“This is really a special project for us,” said Kevin Long, director of crawler cranes/sales for Buckner Heavylift. “We’ve been working in the wind market for 15 years, and it is extra special to work with one of our best clients in our home state of North Carolina.”
Buckner is working for long-time wind contractor client Wanzek Construction and Iberdrola Renewables, which will operate the wind farm.
Located on 22,000 acres, ground was broken in July 2015, and the farm is set to be operational by the end of 2016. According to press reports, the wind farm will consist of 2.0 MW Gamesa G114 model turbines with a 374-foot rotor diameter and 182 feet blade length. The towers are 305 feet tall, and with the blade point straight up they will reach a height of 492 feet. The first phase calls for 104 turbines that will produce 208 megawatts (MW) of power. If built out, the wind farm could have a capacity of 150 wind turbines for 300 MW of full power.
The centerpiece cranes on the job are Buckner’s three 850-ton capacity Liebherr LR 1750s. The three cranes are rigged with 207 feet of main boom and a 161-foot luffing jib. They have 209,000 pounds of carbody counterweight and 540,000 pounds of superstructure counterweight.
“One of the benefits of these cranes is that we have the capacity and boom combination required without a derrick mast,” said Long. “No heavy lift attachment is required, which would add time and logistics.”
The wind farm is being built on wetlands that are close to the coast, Long explained. Logically, wind and weather are always a challenge because wind farms are built in windy areas.
“But the soil here is extremely soft so putting a big crane out there is very challenging because of the ground-bearing pressure and the weight of the crane.”
Wanzek Construction performed copious soil studies and determined that the cranes would need to be set up on two layers of oak crane mat.
“Stabilization is more of an issue [at this jobsite] than any other site we’ve worked at,” said Long.
Typically the cranes would crawl between turbine pads but that’s not the case with this project. Due to the ground conditions, the cranes must be disassembled and moved from pad to pad.
“Every project has its own set of terrain challenges,” said Neil Ducharme, business development manager for Wanzek Construction. “This site required that we build on wetlands. To safely and effectively perform our tasks, we had to strip the cranes down and haul them from turbine to turbine with Wanzek-owned hydraulic platforms trailers.”
Moving the LR 1750 requires 35 truckloads and the turbine pads are anywhere from one-half mile to two miles apart. So that means 104 turbines erected and 104 partial or complete disassembly and reassembly of the three LR 1750s. “We’ve never had a job where the cranes have to be taken apart and put back together this many times,” Long said. “Typically you have to do it five to 10 times at the most, not 104. The logistics involved in getting around the ground conditions overall are quite challenging.”
But Wanzek had planned for this all ahead of time and the process is seamless.
The base and the midsection of the towers are already erected when Buckner’s LR 1750s get to the turbine pad. The three LR 1750s erect the upper tower section, the nacelle and rotors.
The blades are assembled to the hub on the ground and then lifted and secured to the nacelle in one piece, Long said.
At the jobsite Buckner has 12 additional cranes on rent to Wanzek, all of which are telescopic crawlers. There are three 240-ton Liebherr LTR1220s, six 120-ton Liebherr LTR1100s and three 100-ton Tadano Mantis 20010s.
“The job of the telescopic crawlers is to assemble and reassemble the LR1750s,” said Long. “They are using the telecrawlers to pitch and catch the main erection cranes. A set of cranes will disassemble one of the LR 1750s while another set is on the next pad receiving and assembling it.”
The telescopic crawlers also have been used to off-load turbine components and handle other lifting duties at the wind farm.
Long said these Gamesa turbines are fairly large, but typical for most wind farms in the United States.
“Iberdrola and Wanzek Construction are both long-time leaders of this industry,” said Long. “They have shown remarkable leadership through adversities caused by the extreme site conditions.”