It is a amazing construction repair that was done at Oroville Dam after the Feb 2017 failure seen below.
Damage
https://www.youtube.com/watch?v=jxNM4DGBRMU
Repairing
https://www.youtube.com/watch?v=ekUROM87vTA
A good friend of mine retired from the company that did the repairs. He said the repairs cost $1 billion!