Joining of Old to New Sidewalls & Spillway Slab concrete - Lower Transition Slab (RCC to Construction Concrete)
Getting the last sections completed. An interesting RCC design modification. Power jackhammer mini-excavators have been used to cut grooves across the RCC spillway surface. No particular pattern to these cut grooves. In addition, the large flat surface area of the RCC is being air blasted and hydro blasted in what seems to be a "roughing up" or cleaning up of the top aggregate of the RCC. Power washers are then used to move the dislodged material downslope.
The mini-tracked dump units are able to rotate 360 degrees on the central axis over the tracks. This allows "dumping" material over the side of the sloped RCC areas by the sidewalls without having to skid rotate turn the tracks.
Old original Sidewall and New taller Sidewall being joined in a final stage concrete pour. Same for the Old spillway slabs to the New spillway slab area.
Lower transition section of construction concrete has been poured. Water fills a "V" ditch to where the other half of the transition will be likely filled with RCC in the final top surfacing phase.
It’s been interesting to follow along with this. Thanks for your work, and the work of others, keeping us up to date.
This thread needs to be preserved. Without it a lot of what has happened will vanish down the memory hole. The politicians and California DWR will do everything they can to make sure that happens. They MUST ensure they are not held accountable for what happens in the future.
The spillway is the most visible problem and is getting all the attention. But catastrophic failure of the dam could happen in many other ways.
They MAY be working on finding the cause of the “green spot” behind the scenes. Let’s hope so. (As clearly documented on this thread, it’s not rain.) If you don’t know what has caused it you can’t fix it.
The turbines and “drain” at the bottom of the dam may have been “fixed”. They claim all is now well. If everything is now working fine inside the dam, but the spillway must be used again, will water back up so high, again, that the “innards” of the dam are again in danger?
The most serious problem may be the gates, tendons, etc. This could be the weakest link, and lead to failure of the whole dam.
If they are concerned about this they certainly won’t admit it. Whatever work they are doing on it, they are certainly doing a good job keeping the details out of the public eye. As far as I can tell, they are merely “studying” it.
Personally, I think even the incompetent ones among them (they are not ALL incompetent) must know about ALL of these issues by now, and more. Most of them are decent enough people to want to fix it.
However, they live in a political fishbowl and MUST keep their personal concerns away from the public. In their view they MUST put as optimistic a public face on it as possible. The spillway is the most visible problem by far, so fixing it is what they focus the public eye on.
But all of these issues MUST be fixed if the dam is to be safe. There are so many they simply cannot get to all of it at once. For PR and political reasons (and CYA), everything they cannot get to must be downplayed.
To sum up, they know a catastrophic failure of the dam would be the worst disaster in California history. They are not vile enough to want this to happen, and they are trying to prevent it.
But they also know that if the public were made aware of the very real possibility of catastrophic failure, and that the DWR negligently allowed the problem to fester for years, their heads would role. So would the heads of the politicians who let it happen. THAT must be avoided at all costs!
KRCA Copter Photo - RCC spillway completed to Construction Concrete
Oct 27, 2017 photo from KRCA news helicopter shows the RCC spillway slope is completed at the Upper Spillway Construction concrete transition slab. The vertical "drop" from the transition slab is the "Aerator" mechanism to introduce* air bubbles into the spillway flow.
The Transition slab has a coating of white sealant to assist in a moisture controlled curing of the concrete. Work is underway in finishing the RCC sidewall inner wall concrete finish at the junction of the Construction concrete sidewall. A bulk pour of concrete reveals a square type of mass concrete column that looks to be placed upon a concrete footing block as per prior photos. Thus concrete column is "sandwiched" by RCC on 3 sides and abutted to the transition wall face on the 4th side.
Now it is time to "see" the RCC machines that will place the 1 ft top RCC "hardened" layer on the full RCC spillway section.
*Sudden drop in atmospheric pressure levels inject a froth of bubbles within the water flow. Injected bubbles help prevent Cavitation Erosion effects in the downslope RCC surface(s) as the water flow velocity becomes higher.
Oct 27, 2017 photo from KRCA news helicopter shows the RCC spillway slope is completed at the Upper Spillway Construction concrete transition slab.
