Oroville Dam Emergency Response

In the winter of 2017, northern California experienced some of the heaviest rainfall in 110 years. Heavy rainfall and snowmelt rapidly increased reservoir levels, causing spillway failures and creating a potential for catastrophic flooding in the region. The situation demanded immediate heavy civil construction efforts to address the growing crisis.
 
Authorities ordered nearly 190,000 residents throughout the Feather River Basin to evacuate in February after severe erosion damaged a spillway serving the Oroville Dam. This incident stands as one of the most serious dam safety occurrences in United States history, given the dam’s large size, the significant spillway damage, and the number of lives at risk.
 
A blockage causing water to back up threatened the Hyatt Powerplant with potential damage that could have impacted the state’s electrical grid. The potential for power outages during this critical time, when evacuated citizens were living in camps at a fairground and medical personnel were attempting to treat those who had left their prescriptions behind during the evacuation, would have exacerbated the disaster recovery efforts and further threatened public safety.

Forgen, as part of a joint venture team, responded quickly under the direction of the California Department of Water Resources and their prime contractor. They deployed emergency response management, local craft resources, and heavy equipment to assist with the emergency response efforts. This involved significant heavy civil construction work to address the immediate challenges posed by the damaged spillway.

The joint venture as a part of the overall response team worked tirelessly around the clock to haul, place, and grout 200,000 tons of riprap, creating a protective layer to stop erosion and minimize further damage to the emergency spillway. Their erosion control measures were crucial in stabilizing the area and preventing further deterioration.

Between the emergency spillway and the auxiliary spillway, the response team faced an estimated 1.7 million cubic yards of eroded material that had accumulated in the diversion pool. Acting swiftly, our team used mechanical dredging techniques to assist in the removal of the collected material and prevent water from backing up and damaging the nearby Hyatt Powerplant. The team employed custom long-reach excavators and specialty excavators operated from barges to access hard-to-reach locations, effectively handling the extensive debris removal needed to clear the area.

The joint venture team’s efforts successfully eliminated the threat of damage to the power plant and additional damage to the spillway. They also prevented further backups of water flow, which posed real threats to the community and the subsequent rebuilding efforts. Their quick response in critical infrastructure repair played a key role in mitigating the potential disaster.

These actions facilitated the reconstruction of the emergency spillway in 2018, allowing for its fortification with a concrete buttress to increase durability during extreme flooding. This proactive measure aims to prevent another emergency like this in the future, showcasing a comprehensive approach to disaster recovery and critical infrastructure repair.