through the gate once the boom is removed."

The Gate openings are only 17 feet wide. Doing a reference sizing from the spec'd 30 ft by 40 ft new slab dimensions, the outside of the crane tracks are 24 feet 10 inches wide. See image (note: image was enlarged to make the measurements. Smaller image shown with the results here).

[Bobsvainbabblings]

Disassemble and load on the tractor trailer units it was transported to the site on. Those units would fit thru the gates and have multiple wheels to make them “light” enough to travel on the highway. Might be light enough to travel on the sections that don’t have a 28 day cure time. BVB