The City of Oroville, California, with its population of about 18,000 is battling the consequences of an infrastructure failure of the Oroville Dam’s emergency spillway. However, with the weather forecast promising seven to ten continuous days of sunny weather, the workers at the Oroville Dam are furiously executing a plan they hope will ease the situation.
The three immediate objectives are to restore conditions around the Hyatt Power Plant in order to resume operations, lift the emergency evacuation warning for the people who live in areas below the dam, and release water into the Feather River from the entire Oroville complex, which involves a series of dams.
The Oroville River Reservoir is now down to a record low of 838 feet and the first step in the plan was accomplished when they reduced the flow from the Oroville Dam onto the emergency spillway to zero.
When the mid section of the emergency spillway gave way, rock and debris washed down and accumulated in the Thermolito Diversion Pool below the dam, causing water to backup in this area. Because the water level in this Pool is now unacceptably high, the Hyatt Power Plant had to be shut down.
By removing the debris in the Pool, engineers calculate that the water level in this area with fall below the power plant’s turbine level, where is should be, and the plant will be able to be safely put back into operation.
Step two of the plan involves floating barges and excavators working furiously on three sides of the rock and debris to clean it out of the Thermolito Diversion Pool. Some of this excess water that will be released will be diverted to the Feather River to keep the fish and ecosystems alive.
Around the clock monitoring of the emergency spillway area is being conducted with government drones, helicopters, engineers and emergency personnel. Remaining on schedule while no precipitation is forecasted is critical to the success of this operation.
If successful, the power lines that were disconnected because they were in the way of the broken emergency spillway will be reconnected in order to get electricity from the Hyatt Power Plant to area residents. In addition, the situation will be considered manageable, even with the broken spillway, and the evacuation warning will be cancelled.