TUESDAY, APRIL 24, 2018
Phase two of construction on the Oroville Dam is set to begin May 8, according to reports, marking an updated operations plan that implements aggressive outflows of up to 10,000 cubic feet per second.
The updated operations plan was submitted by the California Department of Water Resources to the Federal Energy Regulatory Commission and the California Division of Safety of Dams on April 17.
Oroville Dam Construction
According to Mercury News, crews will start preparing the roller-compacted concrete in the middle chute of the spillway on April 25. This will create a smooth surface for the structural concrete that will top it, with up to five inches of RCC chute being removed.
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| Kelly M. Grow / California DWR |
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Phase two of construction on the Oroville Dam is set to begin May 8, according to reports, marking an updated operations plan that implements aggressive outflows of up to 10,000 cubic feet per second. |
In phase two of the construction work, the energy dissipaters will be hydro-blasted and resurfaced. Steel-reinforced concrete will be set on top of the RCC middle section, with a drainage system being installed beneath. The walls of the middle chute will also be replaced with structural concrete walls and a draining system.
The upper 730 feet of the structure, which was subject to patch repairs, will be demolished and reconstructed with steel-reinforced structural concrete.
Further construction plans also include putting a concrete cap on the underground secant pile wall, as well as a concrete splash pad that will run from the weir 750 feet down to the underground wall, intended to help prevent future erosion. The latter work will need more RCC than what was required for all of the phase one work on the main spillway, noted Jeff Petersen, project manager for Kiewit Infrastructure West Co.
Dam Crisis
The dam’s main spillway suffered concrete damage that led to its closure in February 2017 during a period of extreme rainfall. An emergency spillway was used for the first time during the crisis and caused hillside erosion that threatened the stability of the concrete weir holding the water back. More than 200,000 residents downstream in the Feather River valley were evacuated for fear of an uncontrolled release.
A team of engineers hired to analyze the root cause of the failure cited an “inadequate priority for dam safety” and said the DWR had been “somewhat overconfident and complacent regarding the integrity of its civil infrastructure.” The DWR has been sued by residents and by the city of Oroville over the crisis.
Tagged categories: concrete; Government; Infrastructure; Locks and dams; Program/Project Management
