AEP Texas Inc., on April 5 filed with the Public Utility Commission of Texas an application to amend its certificate of convenience and necessity for the Three Rivers to Borglum to Tuleta 138-kV Transmission Line in Live Oak and Bee counties in Texas.
As noted in the application, the new project would be comprised of two transmission line segments, with the first segment beginning at the existing AEP Texas Three Rivers substation located northeast of the City of Three Rivers on State Highway 72 in Live Oak County, Texas, and extending southeast until it reaches the proposed AEP Texas Borglum substation to be located south of the City of Beeville on U.S. Highway 181 Business in Bee County. That portion of the project is referred to as the Three Rivers to Borglum Segment, or the TRB Segment, and would be designed and built as a single-circuit, 138-kV line.
The application added that the second segment of the project would begin at the proposed Borglum substation and would continue in a northerly direction until it reaches the existing AEP Texas Tuleta substation located north of the community of Tuleta in Bee County. That portion of the project is referred to as the Borglum to Tuleta Segment, or the BT Segment, and would be designed and built as a double-circuit, 138-kV line. The application added that the second circuit would accommodate the rebuild of the existing Tuleta to Normanna to Beeville 69-kV line.
The miles of right of way (ROW) for the 21 TRB alternative routes range from about 28.32 miles for Route TRB-8 to about 46.70 miles for Route TRB-15. The application also noted that the miles of ROW for the 11 BT alternative routes range from about 21.66 miles for Route BT-1 to about 37.52 miles for Route BT-2.
Some of the links used for the TRB Segment of the project consist of rebuilding an existing 69-kV transmission line in the existing ROW. The application added that links that utilize existing easements represent ROW that has already been acquired. The percent of ROW that has been acquired for the TRB Segments ranges from 0% on Routes TRB-2 and TRB-16 to 78.05% on Route TRB-8, which is a 28.32-mile route that would include rebuilding 22.10 miles of the existing 69-kV line.
While the routes would utilize the existing transmission line ROW, the easements might need to be supplemented to accommodate the new 138-kV line, the application added, noting that the percent of ROW that has been acquired for the BT Segments is 0% for all routes.
The area traversed by the alternative routes being evaluated – the study area – for the project is in the vicinity of Beeville, Texas, and encompasses about 375 square miles within portions of Bee and Live Oak counties. The study area is located within the Interior Coastal Plains sub-province of the Gulf Coastal Prairies Physiographic Province. Elevations within the study area range between about 110 feet above mean sea level (amsl) in the southern portions to about 470 feet amsl in the northwestern portions of the study area, the application added.
The study area is primarily rural with residential development concentrated in the cities of Beeville and Three Rivers, the application said, noting that the predominant land use within the study area is rangeland and cropland.
Discussing the need for the proposed project, the application noted that Live Oak County is currently served by two 138-kV lines terminating at the AEP Texas Sigmor 138-kV station, which then serves as a source to the underlying 69-kV system through a nearby AEP Three Rivers 138-kV station. The two 138-kV lines terminating at the Sigmor 138-kV station are the 28-mile, 138-kV San Miguel-Sigmore line and the 66-mile, 138-kV Lon Hill-Orange Grove-Sigmor line.
The current transmission system is not able to reliably serve that area if either of those lines is removed from service in order to perform scheduled maintenance or the result of other outage conditions, the application added.
AEP Service Corporation (AEPSC), on behalf of AEP Texas, submitted a proposal to the ERCOT Regional Planning Group (RPG) to address the reliability of the Live Oak County area electric system. After being reviewed by the ERCOT RPG and the ERCOT Technical Advisory Committee, the proposed project was recommended by the ERCOT Board of Directors as needed to support the reliability of the ERCOT regional transmission system.
Noting that POWER Engineers prepared an environmental assessment and routing study, the application said that the consensus opinion of POWER Engineers evaluators was to recommend Route TRB-8 and BT-1 as the routes that best address certain requirements from an environmental and land use perspective. The application added that AEP Texas determined that Routes TRB-19 and BT-1 provide the best balance of routing characteristics and best address certain requirements.
As noted in the filing, TRB-19 is 28.9 miles long and has an estimated cost of about $36.5m, while BT-1 is 21.7 miles long and has an estimated cost of about $39.5m.
According to the estimated schedule, ROW and land acquisition would begin in April 2020 and be completed in June 2021; engineering and design would begin in January 2021 and be completed in October 2021; material and equipment procurement would begin in March 2021 and be completed in January 2022; and construction of the facilities would begin in June 2021 and be completed in August 2022, which is also when the facilities would be energized.