Arizona’s Salt River Project (SRP; Tempe, Arizona, U.S.), a consortium made up of Arizona Public Service Co. (Phoenix, Arizona), Tucson Electric Power Co. (Tucson, Arizona) and the Santa Cruz Water and Power Districts Association (Santa Cruz, California, U.S.) is finally seeing some light at the end of the tunnel for its proposed 500-kV transmission line, which will run from an area near Palo Verde Generating Station to a new Pinal West Substation in western Pinal County near Hidden Valley, Arizona. Thanks to recent approvals, siting reviews and hearings, it looks like the group may break ground on the first segment in 2005. However, a second segment of the line from Pinal West to the Southeast Valley near Mesa, Arizona, and at least three substations, is moving much more slowly due to population sensitivity issues. Maricopa County, the termination point for the new line, is not only one of the fastest-growing counties in the United States, but it’s also one of the largest in acreage—almost all of which is occupied by at least one resident or business.

Demand Based on Study

After growing concern that many of the new electric generating stations proposed in Arizona were not located near available transmission corridors, a cooperative regional study was conducted by several of the state’s electric utilities, including SRP, the Arizona Corporation Commission and several energy merchants and marketers. The consortium’s new transmission lines and additional substations are based on the results of the Central Arizona Transmission Study (CATS).

Greystone Environmental Consultants Inc. (Phoenix) has been conducting the siting and environmental permitting for the SRP projects, which will span approximately 209 to 241 km (130 to 150 miles) and cost an estimated US$150 million. Alternate route proposals may vary the cost by up to $35 million.

Palo Verde to Pinal West

The first segment of the project consists of building two parallel 500-kV transmission lines that will transport power from the Hassayampa switch-yard near the Palo Verde Generating Station, west of Phoenix, to a new 500/230/69-kV substation located near the Maricopa / Pinal County line. The 88-km (55-mile) section, which has already been permitted, is scheduled to move forward later in 2005 to meet an in-service date of 2007.

Pinal West to Southeast Valley/Browning

A second 500-kV transmission line is planned that will connect the Palo Verde Generating Station to a new substation in western Pinal County near Hidden Valley. The approximately 160-km (100-mile) section includes a new 500-kV and 230-kV transmission lines and substations that will serve Pinal and Maricopa Counties. Subcomponents of the new line include building a new Pinal West Substation in western Pinal County, southwest of the city of Maricopa, and constructing a new 500-kV interconnect with the existing Santa Rosa Substation located south of the Ak Chin Indian Community.

A new Southeast Valley 500/230/69-kV Substation (RS 19) is planned for northwest of Florence, Arizona, in northeastern Pinal County. Depending on route selection, a future Pinal South Substation, south of Coolidge, may be included in the project.

Another substation on the route will be built to accommodate the double-circuit 500/230-kV transmission line northeast of the town of Queen Creek. From the RS 19 Substation, the new 500/230-kV transmission line will continue on to the existing Browning Substation in east Mesa. The SRP consortium’s proposal provides connectivity for several new facilities in Central Arizona to transfer energy to areas where there is customer demand.

California Interconnect

Several generating plants in or near Arizona have excess capacity, while recent energy studies have identified the Southwest coastal region of the United States as having the potential for shortages. Southern California Edison (SCE) is proposing to construct a new 370-km (230-mile) 500-kV transmission line primarily in SCE rights-of-way, parallel to the existing Palo Verde-Devers transmission line No. 1 from California to Arizona. The termination point for SCE’s line is the Harquahala Switchyard located approximately 64 km (40 miles) west of Phoenix.

SCE is also proposing to upgrade four existing SCE 230-kV transmission lines located within an existing 75-km (47-mile) transmission corridor from the Devers Substation to SCE’s San Bernardino and Vista substations. Many stakeholders and benefactors impacted by these large expansion projects are in discussions regarding cost sharing, joint ventures, generation tie-ins and upgrading of converter and substations along specific sections of the route. Several utilities near the proposed route are developing plans to upgrade and/or use the new lines’ capacity, which will generate a considerable number of additional projects as a result of the transmission line projects. l