vtsnowedin wrote:GASMON wrote:Hhvacman the LA times report seems very thorough and professional.
It seems an immense task to repair. The USA once rose to these events with alacrity and engineering prowess. I hope "the lowest bidders" know what they are up against.
Gas
While the quantities of material required are huge there is nothing especially difficult about this project though some will pump it up to get an award or two. This is much less difficult then building inside an operating airport or building a highway or tunnel in an inner city while maintaining traffic unimpeded. Why there isn't even a caisson to sink a foundation in a hundred feet of water and two hundred feet of muck.
Kiewit was my personal pick when I saw the bidders list. They have a very good track record with these big projects. They already are mobilizing, with the goal to have a temporary concrete batch plant suitable for the concrete volume in-place by the time the last spill of the year is done.
Yes, this is not like the Big Dig, the new SF Bay Bridge, or other mega-projects done in tight quarters. The daily logistics are simple, but the seasonal and chronological logistics are a nightmare. Several things complicate the proposed construction:
1. The time frame. They absolutely HAVE to have the new upper spillway done by Nov 1. The old one will be demo'ed. Kiewit can't start now - the DWR is currently spilling 35,000 CFS trying to drain the the lake some more. Nature isn't cooperating, as we are having a very wet spring, along with the heavy snow-melt. They started spilling 5 days ago and the lake level has only dropped 4 feet. They have to get it down another 26 feet. They will have to spill for at least another 10-15 days and will probably have to do one more spill in late May to get the lake back down to 835 feet where the Army Corps of Engineers are telling them they have to set their max level until the new spillway is done. Only then can Kiewit begin demo of the existing upper spillway and start infilling the existing plunge pool rock-canyon with roller-compacted concrete.
2. The unknown geological situation below the existing spillway. As they demo the existing spillway, lots of unknowns will be revealed. Where the competent rock is that can remain. Where the fill, voids, or clay, or incompetent rock is. That will have to be removed and in-filled.
3. The fact that the new spillway engineering isn't yet done and being done in a hurry. Construction will progress while engineering and engineering double-checking is also still in-progress. I've been involved with several projects with that scenario in my career. Starting construction with hurried, incomplete designs means there will ALWAYS be various engineering revisions in the middle of construction, some of which will impact work already completed that has to be corrected. That means time and money. Additional money can be had, but time is fixed. Nature is up to bat next November, no matter what the DWR or contractors or Corp of Engineers say.