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In Race Against Coming Storm, Workers Scramble To Plug Oroville Dam Hole Using Rocks, Sandbags

After discovering a hole in Oroville Dam's emergency spillway, officials said late Sunday that they will attempt to plug it using sandbags and rocks. But, as the LA Times notes, they stressed the situation remains dangerous and urged thousands of residents downstream to evacuate to higher ground. Video from television helicopters Sunday evening showed water flowing into a parking lot next to the dam, with large flows going down both the damaged main spillway and the emergency spillway.

They also showed lines of cars getting out of downtown Oroville. An evacuation center was set up at the Silver Dollar Fairgrounds in Chico.

Almost 200,000 people were ordered on Sunday to evacuate from the area below the Lake Oroville Dam, the tallest dam in the United States, after authorities said its emergency spillway could give way.

While officials said the situation seemed less dire overnight, Sacramento television station KCRA reported that helicopters from around the state were sent to drop chest-high bags of rocks to close the hole in the spillway. The NBC affiliate showed dump trucks dropping off piles of rock -see below -  which were then loaded into the bags with backhoes. The operation to close the gap would begin as soon as it was feasible, the station said.

Officials feared a failure of the emergency spillway could cause huge amounts of water to flow into the Feather River, which runs through downtown Oroville, and other waterways. The result could be flooding and levee failures for miles south of the dam, depending on how much water is released.

So to limit the potential damage and flooding, the primary plan of action currently in place is to plug a hole in the emergency spillway, including using helicopters dropping bags of rock into the crevasse to prevent any further erosion. Here's the loud, chaotic scene as the choppers prepare for the rock drop via @judywbrandt on Twitter.

Meanwhile, as the LA Times also adds, the California National Guard is on standby and ready to assist with the Oroville Dam emergency, Adjutant General David Baldwin said during Sunday night's press conference. The California National Guard put out an alert to all 23,000 of its soldiers and airmen telling them to be “ready to go if needed,” Baldwin said. The last time officials sent out such a broad notification was during the 1992 riots in Los Angeles, he said. The California National Guard would deploy eight helicopters to assist with spillway reconstruction; military police would also be deployed to Yuba County, Baldwin said.

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Finally, the reason for the scramble to fix the dam is because a new storm system is forecast for later this week put water officials on a race against time. Bill Croyle, the acting director of the state Department of Water Resources, said they planned to continue discharging flows at a rate of 100,000 cubic feet per second, with the hope of lowering the reservoir level by 50 feet.

The biggest concern was that a hillside that keeps water in Lake Oroville — California’s second largest reservoir — would suddenly crumble Sunday afternoon, threatening the lives of thousands of people by flooding communities downstream. With Lake Oroville filled to the brim, such a collapse could have caused a “30-foot wall of water coming out of the lake,” Cal-Fire incident commander Kevin Lawson said at a Sunday night press conference. Luckily, so far this scenario has not played out.

Source
Disaster
Environment
Oroville