Thursday, June 24, 2010

Work begins on Fenner windmills

FENNER -- As early as next month, some wind turbines at the Fenner Wind Farm may be ready to harness wind power again.

The 20-turbine wind farm has been shut down for nearly six months, since the Dec. 27 fall of turbine 18. While Enel North America, the company that owns the wind farm, and a team of engineers investigate the cause of the collapse, the remaining turbines have been assumed to in danger of similar failures.

No substantial answers have been formed to explain the unprecedented fall. The company has ruled out malfunctions in the turbine’s foundation, saying it was built to specifications. Geography and historic load are still in question.

The company —which owns six other wind farms with more than 240 turbines — has begun taking measures to reinforce the foundations of each turbine, erring on the side of caution. Mortenson Construction, a company out of Minneapolis, was hired to perform the initial installation of the turbines’ foundation when the wind farm was constructed 10 years ago and will again be contracted to stabilize all 19 foundations.

Mortenson will employ local subcontractors, Enel Spokesman Hank Sennott said, and as many as 50 workers will be on site completing the work. The existing foundations will be excavated to allow contractors room to install 471 dowels, four to six tons of steel reinforcement and 10 truckloads of concrete to each turbine. The additional concrete will reach the same height as the existing base and will add four feet around.

“For all practical purposes they won’t look any different than they did before,” Sennott said, adding that the underlying structure of the foundation will again be covered in earth once construction is complete.

The process of reinforcing one turbine’s foundation takes about three weeks, Operations Supervisor David Haarman said. Once the foundation is reinforced, the turbine will be powered back up and tested to make sure the machine is still functioning properly after being off so long and after undergoing construction.

Pour weather conditions, like rain and high winds, will stall the project though. Regulations require work be halted if lightening is present within 30 miles of the site. Wind speeds in excess of 18 mph can also stop work, Haarman said.

The turbines will most likely be started and stopped several times before turned on full-time, he said. Every turbine will be turned on by fall Sennott expects.

The orange fencing currently cordoning off 325 feet around the turbine - the height of the structure - will be removed once the wind farm is running again. The company has pledged to compensate property owners for any revenue lost from inaccessible crops.

Enel has also documented the condition of the roads they will use and, according to Sennott and Haarman, will repair the damages they cause, including access roads leased from property owners. Dust control measures have also been put in place in an attempt to minimize the amount of dust stirred up by construction vehicles.

The most intrusive noise turbine neighbors can expect will be from construction vehicles and sandblasting at turbine sites, Haarman said. Compared to the noise levels that accompanied the installation of the park, noise will be minimal, he said. All work will be done during the day, he said and even generators running at each turbine to power essential functions - like safety lights and direction - are impressively quiet, he said.

Clean-up at the site of the fallen turbine was finished at the end of May, Haarman said. Gravel has been put down at the site to allow for additional parking for the influx of workers to the wind farm.

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