OROVILLE SPILLWAYS CONSTRUCTION: DWR Meets November 1 Public Safety Milestone (with photos and video)

Workers from Kiewit Infrastructure clean concrete joints and remove small debris from the upper chute of the Lake Oroville main spillway during Phase 2 of the recovery effort at the Butte County, California site. Photo taken October 25, 2018.
Kelly M. Grow / DWR
Oroville Dam’s Main Spillway Fully Reconstructed

From the Department of Water Resources:

The Department of Water Resources (DWR) today announced it has met its goal of completely reconstructing the main spillway at Oroville Dam by Nov. 1 to be prepared for the upcoming winter. The newly constructed spillway is now built to its original design capacity of 270,000 cubic feet per second.

“DWR has again met the Nov. 1 public safety milestone with help from our state, federal and local agency partners, and our construction contractors,” said DWR Director Karla Nemeth. “We thank the surrounding communities for their patience and DWR staff who have worked tirelessly on the Oroville spillways over the past two construction seasons. Today’s milestone is significant, but there is still more work to do before we call this project complete.”

Concrete on the main spillway will have cured by December 1, in time for the rainy season and use of the main spillway if necessary. Dry finishing, joint sealing, completing sidewall backfill and site clean-up on the main spillway will also continue after November 1.

“More than 700 construction workers, many of them from Butte County and other parts of Northern California, literally worked day and night to make incredible progress during the 2018 construction season,” said Tony Meyers, DWR Project Manager for the Oroville Spillways Emergency Recovery Project. “Staff from nearly every corner of DWR worked on the project in some capacity over the past year and a half and their planning, execution and hard work contributed to meeting this November 1 milestone.”

Main Spillway

  • The final erosion-resistant concrete (ERC) slab was placed on Thursday, Oct. 11. Crews placed a total of 378 ERC structural slabs in 2018. Combined with last year’s work, 612 new concrete slabs have been installed.
  • Crews placed the final ERC wall on Thursday, Oct. 18. Crews placed a total of 126 ERC walls in 2018.Together with last year’s work, 204 new concrete walls have been installed.
  • Final concrete placements on the energy dissipaters, or dentates, at the base of the main spillway were completed on Saturday, Oct. 20.
  • The main spillway has now been reconstructed to its original design capacity of 270,000 cubic feet of water per second.

Emergency Spillway

  • The roller-compacted concrete (RCC) splashpad was completed on Friday, Oct. 26. Crews placed approximately 700,000 cubic yards of roller-compacted concrete on the splashpad.
  • Crews also completed construction of the RCC buttress at the base of the emergency spillway earlier this month.
  • Placement of a structural concrete cap connecting the RCC buttress to the emergency spillway structure will be complete in early 2019.

Other Updates

DWR has completed an operations plan for the 2018-19 flood season that will guide reservoir operations from November 2018 through April 2019. The plan calls for DWR to maintain lower-than-average lake levels during the winter months to provide operational flexibility to ensure flood protection, meet water deliveries, meet environmental requirements, and prevent use of the emergency spillway this winter, as construction will continue on the emergency spillway into early 2019. DWR updated the plan with recommendations from the U.S. Army Corps of Engineers, the Federal Energy Regulatory Commission and the Division of Safety of Dams.

The Oroville Dam Safety Comprehensive Needs Assessment (CNA) Ad Hoc Group met for the second time Tuesday, Oct. 30. The Ad Hoc Group consists of 12 community members appointed by State Senator Jim Nielsen and Assembly Member James Gallagher to provide community perspectives to both DWR and an Independent Review Board (IRB) of dam safety experts throughout the CNA process. Video and material of the meetings will be posted online in the coming days.

Latest videos from the Department of Water Resources …

This time lapse video shows daily construction progress from April 20, 2018 through October 30, 2018. The camera angle looks up the lower chute of the spillway from the diversion pool until early August, then shifts to the middle chute from August 10 to September 4. The time lapse video then resumes footage from the lower chute vantage point from September 4 through October 30.

Pictures and graphics …

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