American Electric Power (NYSE:AEP) subsidiary Appalachian Power on Dec. 19 filed with the Virginia State Corporation Commission for approval for a certificate of convenience and public necessity (CPCN) to reconductor its 36-mile portion of the Cloverdale-Lexington 500-kV transmission line.
The project, which will entail replacing nine towers and adding three towers and replacing existing conductors with new, higher-capacity conductors, is estimated to cost $36m and is scheduled to be placed in service in June 2016. The line was originally built in 1966.
Appalachian Power said in the filing that the purpose of the project is to bring the line up to NERC reliability standards, relieve market congestion, improve the transmission system in Roanoke, Va., and adjacent communities and to improve the operational interface with Dominion Resources (NYSE:D), which shares ownership of the line.
“Completion of the project will further increase the limit on the transfer capability of the interface to 3992 MVA, more than double its capability today,” according to the filing. “This increased capability will alleviate the projected thermal overloads and will also eliminate the need to rely on the Special Protection Scheme currently used to manage power flows on this interface during pumping operations at Dominion’s Bath County pumped storage facility.”
Other alternatives to the rebuild, such as constructing a new line, were considered and rejected after analysis proved they would be either three times more expensive or would adversely affect “human, scenic and natural resources.”
All of the proposed work will take place within the existing 175-foot transmission line right-of-way (ROW), and more than 90% of the existing towers will be retained, the company said. The new towers will be on average 10 feet taller than the existing towers, which are an average of 110 feet tall.
Appalachian Power asked for expedited consideration of the project, as the process of engineering, design, permitting, coordination of outages, material procurement and construction is estimated to take 24 months after commission approval.
As the construction schedule is “very constrained,” the company has already begun pre-construction work, including engineering, acquisition of third-party access road easements, permitting and procurement, according to the testimony of Timothy Earhart, AEP’s supervisor of transmission line engineering. The company hopes to begin construction in June 2014.
“The entire 500-kV line must be taken out of service to replace the conductors. As a major [extra high voltage] transmission line that is a primary component of the AEP-Dominion transmission interface, the Cloverdale–Lexington 500-kV line can accommodate only a very few planned outages of limited duration that must be scheduled well in advance with the regional transmission organization [PJM Interconnection] and other affected utilities,” Earhart said in his testimony. “For this reason, an outage of the line has already been scheduled in anticipation of the project. Once the commission approves the project, the portion of the construction work that can be completed while the line is in-service must be finished first to ensure that the reconductoring can be completed within the narrow outage window.”
The Cloverdale-Lexington line is shared between Appalachian Power and Dominion Virginia Power, a subsidiary of Dominion Resources. Dominion Virginia Power in May 2012 requested approval to rebuild its 7.4-mile portion of the Cloverdale-Lexington line to meet NERC reliability standards. The commission approved that project on Sept. 7, 2012. The project is estimated to enter service in 2014.