Transmission Line and Towers

Southern California Edison Tehachapi Renewable Transmission Project – Chino Hills Undergrounding

Chino Hills, CA

The Chino Hills Undergrounding Project was a component of Southern California Edison’s (SCE) Tehachapi Renewable Transmission Project (TRTP), which consisted of new and upgraded high-voltage electric transmission lines and substations capable of carrying 4,500 megawatts of electricity from renewable and other generators from Kern County south through Los Angeles County to San Bernardino County.

The California Public Utilities Commission required a portion of the 500 kV lines associated with this project to be installed underground through the City of Chino Hills.  As such, this project marked the first installation of underground 500 kV XLPE cable in North America.  In addition, it was the first time such cable was used in duct and manhole systems anywhere in the world. The project required the construction of 17,000 linear feet of duct bank, two transition stations (each approximately 3 acres in size), and several miles of permanent and temporary access roads.

Since undergrounding of transmission lines of this voltage is not common in the United States, this project required specialized expertise.  Cordoba Corporation provided highly specialized underground cable splicing experts to assist with quality control and technology application oversight. The work included source inspection of tooling and materials and the verification of installation processes. In addition, Cordoba Corporation also provided experienced and qualified civil inspectors to assist with onsite quality control.