Oroville Spillways phase 2 update — $870 million project makes progress

Here’s a video from the California Department of Water Resources (DWR) showing construction progress on the $870 million Oroville Dam Spillways project.

The video citation reads: “The crew pours concrete for the top section of the cut-off-wall that will connect to the splashpad. A section of ground near the lower spillway is removed for a new road. Work continues between the emergency spillway weir and cut-off-wall, prepping the ground for the splashpad.”

DWR says it expects the federal government to pay the bulk of the estimated $870 million to repair the spillways.

DWR spokeswoman Erin Mellon said during a media call that the Federal Emergency Management Agency (FEMA) has paid 75 percent of costs that have been submitted thus far, and the state has no indication that is going to change.

“We’ll keep submitting them until they tell us otherwise,” she said.

Anything the feds don’t pay will be picked up by the State Water Project Contractors, the agencies that actually get water from Lake Oroville, The Mercury News has reported.

The cutoff wall designed to block uphill erosion of the type the prompted evacuation orders last Feb. 12 is expected to be done in March, said Ted Craddock, assistant deputy director of the State Water Project.

It is a secant wall, which is a series of holes drilled down to bedrock and filled with concrete. The filled holes are 35 to 65 feet deep, and the structure stretches 1,450 feet, 730 feet away from the spillway weir.

Kiewit Infrastructure project manger Jeff Petersen said a concrete beam is being poured to link the top of the pillars together. “The bottoms are anchored to bedrock,”  he said. Then, a splash pad of roller compacted concrete will be placed between the cutoff wall and the weir, to armor the hillside in case the emergency spillway ever has to be used again.

The weir will also be buttressed with a new concrete structure. Petersen said rock crushers will have to create 1.2 million tons of aggregate for the work left to do.

Petersen said Kiewit planned to be ready May 1 to start phase 2 of the main spillway reconstruction. The start date will depend on the lake level, weather and other factors, however.

The work program includes removing the 730 feet at the top of the upper chute from the radial gates, and replacement with steel-reinforced structural concrete.

A 2.5-foot layer of steel-reinforced structural concrete will be placed over the over 1,050 feet of roller compacted concrete in the middle chute, and the roller compacted concrete walls of that section will be replaced with structural concrete.