High cost for underground power lines

As some call for Eversource to bury more utilities, providers estimate nearly $62B statewide

Eversource estimates at more than $28 billion the cost of entrenching one of every four miles of its Connecticut power lines, in any effort to reduce the odds of power outages during storms — and more than $61 billion for the remaining wires.

The utility filed the figures with the Connecticut Public Utilities Regulatory Authority, in response to questions posed by the office of Connecticut Attorney General William Tong into the response of Eversource and Avangrid subsidiary United Illuminating to mass outages caused by Tropical Storm Isaias in early August.

During tandem hearings by PURA and the Connecticut General Assembly, Eversource CEO Jim Judge has said the cost of trenching power lines underground is too prohibitive to consider on any widespread scale. The subsequent estimate averages out to about $50,000 for each of

Eversource’s 1.2 million customers in Connecticut — or $75,000 if excluding the third of customers already connected to the grid via underground lines.

The $61.7 billion figure amounts to a fraction of Eversource’s costs to remove trees and branches threatening lines and repairing lines after storms, totaling more than $1.5 billion between 2010 and 2019.

Generally, Eversource had lower Isaias power restoration times in towns with a higher percentage of electric lines underground, according to data the company filed with PURA in response to Tong’s questions.

But there were significant outliers, including Danbury, Greenwich, Bethel, Brookfield and Redding. All rank in the top third of municipalities for higher percentages of underground lines, but had Isaias average power restoration times lagging most other cities and towns in Eversource’s territories.

“The length of restoration in any community depends on the significance of the damage in that location,” stated Eversource spokesperson Mitch Gross, in an email response to a query. “We agree that undergrounding parts of the system could be beneficial but we don’t necessarily draw a correlation between towns with undergrounding and the length of the outages in that town in this storm restoration. We’d have to analyze the circumstances in each municipality to determine the benefit of undergrounding there.”

Eversource estimates the cost of burying an overhead line at $1 million a mile on rural roads, and as much as $14 million along city streets. By comparison, a “rebuild” of a damaged overhead line along town roads averages more than $300,000 — a differential that would take three failures along the same stretch of power line before the investment in a replacement would pay for itself.

While underground lines are far more expensive to fix in the event of any failures — flooding represents one peril — there are other financial benefits including ongoing maintenance. Eversource spent less than $15 million last year on the operation and maintenance of underground lines and systems in its grid, versus $130 million for the lines strung overhead. Strung out over the lifeline of a power line that spans several decades, that can amount to billions of dollars in savings.

Isaias overwhelmed the Connecticut grid, with Eversource crews responding to more than 21,600 points of failure. More than a million customers lost power during the storm and afterward, for intervals spanning a few minutes to more than nine days in a handful of towns including Greenwich, Wilton and Redding.

Some municipalities require new real estate developments to use underground lines, including Bethel which is among the dozen Eversource territories with the highest preponderance at more than 40 percent. But Isaias showed that extensive vulnerabilities remain, including east of downtown where the town’s schools, police station and a senior complex are located.

First Selectman Matt Knickerbocker said it took Eversource six days to restore power to the police station, with repeated pleas through a utility liaison not producing results. First and foremost, he remains a vocal critic of Eversource’s organizational procedures in prioritizing field crew dispatch after storms, saying the town has been at the end of the line repeatedly when it comes to full power restoration after major storms in Connecticut.

“We haven’t gone back and said, ‘OK, let’s take these [lines] that are up in the air and stick them underground,’” said Knickerbocker, who is also president of the Connecticut Council of Small Towns. “Frankly, that’s their problem not ours — they should be paying for that.”