The debris at the base of the main spillway has formed a dam that has raised the level of the water below the power plant outlet by about 20 feet. That’s driving the need to clear the debris to enable restart of the power plant and outflow of 14,000 CFS via that path.
Peter,
Thanks for posting that video. Why is it that a one man organization can transmit such in-depth and understandable coverage of the problems facing Oroville dam … while all the news agencies produce such worthless drivel? That’s why I don’t waste my time following MSM news. Give me a story by Juan Browne any day.
Grover
I just found this interesting article on atmospheric rivers.
This is also worrisome, since reconstructions of historic flood events —like the Great Flood of 1862 — as well as a simulation of what would be a devastating flood both involved many weak to moderate atmospheric river events hitting in rapid succession; the same thing that's happening now. Noah Diffenbough, a climate scientist at Stanford University, says California's wet winter demonstrates how we're already hitting the limits of water infrastructure that was designed in a completely different climate.
Juan Browne update video for 2/22/2017. This one is only 4 minutes long. He shows that Lake Oroville’s inflows and outflows are about matched. The reservoir water surface elevation is remaining around 853’. He also talks about other reservoirs upstream of Oroville. Essentially, he just pointed them out and said that they are used primarily to produce electricity - not for water storage. None of these dams/reservoirs are showing any problems.
Grover
Here is Juan Browne’s latest video dated 2/27/2017. The weather is finally cooperating. It looks like 7 days of dry weather is ahead. The reservoir elevation is down to ~ 838’ which gives them at least 60’ of storage. So, they’re going to shut of the spillway and excavate the debris (from the blown out spillway) so the tail water to the power plant can be lowered. After the new power lines are installed, the power plant can be operated again.
Grover
Here’s a 5 minute (silent) video showing computer simulations of dam breaches on flooding extents downstream of the Oroville Dam. There were evaluations of a complete collapse and 2 partial collapses. The flooding in the central valley varies considerably. This technology should be available to every dam operator. If I lived downstream of a dam, I’d want to see similar simulations to see how bad it needs to get before it directly impacts me. (I wonder if nuclear power plant operators do similar computer simulations.)
Grover
Here is the latest 15 minute video from Juan Browne (on the Blancolirio channel.) The DWR has announced their plans to rebuild the spillway. (un)Surprisingly, the new design is quite a bit like the old design. They will rebuild the entire spillway to modern standards. The upper portion will be given top priority. They plan to fill the part of the newly formed canyon under the spillway with roller compacted concrete (RCC.) Because of time limits, they want to have enough capacity in the spillway to handle 100,000 CFS by November 2017. Next year, they will build side walls higher so that it will ultimately be able to carry 270,000 CFS.
DWR preselected 4 construction companies to submit bids for their designs. The deadline for bids is next week (4/12/2017.) One of the bids will be selected by 4/18/2017 and a notice to proceed will be given shortly thereafter. Of course, the best laid plans are still subject to the weather and snow melt. DWR is currently expecting 2 more events where the busted spillway will be used this spring.
DWR will also reinforce the emergency spillway. They presented conceptual designs, but haven’t determined the extent of each feature yet. That may be part of the contractor’s bidding process to submit final proposals. The goal is never to need to use the emergency spillway; however, it needs to be ready - just in case.
As of this posting (4/8/2017 10:00 AM PDT,) the reservoir was at 851.60’ elevation with a strong storm in place. Juan expects about 4" of water in the high country. A few more of these would throw a monkey wrench in the works. I hope their contingency plans are robust enough to handle potential changes.
Grover
I really hate Mollom (the spam gate.)