Oroville Dam: Crews work into the night to bolster eroded spillway as next storm approaches

The Sacramento Bee ^ | February 15th, 2017 | By Phillip Reese and Ryan Lillis

[Mariner]

Oroville

Crews worked into the night Wednesday to shore up the emergency spillway at troubled Oroville Dam, racing to fortify the structure before the next series of storms, the first of which was forecast to hit before midnight.

Three storm systems will move into Northern California during the next six days, according to the National Weather Service. The first system will drop about an inch of rain in the Oroville area between 10 p.m. Wednesday and 4 p.m. Thursday. Greater amounts of precipitation will fall in the mountains northeast of the reservoir.

Forecasters are confident that the first two storm systems will not cause huge inflows into Lake Oroville. They are less confident about the third system, which is due sometime Tuesday. That storm could be bigger and warmer, meaning more rain and snowmelt streaming into the swollen reservoir.

“The third wave is looking like our problem child,” said Michelle Mead, warning coordination meteorologist at the National Weather Service in Sacramento.

Oroville Dam, about 65 miles north of Sacramento in Butte County, holds the state’s second-largest reservoir and serves as a crucial flood-control structure for the eastern Sacramento Valley. Wednesday’s all-out effort to bolster the dam before a new round of storms capped an anxious week that has seen serious malfunctions in both its main and emergency spillways, hobbling the dam’s ability to release water in the midst of an unusually wet winter.

[Mariner]

As soon as rushing water gets under the concrete the whole mess will find the bottom of the hill.

[Rebelbase]

“They are placing 1,200 tons per HOUR”

How is that possible using Helicopters that carry rock in bags that are rated at a one or two tons?

[digger48]

Best case 120,000 tons with a concrete veneer. Not much given the scale.

Exactly. Those are some big holes.

[Vermont Lt]

Unless you have flood insurance (most mortgage companies would require this in a flood plane) the payouts are minimal at best. Here’s praying that the rain goes elsewhere.

That much water rushing downstream would be unprecedented.

[blueplum]

great closeups and perspective

UPDATE “ROCK SHOT” at Oroville Dam: Repair Before Rain Overtops Spillway Again
https://www.youtube.com/watch?v=FTaSmqru8mM

[crz]

Although this isnt a collapsing dam, the outflow would look something like this. Although you can times this by about a hundred thousand.

It will spread out after the intial breach and collect a ll the debris and take it down stream. The debris is what is really bad. After it collect all the houses, trees, mud, cars, bridges and everything, the force behind it will keep steamrolling everything in its path. Then it spreads out sideways and floods since the intitial stream wont be able to hold it since that will be filled with everything of imagine. Basically, it will go where the least resistance is.
https://www.youtube.com/watch?v=ORZQUlk8vxg

[palmer]

They trucked in most of the rock.

[crz]

So they are trying to dump pebbles into a massive flow. Ya that’ll work alright.

They should be working on the EM spillway in case that runs again. I would have got down there with every GD bulldozer I could find and PUSH the berm out in front of that thing so that water flows AWAY from the spillway instead of collecting into one stream.

Like one other guy on here said. Those pebbles they are dropping into that primary spillway are going to bunch up and restrict flow. And that is exactly what they are dumping..pebbles.

Didnt these geniuses ever learn anything about hydraulics in school?

[Mariner]

The main spillway is getting worse and you can see it cutting into the base of the mountain that supports the dam here:

http://www.sacbee.com/news/local/article133030359.html

[CurlyDave]

...and the houses should have insurance...

Actually most homeowner policies do not cover floods. It is usually a very expensive optional add-on.

[editor-surveyor]

.
>> “It is usually a very expensive optional add-on.” <<

With a huge deductible.
.

[Fai Mao]

>> “It is usually a very expensive optional add-on.” <<

Look at where I live.
I have to have flood, typhoon and Tsunami insurance. It is cheaper here because the building code don’t let you build wood frame construction. Our house has 8 inch thick reinforced concrete walls and an 8 inch thick reinforced concrete roof. No shingles, no carpet and a foundation that is three feet thick

[editor-surveyor]

.
The dam is not in any danger at all.

It never was.

It’s all incompetent knee-jerk as far as the evacuation is concerned.

The rock they are placing will protect the main spillway from being torn away from the dam.

[Golden Gate]

My best suggestion is could they use steel I-beams to build a structure to:

1. Support the wall of the E-Spill.
2. Have steel plating on top, and the excess water could run over the top for... ? 50 feet to 200 feet...? This would protect the ground near the E-Spill.

(Note: I also have some similar ideas for repairing the big hole in the "Main" Spillway... hopefully will post on Thursday.)

SEE my rough diagram here below for the E-Spill support. I don't have time for more labeling or explaination. Hope to be back on line tomorrow before noon.

Note the use of large "augers" drilled into the ground to anchor it. Maybe use heavy cable or chain to attach the I-beam frame structure to the anchors. Also, consider the use of an abundance of heavy concrete "K-rail" freeway barriers to help add weight. Maybe design and build them into the structure as they weld it together.

Get the Ironworkers & Welders working on this! (...upon approval by DWR / Army Corp)



FYI: Image Link: IMG: http://i65.tinypic.com/n2bvpg.jpg

[meyer]

A lot of rock was placed by truck. They choppers were carrying bagged stone to inaccessible areas while they used earthmoving vehicles to build a new road that allowed them to backfill and harden the area along the emergency spillway. It’s a combination of riff raft and concrete.

They’ve been very busy.

[21twelve]

I think you meant rip-rap. Unless they are picking up some of the riff-raff from LA and San Francisco and laying them out along the spillway! (That has been suggested by other Freepers.)

[meyer]

Some images of the work in progress...

http://m.imgur.com/a/OeOJ5

[meyer]

I think you meant rip-rap.

LOL - spell checker... whatever they can find to plug that hole!

[Orangefell]

But the rock they are placing is intended to fix the damaged emergency spillway. The main spillway nor the dam itself was never the reason for the evacuation.

[TYVets]

Oroville, CA:

Wednesday Night 100% Precip. / 1.32 in Showers early with a steady rain developing overnight. The rain will be heavy at times.

Low 54F. Winds SSE at 15 to 25 mph. Winds could occasionally gust over 40 mph.

Chance of rain 100%. 1 to 2 inches of rain expected.

Forecast for rain each of the next ten days. (Intellicast)