Loading ...I have repaired hundreds of dams including ones like Oroville, which were in the process of failure. I know a lot about dams.
The spillway failure is a common type of failure, where phreatic, or surface water entered the spillway, migrating beneath the slabs. (A static element on a dynamic element, A hard element on a live element). The dam is hydrated and dehydrated as water levels rise and fall, moving, as soils swell from pressures and water mass. In times of high rain the phreatic surface (hydrated soils line) moves toward the surface, venting into the void so produced.
This creates a void. Moving water over the years has eroded soils from beneath the slab downstream and left a channel. Now, the spillway has been actuated in a high-flow event and the plates of the spillway have failed into the stream, scouring from beneath them. They will continue to fail as the water continues to flow. The hydraulic jump exacerbates this erosion.
If the flow continues for a long enough time, with sufficient velocity, the reservoir will be voided by the migration of the erosion to the pool (cut-back). I cannot tell if failure is imminent, from Ohio, but it is an unacceptable situation that has been allowed to develop. It is a case of pennies pinched producing dollars spent, perhaps tragedy.
What we can learn as a nation is the information that is being disseminated. Words chosen carefully, to not excite, to not scare. The issue, as it now stands is serious, life-threatening even. The officials, the owners reps, the media will tell us now, that there is nothing to be be frightened about – all under control (remember Katrina??).
More at https://www.linkedin.com/pulse/oroville-dam-failure-scott-cahill