25 Ton Vaults Protect Electric Utility on Pacific Ocean Floor

Sylmar Ground Return System Replacement

Los Angeles, California

There’s a transmission line from Northern Oregon to Southern California called the Pacific Direct Current Intertie that delivers hydroelectric power to Los Angeles County. The 850 mile transmitter ends 6,000 feet offshore in Santa Monica Bay at the Sylmar Ground Return System. Built in 1970 the system risked failure due to deterioration of underwater electrode array vaults, corrosion of marine cables, and overall metal fatigue.

Jensen Precast custom designed, engineered, and manufactured 36 corrosion-resistant precast concrete vaults at 25 tons each for the $114 million project. “Replacing Sylmar’s underwater section meant building a new structure to house 144 electrodes, 100 feet below mean sea level,” says Thomas Morales, Jensen Precast Director of Sales Operations. “Because it would be on the ocean floor, it would need lasting durability. We used fiberglass rebar at the request of the Los Angeles Department of Water and Power, along with high quality precast concrete to deliver a corrosion-resistant solution for the underwater installation.”

The ambitious project maintains the reliability of power delivered to Southern California, sends renewable energy to California to help meet its goal of 33% renewable energy by 2020, and increases the available share of renewable energy from wind power in the Pacific Northwest.

Product: Precast concrete vaults 6’W x 20’L x 54”H. Made in United States.

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