A major milestone has been reached at the Oroville Dam project in California, US, with the Department of Water Resources (DWR) meeting its goal of completely reconstructing the main spillway at the dam by 1 November in time for the upcoming winter. The newly constructed spillway is now built to its original design capacity of 270,000 cubic feet per second.  

Concrete on the main spillway will have cured by 1 December, 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 continue.

 “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.”

The final erosion-resistant concrete (ERC) slab was placed on 11 October. 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 18 October. 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 20 October.

On the emergency spillway, the roller-compacted concrete (RCC) splashpad was completed on 26 October. 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 in October.

Placement of a structural concrete cap connecting the RCC buttress to the emergency spillway structure will be complete in early 2019.