San Diego Gas and Electric (SDG&E) proposed a new 117-mile, high-voltage transmission line that will have a 1,000 megawatt capacity to transport renewable energy from Imperial Valley, California to the San Diego area. The Sunrise Powerlink is part of an ongoing effort in California, mandated by state law, to increase use of renewable energy. The proposed alignment traverses a wide variety of terrain, including both remote-access and environmentally sensitive areas. The project is expected to inject $1.7 billion into the US economy and enable the creation of thousands of new jobs in Southern California’s renewable energy sector.
San Diego Gas & Electric, Burns and McDonnell, URS Corporation, Crux Subsurface, Quanta Subsurface
Crux was contracted to provide geotechnical drilling services at boring locations spread throughout the 117-mile alignment. The line begins near San Diego and runs east through the Cleveland National Forest, reaching an elevation of 4,500 feet, before returning to sea level in the Imperial County desert. The project was considered environmentally sensitive as the alignment travels through several different ecosystems, each with its own sensitive species of wildlife. Special care was taken to minimize impact and avoid any sensitive species.
The environmentally sensitive terrain and difficult-access boring locations called for a unique drilling program. Crux employed a variety of equipment to complete borings, ranging from helicopter-portable drills in remote and sensitive areas, to track- and truck-mounted drills at more conventional-access sites. In total, Crux completed over 60 geotechnical borings to depths of 50 feet. Drilling was completed using an HWT casing advancer system and HQ3 wire line triple tube coring system.