Closed Circuit

​By Kevon Storie

Photos by Gerry Hartill

Years of planning and months of hard work came to fruition in the closing weeks of 2018 when the Desert Southwest region energized the Hassayampa Switching Station, a major upgrade to WAPA’s relay and communication systems.

Crews checked readings and switches in the final segments Nov. 30, just ahead of the Dec. 1 deadline. The regional partnership brought together WAPA, the Central Arizona Project, switching station owner Bureau of Reclamation, Arizona Public Service, Level 3 Communications—now CenturyLink—and  WAPA’s construction contractor to replace infrastructure that was more than 30 years old.

Finding opportunity in change
The project prepared the switching station to handle changes resulting from the expected closure of the Navajo Generating Station. Reclamation bought power from the coal-fueled powerplant to supply the multiple pumping stations along the 336-mile canal system CAP operates. The Colorado River Basin Project Act created CAP 50 years ago to supplement the water supply in Phoenix and Tucson.

The HSS project originated when CAP asked WAPA to evaluate replacing the existing 230-kilovolt Hassayampa Tap with a new switching station. The request anticipated CAP’s need to replace power from the Navajo Generating Station with new sources.

Following multiple studies, WAPA contracted to upgrade the facilities that feed the Hassayampa Pumping Plant. These improvements to the transmission infrastructure will connect CAP, through Arizona Public Service and WAPA, to the Mead and Palo Verde market hubs, the major electrical trading hubs in the western United States. CAP will then be able to purchase power on the open market to replace the power from NGS.

Improving infrastructure
This undertaking had significant impact on WAPA facilities over several months. Construction of the new switching station required relaying and control equipment upgrades at the Hassayampa Pumping Plant along with the Parker, Harcuvar and Liberty substations.

Replacing the conductors on five miles of existing transmission line and installing one mile of double-circuit transmission line completed the interconnections between HSS, Arizona Public Service Company’s Sun Valley Substation and the Hassayampa Pumping Plant.

The pumping plant’s load did not change, but higher fault current levels due to the interconnection to Sun Valley Substation required replacement of motor-operated interrupter switches at the Hassayampa Pumping Plant.

The old instrument transformers at the pumping plant were also replaced as part of the project for long-term reliability. “These changes will greatly improve the reliability and operational capabilities of the organization’s bulk electric system,” said Supervisory Electrical Engineer Rob Arlt.

Talking it out
With so many partners and so many pieces of critical infrastructure affected, careful coordination was essential to completing the HSS project. CAP is only able to shut down Hassayampa Pumping Plant for short periods, so construction had to be coordinated to fit their pumping schedules.

Transmission line outages in Arizona are normally scheduled for winter, but the best time for the three-week pumping plant outage was August, so construction activity was coordinated to connect the Hassayampa Pumping Plant to Sun Valley Substation during that time. Several short pumping plant outages were scheduled between January and April to replace the interrupter switches in preparation for the interconnection to Sun Valley during August.

Partners worked closely to develop scheduling and sequencing plans and draw up written agreements with clear roles and responsibilities. Each partner performed work in coordination with others to meet the schedule.

In addition to the permanent backup generator, which supplied power to critical auxiliary equipment during the outages, several large diesel generators were brought in to facilitate maintenance work inside the pumping plant by CAP crews during the August outage.

Job well done
As with any transmission construction project, the Hassayampa Switching Station project encountered its fair share of changes, setbacks and difficult timelines, but the crews proved to be up to the challenge.

“The partners did a great job of interacting and working with our customers, Arizona Public Service and CAP, regarding the impacts and upgrades related to their respective facilities,” said Arlt. “This project is a true example of ‘above and beyond’ in terms of effort, dedication and sheer will to provide the customer with a quality product on time and on schedule.”

Note: Storie is a technical writer who works under the Wyandotte Services contract. Rob Arlt and Gerry Hartill contributed to this story.

Last modified on March 8th, 2024