Power Lines N.C. 107

The NCDOT examined the option of putting utility lines underground as part of coming roadwork on Sylva’s business corridor, but decided it was prohibitively expensive.

By Dave Russell

 

R-5600, the N.C. Department of Transportation construction project to reshape N.C. 107/U.S. 23 Business, would change many things about the roads, but power delivery wouldn’t be one of them.

Duke Energy power lines will still be overhead, and not underground as many had hoped.

“I know that early on there was a lot of conversation about whether or not we could put the lines underground, but it was more expensive than the project itself,” said Lisa Leatherman, community relations manager for Duke Energy.

The current project schedule calls for right-of-way acquisition to begin in early 2020 and construction in late 2021. The work would cost an estimated $21.5 million, not including utilities and right-of-way acquisition.

Underground power lines would cost $26 million, according to the NCDOT.

“Part of the reason for that is when we put those utilities underground, those being our primary three-phase lines that feed the community, is that you have to have redundant systems,” Leatherman said.

In engineering parlance, a redundant system “duplicates critical components or functions of a system with the intention of increasing reliability of the system, usually in the form of a backup or fail-safe, or to improve actual system performance.”

“The lines in question are main lines that connect two substations and serve a large portion of the area,” Leatherman said. “An underground system would require a duct bank to be installed with vaults and manholes with all lines encased in concrete. Duke Energy would have to install equipment outside of the duct system to pick up other lines and would require special equipment. This work would be labor intensive. We would also need to secure rights-of-way from private property owners where manholes can be accessed by truck in order to conduct this work.”

A duct bank consists of underground conduit encased in concrete for protection against dig-ins or other disturbances, she said.

Repair costs for an overhead system would be less than a repair to an underground system.

“If the duct system was in place, any repairs and maintenance would be costly,” she said. “On an overhead system, faults are typically easier to identify by easily seeing where damage is overhead unlike an underground system.”

Line technicians would need special training and certifications to work in confined work spaces, and special equipment would need to be purchased to work on the infrastructure, she said.

The overhead system would include new lines, power poles, etc.

“Based on the design plans provided by the NCDOT, Duke Energy would need to install all new materials, lines and equipment,” Leatherman said.

At the Sylva town board’s Aug. 8 meeting, board member Mary Gelbaugh said she had done some research on the issue and hoped the power lines would go underground.

“I was initially very excited underground was the answer,” she said. “From my point of view, influenced by what I had read and heard, underground would cause less impact to existing businesses and right of way needs, thus sustaining our existing economy.”

She realized the cost would be higher, but felt that the impact to Sylva’s tax base would be even greater, she said.

“While this is their specialty, certainly not mine, I am still not convinced underground isn’t a viable answer,” she said. “I corresponded with several board members and the DOT Division 14 on my perception, which was unfortunately debunked.”

The N.C. Department of Transportation proposes for N.C. 107 the elimination of the center turn lane with sidewalks replaced and a 5-foot bike lane added. Upgrades are slated for the N.C. 107/U.S. 23 Business intersection, and from U.S. 23 Business to Dillardtown Road and Municipal Drive, near the Sylva Fire Department. DOT’s preliminary estimate listed 55 businesses facing potential relocation, though that number is fluid.