The lights are back on, but storm restoration work in Arkansas is far from over. Between April 4 and May 10, 59 Entergy Arkansas Inc. transmission line segments were knocked out, 26 of which required significant reconstruction to put back in service. As of mid-May, all but one were back on.
Two damaged 500-kV segments represent enormous construction projects, and for weeks, massive resources were focused on getting them back in service. About 320 transmission linemen, engineers, safety specialists and others have been spending long days slogging through snake-infested flooded fields and steep terrain to get to the trouble areas. 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 — four on the high side of the Arkansas River levee, four on the river side — were either damaged or on the ground.
“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 ft to 5 ft (1 m to 1.5 m) 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 in early May.
On the line between Keo and West Memphis, damage is more extensive. In storms that hit the morning of April 15, 51 steel lattice structures were knocked to the ground. Engineers determined the best course of action would be to replace the towers with steel H-frame structures.
Meanwhile, almost 200 workers are in the field rebuilding the line section damaged during the storm. The first step is to drive foundations — 48-inch (122-cm)-diameter steel caissons — at least 20 ft (6 m), but preferably 30 ft (9 m), into the ground. Using a pile driver 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 crossarms and all the hardware for hanging wires, then finally stringing up three heavy 500-kV aluminum conductors across 11 miles (18 miles) 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 to 16 hours a day during 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 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, whose 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 Wal-Mart 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 them into the field with a box lunch. In the evening they ate dinner at the staging area.
“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.”