Farmington's big, new electric substation is built to blend in

High-capacity Cottonwood Substation is perched high on a prominent hill, but built as an homage to ancient architecture

Hannah Grover
Farmington Daily Times
John Armenta, Engineering Manager for Farmington Electric Utility System, right, explains some unique features of the powerful new Cottonwood Substation Aug. 10 in Farmington. The high-capacity substation has state-of-the-art safety features to protect workers and avoid power outages.

FARMINGTON — People driving along 30th Street near Farmington Avenue may have noticed a new electric facility surrounded by a wall high on a hill.

Or at least wondered what the heck it is.

This facility is the new Cottonwood Substation, which will serve thousands of Farmington Electric Utility System customers.

What is a substation?

Energy generated by power plants, dams, wind turbines or solar arrays is sent through high voltage transmission lines to substations. The substation includes a transformer that reduces the voltage before the electricity is sent through the power lines to houses. Poles outside the houses also include small transformers that reduce the voltage to 120 volts, which is a safe level for household use.

The Cottonwood Substation has more capacity than the substation it replaces, and can accommodate future growth in the area.

The Cottonwood Substation features two transformers that reduce the voltage from 115 kilovolts to 13.8 kilovolts.

Farmington Electric Utility System includes 36 substations, including the $10 million Cottonwood Substation.

Cottonwood Substation replaces Sullivan Substation

The Cottonwood Substation was built to replace the aging Sullivan Substation. Farmington Electric Utility System Director Hank Adair said the Sullivan Substation, located near the intersection of Sullivan Avenue and 30th Street, has reached the end of its useful life. Within the last six months, there has been one power outage in Farmington because of the Sullivan Substation.

John Armenta, an engineering manager for Farmington Electric Utility System  talks about the new Cottonwood Substation, Friday, Aug. 10, 2018 in Farmington.

Farmington Electric Utility System Engineering Manager John Armenta said the Sullivan Substation was built in 1971 and the transformer was upgraded in 1978. Since then, there’s been a greater demand for power in Farmington. In addition, Armenta said safety codes have been updated 11 times since 1971.

The Sullivan Substation currently serves about 3,000 residents in Farmington. The Cottonwood Substation will serve those same 3,000 residents and is built to accommodate population growth. Farmington Electric Utility System can also use the additional capacity at Cottonwood Substation to accommodate customers while it is working on other substations. It will soon begin upgrades at the Foothills Substation.

John Armenta, an engineering manager for Farmington Electric Utility System  leads a tour of the Cottonwood Substation, Friday, Aug. 10, 2018 in Farmington.

There are four lines that leave the Sullivan Substation to transport power throughout the city. The Cottonwood Substation has the capacity for eight, however the utility will begin with five.

Design increases safety, reliability

He said the Sullivan Substation needed a “ring-bus” design for circuit breakers to increase reliability, but there was not enough land available to build one. In Cottonwood’s ring-bus design, the circuit breakers are connected to form a rectangular ring. This allows the utility to open and isolate any of the circuit breakers without disrupting service.

John Armenta, right, an engineering manager for Farmington Electric Utility System answers questions about the Cottonwood Substation, Friday, Aug. 10, 2018 in Farmington.

“We can actually lose an entire section of transmission line without losing any service to our customers,” Armenta said.

The Cottonwood Substation also includes various features that increase worker safety by isolating arc flash — electrical discharge between conductors that causes an explosive burst of heat and light.

Even the four to six inches of gravel on the ground at the substation is intended to keep people safe. Armenta said the gravel is an important part of the electrical grounding process.

Future uncertain for Sullivan Substation

Armenta said the electric utility has not yet decided what to do with the old Sullivan Substation. He said some of the equipment will be moved to other locations. Armenta said there is a possibility it could be used as a satellite warehouse and store the utility’s mobile substation.

“There are still lots of possibilities,” Armenta said.

Adair said one of the possibilities is installing a small solar array. The array would not generate much electricity. It takes between six and eight acres of land to generate one megawatt of electricity. The Sullivan Substation occupies less than an acre.

The Cottonwood Substation, highly visible on an otherwise undeveloped hillside,  was literally built with looks in mind. It's design is an homage to the designs used in traditional pueblos, with features that mimic ladders as part of the design.

Cottonwood designed for aesthetics

The walls of the substation are designed to resemble ancestral Puebloan architecture and features within the substation mimic the appearance of ladders.

“I knew it was going to be a high-profile station,” Armenta said.

He said the substation’s prominent location on a hill above 30th Street and Farmington Avenue made it visible to lots of people.

Not all substations receive the aesthetic design that was incorporated into the Cottonwood Substation. Some just have chain link fences surrounding them. But Armenta said he wanted it to look good.

The Cottonwood Substation is pictured on Friday, July 10, 2018 in Farmington.

“We have to put them on hills for a lot of reasons,” he said.

He said placing substations on hills helps with drainage and also allows the utility to use terrain to accommodate the transmission lines. This reduces the number of structures the substation needs. Finally, Armenta said the hilltop location reduces noise.

“If you have a transformer below you, all the noise tends to go up,” Armenta said.

Twin Peaks Substation in the works

The Farmington Electric Utility System is in the process of designing and constructing the Twin Peaks Substation, which will serve the Kirtland area.

Adair said it takes about two years to plan and construct a substation.

Hannah Grover covers government for The Daily Times. She can be reached at 505-564-4652 or via email at

Design features of Farmington's newest electrical substation are explained by John Armenta, an engineering manager for Farmington Electric Utility System, during a tour Aug. 10.