T&D World Magazine

Transmission Reconstruction Continues Well After Arkansas Skies Have Cleared

The lights have been back on for a couple of weeks, but storm restoration work in Arkansas is far from over. Over the last five weeks of storms, 59 Entergy Arkansas, Inc. transmission line segments were knocked out, 26 of which required significant reconstruction to put back in service. All but one of those are back on now, and power is being routed around it so it is not causing customer outages. A second major post-storm transmission restoration was completed last week.

Those two damaged 500-kV segments represent enormous construction projects, and for weeks massive resources are being focused on getting them back in service. About 320 or transmission linemen, engineers, safety specialists and others have been spending long days slogging through snake-infested flooded fields and steep terrain to get to where the trouble is. Mud boots, airboats, bucket trucks and helicopters move workers and equipment to where they need to be to get the power flowing again as quickly and safely as possible. Both troubled transmission lines are very important to the Arkansas transmission grid and, in turn, to the system grid.

On the line between the Mabelvale and the Mayflower substations, which was hit by a tornado the afternoon of April 25, eight steel lattice towers were either damaged or on the ground. Four are on the high side of the Arkansas River levee, four on the river side. “It’s been a challenge,” said Allen East, manager of the Entergy Arkansas transmission/substation grid. “The work involves first deconstructing and removing the ruins of the old towers, then building new towers on dry land off-site and flying them into place with helicopters.”

On the river side of the levee, floods covered the foundations with 3-5 ft of water. The solution was to build a culvert around them, pump out the water, then mount the tower. About 130 workers were assigned to the job. That line returned to service earlier this month.

On the line between Keo and West Memphis, damage is considerably more extensive. In storms that hit the morning of April 15, 51 steel lattice structures were knocked to the ground. To expedite the restoration, engineers determined the best course of action would be to replace the towers with steel H-frame structures. The vendor for these poles, Valmont Industries, Inc., based out of Birmingham, Alabama, is working double shifts to meet the tall order. Meanwhile, almost 200 workers are in the field rebuilding the line section damaged during the storm. The first step is to drive foundations – 48-in-diameter steel caissons – at least 20 ft, but preferably 30 ft, into the ground. Using a pile driver (basically, a giant vibratory hammer) to drive the caissons, this takes anywhere from one to six hours to drive to the required depth, depending on the soil. The structures are transported to their location along the right-of-way with a helicopter.

Then it’s a matter of bolting the uprights to the foundations, adding the cross arms and all the hardware for hanging wires, then, finally stringing up three heavy 500-kV aluminum conductors across 11 mi of rice, corn and soy bean fields and fish ponds.

Large-scale power restoration work has been likened to a military operation and all the logistics that go with it. Workers typically put in 14-16 hours a day when doing storm restoration, and when they’re off they need to rest up and refuel their bodies. The approximately 150 contractors in from out of town sleep at any of several local hotels.
Some park their trucks at the work site and carpool in pickups to the staging site, then to their hotels. Some drive their bucket trucks everywhere they need to go. Food is more complicated. “It got to the point that commercial restaurants couldn’t handle the load,” said Jay Hartman, who’s regular job is manager of customer operations support for Entergy Arkansas, but during storms he’s the go-to guy for logistics management. “It would take two hours to get breakfast sometimes.” When time is money, that wouldn’t do.

So Hartman set up a staging site at the former Walmart location on Bowman Road in west Little Rock, including a temporary catered restaurant/tent that could feed 150 people a hearty breakfast on-site and send the men into the field with a box lunch. In the evening they ate dinner at the staging area. This staging area was shut down with the completion of the Mabelvale-to-Mayflower reconstruction project.

“It’s been a tough spring, but we have the expertise and the resources to get the job done,” said East. “Most importantly, we have a can-do attitude to tackle the task and get it done safely. We have an amazing and dedicated group of people here in the transmission group, and they’re really earning their keep right now. Kudos to the many contractors working on this project, too. We couldn’t do these huge projects without them.”

Entergy Arkansas provides electricity to 697,000 customers in 63 counties. Entergy Corporation is an integrated energy company engaged primarily in electric power production and retail distribution operations. Entergy owns and operates power plants with approximately 30,000 MW of electric generating capacity, and it is the second-largest nuclear generator in the United States. Entergy delivers electricity to 2.7 million utility customers in Arkansas, Louisiana, Mississippi and Texas. Entergy has annual revenues of more than $11 billion and approximately 15,000 employees.

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