Virginia Electric and Power (Dominion Energy Virginia) on Sept. 22 filed with the Virginia State Corporation Commission (SCC) an application seeking approval to rebuild, entirely within the company’s existing right of way (ROW), about 17.7 miles of its existing 500-kV Dooms-Valley Line #549 transmission line in Augusta County, located between its existing Dooms substation and Valley substation.
There is an immediate and current need for the rebuild project to assure that Dominion Energy Virginia can continue to provide reliable electric transmission service consistent with the company’s obligation under Virginia law to serve retail electric customers in its exclusive service territory, the company said.
With authorization from the SCC by September 2018, and the ability to obtain outages from PJM Interconnection, the company anticipates that the rebuild project could be in service by June 1, 2020.
The company added that for the rebuild project, it proposes to:
- Remove existing 500-kV “COR-TEN” weathering steel lattice structures of Line #549 originally built in the 1964-1966 timeframe, and replace them with new double circuit galvanized structures supporting the 500-kV line with 230-kV underbuild to support future load growth
- Remove and replace existing 2-2049.5 bundled AAAC conductors of Line #549 with three triple-bundled 1351.5 ACSR phase conductors
Rebuilding Line #549 as proposed, with modern facilities and in accordance with good utility engineering practices and National Electrical Safety Code requirements, would increase the transfer capability of Line #549 from 2913 MVA to 4330 MVA, the company said.
The estimated total cost of the proposed rebuild project, which assumes completion by June 2020, is about $62m in 2017 dollars, of which about $58.7m is for transmission line construction work and $3.3m is for substation work.
The company also said that the proposed facilities would afford the best means of meeting the continuing need for reliable service while reasonably minimizing adverse impact on the scenic, environmental and historic assets of the area. Since the existing corridor is adequate to build the proposed rebuild project, no new ROW is needed; therefore, any alternative to the rebuild project requiring the addition of new 500-kV facilities in a new ROW with additional costs and impacts was not considered, the company said.
Among other things, the company said that it considered and rejected building the rebuild project with a single circuit galvanized 500-kV structure. Good utility practice requires the company to plan for future life of the asset, the company noted, adding that with an anticipated service life of 60+ years, it is anticipated that a new 230-kV line in the area would be needed during that timeframe.
Therefore, the company said, replacing the aging 500-kV infrastructure with new double circuit 500/230-kV lattice towers and tubular steel 3-pole structures would enable the company to maintain the overall long-term reliability of its transmission system, while also allowing for flexibility to add a 230-kV line in the future.
Building the new transmission facilities in that manner would avoid the need for the company to acquire new ROW, with additional costs and impacts, in the future if the need for a 230-kV line is shown, the company said.