MARS HILL – Underneath a bank of fog, construction crews on Mars Hill Mountain were busily stacking tower sections and assembling blades this week as they worked to complete what in the past two weeks has been the most visible part of the biggest wind power operation to come to New England.

Crews are installing 28 wind turbines along the mountain ridge – which stretches north to south about four miles – for wind farm developer Evergreen Wind Power LLC of Bangor. The corporation has worked for four years and is spending about $55 million to develop the Mars Hill Wind Farm, which officials say will generate at full capacity about 42 megawatts of electricity, enough to supply about 45,000 homes. Whether the electricity will be sold to customers in Maine or elsewhere is still being negotiated.

Crews have been on the mountain since March, clearing trees, building a road along the ridge that connects to the 28 tower sites, running underground electrical conduit, and preparing each of the site pads for its 262-foot-high turbine. Most of that work has gone unnoticed, except for the change in the tree line and the occasional truck that heads down Main Street hauling a huge tower section or blade bound for temporary storage sites in Presque Isle and at the base of the mountain.

But ever since Oct. 13, when crews finished installing the first wind turbine, residents from miles around have been able to view daily progress on the wind farm just by taking a glance toward the mountain. As of Tuesday morning, three wind turbines were up on the northern end of the ridge. To the south, the base sections of five more towers were heading skyward.

“Look at the beauty,” project manager Andy Perkins said as he gestured toward a completed turbine. Its three long blades at crisp 120-degree angles were just visible through the morning mist.

Perkins gave a tour Tuesday of the work under way at the wind farm site, providing a glimpse of the mountaintop development. At a tower pad site that overlooked the border with Canada, Perkins pointed out the base section of a tower that was bolted to a round concrete slab. Rock anchor bolts about 21/2 inches wide poked through the concrete in a circle around the tower base. Perkins said that for each bolt, workers drilled 45 feet into the ground, made sure they had hit bedrock, grouted the bolts into the ledge, and then made sure they could withstand about 400,000 pounds of force.

“These concrete slabs are tied right into the mountain,” Perkins said.

The strength of the pads is crucial, he explained, because of the heavy loads they will bear.

Powering his truck up the String Road – the name crews gave to the winding roadway that connects the 28 tower sites – Perkins pointed out site after site where tower sections are laid out on their sides, ready to be attached to their concrete foundations. Towers will be installed about every 750 feet along the road, from the north end near the East Ridge Road to the south end near the mountain summit.

At tower No. 18, workers were completing their ninth base section installation. Crews used a 280-ton crane to raise the section – which was 15 feet in diameter and 77 feet tall – into a vertical position. Perkins said they would slowly swing the section over to the concrete pad, bolt it down, then stack on the middle and upper tower sections, each more than 90 feet tall. Next, they put on the nascell, which houses the generator and speed increaser. Installation of the rotor, or the blades and their hub, is the final step in completing the wind turbine.

Down the road at tower No. 12, workers were preparing for that final step by “stabbing” the blades into the hub. The fiberglass hub sat in the middle of a tower site with one blade already attached, looking like a giant exclamation point. Workers used a 400-ton crane and a heavy-duty yellow sling to hoist a second 115-foot-long blade off the ground. A rope attached to a blade sock – a smaller sling that fit over the tip of the blade – allowed two workers to gingerly nudge the fiberglass part into place.

Perkins called it precision work akin to docking a space shuttle. One wrong move could ruin a bearing in the hub or one of the dozens of studs at the base of the blade.

The project manager said it takes crews about a day to build a single rotor. With the experience they gained from putting up the first three turbines, Perkins estimated crews would have No. 12 up by midafternoon.

“It’s a production line,” he said. “Once you get the first one in, you can build a little faster the next time, and a little faster the next time.”

Officials expect work to wrap up by mid-December and for commercial operations to get under way before year’s end.

For Perkins and his crew, though, it’s a one-day-at-a-time process. Their count: three down, 25 to go.

Meanwhile, down at ground level, Town Manager Ray Mersereau was eyeing the project as a windfall for this small community.

“This project has been a unique opportunity for this town,” Mersereau said. It puts Mars Hill on the map by having something not many towns have.

“I think most people in town are for it, and it has passed all the needed local boards,” he said. “The majority are certainly for it. We do have the downside of seeing the towers on top of our beautiful mountain, and I understand those concerns.”

Once the project is completed and on line, the town of Mars Hill will get $500,000 yearly in property taxes. The 20-year agreement will bring $10 million in taxes to this town of 1,400.

“That’s significant,” Mersereau said. “There are not many kinds of projects that can bring that kind of thing to a community our size.” The Annual Register of Maine places the value of the community at just over $42 million in 2004-2005.

The yearly property tax on the project will amount to about 20 percent of the property taxes collected in the community. The town’s annual budget is $1.6 million.

Then there are the jobs such a project brings.

Several full-time jobs will be created to operate the facility, and many local people and people from elsewhere in Maine are working on the construction side of the project.

“There are many economic spin-offs from a project like this,” Mersereau said.

People will come to see the project once it is completed, and that will bring something else to the community.

“Time will tell if we capitalize on that,” Mersereau said. “It would be great.”

He said the chairlift on the mountain could be operated to bring benefits to the Maine Winter Sports Center. He didn’t have any idea how the tourism could be marketed.

“It’s a substantial project, and it’s different,” he said. “It should create some interest.

“I think it will be a positive for the community as a whole,” the town manager said.

BDN writer Beurmond Banville contributed to this report.