Power reliability: NPPD reconstructs tornado-damaged line

May 28, 2014
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Restoration of the high-voltage power line between McCool and Hallam, Nebraska, begins. The line was damaged by tornados on May 11, 2014. NPPD expects the line to be energized and ready for summer loads by July 1, 2014.

Columbus, Neb. – In mid-May, tornados tore through approximately 15 miles of the Nebraska Public Power District’s  high-voltage power line between Hallam and McCool in the south central part of the state. Three other power lines damaged by the storm were restored to service within days, but reconstruction of the fourth and final line is underway. And while approximately 100 splintered structures may look like a gigantic game of Pick Up Sticks, the process is not that easy.

It begins with an assessment of all parts and pieces to be replaced. Once NPPD knows the magnitude of damage, it determines the time required to reconstruct. In this case, NPPD plans to energize the 345,000-volt power line by July 1, in time for summer’s heat. Bid requests were issued to contractors with high-voltage line reconstruction experience, and Brink Constructors of Rapid City, S.D., was selected to perform the work . Materials were ordered and  five days later began arriving at the construction site.

When we say materials, we’re talking more than 200 poles and 100 cross-arms, not to mention hundreds of insulators and thousands of nuts and bolts to hold it all together. Did we mention there were two steel structures also destroyed? In total, approximately 1.3 million pounds of damaged structures will be rebuilt. Nearly 90 miles of new conductor, 15 miles of fiber optic cable, and 15 miles of shield wire (the single wire at the top that “shields” the structure from lightning) will replace an equal amount of the same damaged by the storm. NPPD recycles whatever damaged materials it can.

Of an estimated $16.9 million in damages to the initial four power lines, this particular section represents an estimated $16.5 million of the cost.  (That’s a little over $1 million per mile.)

“NPPD’s business is ensuring power is generated and delivered safely and reliably to the people of this state,” explained Tom Kent, vice president and chief operating officer. “While we have several paths that carry power throughout the state, every transmission line has a purpose, and collectively, the entire grid can affect livelihoods and the economy of this state.” 

Transmission crews are assigned various tasks to rebuild the power lines and crew sizes vary. At least 30 individuals will be needed to complete the reconstruction, which is done in phases: foundations, structures, cross-arms, hardware, conductor/shield wire, and final inspection before being energized.

“In mere minutes, Mother Nature can destroy what takes several months and so many to build,” said Kent. “Electricity is something we all take for granted, until we don’t have it. NPPD wants to make sure we do.”

NOTE: High Resolution photos of  reconstruction’s start and damaged structures are available at:

http://www.nppd.com/newsroom/media-library/

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