American Electric Power’s (NYSE:AEP) Appalachian Power on Dec. 20 filed with the Virginia State Corporation Commission an application for a certificate of public convenience and necessity for the Glendale Area Improvements 138-kV Transmission Project, to be located partly in Carroll County and partly in the City of Galax in Virginia.
The company said that the project would maintain reliability for its customers in Galax, as well as parts of Carroll and Grayson counties – collectively referred to as the Galax load area – in light of thermal and voltage violations of applicable transmission planning criteria in the event of certain N-1-1 contingencies under projected 2021/22 winter peak loading conditions for the Galax load area.
In order to address the criteria violations, the project needs to be in service by December 2021, the company said.
As noted in direct testimony of James Bledsoe, manager, Transmission Line Engineering for AEP’s American Electric Power Service Corporation (AEPSC), the project consists of the new two-mile Wolf Glade 138-kV Extension transmission line; the Relocated Cliffview 69-kV Tap (0.5 mile); the new Wolf Glade substation; and associated improvements at two existing substations.
Once the project is completed, the existing Cliffview substation and about 14 miles of existing double-circuit transmission line would be retired, Bledsoe said.
The proposed Wolf Glade line would be a double-circuit, three-phase design and have a nominal phase-to-phase voltage of 138-kV. The proposed line would tap into the existing Huffman-Wythe 138-kV circuit – located on Appalachian’s existing Jubal Early-Piper’s Gap 138-kV transmission line, about 4.5 miles northeast of the company’s existing Jubal Early substation, Bledsoe added. The line would loop through the proposed Wolf Glade substation to provide a new 138-kV source – the Wolf Glade 138-kV Extension – that would address the projected thermal and voltage violations in the Galax load area.
The proposed route for the 138-kV line generally runs north to south from the tap point to the proposed substation, paralleling roads and parcel boundaries to the extent practical.
Bledsoe also said that about half a mile of the existing double-circuit Cliffview 69-kV Tap transmission line would be relocated and extended to terminate at the proposed Wolf Glade substation – the Relocated Cliffview 69 kV Tap – and the existing Cliffview substation would be retired.
The proposed Relocated Cliffview 69 kV Tap traverses west to east through a wooded area between the existing 69-kV transmission line and the proposed substation.
Bledsoe added that Appalachian reasonably expects that it would be able to acquire right of way (ROW), engineer, build, operate, and maintain the proposed project along the proposed routes efficiently and effectively with minimized adverse impacts on the environment.
While structure types would be determined during final engineering, based on preliminary engineering, the company anticipates primarily using 138-kV and 69-kV double-circuit steel monopoles with davit arms in connection with project construction. A 138-kV, two-pole, dead-end structure may be used at the Wolf Glade 138-kV Extension tap point and at heavy angle locations.
For the Wolf Glade 138-kV Extension, the anticipated 138-kV structure heights range from about 100 to 135 feet, with an average height of about 110 feet, Bledsoe added. For the Relocated Cliffview 69 kV Tap, the anticipated 69-kV monopole structure heights range from about 75 to 95 feet, with an average height of about 85 feet.
There would be about 21 total transmission line structures associated with the project, he added.
Discussing the proposed Wolf Glade substation, Bledsoe said that the graveled and fenced portion of the substation would be about 330 feet by 250 feet, and would be located on a 16.7-acre parcel, which the company has purchased. He noted that the property was formerly cleared and graded by Galax and is zoned “Heavy Industrial Use,” which allows for public utilities as a permitted use within that zoning classification.
Of other substation work, he noted that to accommodate the new 138-kV upgrades, there would be remote work required at Appalachian’s Jubal Early and Huffman substations. No expansion of the existing fenced areas at those substations would be necessary for those improvements. Also, he added, once the new Wolf Glade substation is in service, the existing Cliffview 69-kV substation would be retired. The existing Cliffview substation cannot accommodate the project’s required 138-kV/69-kV/12-kV facilities due to size, terrain constraints, and outage restrictions, Bledsoe said.
According to the company, the total estimated conceptual cost of the project – the Wolf Glade 138-kV Extension, Wolf Glade substation, Relocated Cliffview 69-kV Tap, and associated improvements at the Jubal Early and Huffman substations – is about $38m, consisting of $13m for transmission line-related costs and $25m for substation-related costs. The retirements of the Cliffview substation, about 0.2 miles of the double-circuit Cliffview 69-kV Tap, and about 14 miles of the 88-kV – operated at 69-kV – double-circuit transmission line between Byllesby and Wythe, which would occur after the project is complete, have an estimated conceptual cost of $10m, the company said.