San Diego Gas & Electric (SDG&E) on Monday completed and put into service its 500-kV Sunrise Powerlink, a $1.9 billion transmission line linking San Diego to the renewables-rich Imperial Valley.

The line—capable of transporting 800 MW of additional imported power into San Diego—is expected to play an important role for the region this summer. The nearby twin reactor units at the 2,200-MW San Onofre Nuclear Generating Station jointly owned by Southern California Edison and SDG&E have been offline since January after leaks were discovered in the plant’s steam generator tubes, leaving the region with dangerously narrow reserve margins. Eventually, the Sunrise Powerlink is expected to carry 1,000 MW of power.

The project’s completion ends a five-year-long environmental review and permitting process and 18 months of construction—tightened from the initially anticipated 24 months—that connected more than 110 miles of overhead 500-kV and 230-kV transmission towers and conductor, 6.2 miles of underground 230-kV cable, and a 40-acre, 500-kV transmission substation. More than 4.7 million work hours were required to complete the project.

The utility said in a statement that the project underwent extensive regulatory review, constituting the “most comprehensive study of a proposed transmission power line” in California’s history.

"Design, planning, construction and implementation of the project required scores of public hearings, detailed construction schedules to accommodate a wide array of environmental regulations and coordination of thousands of helicopter flights to ferry crews and material to the construction sites along the route," said Jessie J. Knight, Jr., SDG&E chair and CEO.

Source: SDG&E
—Edited by Senior Writer Sonal Patel (@POWERmagazine)