Arizona Electric Power Cooperative (AEPCO), formerly known as Southwest Transmission Cooperative (SWTC), in an April 6 filing submitted to the Arizona Corporation Commission, requested that the commission extend the time for AEPCO to build the San Manuel Project to July 16, 2023.
A certificate of environmental compatibility (CEC) was approved for the project in a July 2009 decision. AEPCO added that it also requests that the commission amend that July 2009 decision to authorize the construction of a double-circuit transmission line energized at 115 kV instead of the originally approved 230-kV configuration.
“The commission’s approval of this application is requested because the purpose for the project has only been delayed, not changed, by the economic recession,” AEPCO said. “AEPCO remains committed to the project for reasons of system reliability and the other benefits that the project provides to the AEPCO transmission system.”
AEPCO noted that it applied in 2009 to the Arizona Power Plant and Line Siting Committee for a CEC to build the project – that is, an approximately 4.5-mile, 230-kV double-circuit transmission line, which would initially be energized at 115 kV. The line was intended to connect the existing Arizona Public Service (APS) San Manuel substation to a point on AEPCO’s existing Apache to Hayden 115-kV transmission line.
AEPCO added that the purpose of the project was to:
- Support anticipated population and energy growth in Trico’s service territory in southeastern Pinal County
- Provide a second interconnection with APS to reduce constraints on the transmission system and allow AEPCO to continue to reliably provide power to the Trico service area
- Facilitate the development of future solar resources on BHP’s non-operating mining real estate in the area
- Provide a direct transmission path from AEPCO’s Apache generating station to southeastern Pinal County for the first time, which is important for economic supply and reliability purposes
The committee granted the CEC, which the commission approved in its July 2009 decision, AEPCO said.
The CEC originally gave AEPCO a period of five years, until July 2014, to build the project. AEPCO added that in 2013, it requested an extension of time to build the line, until July 2018, due to the residual effects of the economic recession in the area; that extension was approved in a May 2013 decision.
The current CEC is scheduled to expire on July 16, 2018, but under a CEC condition, that deadline may be extended by the commission if the request to extend it is filed prior to expiration.
AEPCO added that many of the conditions that justified the first-time extension still exist in southeastern Pinal County. For instance, AEPCO said, as has been true for other Arizona utilities, Trico has not experienced the population and energy growth that was projected to occur in 2009 when the CEC for the San Manuel Project was granted, nor is Trico’s service territory expected to grow as originally projected in the foreseeable future.
AEPCO noted that it still needs to establish an interconnection point with the APS 115-kV system at the San Manuel substation in order to provide Trico with increased quantities of cost-effective power and a direct transmission path from AEPCO’s Apache generating station to southeastern Pinal County, thereby improving supply and service reliability in the area.
AEPCO also said that granting a five-year extension to build the project allows AEPCO and BHP time to continue to explore and develop partnerships with solar developers to bring renewable generating resources to the area.
Regarding its request to permanently energize the line at 115 kV, AEPCO said that due to changes in anticipated growth, it no longer needs the line to accommodate 230 kV. The vast majority of the line was designed to operate at the 115-kV level, and the likelihood that any part of the line would be energized at a higher level is low due to the increased cost involved, AEPCO said. The towers would remain double circuit, and while the spacing between the towers may not change, the tower heights would be reduced by 15 feet to 20 feet, AEPCO said.