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

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

[KC Burke]

Ping your list.
video

https://twitter.com/WeatherNation/status/911369885577441280

[KC Burke]

another

https://www.youtube.com/watch?v=8RHNAcgcu8w&feature=youtu.be

[EarthResearcher333]

Guajataca Dam Update - Photos - Dam Experiencing Overtopping Failure at Designed Point - Special Spillway to Collect this overflow - Erosion may lead to full breach

Early News media reporting are showing to be incomplete in information details on the Dam. An Emergency Safety feature is engaging to control the overtopping failure. This area is on the South end of the Dam, not the North as reported.

Note: Without design specifications to this dam, information was constructed from satellite elevation data, imagery data, technical report information, and dam design background knowledge.

Fig. 1 reveals that the Dam was designed for an Emergency Overtopping Area in the southern end of the dam. This is the lowest elevation in the curved section. The embankment in this area is sloped to guide water into a circular concrete collection zone at the top of a concrete spillway. Fig. 2 Shows the overtopping flow at this low elevation point. The flow is entering into the collection zone of the circular concrete spillway. At the time of the video, the overtopping has not eroded to the left into the main dam. However, this water flow volume is testing the limits of the spillway capacity.

Fig 3. shows that the lower spillway is damaged from these high flows. The riprap rock has been washed away. This is a primary indicator that the riprap was handling flows exceeding the dissipation energy it was designed for. Another possibility is that the spillway concrete was not maintained and experienced a failure in a section of the spillway concrete. If so, this failure would have allowed the flows to undermine the base foundation that the riprap rock was emplaced upon, making it easier to wash the rock away.

The overtopping failure flow has been somewhat mitigated IF the dam does not develop a deeper erosion "V" breach. A "V" breach could expose a much higher surge in flows as the lowest section of the "V" determines the height and volume of the reservoir release in a shorter period of time.

Fig. 4 shows the failure of the spillway and the erosion that is cutting into the base of the dam surrounding the spillway. This erosion is likely "back cutting" or back stepping the loss of the soil like foundation supporting the spillway. If high runoff conditions continue to enter into the reservoir, there could be a point where a collapse of this overtopping & spillway section could result. Thus, if so, a larger surge of flood water would cascade down the river channel.

Fig. 1 Guajataca Dam was designed having a lower elevation "Controlled" failure "Overtopping point" in the southern end of the dam. A "Controlled failure spillway", concrete lined, was designed to guide this water to energy dissipation riprap of large rocks.

Fig. 2 Image shows a wide water flow into the "Controlled Failure Overtopping" area and the water entering the "Controlled Failure Spillway".

Fig. 3 Image reveals the broken spillway (see depth of water drop) from high flows and "back cutting" erosion. The Energy Dissipator RipRap rocks have been washed away. The high flows are causing more flooding downstream.

Fig. 4 Image shows the failure of the spillway and the erosion that is cutting into the base of the dam surrounding the spillway. This erosion is likely "back cutting" or back stepping the loss of the soil like foundation supporting the spillway. If high runoff conditions continue to enter into the reservoir, there could be a point where a collapse of this overtopping & spillway section could result. Thus, if so, a larger surge of flood water would cascade down the river channel.

[Jim W N]

Video of Lake Guajataca, PR.

https://twitter.com/WeatherNation/status/911369885577441280

[EarthResearcher333]

Hi Jim, KC Burke put out this link a couple posts up. I used this video to capture the images and make notations. Thanks for following up.

[KC Burke]

You got to be up pretty early to out gun me, ol’ timer.

[Jim W N]

Dire straits.

PR seems like an example of going from the intermediate stage to the final stage of dam failure (don’t have the more formal terms in front of me) very quickly, a constant concern for those living below Oroville Dam as you point out.

I still wish they would require all DWR officials responsible for Oroville Dam to move to Oroville. Suddenly things would change.

[Jim W N]

[KC Burke]

LOL. I’m cautioned now.

[Jim W N]

I don't know. Either that guy or this guy...

[KC Burke]

I’ll be Jimmy if you don’t mind. I was always told I sounded like him.

[Jim W N]

Don't know who Jimmy is, but these guys are Jack Palance as "Wilson", the "Prince of Darkness" as Pauline Kael so eloquently described him, and Alan Ladd as Shane, the good guy. Either way, looks like I'll have to get up early if I want to match your draw.

[KC Burke]

Whoops, I guess if I look it is Ladd. I saw the fringed buckskin and thought Jimmy Stewart...LOL

[EarthResearcher333]

Shotcrete Inner Sidewall finishing - Worker using a "guide cable" - Simple pre-alignment with board & anchor for taut cable

A simple, but effective, tightly pulled guide wire (small cable) is being used to assure the proper finish of the shotcrete wall that lines the RCC. Layers of steel mesh and individual vertical reinforcement bars with separate anchor bars were placed prior to this shotcrete wall layer. Earlier images of the "stay in place" fine metal mesh revealed anchors that extend into the wide layer of RCC that was being placed during construction. This adds an additional contribution to a tie-in to the anchorage of the steel mesh, vertical reinforcement bars, and the "drilled then hammered in" anchor bars.

See: Prior post 4250

Prep work with rebar for Inner Shotcrete Sidewall (post 4250)

Fig. 1 Reveals how the upslope alignment of this sidewall layer is carefully maintained by the "guide cable/wire" reference in the finish work. What looks to be a colored wood stud (or a denser material) is being used to hold the guide cable/wire and keep its tension. This approach is effective and can be easily adjusted, repositioned, and aligned. Most likely there is a survey "shoot laser" that is being used to keep this placement of the guide wire accurate to the upslope alignment of the sidewall surface. Another clue to the "laser" is that the board does not have an optical survey "target". Overspray of the shotcrete on the board infers that the board is positioned, and thus the cable, before the shotcrete layer was placed. This would serve as a depth to completion reference in the process of applying the shotcrete..

Fig. 2 Reveals the skill of the concrete workers as the wall is very well finished and clean. There is a significant amount of this work to be done as both sides of the RCC temporary spillway will require this shotcrete surfacing process. The "meet up" date to the upper construction concrete spillway section by the RCC is stated to be the last week of October. This would mean that these workers would be scurrying to finish the inner walls as this happens after the main RCC is emplaced. The other "race" will be the chemically treated 10 to 12 inch hardened RCC layer that still needs to be applied to the RCC spillway horizontal surface. This is also noted to be started when the RCC meets up with the upper construction concrete spillway section.

Note to KC Burke: I'm up late - not early. So you, Abb, and others can be the "early birds"… :)

Fig. 1 Worker carefully finishing shotcrete surface of concrete wall to a guide wire/cable. Simple arrangement allows wire to be repositioned as construction work progresses. No sign of a survey target - indicates wire placed by a laser "shoot" (from a survey position).

Fig 2. Professional finish, including the vertical continuity, of the wall reveals the skill of the concrete workers. Notice the "excess" shotcrete on the plastic. Likely from the finish process of a careful removal of shotcrete to arrive at the final aligned vertical surface.

[EarthResearcher333]

Worker's construction hat shows he is "all-in" on shotcrete. He even keeps a trimmed line on the brim. Does this make it a stronger hard-hat? :)

[mad_as_he$$]

This is truly an epic construction event. Kiewit is now claiming that they have worked more than 500,000 man hours without a OSHA recordable injury. If true, that is an admirable record and their techniques and safety program needs to be studied and shared.

Weather will now become a negative factor.

Rumors persist in the water community about damage to the main spillway structure relating to the floor and the tension bars. Sadly, only time will tell.

[Repeal The 17th]

Just where are we at here?
Is this the temporary sidewall along the temporary section
connecting between the upper and lower spillway sections?
Does this all get ripped out during next year’s construction season?

[EarthResearcher333]

This is the temporary RCC sidewall that will be deconstructed in next year's construction season. Yes, this section will connect between the upper and lower spillway sections. These photos are at the downslope beginnings of the RCC nearest the lower construction concrete section.

[The Westerner]

Just heard about the Puerto Rican dam failure after speaking with someone from there, but leaving here now. PR has had a Moonbeam type government which (obviously) led to lack of maintenance or replacement of electrical grid. The saddest thing is that much of PR was already without electricity. That dam supplied electricity so it’s going from worse to worst case. Even the harbor is blocked with leisure boats, so relief ships can’t get through.

[Repeal The 17th]

Kind of sad, really, to think about...
how the worker is taking such great care to build something
that is scheduled to be demolished in 6 months.