This image shows just how many people Oroville provides water to—and why the lake's near-rupture is a very big deal (wired.com)
Astounding!”
I caught that gem buried towards the end of today's LAT article!!
Soft bedrock is not the only problem, he added. The concrete weir at the top of the emergency spillway was “just plopped on top of that ridge. It’s a design area that will probably get a lot of scrutiny and had to be a major concern as [the spillway] was eroding up the hill.”
Vogel confirmed that the weir, which she said ranges in height from 25 feet to 45 feet, was not anchored.
This image shows just how many people Oroville provides water to—and why the lake's near-rupture is a very big deal (wired.com)
I don’t know anything about dams and weirs but that sounds like a deep liability.
This state’s priorities are so bad we could replace the governor and legislature with squirrels and they’d do a better job.
Just as I was about to post this research/conclusion independently this morning. Good to have an official come out and confirm the truth (the evidence is overwhelming that this was the case). Now they unleashed another can of worms. Waterflow under this structure is now a real part of the equation and very likely associated with the huge water bubbling in front of the this Weir. Another big issue is that this structure is not Solid Concrete. It is only a concrete shell that is filled with aggregate. Weepage, from leakage waterflow into the center filled aggregate can compromise the integrity of the strength of the Wier (capillary action). There are drain channels at the bottom of the Wier footing to keep the aggregate dry. A strong penetration of waterflow through the highly fractured rock may make these drains insufficient.
First image: Blueprints of Emergency Spillway & "Its Plopped on top of that Ridge"
Second image: It is sitting atop highly fractured rock, called "rotten rock" in structural terms. Erodes swiftly as proven by the recent 12,000cfs short time overtopping.
Here is another insanity: The original designers stated that this Emergency Spillway + the Main Spillway could handle 624,000cfs. Yet only a dinky 12,000cfs over the Emergency Spillway cut down to 797ft (36ft crevasse/hole) only 300ft from the main spillway. Yikes! Imagine if they tried what they said it could do?
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----- https://archive.org/stream/zh9californiastatew2003calirich#page/92/mode/2up page 92-93: The emergency spillway, in conjunction with the flood control outlet, has the capacity to pass the maximum probable flood release of 624,000 cfs for the drainage area (peak inflow 720,000 cfs) while maintaining a freeboard of 5 feet on the embankment. The maximum probable flood has a probability recurrence interval in excess of 10,000 years.
Looking at the weather forecast I’d leave now.