Western Area Power Administration (WAPA) and Southline Transmission, a subsidiary of Hunt Power have agreed to develop a 579km transmission line project in the US Southwest.

The Southline Transmission project will be a 1GW transmission line between southern New Mexico and southern Arizona aimed at delivering electric system benefits to the Desert Southwest Region.

It will involve upgrades to the existing electrical infrastructure of WAPA and also construction of new transmission lines.

By interconnecting a number of existing substations, the Southline Transmission project, is expected to boost reliability, help in removing transmission congestion, address increased energy demand and enabling construction of new sources of power generation.

The new transmission line comprises two sections with one being construction of a 345kV double-circuit transmission line stretching from south of Las Cruces, New Mexico to south of Willcox, Arizona.

The other section will be upgrades to existing transmission lines of WAPA from single-circuit 115 kV to double-circuit, 230 kV between Willcox and a substation northwest of Tucson.

WAPA administrator and CEO Mark A. Gabriel said: “Public and private organizations each bring unique strengths toward infrastructure development and modernization.

“Our successful partnership with Southline Transmission, L.L.C., allows us to use these strengths to develop new critical energy infrastructure that will support affordable and reliable electricity for our customers for decades to come.”

Under the participation agreement signed by WAPA's Desert Southwest Region and Southline Transmission, a commercial framework has been agreed that allocates transmission rights on each segment of the project.

Once the new transmission line is energized, WAPA's share of transmission capacity will be incorporated under its Parker-Davis Project.

Construction on the transmission project is expected to commence in late 2018, with transmission operations to begin in a phased manner starting from 2020.

Hunt Power president Hunter Hunt said: “We are thrilled to advance our long-running successful relationship with WAPA with this important milestone for the Southline Transmission Project.

“We look forward to working with WAPA and all our stakeholders to deliver this much needed project in a manner that maximizes benefits while minimizing impacts.”