Arizona Electric Power Cooperative (AEPCO), formerly known as Southwest Transmission Cooperative (SWTC), on May 14 requested that the Arizona Corporation Commission modify its April 14, 2010, decision to allow double-circuit structures to be built along an approximate one-mile portion of the Valencia 115-kV Transmission Line Tap and Optical Fiber Optic Ground Wire (OPGW) Installation Project.
In that 2010 decision, the commission approved a certificate of environmental compatibility (CEC) – CEC 152 – that was granted by the Arizona Power Plant and Transmission Line Siting Committee to SWTC authorizing AEPCO to build the Valencia Project, which consists of about 2.7 miles of a new single-circuit, 115-kV transmission line from the existing Valencia substation to an interconnection point with the existing Central Arizona Project (CAP) Del Bac to Spreader Yard transmission line, within a corridor that extends 400 feet north and 300 feet south of Valencia Road.
AEPCO also noted that CEC 152 was modified by a November 2017, decision to extend the time to build until April 20, 2022.
The company said that it requests that the commission allow AEPCO to build double-circuit-capable structures instead of single-circuit structures for the line between the CAP interconnect and Valencia substation. Currently, an aged 46-kV, radial transmission line owned by Tucson Electric Power (TEP) runs for about one mile between the CAP transmission line and S. Camino Verde Road, and then continues generally north to the existing TEP Bopp Donald substation.
AEPCO added that the TEP 46-kV line will be taken down and a new 115-kV transmission line will be built in its place. The additional circuit will be a replacement for the 46-kV line for TEP, the company said, adding, “Effectively, the one mile of existing line will be converted into a double circuit line, with shared ownership between TEP, the Central Arizona Water Conservation District, and AEPCO.”
After passing S. Camino Verde Road, the Valencia line will convert to a single-circuit, 115-kV line built on double-circuit-capable structures and continue as authorized in the 2010 decision until it reaches the Valencia substation, the company said.
All other authorizations for the Valencia Project contained in CEC 152 will remain as originally certificated, the company said.
AEPCO requested that the matter be considered on an expedited basis so that it may begin construction of the line by October. CAP has a scheduled outage on the Spreader Yard to San Xavier 115-kV portion of the Rattlesnake to Del Bac 115-kV transmission line in October, AEPCO said, adding that that outage will allow TEP to transmit its 46-kV load on the existing CAP 115-kV transmission lines, which will maintain service to TEP loads while the one mile of double-circuit transmission line is being built. The remainder of the Valencia Project will be built after the TEP loads are transferred back to the TEP 46-kV line from the CAP 115-kV transmission line, the company said.