OROVILLE DAM SPILLWAYS: DWR Meets November 1 Milestone: Flood Control Spillway Ready for Rainy Season (with pictures and video)


From the Department of Water Resources:

The Department of Water Resources (DWR) today announced it has met its goal of repairing and reconstructing the main, gated flood control spillway at Lake Oroville by Nov. 1, 2017 to handle flows of 100,000 cubic-feet per second this winter.

Preparing the main spillway for the rainy season was a primary objective of the Lake Oroville Spillways Emergency Recovery Project, which has now completed its first phase after a massive construction effort that rebuilt and strengthened more than 2,270 feet of the 3,000-foot-long main spillway.

“Today is a truly significant day for DWR, our state, federal and local agency partners, and the contractors who have worked together so well to meet this critical milestone,” said DWR Director Grant Davis. “It is also a very important day for the surrounding communities, and everyone who depends on the Oroville Dam facilities for flood protection. However, today is only a milestone and we have much more work to do before the project is complete, and we’re eager to begin phase two.”

DWR awarded Kiewit Infrastructure West Co. (Kiewit) the contract to reconstruct both the main and emergency spillways in April of this year.

“More than 600 Kiewit workers, many of them from Butte County and other parts of Northern California, have put in over 720,000 hours to date since May this year to help deliver the first phase of this very important project on schedule,” said Jeff Petersen, Kiewit project director. “We take great pride in the speed in which the entire project team has worked safely and productively to meet expectations. Our commitment continues to be to deliver the highest quality, most reliable spillways that the communities in this region deserve.”

Earlier this month, DWR released an operations plan for the 2017-’18 flood season that will guide reservoir operations between November 1 and April 2018. The plan calls for DWR to maintain lower-than-average lake levels during the winter months to provide space for inflows and manage releases from the substantially reconstructed main spillway.

Phase 1 Completion of the Main, Flood Control Spillway

  • Reconstruction of 2,270 feet of the main spillway:
    • Placement of all reinforced, structural concrete slabs and walls is complete in the upper and lower chutes. This includes 870 feet of the upper chute and 350 feet of the lower chute of the spillway.
    • The 1,050-foot middle section of the main spillway chute is complete, with approximately 350,000 cubic yards of roller compacted concrete placed. This middle section will be completed to final design with a top layer of structural concrete in 2018.
  • The top 730 feet of the main spillway leading to the radial gates has been patched and reinforced. It will be removed and reconstructed with structural concrete in 2018.

Construction at the Emergency Spillway

  • Construction of the secant pile wall, or cut-off wall, downhill of the emergency spillway is scheduled to be complete by the end of January 2018.
  • Crews have completed 50 percent of the secant pile wall.

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Videos from the Department of Water Resources …

This timelapse video shows daily construction progress from June 26 through October 31. The camera angle looks up the lower chute of the spillway from the diversion pool until mid-August, then shifts to the middle chute from August 15 to September 11 where roller-compacted concrete was placed. The timelapse video then resumes footage from the lower chute vantage point from mid-August through October 31.

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