APS to delay in-service date for Sun Valley-Morgan 500-kV line

Arizona Public Service (APS) plans to officially extend the anticipated in-service date for its proposed Sun Valley-Morgan transmission project from 2016 to 2018 when it files with the Arizona Corporation Commission its 10-year transmission system plan required by Arizona’s line-siting statues. That plan will be filed by the end of January.

The extension was made public via APS’s open-access same-time information system and has been communicated to the U.S. Bureau of Land Management (BLM), which is soliciting public comments on the draft environmental impact statement (EIS)/draft resource management plan amendment (RMPA) for the proposed 38-mile transmission project west of Phoenix, Ariz.

APS is proposing to build the dual 500/230-kV overhead transmission project from the Morgan substation near Peoria, Ariz., to the planned Sun Valley substation near Buckeye, Ariz., primarily using private, state trust lands and about nine miles of public land managed by the BLM. BLM selected the APS proposed action as the agency-preferred alternative route.

“This is a local-benefit line in terms of reliability,” Richard Stuhan, APS project manager, told TransmissionHub on Jan. 28.

The utility says the project is needed to facilitate the incorporation of new sources of generation, including renewables, which are included in pending generation interconnection requests for the Palo Verde Hub, a major electrical trading hub located west of Phoenix.

“Predominantly, the 500-kV circuit is a reliability path that increases our ability to move power from the Palo Verde Hub into the Phoenix load center,” Stuhan said. “For the 500-kV circuit, the piece from Morgan to Sun Valley completes a continuous path starting at the Palo Verde hub and connecting to, ultimately, the Pinnacle Peak substation in northeast Scottsdale [Ariz.]”

Coupled with existing transmission, including that owned by Salt River Project (SRP), the area’s other major utility, the circuit will also enhance reliability in the metropolitan Phoenix area.

“This helps create a 500-kV loop around the Phoenix load pocket, which also enhances reliability,” he said. “[SRP has] lines to the south end of the metropolitan area, we have lines to the north, so with this new system, everyone should be able to better serve their customers.”

The project is also proposed to have a 230-kV circuit that will provide backbone service in a rapidly growing area of northwest Phoenix that, at present, has no dedicated 230-kV service.

“With all the long-term plans of the municipalities, we need the 230-kV circuit to form that backbone for the projected development in that area,” Stuhan said.

The project will potentially enable more renewable generation to connect to the system, as a number of the pending interconnection requests are for solar and other types of renewable generators.

In addition to increasing capacity from the Palo Verde Hub, the project will also connect the Palo Verde transmission system to the Navajo transmission system in the Four Corners area, the site of the Four Corners coal-fired power plant. As transmission lines are agnostic with regard to the source of the electrons they transmit, the new lines could carry renewable as well as fossil generation.

“The key thing is there are a number of types of interconnection requests there, and this provides a new path to bring that to the Phoenix load pocket,” Stuhan said.

The BLM public comment period on the draft EIS ends Feb. 8 and, while comments continue to filter in, no new issues are being raised.

“It’s primarily property owners concerned about what a transmission line would do to their property and environmental groups that are concerned about the it would do to the environment,” a BLM spokesperson told TransmissionHub.

BLM officials expect to issue a final EIS during the summer of 2013.

The estimated project cost $127m.

APS is a subsidiary of Pinnacle West Capital (NYSE:PNW).