California spillway collapse

From the link in the previous post, the emergency spillway:

 

The dam was intiated under the administration of Governor "Goody" Knight, who was Brown's predecessor.

 

Reagan's crew was over the final buildout in 1967-68 while the lake was filling and ancillary things like spillways were being installed.

 

Holy shit, I would grab my belongings and go live in a hotel or apartment for awhile.

The physics of dam construction and how they hold back all that water pressure dictate that the base of the dam has to be a lot thicker than how thick it needs to be at the top. All that erosion cannot be good.

But, I suspect this emergency spillover area is not part of the main face of the dam and its earthen fill. Looks like it might be over some of the original terrain of the valley prior to the dam's construction. If voids within those natural features, and other things, like this major erosion, weaken the area to which the dam is anchored... or if engineering assumptions about how dense those valley walls are/were, you have the makings of a disaster.

Several dam failures have been caused, not by the face of the dam giving way, but by the sides/anchoring valley walls giving way. There's a famous one in CA with film (or at least a sequence of photos) of it giving way, IIRC. Pretty sure it was north of LA. Worth looking up.

 

They think they'll have the water down to a safe level by this weekend, even with rain expected. The big challenge is getting everything shored up before the spring snow melt.

Inside the desperate battle to shore up the eroded hillside next to Lake Oroville

 

Baldwin Hills dam failed in 1963. Five dead, 277 homes destroyed, according to Wiki. Baldwin Hills is between Culver City and Inglewood in SW L.A. Sidebar: KTLA news used a helicopter to cover this event, thought to be the first time a helicopter was used in breaking news reporting.

 

I thought he was referencing the St Francis dam, which actually is north of LA
St. Francis Dam - Wikipedia

 

I'll check later. I've had a shitload of things fuck up at work this afternoon.

 

Probably. That was in the '20s. Before my time.

 

This is how dire the drought was the past 4 years, last year the reservoir created by that dam was at less than 40% capacity.

 

If you click on the picture and blow it up look at the upper left corner. The grey rock and trucks they're using to bring it in becomes more clear as well as the scope of what they're dealing with.