The Public Service Commission of South Carolina, in a Nov. 2 order, granted to South Carolina Electric & Gas (SCE&G) a certificate of environmental compatibility and public convenience and necessity for the construction and operation of two 230-kV transmission lines – the Graniteville #2 – South Augusta 230-kV Tie Line and the Urquhart-Graniteville 230-kV Line – and associated facilities in Aiken County.
As noted in the order, SCE&G filed its application for the certificate in July.
As indicated in the company’s application, SCE&G‘s Transmission Planning studies indicate that the occurrence of certain contingencies will result in heavy electrical loading on the existing Vogtle-Savannah River Site 230-kV Tie Line, a critical Southern Co.-SCE&G interconnecting 230-kV Line, as early as 2019.
The commission added that a company witness testified that to prevent future excessive loading conditions on that line, as well as to distribute the flow of power more reliably and evenly into the SCE&G system, additional electrical transmission paths are needed and necessary between Southern Co. and SCE&G.
Having considered various alternatives, SCE&G and Southern Co. agreed to establish two new Southern Co./SCE&G interconnecting tie lines – the Graniteville #2 – South Augusta 230-kV Tie Line and the Graniteville #2 – South Augusta 115-kV Tie Line – which will cross the Savannah River and enter South Carolina at SCE&G’s Urquhart Generating Station site. The commission added that in addition to decreasing the power flow on the existing Vogtle-Savannah River Site 230-kV Tie Line and more reliably and evenly distributing the flow of power into the SCE&G system, the new tie lines will increase the transfer capacity for all utilities interconnected to SCE&G’s electrical transmission system.
At a hearing, the company witness testified that the proposed Graniteville #2-South Augusta 230-kV Tie Line would run from Southern Co.’s South Augusta substation to SCE&G’s Graniteville Substation #2 in Aiken County along existing rights of way (ROWs) – with the exception of an about 0.46-mile segment on the Urquhart generating station site for which SCE&G will dedicate a new 100-feet-wide ROW – and that the portion of that line to be owned and operated by SCE&G and for which a certificate was requested in the application would be about 18.1 miles measured from the first transmission line structure on the South Carolina side of the Savannah River to the Graniteville Substation No. 2.
With respect to the second new line – the Urquhart-Graniteville 230-kV Line – the company witness testified that it would run for about 17.6 miles along existing ROW from the company’s Urquhart substation in Aiken County to the company’s Graniteville Substation No. 1 in Aiken County.
The commission added that the associated facilities to be added to SCE&G’s transmission system – that is, the 230-kV line terminal and the 230-kV power circuit breaker at the Graniteville Substation No. 1, will accommodate the Urquhart-Graniteville 230-kV Line.
The company witness further testified that the proposed Urquhart-Graniteville 230-kV Line will serve as a replacement for the existing Urquhart-Graniteville #2 230-kV Line, which is one of two transmission lines that service the Urquhart Generating Station’s two 230-kV generators.
The existing 230-kV line will be operated at 115 kV and will become a portion of the Graniteville #2-South Augusta 115-kV Tie Line. Replacing the existing Urquhart-Graniteville #2 230-kV line with the proposed Urquhart-Graniteville 230-kV Line on double-circuit 230-kV structures alongside the Graniteville #2-South Augusta 230-kV Tie Line will maintain the current operating flexibility and level of reliability required for the Urquhart generators.
The witness concluded that the proposed lines and associated facilities are critical to the operational integrity of SCE&G’s electrical transmission system, are necessary to ensure that the company’s system remains in compliance with NERC standards and its own long-term planning criteria, and represent the most cost-effective proposal in light of system needs and constraints and the best long-term solution for the continued transmission of safe and reliable electric power to SCE&G’s customers, the commission added.
The evidence supports a finding by the commission that the proposed lines and the associated facilities are needed, that they serve the interests of system economy and reliability, and that they are required by public convenience and necessity, the commission said.
The commission also noted that based on the evidence of record, it finds that the environmental impacts of the proposed lines and associated facilities have been appropriately evaluated and described, and are not significant. Those impacts are justified considering the state of available technology, as well as the nature and economics of the various alternatives to proposed siting of the proposed lines and the associated facilities, the commission said.
Among other things, the commission said that by building the lines primarily within existing ROWs, the company has selected the route for the lines and associated facilities in a way that appropriately minimizes environmental, land use, cultural resource, and aesthetic effects.