The California Division of Safety of Dams provided its approval on July 13 and the Federal Energy Regulatory Commission on July 15. The independent Board of Consultants approved DWR’s construction plans in June, pending final approval from FERC. DWR says the work to be completed this year now has all required approvals from federal, state and independent oversight groups.
The first phase of construction will be completed by Nov. 1, 2017, DWR says, with the objective of ensuring the main spillway can safely pass Feather River watershed flows this year. This phase involves:
- Removing and reconstructing 2,270 feet of the main spillway
- Repairing the upper 730-foot-long portion of the main spillway that connects to the radial gates
- Constructing an underground cutoff wall below to emergency spillway to prevent uphill erosion if this spillway is used again.
The remaining construction, which also requires federal and state approval, will be completed in 2018 and includes demolishing and reconstructing the uppermost 730-foot-long portion of the main spillway, the addition of structural concrete to the entire main spillway, resurfacing and hydro blasting of the energy dissipaters at the base of the spillway, and construction of a roller-compacted-concrete buttress and splashpad on the emergency spillway to dissipate the energy of any water flows.
Lake Oroville was at 800 feet as of July 26, and reservoir releases were at 6,500 cfs. DWR has established a projection schedule, with guidance from FERC, to draw down the reservoir’s elevation to 700 feet by Nov. 1.
Earlier this month, HydroWorld reported that Grant Davis has been selected to be director of DWR.