This image (post 1043) reveals how much hydraulic underflow water is beneath the concrete Main spillway. The dam expert, Scott Cahill, identified this severe issue. He said that these hydraulic underflow drains should have just a “trickle”. Instead, they are “jetting” water out in great volume. These drains are “jetting” all down the side walls of the main spillway. So there is hydraulic underflow water that risks the stability of the sub strata the spillway is built upon.
Scott stated that this is should not be happening (i.e. can lead to a failure mode).
Look at the lower right section of the image. Near the yellow jacketed construction worker & the concrete sidewall of the spillway. You can see a water jet coming out of the side of the wall into the main waterflow. This is waterflow from upper areas underneath the main spillway (under the concrete & soil/rock base). These “jets” are all going on both sides all the way up the spillway walls. That is a tremendous amount of “unwanted” waterflow under the spillway.
those water jets are normal..at one time they were all the way up and down the spillway before it was damaged
Someone grabbed a screen shot from this video:
https://www.youtube.com/watch?v=E0Rzi8kELM4
Oroville Dam Spillway 2-15-17 8:30am Evacuations Lifted