Oroville Dam Emergency Recovery, Oroville CA, California Department of Water Resources

The Oroville Dam in Northern California is the highest in the country at 770 feet – four stories taller than the Hoover Dam. In February 2017 its primary and emergency spillways suffered significant damage just days apart, prompting public safety officials to evacuate thousands of downstream residents for fear of emergency spillway failure.

TRC had the privilege of supporting the Department of Water Resources (DWR) in the $1.1 billion overhaul of the 50-year-old infrastructure providing construction management support and performing contract administration, claims support, schedule review, blasting inspections and round-the-clock field inspections (including drone flight photographic/video documentation).

Our experts were among the first on-site under an on-call construction contract we have held with the DWR since 2008 augmenting the DWR team. During the peak of work on the recovery project, the TRC team consisted of 60 people on site overseeing the work of more than 700 construction personnel.

The first phase of the project focused on making temporary repairs to the main or flood control outlet spillway and the emergency spillway. Phase II work, completed in 2018, included the substantial demolition of the 3,055-foot long main spillway and the erection of a more resilient replacement. Work crews also built a 1,450-foot long secant pile wall anchored to bedrock and a 1,850-foot long roller compacted concrete emergency spillway that resembles a stairway to dissipate the energy of the water cascading down at times of peak lake levels.

Work concluded in 2020 with the regrading of eroded hillsides, hydroseeding of new vegetation, installation of new main spillway lighting system, and completion of infrastructure improvements to the upper overlook parking lot, and a number of boat launch and recreation facilities around Lake Oroville.