BLM identifies preferred route for SunZia transmission line

The Bureau of Land Management (BLM) has identified a 530-mile route as its preferred alignment for the proposed 500-kV SunZia transmission project that will connect New Mexico and Arizona. The route was identified in the draft environmental impact statement (DEIS) on the project that was published May 29.

BLM, which is the lead federal agency for preparing the DEIS, selected a route which “would be constructed along established utility corridors where existing access is available,” according to the DEIS. For more than half of its length – 296 miles – the route parallels existing or designated utility corridors, including pipeline and transmission line corridors.

The route originates at the new SunZia East substation in New Mexico and heads west, with significant portions running parallel I-25 and the Rio Grande River. The route follows a pipeline corridor north of I-10 in New Mexico and continues into Arizona, where it alternately uses existing pipeline and utility corridors where available before terminating at a new substation in Pinal County, Ariz.

The route was selected as BLM’s preferred alternative because it would maximize use of existing utility corridors and infrastructure while minimizing impacts to sensitive resources, residential and commercial uses, and military operations within restricted airspace north of the White Sands Missile Range, according to the document.

BLM estimates that approximately 191 miles of the right-of-way (ROW) for the preferred route would be located on federal lands, with about 137 miles of the BLM preferred route crossing public lands in New Mexico and about 54 miles of such lands in Arizona.

The proposed project would include two new, single circuit 500-kV transmission lines located adjacent to one another. One of the lines would be constructed and operated as an AC line, and SunZia may construct and operate one of the proposed transmission lines as either AC or DC, according to the draft EIS.

The requested ROW width would be about 400 feet, to accommodate a separation of 200 feet between the two lines, but could be up to 1,000 feet wide in areas where terrain poses engineering or construction constraints, the DEIS said.

In addition to the SunZia East and Pinal County, Ariz., substations, new substations would be constructed and operated near Deming and Lordsburg, N.M.

The purpose of the proposed project is to transport electricity generated by power generation resources, including renewable resources, to western power markets and load centers. The project would enable the development of renewable energy resources including wind, solar, and geothermal generation by creating access to the interstate power grid in the Southwest, according to the BLM.

The project’s developers “are still digesting much of the information” in the DEIS, a spokesperson told TransmissionHub on May 31, but acknowledged, “It’s a huge milestone.”

Once the final EIS is issued, the developer plans to more forward with the state permitting efforts in both New Mexico and Arizona.

SunZia developers are reluctant to estimate a final price tag for the project, noting that “So much of the final cost will depend on the final record of decision and what comes out of the [DEIS] review process.” However, the developer said that projects of this size and scale “typically average in the range of between $1m and $2m a mile.”

The 90-day public comment period for the DEIS will end August 22.