Replies to post #74108 on Mohacsy's Safe Portfolio Member Forum

[Elroy Jetson]

Engineer should design things to fail gracefully, but as you can as you can see in the 3 photos below, even a graceful failure endangers the 16,000 people who live in Oroville.

So they've been evacuated until the repairs are complete. The Oroville dam is the second largest in California and taller than the Hoover Dam. The largest is at Mt Shasta.


The dam won't fail because the brown colored shale hillside "emergency spillway" to the left of the dam and to the left of the spillway is lower.

Trees were removed from the brown area last week to prevent them from impeding the water if it were released there.

They're concerned about erosion on that hillside because this is designed to give way first to release part of the water behind the dam to protect the dam.

They're now draining 1.2 acre feet of the 35 million acre feet of water stored behind the dam to allow for any future storms.

[Elroy Jetson]

People evacuated from Oroville are returning home.

The photos can be misleading at to the true size of the Oroville project.

Repair crews are dropping 40 gigantic truckloads of rock an hour on the eroded slope of the emergency spillway, a process which continues in spite of their belief the slope as it is now is safe enough to use if needed.

Helicopters are dropping bags of rocks into the eroded hole in the Spillway along with a giant machine pumping cement into the hole.

They're releasing 100,000 cubic feet per second out of the normal outlets, which generate electricity, until the dam is empty enough to catch a storm without resorting to the use of the Spillway or the emergency spillway.

If the next storms are cold enough to become snow rather than rain, the dam level will not increase for a few months.

Cement pump at one site on the shale hillside which is an emergency spillway.

[Elroy Jetson]

This is an interesting close-up of the sinkhole damage on the spillway on the Oroville dam.





Water rushing down the spillway prior to the spillway being closed. The town of Oroville in the foreground.