Each winter, osprey fly thousands of miles to South America, only to return each spring to the same exact spot. For example, the protected birds built their nests on wood platforms on Dominion Energy’s decommissioned transmission line in the Outer Banks.
Back in 1986, Dominion Energy built a new transmission line across the Currituck Sound, leaving the old structures in place and installing platforms, hoping the osprey would not relocate to the new structures and cause outages. The plan worked, but over time, nine of the dozen platforms deteriorated and crumbled down into the water below. The original platforms, which were wood frames with chain-link fencing to support the nest, needed to be larger, more durable and easy to install and remove.
Dominion Energy then searched for a new type of platform that could withstand wear and tear from salt air and water corrosion. By turning to Preformed Line Products (PLP), the utility discovered a new aluminum platform with stainless-steel hardware that served as the perfect fit.
Bald eagles and osprey often try to build nests within Dominion Energy’s transmission system. As a result, these birds put themselves at risk of electrocution by making contact with an energized conductor while trying to build a nest. Also, if they drop large limbs, this material can fall onto the energized equipment, causing the line to operate or lock out. Finally, the nesting material may ignite or catch on fire with contact from the energized lines.
For many years, Dominion Energy has purchased wildlife protection products, and over the last three years, the company has focused on installing bird deterrents on its transmission line. These deterrents wrap around the arm and have rods that are about 18 inches high. The linemen have installed these deterrents above the conductor or insulator strings on many various structure types, and they have proven to be successful.
Up to this point, however, it had been challenging to find a proper platform to accommodate the nests of these large birds of prey. Oftentimes, the birds would roost on the structures overnight, and then when they take off in the morning to look for food, they excrete debris all over the line, which creates a conductive path bridging the gap between the structure and conductor.
Designing a New Platform
When PLP was looking to design a bird platform, they invited Dominion Energy linemen, supervisors, managers, reliability team members, and biologists to attend a hands-on demonstration of its new product — the Raptor Protector Platform.
After learning how to install the platform, they all provided feedback on the product. For example, the biologists liked the fact that the platform featured pegs, which held the nest in place. Also, the device offered a perch for the platform, but up to this point, Dominion Energy has only installed the platform on the side of pole with the birds using the top of pole to perch.
Next, the company installed a trial platform in Clarksville, Virginia in February, right before the osprey were set to return in March. Up to that point, the osprey built their nest between two energized conductors on a switching structure — presenting a danger to the birds and a possible outage to Dominion Energy — so the company installed the platform on another structure about 20 ft away. The company also mounted a webcam on the pole so the Dominion Energy team could observe whether or not the birds would land on the new platform, rather than the energized switch. Fortunately, the osprey selected the platform as their new home, even after five years in their previous, more dangerous location.
Over the last five years, Dominion Energy has experienced multiple line operations and one lockout from the osprey nest. Since the new platform has been installed, however, the company has not experienced any operations or lockout on the line due to the osprey nest, which sold the company on the efficacy of the product.
In addition to the platform at Kerr Lake, Dominion Energy also installed a platform on a new pole outside a small substation. As such, the osprey, which was nesting on a backbone structure, relocated to this new pole.
The final two platforms were installed in the middle top section of a steel lattice structure near a local reservoir. For the past four years, osprey have nested on the arm of a lattice tower, right above the energized conductor. In this particular location, the right-of-way is very crowded with four transmission lines plus other utilities. Without any room to set a pole off to the side, Dominion Energy tried a different experiment by installing a platform in the middle of the lattice structure up high. Instead of dropping sticks at the end of the arm above the conductor, the birds have moved to the middle of the structure. That way, the nesting materials will fall straight down and will not make contact with the wires.
Dominion Energy installed the platforms late last fall, and birds have already started to build nests on the platforms this spring.
Performing Installation by Helicopter
Dominion Energy then installed 12 platforms on structures, which spanned 2 miles across Currituck Sound in North Carolina. Dominion Energy contracted with Air2 to remove the old wood platforms and install the new Raptor Protector Platforms from PLP on adjacent concrete poles.
As part of this process, the Air2 linemen were suspended below a helicopter by a 75-ft tether and dropped off on the concrete structure. They would remove the old platform and connect it to the helicopter’s rope. The helicopter would then drop off the old platform, pick up the new one and deliver it to the linemen. After the new one was installed, the linemen would be moved to the next structure.
The helicopter provided a safe and quick way for the linemen to remove the old platforms and install new ones. While Air2 scheduled four days for the installation, the linemen and the helicopter pilot were able to finish the task in just a day and a half. Because the platforms were lightweight and easy to install, the job took less time than anticipated.
Today, the osprey can safely build their nests on these 12 new aluminum platforms, therefore protecting both the reliability of the transmission system and the future of the avian species. ♦
Carter Clevinger is a project manager II in Dominion Energy's electric transmission reliability group. He has been with the company for almost 32 years and has extensive experience in both distribution and transmission