AUSTIN (KXAN) — Precipitation in the winter, whether freezing rain or snow, accumulates on tree branches and overhead power lines; this routinely leads to power outages once enough piles up. When this happens, it prompts some to ask: Why can’t we just bury the power lines underground?

On Thursday, Austin Energy General Manager Jackie Sargent was met with that same question as more than 148,000 customers and even more residents remain without power.

“It’s very expensive to retrofit a system and go back and bury power line,” she said. “Very expensive. Billions of dollars.”

As new developments have come online in the Austin area, with them has come the opportunity to bury power lines. That comes with its own set of challenges, Sargent said; namely, buried lines are vulnerable to flooding and breaks in lines are more difficult to identify when underground.

It’s a sentiment echoed by Peter Lake, chairman of the Public Utilities Commission of Texas. Lake said the two biggest reasons why more cities don’t use underground power lines are the increased cost and the greater difficulties with repairing them.

“Just like anything they come with pros and cons,” Lake said. “The primary benefit is that when we have ice on trees and branches are falling, if the lines are underground, then outages are less of an issue. The downside of underground power lines is the extraordinary increase in cost.”

Lake notes that while the cost per mile of new power lines can vary, underground lines cost at least $1 million or more per mile.

“In addition, maintenance on underground power lines is also challenging,” Lake said. “Instead of having somebody in a truck on the side of the road up in the bucket work in a powerline, you’ve got to dig up the street, you got to dig up yards, which of course is more disruptive to homes and families.”

Severe weather, depending on the variety, impacts underground and overhead lines differently. Underground lines are more protected from a winter storm, but flooding can cause catastrophic damage.

“In the normal course of business, on a normal day, you can have problems with transformers or conductors that disrupt the flow of power, at which point, that’s when you normally see the linemen out on the roads, repairing a transformer or adjusting the conductors,” Lake said. “All of that normal kind of maintenance gets much, much more difficult, and much more expensive, if every inch of that line has to be dug up just to find the single transformer that actually is the problem.”

Austin Energy spokesperson Matthew Mitchell echoed Lake’s concerns with underground lines. He also notes that Austin was built on top of limestone, which would make burying the lines even more expensive and difficult to maintain.

“Burying power lines – moving overhead distribution systems running alongside roads, homes and businesses underground – is a question utilities often hear after storms,” Mitchell said. “Austin Energy has looked into the issue and determined that at this time, it would be too expensive to begin this process and that’s not a cost we’d want our customers to burden. Burying lines would involve billions of dollars and take decades to complete.”