Utility replaces damaged wood poles with Duratel poles in Missouri and Illinois services territory.
Woodpeckers burrowed softball-sized holes into wood poles in Ameren's service territory. In some cases, the birds nearly hollowed out the wood poles and only a half-inch of wood held the damaged poles intact.
The birds often create large cavities in wood power poles because they enjoy the vibration, are searching for food or need a home to build a nest. In both Illinois and Missouri, woodpeckers drilled holes, which expanded vertically inside the length of Ameren's poles for up to a few feet.
Ameren field crews and its contractors discovered significant woodpecker-damaged poles in various locations within its service territory. For example, one year ago, linemen identified woodpecker-damaged poles near a golf course fairway at the Lake of the Ozarks in Osage Beach, Missouri. The wooded right-of-way adjacent to the fairway became a woodpecker haven.
An inspection team also recently spotted cavities in wood poles in a 15-mile stretch of subtransmission line that ran through a remote, hilly and rocky region in Missouri. While performing a visual inspection, the crew spotted the holes, which began at about 10 ft off the ground and ran up to the top of the poles.
Last spring, Ameren linemen replaced six wooden poles near the Tan-Tar-A golf course in Osage Beach. Rather than replace the woodpecker-damaged poles with new wood poles, the linemen instead replaced them with composite poles from Duratel.
The linemen set the new poles next to the old wood poles, which featured a 34-kV subtransmission circuit with 12-kV distribution underbuild. The field crew then transferred the conductors from the old poles to the new poles and sawed out the damaged wood poles.
A year later, Ameren faced a similar problem in another area of its service territory and turned to its contractor, Asplundh Construction Corp., and Steve Walker, general foreman, to set the new poles. Crews discovered damaged single- and double-pole structures scattered throughout a 3-mile region near Pilot Knob, Missouri. After identifying the woodpecker damage on the wood poles, Ameren sent its construction supervisors and its contracting crew to inspect the section of line. The team identified 15 poles that required immediate attention and replacement due to significant damage.
Ameren made arrangements with a local company to schedule the outages on two separate weekends. On the day of the first outage, the linemen transferred the conductors to the new poles and then re-energized the line.
During the first outage, the crews worked on about half of the poles. Once they took a structure down, they took the conductor out of the shoe, laid it on the ground and then set the new pole. It often took a day per structure to do the work, but in very remote locations, it took up to a day-and-a-half.
Reaping the Benefits
From the linemen's perspective, the pole-setting and wire-stringing process was no different with the Duratel composite poles than with wood poles. One advantage, however, that the field crews quickly noticed was that the composite poles were easier to handle because of their lighter weight and smaller diameter at the ground line.
Because wood poles are tapered, they vary in diameter from top to bottom, unlike Duratel poles, which have a uniform diameter. For example, the 70-ft Duratel poles used on the Lake of the Ozarks project had a diameter of 12 inches at the ground line, while the 70-ft wood poles measured between 18 and 20 inches in diameter.
The 70-ft composite poles also weighed about 900 pounds, compared to wood poles, which can weigh up to 4,750 pounds. Because the Duratel poles weigh one-quarter of the weight of the wood poles, the field crews could transport more poles on a trailer to the job site, reducing material delivery. The poles were also easier to handle in the remote areas.
Another advantage of the Duratel poles was the ease of installation. The composite poles are hollow inside and contain a interior pre-installed ground wire. Rather than having to staple a ground wire on to the pole after it has been set, the linemen connected the pole ground to the pre-installed ground wire after setting the Duratel pole. The pre-installed ground wire eliminated the possibility of any contact with an energized circuit during installation.
Using Specialized Equipment
Because the Duratel poles have a pre-determined diameter, it took the guesswork out of finding the correct tools to do the job. From the beginning to the end of the projects, the field crews always knew what length of bolt and what type of hardware they needed to install the composite poles. When installing wood poles, however, linemen often estimate the required bolt lengths. As a result, they must stock various sizes of bolts and other hardware on their trucks.
The linemen, however, couldn't use their traditional wood drill bits to drill into the composite poles. For that reason, Ameren turned to Aircraft Dynamics, which manufactures Robotool BlackWidow fiberglass bits. Using these bits, the linemen were able to easily drill holes into the composite poles.
Along with investing in specialized drill bits, Ameren and its contractors also had to turn to off-road equipment to access the poles in a remote part of Missouri. Even in the best of conditions when the soil is dry, linemen need a four-wheel-drive vehicle to access this part of the line, which was located in an area with oak, hickory and other hardwood trees. The team relied on special equipment such as Polaris Ranger, John Deere crawler and a Go-Tract machine to reach the remote and mountainous territory.
In especially rocky terrain, the field crews also had to use a rock auger on a Flex Track, which is a bulldozer with rubberized wheels. Due to the smaller diameter of the composite poles, the linemen were able to use a smaller auger to dig the hole for the pole.
Now that Ameren has installed the Duratel poles in different locations within its service territory, the utility expects to minimize outages and prevent untimely pole replacements in the future.
The poles have such a slick surface that the woodpeckers can no longer land on and hold on to the poles and create cavities. In addition, it's difficult, if not impossible, for squirrels and other varmints to climb the poles.
Another benefit is that the composite poles are said to outlast a wood structure or a wood pole. In fact, these poles could last about twice as long as a conventional wood pole without decay at the ground line. While the composite poles are slightly more expensive than conventional wood poles, the overall pole actually costs less when you take into account the transportation, installation, replacement and maintenance.
The composite poles are a new technology being used by Ameren, and so far, the utility has received a positive response from the linemen. For example, at the Lake of the Ozarks site, the linemen return to inspect the composite poles from time to time. So far, the poles are in the same shape as when the linemen set them more than a year ago.
By replacing the wood poles with Duratel poles, Ameren is able to prevent premature deterioration due to woodpecker damage. By replacing the damaged wood poles with Duratel composite poles, the linemen are improving the reliability of the system and keeping woodpeckers away from the poles and in the nearby trees where they belong.
Cary Gill (firstname.lastname@example.org) is a construction supervisor for Ameren Missouri. He has been with Ameren for 28 years and has worked in the power industry for 33 years. Prior to joining Ameren, he served as a lineman for several contractors.
Dan Graue (email@example.com) is a construction supervisor for Ameren in the Lakeside district at the Lake of the Ozarks. He has been with Ameren for 23 years, and prior to working as a supervisor, he served as a lineman.
Matt Jolani (MJolani@ameren.com) is a standards engineer for Ameren in St. Louis, Missouri.
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Aircraft Dynamics www.aircraftdynamics.com
Asplundh Construction Corp. www.utiliconltd.com
John Deere www.deere.com