Construction began last year for possibly the first in-service six-conductor 765-kV overhead transmission line in the United States, running from the Wyoming Substation in West Virginia to the Jackson Ferry Substation in Virginia. An increasing demand for electricity poses a significant threat to power reliability in southern West Virginia and southwestern Virginia, forcing American Electric Power (AEP; Columbus, Ohio, U.S.) to reinforce its transmission system.
In 1973, the company completed the last major “backbone” 765-kV transmission line that serves the affected area. Since that time, energy demands in this region have increased by more than 135%. In 1973, customers set a peak usage of 2720 MW. In 2001, that number topped 6400 MW. Forecasts indicate that the electrical system will not be able to reliably carry the amount of electricity that customers in the area will need in the future.
In response to this threat, AEP is building a 144-km (90-mile) 765-kV transmission line from the Wyoming Substation in Wyoming County, West Virginia, to its Jackson Ferry Substation in Virginia, which will reinforce AEP’s existing transmission system and provide sufficient capacity to meet the growth in demand for electricity. AEP’s in-house staff began engineering for the US$287-million line in 2003. When finished, the line will consist of six-bundle conductor strung on guyed-V steel towers. The steel will be darkened by etching to reduce the line’s visual impact. Approximately one-third of the structures will be self-supporting and two-thirds will be guyed-V.
Experts from Virginia Tech and West Virginia University were charged with determining the route, which has proved to be the most reasonable and least detrimental to the environment.
Right of Way
Surveying and right-of-way acquisitions for the 200-ft (61-m)-wide corridor, which will run from the Oceana, West Virginia area, to Wythe County, Virginia, was also completed in 2003 and 2004. The prime contractor for the overhead transmission line, PAR Electrical Contractors Inc., a Quanta Co. (Kansas City, Missouri, U.S.), subcontracted right-of-way clearing to Phillips & Jordan Inc. (Wilmington, North Carolina, U.S.). Central Contracting Inc. (Saint Albans, West Virginia, U.S.) is the access road contractor, grading and developing all access roads to the 300-plus tower sites. Black & Veatch (Overland Park, Kansas, U.S.) assisted AEP with tower design.
About 51 km (32 miles) of the route are in West Virginia and 93 km (58 miles) are in Virginia. A major part of the easement clearing was completed in early 2004 for a midyear start. PAR Electrical crews began construction of foundations and tower erection on the West Virginia termination point of the line in April 2004.
The tower structures, which are being designed and fabricated by Canadian manufacturer Locweld Inc., will average 40 m (132 ft) in height, with the tallest reaching about 54 m (180 ft). Alcan Cable (Atlanta, Georgia, U.S.) is providing the 144-plus km (90-plus miles) of six-bundle 765 cable. Sherman & Reilly Inc. (Chattanooga, Tennessee, U.S.) was responsible for designing and manufacturing the large traveler stringing blocks to accommodate the large conductors.
Helicopter assistance is being provided by Columbia Basin Helicopters Inc. (Basin City, Oregon, U.S.) for pulling lead lines, ferrying crews and structure transport. PAR Electrical Contractors has not made a final selection of all the subcontractors at this point.
Because of its unusually large size, the six-bundle 765-kV project has been in the works for more than 15 years. Although AEP has observed six-bundle projects in Russia and South Africa, this will be its first such project in the United States. AEP expects the high-voltage line to be energized by June 30, 2006. The entire project, including the associated terminal expansions and installation of a current limiting reactor at Axton, Virginia, will cost AEP $270 million. l