Salt River Project Agricultural Improvement and Power District (SRP) on Aug. 1 filed with the Arizona Power Plant and Transmission Line Siting Committee an application for a certificate of environmental compatibility (CEC) regarding the proposed 230-kV Southeast Power Link Project.
The project involves a new approximately seven-mile, overhead, double-circuit 230-kV transmission line and a related 230/69-kV substation, to be located generally east of the Phoenix Mesa Gateway Airport in the City of Mesa, Town of Queen Creek, and Maricopa County in Arizona, SRP noted.
The line would enhance the capacity and reliability of the transmission system by connecting the existing Santan-Browning 230-kV transmission line in Mesa, Ariz., to the permitted, but unbuilt Abel-Pfister-Ball 230-kV transmission line in Queen Creek, SRP said.
SRP noted that the new substation (RS-31) would be located on the east side of the Loop 202 and the planned State Route (SR)-24 interchange in Mesa.
SRP said that it proposes to use tubular steel structures, adding that alternatively, depending on final Federal Aviation Administration (FAA) requirements, SRP may use concrete or wooden poles in an H-frame structure, and/or may build a portion of the project using two sets of single-circuit structures. SRP said that it is requesting approval of a corridor 300 feet to 1,000 feet wide, centered on the centerline of each identified linear feature and would require between a 100-foot and 205-foot right of way (ROW) – where available – depending on final configuration.
SRP said that it requests a 10-year term for the CEC, noting that by granting the 10-year term, the Arizona Corporation Commission (ACC) would enable SRP to respond to growth as businesses decide to move into the corridor or expand their operations.
Discussing the project’s need, SRP said that in the near term, SRP needs to site the project to support current economic development and to coordinate with existing infrastructure projects in the area. The southeast valley is poised for substantial economic growth in a largely undeveloped area anchored by the Phoenix-Mesa Gateway Airport.
SRP added that current plans northeast of the airport emphasize industrial development in the Elliot Road Technology Corridor, which is generally located in Mesa along Elliot Road between Hawes Road and Signal Butte Road. Future high-tech manufacturing, data centers, and other high-load-factor customers will place unique demands on the electric system and will require enhanced reliability, SRP said.
The central region east of the airport will emphasize mixed-use residential and commercial development, whereas locations south of the airport in Mesa and Queen Creek will bring additional heavy industrial, light industrial, business park, and commercial uses, SRP said.
SRP noted that it established the project scope based on a series of internal and independent third-party transmission system studies, which considered NERC reliability standards, load growth forecasts, environmental impact, cost, and reliability. In all cases, SRP said, the study results show that the most cost-effective and reliable means to serve the area is a new double-circuit, 230-kV transmission line linking the north and south portions of the transmission system.
SRP noted that the project creates a robust and reliable system with connections to four 230-kV substations – Santan, Browning, Ball, and Pfister. The new RS-31 substation along the new line would serve the local load. SRP also said that the project is in a central location relative to the load it would serve, reducing the need for 69-kV transmission lines and maximizing reliability.
Discussing the proposed alignment, SRP noted that after soliciting input during the public involvement process, working with stakeholders and property owners, and evaluating the potential alignments that it developed, it was able to select one general alignment, which has some options for placement of the line along the linear features that it follows. In addition, SRP said that it has identified a substation siting area for the new RS-31 substation.
The SR-24 alignment is less than ideal because of the FAA issues that it presents, but all of the alternatives to that alignment would have greater public impact, SRP said. The project was divided into four distinct geographic areas:
- Northern Routing Area, which originates at the northern interconnection point with the existing Santan-Browning 230-kV transmission line and connects the proposed transmission line with the Substation Siting Area to the south
- RS-31 Substation Siting Area, which is generally located on the eastern side of the Loop 202/SR-24 interchange; it encompasses 226 acres, of which about 40 acres would be required for the new RS-31 substation
- Central Routing Area, which exits the RS-31 Substation Siting Area and generally follows the future SR-24 alignment to the southeast
- Southern Routing Area, which connects the proposed transmission line along SR-24 to the interconnection points with the permitted, future Abel-Pfister-Ball 230-kV transmission line to the south
Of the Northern Alignment – Loop 202 Proposed Alignment – SRP said that starting at the existing Santan-Browning 230-kV transmission line, at the intersection with Loop 202, the proposed alignment travels south along either the east or west side of Loop 202 to the RS-31 Substation Siting Area. The proposed alignment total length is 1.55 miles – east side of Loop 202 – to 1.67 miles – west side of Loop 202 – and the width of the corridor requested is 500 feet on either side of the Loop 202 ROW. The proposed alignment, SRP added, closely follows an existing linear feature – the Loop 202 – and is the shortest and least-cost option; it also would require traversing parcels owned by the Arizona State Land Department regardless of whether the route is located on the east or west side of the freeway.
SRP said that it understands that if the proposed alignment is chosen, that the committee may specify construction on either the east or west side of the Loop 202.
In an Aug. 3 filing submitted to the committee, SRP said that it replaces the section entitled “Central Alignment” on two pages of the application with the following text:
- Central Alignment, SR-24 Proposed Alignment – From the RS-31 Substation Siting Area, the proposed alignment travels southeast along the south side of the future SR-24 to an intersection with Crismon Road. The proposed alignment length is 2.55 miles. That area of the project is impacted by current FAA surfaces, which would require the construction of poles at heights as low as about 65 feet and with shorter spans. SRP has pending with the FAA an application to modify airport procedures. If the application is granted, SRP would built at, or near, standard heights. FAA requirements regarding radar interference may also require shorter poles, such that on parts of the alignment, the tow circuits may be built on separate structures
Discussing the Southern Alignment, SRP said in its Aug. 1 application that starting at the intersection of the future SR-24 and Crimson Road, the proposed alignment travels south along Crismon Road for its entire length of 2.11 miles to an interconnection point with the permitted, future Abel-Pfister-Ball 230-kV transmission line. The width of the corridor requested for that route is 300 feet. SRP added that the proposed alignment was selected because it is the most direct approach, and a portion of it already includes existing 69-kV transmission that would be rebuilt with the project. Similar to the route along SR-24, FAA approval would be required for poles along the northern portion of this route, and absent FAA approval, SRP would likely use alternative construction techniques for at least a part of the alignment, SRP said.
Among other things, SRP discussed estimated costs of the proposed line and route –
- Northern Alignment: Loop 202 Proposed Alignment (P1-P3) – $9.7m (east side of Loop 202) to $12.3m (west side of Loop 202); RS-31 Substation Siting Area – About 40 acres, $22.9m
- Southern Alignment: Crismon Road Proposed Alignment (P6-P14) – $10.7m
In its Aug. 3 filing, SRP modified another section in its application, noting this cost –
- Central Alignment: SR-24 Proposed Alignment – (P5-P6) – $13.7m
The committee on Aug. 3 said that a hearing will be held at the Mesa Convention Center in Mesa on Sept. 6, will continue on Sept. 7, and will recess until Sept. 10. The hearing will continue on Sept. 11 through Sept. 14, as necessary, unless a tour is taken. The committee added that if a tour is taken, the hearing will begin on Sept. 11 or an alternative date and time set by the committee chairman.