The US Army Corps of Engineers awarded $1.86 billion in contracts to Barnard Construction to improve dam safety at the Prado and Whittier Narrows Dams in Southern California. Both projects aim to mitigate flood risk for nearly 2.5 million people and $400 billion in infrastructure. the region between the dams and the Pacific Ocean.
The $1.13 billion Prado Dam spillway modification project on the Santa Ana River near Corona, California, will improve the retention capacity of a facility that has suffered increased runoff due to regional urbanization since its completion in 1941. TThe “dry dam”, with generally low water levels behind the reservoir, has a main dam, consisting of a large embankment, auxiliary dam, concrete outlet for controlled water release, and a large concrete spillway to handle excess water flows.
“At Prado Dam, we are combining smarter contracts with innovative labyrinth spillway engineering to provide a higher level of safety for 1.4 million Americans,” Assistant Secretary of the Army for Civil Works Adam Telle said in a statement.
The project combines two project phases into one. The first phase addresses potential safety issues by replacing the old spillway with a maze-style structure. Crews will tear down the existing walls and slabs, rebuild them, and then tie the new system into the dam’s earthen embankments. The second phase will raise the spillway crest 20 feet to match the elevation of the 2005 main dam embankment elevation.
Major construction is expected to begin in the spring of 2027 and is expected to be completed by 2033. The dam will remain fully operational and continue to reduce the risk of flooding during construction.
At the same time, the Corps awarded Barnard a $735 million contract for the Whittier Narrows Dam, a three-mile-long structure that manages the flows of the Rio Hondo and San Gabriel rivers in Los Angeles County. Completed in 1957, the dam is located about 11 miles east of downtown Los Angeles, making it the most urban dam operated by the Corps.
The dam is classified as high risk due to its location in a densely populated urban corridor and the project will focus on critical safety improvements to the embankment and outlet structures.
Both projects will be delivered through integrated design and build, requiring early contractor involvement.
“When we considered the most effective way to deliver these projects, early contractor involvement was the clear choice because we could partner with Barnard earlier than in a traditional construction contract,” says George Sunny, project manager for the US Army Corps of Engineers Los Angeles District. “Together, we’ve proactively identified innovations and solved constructability issues before they even started.”
Major construction of the Prado and Whittier Narrows projects is scheduled to begin in the spring of 2027, with completion expected in 2033. The Corps says both dams will remain fully operational throughout construction to maintain flood risk management in the region.
