The U.S. Bureau of Land Management (BLM) and the Western Area Power Administration (Western) have prepared a Final Environmental Impact Statement (EIS) for the proposed Southline Transmission Line Project and will announce the availability of the Final EIS in a notice to be published in the Nov. 10 Federal Register.
Neither the BLM nor Western will issue a final decision on the proposed project for a minimum of 30 days after the date that the U.S. Environmental Protection Agency publishes its Notice of Availability in the Federal Register.
Southline Transmission LLC has filed a right-of-way (ROW) application with the BLM proposing to construct, operate, maintain, and eventually decommission a high-voltage, alternating current electric transmission line. The BLM and Western agreed to be joint lead agencies. Western is a power-marketing agency within the U.S. Department of Energy and is also a participant in the proposed project with Southline.
The project would consist of two sections.
- The first section would entail construction of approximately 240 miles of new double-circuit 345-kilovolt (kV) transmission line in a 200-foot ROW between the Afton Substation, south of Las Cruces, New Mexico, and Apache Substation, south of Willcox, Arizona (Afton-Apache or New Build Section).
- The second section would entail the upgrade of approximately 120 miles of Western’s existing Saguaro-Tucson and Tucson-Apache 115-kV transmission line in a 100-foot existing ROW to a double-circuit 230-kV transmission line in a 100 to 150-foot ROW (Apache-Saguaro or Upgrade Section).
The Upgrade Section would originate at the Apache Substation and terminate at the Saguaro Substation northwest of Tucson, Arizona. Both new permanent ROWs and temporary construction ROWs would be required in the New Build Section and in some portions of the Upgrade Section for the transmission line, access roads, and other permanent and temporary Project components.
The proposed project would involve the interconnection with and expansion and upgrade of 14 existing substations in southern Arizona and New Mexico, as well as the potential construction of a new 345-kV substation facility in New Mexico. The project would also include installation of a fiber optic network communications system.
The New Build Section (Afton–Apache) would include construction and operation of:
- 205 miles of 345-kV double-circuit electric transmission line as well as associated roads and ancillary facilities in New Mexico and Arizona with a planned bidirectional capacity of up to 1,000 MW. This section is defined by endpoints at the existing Afton Substation, south of Las Cruces in Doña Ana County, New Mexico, and Western’s existing Apache Substation, south of Willcox in Cochise County, Arizona;
- 5 miles of 345-kV single-circuit electric transmission line between the existing Afton Substation and the existing Luna-Diablo 345-kV transmission line;
- 30 miles of 345-kV double-circuit electric transmission line between New Mexico State Route 9 and Interstate 10 east of Deming in Luna County, New Mexico, to provide access for potential renewable energy generation sources in southern New Mexico. This segment of the proposed project is included in the analysis, however, development of this segment would be determined at a later date; and
- One potential new substation on approximately 25 acres of land in Luna County, New Mexico (proposed Midpoint Substation), to provide an intermediate connection point for future interconnection requests
The Upgrade Section (Apache-Saguaro) would include:
- Replacing 120 miles of Western’s existing Saguaro-Tucson and Tucson-Apache 115- kV single-circuit electric wood-pole H-frame transmission lines with a 230-kV double-circuit electric steel-pole transmission line. This section is defined by endpoints at the existing Apache Substation, south of Willcox in Cochise County, Arizona, and the existing Saguaro Substation, northwest of Tucson in Pima County, Arizona;
- 2 miles of new build double-circuit 230-kV electric transmission line to interconnect with the existing Tucson Electric Power Vail Substation, located southeast of Tucson and just north of the existing 115-kV Tucson-Apache line; and
- Interconnection with and upgrade of 12 existing substations along Western’s existing Saguaro-Tucson and Tucson-Apache 115-kV lines in Arizona. Substation expansions would be required for installation of new communications equipment, new 230-kV bays with transformers, breakers, switches, and ancillary equipment. In some cases expansion may require a separate yard.
In addition to the “Proponent Preferred Action,” Southline also submitted the “Proponent Alternative” route for the New Build Section of the proposed project, both of which were the product of extensive stakeholder outreach. In addition to the Proponent Preferred Action, the Proponent Alternative and the No Action Alternative, the BLM and Western are considering local alternatives and route variations.
Western considers funding help for the project
Western needs to respond to the project proposed by Southline, which would, in part, include an upgrade of two existing Western transmission lines and associated substations and the use of existing Western transmission easements. In addition, Southline has requested consideration of this project for funding under the amended Hoover Act of 1984. Western needs to determine the nature and extent of its participation in the proposed project, and whether it will provide funding. In the context of making these determinations, Western will evaluate the upgrade of its existing Saguaro–Tucson and Tucson–Apache 115-kV transmission lines.
As part of its decision whether to use its amended Hoover Act borrowing authority to finance the project, Western would decide on the amount of funding, potential ownership of capacity rights on the upgrade, repayment provisions, and the nature and extent of its participation in the proposed project. Specifically, funding would be used to construct the proposed transmission lines and substation upgrades, and remove the existing Western transmission lines.
Before committing funds for construction, Western must determine that the proposed project is in the public interest; that it would not adversely impact system reliability, system operations, or other statutory obligations; that it has at least one terminus in Western’s service territory; that it will deliver, or facilitate the delivery of renewable energy; and that it is reasonable to expect that the proceeds from the project would be adequate to repay a loan from the U.S. Treasury. Western’s decision would be partially informed by the required analysis and disclosure in this Final EIS.
Alternatively, Western could choose to participate with Southline with the upgrade of the two transmission lines and associated facilities and the use of its borrowing authority to advance the proposed project. The current condition of the lines and their inclusion in Western’s 10-year capital plan indicates, however, that the lines would be upgraded within the next 10 years even if Western does not participate with Southline or make use of its borrowing authority.