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.

[Ray76]

A controlled blast breaks up a section of the upper chute of the Lake Oroville flood control spillway in Butte County, California. Photo taken August 2, 2017.

Roller-compacted concrete fills an area of erosion between the lower and upper chutes of the Lake Oroville flood control spillway in Butte County, California. Photo taken August 2, 2017.

The first section of structural concrete is being formed in place on the lower chute of the Lake Oroville flood control spillway in Butte County, California. Photo taken August 2, 2017.

[EarthResearcher333]

Hi Ray76, green colored rebar is indicative of epoxy coated steel. This is different from the rebar they were prefabricating in the upper main spillway in June. Curious.

Prefab Rebar mesh staging in Upper Main Spillway - non-epoxy coated

[Ray76]

Zoom in and you can see uncoated rebar beneath the coated rebar. Curious indeed.

[EarthResearcher333]

Farmers file $15M claim against DWR from spillway crisis & lost orchard acreage - claim a precursor to lawsuit

= = SFgate Article clips: (emphasis mine): Lawyers filed a $15 million government claim on Tuesday on behalf of walnut farmers who say they lost more than two dozen acres of land along the Feather River when the Oroville Dam spillway failed in February, causing massive flooding and destructive erosion in the area below.

The claim is a precursor to a lawsuit. It alleges that the state Department of Water Resources and the Division of Safety of Dams failed to protect the property of landowners downstream of Lake Oroville. State officials did not respond to a late request for comment on the claim. The claim was filed on behalf of JEM Farms and Chandon Ranch, which operate a total of 2,000 acres of walnuts on both sides of the Feather River in Butte County. The landowners say they lost about 27 acres of land, and the $15 million claim includes production losses and cleanup costs.

. .

“There were multiple red flags that the state ignored,” said Niall McCarthy, an attorney with Cotchett, Pitre & McCarthy, the firm representing the farms. “The state knew there was a problem, they did a minimalist approach to the repairs, and as a result our people lost their property.”

= = end clip more at link: Farmers seek damages over Oroville Dam spillway failure

http://www.sfgate.com/news/article/Farmers-seek-damages-over-Oroville-Dam-spillway-11730191.php

[KC Burke]

Of course what we are talking about is not mesh in either case but pre-tied and (here) tied-in-place mats of reinforcing bar.

I believe the earlier picture may have been for vertical wall placements or non spillway slabs. Hence the lack of epoxy. It was being pre-tied flat and stacked on cribbage 2 x 4 s for separation at the time of later crane pick.

Epoxy shows up a lot in roads and bridges due to salts used on roads. Here it’s use is just for long life durability.

[KC Burke]

My #4105 was to you as well. As far as upper layer in epoxy and lower layer not it could have been an upgrade. Without road salts epoxy is kind of rare for many situations. Spillways this size are outside my wheel house of frequently-built.

[EarthResearcher333]

Mesh as in "Pattern" i.e. the preformed wire tied sections in the Upper Main spillway. Simpler for discussion using a common term then to add more words to make a distinction from wire mesh.

There is one consideration for the epoxy coated reinforcement steel bar on top; that is for an extra measure of protection from any small surface cracks that may transmit moisture. The upper surface of the concrete in the lower spillway will see flow velocities of 90+ feet per second (surface cavitation risk if surfaces not kept optimal).

It's also possible a "decision" was made to upgrade to this epoxy coated steel (for the upper layer) after debating the pro's/con's in the early engineering phase. I do believe the extremely corroded rebar observed in the drain cracked slabs may have influenced this decision too (if so, that could have created a huge order change in materials/fabrication turn around time).

[Ray76]

Thanks for the ping.

[abb]

http://www.mercurynews.com/2017/08/06/oroville-dam-six-months-after-disaster-a-race-to-repair-before-next-winter/

Oroville Dam: Six months after disaster, a race to repair before next winter

By Paul Rogers | progers@bayareanewsgroup.com
August 6, 2017 at 6:00 am

Six months ago, relentless winter storms dumped nearly 13 inches of rain in four days on the Sierra Foothills, tearing an enormous hole in the spillway at Oroville Dam, the nation’s highest, and leading to an unprecedented emergency that prompted the evacuation of 188,000 people from nearby towns.

Today, what could have been ground zero for America’s worst dam disaster is now a hotbed of construction activity. Hundreds of construction workers are laboring 20 hours a day, six days a week with huge dump trucks, cranes, excavators, bulldozers, concrete pumps and other equipment to demolish and rebuild the 3,000-foot-long main spillway — a massive chute as wide as 15 lanes of freeway– by Nov. 1, before the next winter rain season begins anew.

Residents of the area are watching nervously.

“In many ways things are back to normal because we don’t have an imminent threat,” said Larry Matthews, 66, who lives in Yuba City, south of Oroville. “But people have a real concern that maintenance wasn’t done correctly. They want it fixed correctly. There’s a certainly some paranoia but you can’t blame people for that.”

[EternalHope]

Most of us don’t have anything to contribute at this point so we don’t post.

However, we are still following this thread.

We lurkers appreciate all the good work you and the others currently posting are continuing to contribute!

[meyer]

Just checking in. The progress is pretty fast. They’re getting a lot done.

[EarthResearcher333]

Curious Development - DWR's Green Wet Spot Response is MIA

When DWR was asked, by a public speaking citizen, at the July 24, 2017 Town Hall Meeting, about the recent report released by CCRM (Bea-Johnson et al) Leakage issue at the dam, David Gutierrez noted that DWR will have a public response/mini report put out in a few days (inferred by Friday July 28).

July 28 comes and goes - Nothing from DWR. Another week passes (week of July 31) - still nothing.

A rebuttal proof that DWR has been repeating about the Green Wet Area is "that it was green before the reservoir was filled" (David Gutierrez). Going back through the historical footage of the dam, the dam was nearly complete (922 ft) and yet there was no sign of "greening" in the future wet spot area.

If DWR is hanging their hat on this rebuttal position point (as a key point), they need to provide photographs as the available historical photographs do not support their position (at least this notable photograph disproves their statement).

This gets to the delay in their report. Their prior claims of "rain falls…then grass grows" and "it's a natural spring" fell somewhat flat as "uphill water flow" was needed to support the natural spring (water does not flow uphill). The "rainfall" position also could not answer why only one area is concentrated in growth (i.e. there should be green areas all over the dam if from rainfall).

Perhaps DWR is having difficulty in putting together a coherent explanation (why its taking so long - going on two weeks now). Keep in mind, there are very capable dam engineers who specialize in seepage in earthen dams. Whatever DWR puts together has to endure scrutiny on this anomaly - including these independent seepage experts who could find any "holes" in any DWR explanation. DWR could ill afford to posit another position that doesn't hold up to scrutiny. (they are already on shaky ground based on this historical photograph - that is why they need to come out with real photographs and real data).

Dam face clean - no Green Growth in historical photographs. Photograph is prior to reservoir being filled. Conflicts with DWR's assertion of this area being green before the reservoir was filled.

[alfa6]

Most of us don’t have anything to contribute at this point so we don’t post.

However, we are still following this thread.

We lurkers appreciate all the good work you and the others currently posting are continuing to contribute!

A BIG DITTO TO THAT

And a big tip of the alfa6 lid to ER 333, meyer, abb, KC Burke and anybody else I left off, Soorry

Regards

alfa6 ;>}

[Ray76]

The first section of structural concrete is being formed in place on the lower chute of the Lake Oroville flood control spillway in Butte County, California. Photo taken August 2, 2017.

The first section of structural concrete has been placed on the lower chute of the Lake Oroville flood control spillway in Butte County, California. Photo taken August 4, 2017.

[The Westerner]

Stalling. Panicking most likely. Why? Someone who may not be running for office again wants the “Obama” treatment in the msm, i.e., nothinng bad is said about his years in office. Which means he's running for the Presidency or Sainthood whichever comes first!

[mad_as_he$$]

Cement is at a premium in the region. They are using massive quantities of it every hour. Nothing like a big project to put a crimp on the supply/demand curve.

[EarthResearcher333]

Early Oroville Dam Construction Deviation - created excavated "flat bench" in left abutment - Impeding drain flow?

Comparing the original HYD-502 Dam Embankment plans verses the "As-Built" Dam Embankment, a very important change is noticeable. The Left canyon was blasted/excavated with a long and deep "flat bench" that extended into the future Zone 3 fill embankment.

Although this "flat bench" area would facilitate equipment, temporary buildings, and construction materials for the Hyatt Power plant tunnel exploration and final construction, this "flat bench" caused a "drainage" flow topology change from the original HYD-502 design.

The engineers likely felt that this "flat area" would not pose much of an issue as the Zone 3 embankment is the "dry" side of the dam. In essence, the Zone 3 material would only need to drain any percolation of rainfall. Thus any "pooling" of water in this flat area would eventually seep its way into the horizontal drain channel below (just above the original Feather River Channel is where the horizontal drain boulders, rock, cobble, gravels resides)(see fig 1.).

The problem with blasting and excavating this flat area deeper into the future Zone 3 embankment fill is that this deviates from an optimal drain flow along the hillside to the bottom horizontal drain in this area of the Zone 3 embankment. The original Embankment plans show the topology of a gradual slope to the bottom. The only way to "restore" this important draining "slope" section would have been for the original excavation to "re-build" the slope with competent conditions to the original canyon rock. But this would have been very unusual to use concrete & anchoring to restore the prior blasted/excavated hillside design spec topology. Once the decision was made, it became locked in.

Fast Forward to the Green Wet Area mystery. The Green Wet Area & the Erosion channels exist at the junction of this flat area boundary. Coincidence? (there is more to this combination - later posts to come). A real issue that DWR is investigating is how much water is flowing, why its flowing, and where to. The Left canyon is a natural semi-barrier of rainfall seepage into the Zone 3 to where the canyon hillside will "guide" the waterflow at the abutment junction down towards the canyon bottom (where the Horizontal drain exists). However, this flat area could disrupt the flow as the water could pool, forcing a hydraulic gradient to pressure the water eventually towards the drain zone or ?.

The "Flat Area" was covered with aggregate and compacted. This foundation likely was upon the native fractured metavolcanic rock. A safe assumption would be that there was no sub-grouting in this "flat area" to prevent any water flow from "finding" fissures or cracks to flow to the lower Feather River water table.

So what happens to any water that reaches this Flat Area? Over time, has it created a puzzle for engineers looking for accurate toe drain seepage flows in seeking answers to the Green Wet Area?

Fig 1. Forensic Overlay reveals the introduction of a "flat area" intruding into the Zone 3 embankment. Original HYD-502 design had a fully sloped canyon wall to the bottom drain layer - did not have this "flat area" intruding into the Dam Zone 3 embankment.

Fig 2. Early Construction photograph showing the Flat Bench Area "line" as the Zone 3 Embankment material is being constructed. This Flat Area creates a "flow" disruption to the outer area of Zone 3 seepage to the drain zone".

Fig 3. Early Construction photograph revealing the large flat construction area blasted/excavated into the left canyon hillside. Construction materials & facilities staged in the work for the Hyatt Power Plant tunnel & facility work. "Flat Area" disrupts original embankment design with sloped topology.

[EarthResearcher333]

Finish surface pattern looks like they may have used a riding trowel concrete finishing machine. Another interesting item is the tilt angle of the anchor bars. The tilt looks to be a pre-determined angle in the direction in the downslope - thus the tensile forces look to be optimized for the anticipated stresses.

[EarthResearcher333]

Article: Is ‘Green Spot’ a Sign of More Trouble for Oroville Dam?

A good article that describes both sides of the story on the Green Spot (DWR's internal puzzlement and references to Green Spot history).

This article reveals DWR's position of the Green Spot being observed before the reservoir was filled. Quote: "The consultants' report noted that the final construction report for the dam, which went into service in 1968, indicated that the green spot area was observed even before Lake Oroville began rising behind the structure."

This is key. Exactly what did the final construction report say on the dam concerning the Green Spot? The article uses the word "indicated". Yet there are historical photographs that show this area to be "clean" just before its filling of the lake. Springs in metavolcanic rock are common. However the best evidence is photographs (as shown a few posts above) of the prior green spot. Otherwise, DWR should release the full wording reference of this "final construction report" & "indicated" sections of the report document to the public.

= = Article clips (emphasis mine): "From Day 1 of the Oroville spillway crisis in February, the California Department of Water Resources has never wavered in its declarations that, despite the disintegration of the massive concrete flood control outlet and a near-disaster caused by uncontrolled emergency reservoir flows down a rapidly eroding hillside, the stability of the massive dam itself was not and has never been threatened."

"Despite those oft-repeated assurances, public questions about the dam’s integrity have persisted — in internet forums, in community meetings and, most recently, in a report released last week under the auspices of UC Berkeley’s Center for Catastrophic Risk Management."

"That’s in part a reflection of public distrust of DWR after the spillway incident and in part a recognition that anything that seriously compromises the 770-foot-tall dam could endanger tens of thousands of lives, cripple a key element of California’s water-supply network and put the state’s entire economy at risk."

"Specifically, the questions have focused on an extensive area of moisture on the left side of the dam’s downstream face that’s known, even to the Department of Water Resources, as “the green spot.”

"The spot, characterized by what state inspectors have termed “lush” vegetation during wet seasons that turns into dense thickets of dry weeds by late summer, is clearly visible on satellite images and measures about 700 feet long by 130 feet wide. That’s roughly the size of two football fields.

"Last week’s study, led by internationally known civil engineer and risk management analyst Robert Bea, included several subreports asking whether the moisture at the green spot is a sign that water is leaking through the dam and weakening its inner structure."

"Publicly, DWR officials have tended to dismiss those concerns. In response to questions at community meetings in Oroville and Yuba City in May, for instance, the agency said the green area is due to rainfall, that it first appeared while the dam was under construction, and that it poses no risk to the dam."

"But outside public view, documents KQED obtained under the California Public Records Act show the Department of Water Resources has puzzled for years over the source of the seepage feeding the “green spot” and has been slow to act on a 2014 recommendation from independent experts to investigate the issue."

. . . "The consultants’ report noted that the final construction report for the dam, which went into service in 1968, indicated that the green spot area was observed even before Lake Oroville began rising behind the structure."

“The green spot is believed to be associated with pre-existing natural springs in the downstream left abutment area of the dam foundation,” the Part 12D report says. The concentration of moisture, the document speculates, could be due to the composition of the rock and earth used to build the dam’s downstream embankment. The fill, which may contain excessive volumes of very fine, dense material, “may prevent free drainage of flows from those underlying springs.”

"The four consultants said that although there was no evidence of movement or instability in the green spot area, they recommended the Department of Water Resources investigate to see whether the persistent moisture could pose a risk to the dam, especially in the event an earthquake occurred during a period of particularly wet conditions."

= = end clips More at link:

Is ‘Green Spot’ a Sign of More Trouble for Oroville Dam?

https://ww2.kqed.org/news/2017/07/28/oroville-dam-green-spot-department-of-water-resources/

[KC Burke]

That could also be a vibrating screed finish. Perhaps we will see in later pics.

Thanks for your hard work.

As-builts should have enlightened DWR about the wet spot years ago. Perhaps it did.