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Releases at Oroville Dam Spillway halted due to hole



From KRCR

OROVILLE, Calif. - Post Conference Update: At the press conference Tuesday evening, the Department of Water Resources said its engineers were actively brainstorming a solution to fix the hole.

Officials said they have three or four days before they have to start letting the water spill again. If and when they do, the hole, estimated 180 feet wide by 250 feet long and 30 feet deep, will likely get bigger.

In the meantime, the DWR said it does not know what caused the erosion, but engineers are looking into a quick fix because of expected rain in the next few days.

Officials said they haven't had a release over the spillway like this since 2006, but the spillway's capacity was much higher than the 60,000 cubic feet of water per second that was coming down when the hole formed. Capacity is about 150,000 cfs.

The DWR said they are also in the process of determining how long a permanent repair will take. "[We are] also looking at the time frame with weather and current predicted weather and how it's going to affect the lake," explained Eric See, an official with the Department of Water Resources in Oroville. "So there's lots of different things to consider because that can affect the type of repair that you would do and type of actions you would take. And again, you always have to be weighed with how safe we can get our workers in there to get this completed safely."

Read more and watch vid: http://www.krcrtv.com/news/local/butte/ ... /317257996

KCRA news says that Oroville will fill to 101% by late Saturday if nothing is done. They will need to do something or let the spillway continue operating and fix the damage at a later date. A road is being created by the spillway to get equipment in to work on the problem.

OROVILLE
State engineers gingerly began releasing water again through the damaged Oroville Dam spillway Wednesday in a controlled test to see how much water the scarred facility could handle, as reservoir levels continued to climb behind the critical flood-control structure.

With dozens of engineers monitoring from strategic locations around the dam’s exterior, a sheet of white water began cascading down the 3,000-foot-long spillway a little after 3 p.m. Within seconds of hitting the damaged area, a crater about 250 feet long, a portion of the water turned into a long ribbon of mud as sediment that had been trapped inside the hole ran down the concrete spillway.

Misdirected by the jagged chunks of concrete lying in the spillway, some of the water left the chute and ran down an adjacent hill.

California Department of Water Resources officials said they planned to open the spillway for more than two hours Wednesday, ramping up the water release to about 20,000 cubic feet per second. That’s considered a “light spill,” engineers said, and was less than half as much water as the spillway was releasing when the giant scar was discovered Tuesday and releases were shut down.

More info and vid: http://www.sacbee.com/news/state/califo ... 79999.html