The ‘68 photo indicts the design. Having just become operational the spillway must have been considered as working as designed.
It will be interesting to see how it works (or doesn’t work) later today when they start spilling. They’re going to ramp up to 50,000 later.
I watched the press conference - one caution that he made repeatedly was “what you see today may not be there tomorrow”, meaning that while they did a lot to strengthen and secure the remaining portion of the spillway, it still might be further damaged when used.
They plan on running for about 5-7 days. They will shut down the plant for the spill. I don’t know if it will stay shut down for the duration, or it it’s a precaution for the initial operation to protect from potential issues.
Yes to the 2nd statement. As to the first, there wasn't much technical history on Stagnation Pressure dam spillway failures (only one prior in 1954). Later on, more dam spillway failures occurred & were determined to be from Stagnation Pressure issues. Since Oroville was in "maintenance mode" by then, and not an "engineering analysis" mode, someone would have needed to escalate the question of "do we have a risk in this design?". The only proof of this concern would be if there was a "risk assessment & analysis" done.
One of the failure analysis experts named to the Oroville FERC panel has spent many years going to dams, working with engineers and doing Stagnation Pressure Failure risk analysis. It would be an honest question for someone to ask if there was any concern or thought of doing a risk assessment analysis for the Oroville spillway some time ago.