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Comment by dogsgobork | Hacker News Reader

Video of the new spillway being used https://www.youtube.com/watch?v=EFZNUyS89fg

The end of the spillway with the enormous waterfall makes me uncomfortable since erosion back from that point working backwards along fissures to undermine the spillway basin seemed to be an aspect of design contributing to the previous failure. But presumably they have accounted for all that. It would be interesting to read the post-mortem of the previous failure and the challenging new engineering decisions behind the new design.

Fortunately the article contains such a source: https://issuu.com/asdso/docs/independent_forensic_team_repor...

At the end of the spillway the water is send upward. This is a way to dissipate the energy of the water coming down and avoid digging a hole or eroding the river itself. This appears to be a common feature in most spillways.

Here's a (pre-repair) photo of those energy dissipator blocks at the bottom of the spillway, including people for scale:

http://media.fishreports.com/reports/img-20170303-78a7bb40.j...

Hard to comprehend how massive those blocks are...

Yah, it's kind of hard to show the magnitude of the spillway and the repair work in a few pictures.

Juan (blancolirio) posed a very good time-lapse/montage (including footage from the DWR) that shows the entire repair project. The audio has comments from Keiwit's executive project director of the repair project about the insane amount of material and work that was needed.

https://www.youtube.com/watch?v=v6lus-PXS4k

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