Nearly 12 feet underground and spread across two miles near Lake Mathews sit six concrete vaults that will house Southern California Edison electrical equipment and cable.

This is just one of the projects in SCE’s initiative that aims to eliminate equipment-initiated wildfires by taking power lines out of the air and putting them underground in high fire risk areas.

“It’s a process. Every step is a process,” said Joey Legere, SCE Civil Undergrounding inspector. “But it’s all worth it because we are doing it to keep customers safe. With the wires underground, it limits the danger of something hitting our lines and starting a fire.”

While undergrounding isn’t the answer for every line, in some areas, it is the best option. SCE has reduced the risk of catastrophic wildfires by 85%-88% below pre-2018 levels by hardening the electric grid with coated electrical wires, undergrounding and using innovative technology.

The area was selected to have its wires buried because of its fire risk. After an in-depth evaluation to ensure the project is doable, the SCE planning department designs the project and hands off the work to civil construction crews who handle the excavating.

The build begins with a backhoe. Crews first need to carve out a hole big enough to fit the vaults that will hold the electrical equipment. Then, trenches are dug along the entirety of the project line, in this case about two miles, which will act as pathways for new wires that are encased in a protective covering and run between the vaults.

Crews then lower the vaults into the ground with a crane before all the electrical equipment and underground cables are added inside.

“By having all of our electrical equipment inside of these concrete boxes, it gives us access to maintain our facilities, it will be an access point if we ever need to replace the cable or equipment and it limits Public Safety Power Shutoffs,” said Don Woodruff, SCE Civil Undergrounding advisor.

No undergrounding project is the same, this one took about three months, but they do have one thing in common; projects of this magnitude come with a specific set of obstacles. One of the biggest being environmental — including wildlife.

“We have a lot of kangaroo rats that live out here, so we need to be careful not to disturb them or any of the other creatures in the area. We have a surveyor on-site to make sure we are environmentally sound, and they give us the all clear before we start,” Legere said.

Cities and counties also play a role. With safety and traffic patterns in mind, each one has their own set of rules and regulations specifying what time and how long crews can work each day.

“The locations selected for undergrounding usually have limited roadway access and very challenging terrain, so construction can be disruptive to customers who live in those areas, especially if we are shutting down lanes of traffic,” said Sunny Chu, SCE principal manager of the Targeted Undergrounding Task Force team. “As we ramp up the program to underground over 100 miles per year beginning in 2026, our goal is to minimize the risk of catastrophic wildfires while also limiting the impacts of construction on our customers.”

Once the excavation is complete, electrical crews are brought in to install the cables in their newly formed pathways.

“Those crews will come in, install everything, de-energize the old lines and reenergize the new cable,” Woodruff said. “After that, they begin taking down whatever portion of the poles possible, but if there are other utilities wires or equipment attached, they will remain until that utility owner removes them.”

The company plans to relocate up to 600 miles of overhead distribution lines underground in high fire risk areas by the end of 2028.

For more information on SCE’s targeted undergrounding efforts, visit sce.com/tug.

For more information on SCE’s wildfire mitigation efforts, visit edison.com/wildfiresafety.