A “highly unusual” combination of weather conditions forced Canadian Hydro Developers (CHD) to shut down all 45 wind turbines in the Melancthon I plant at a time when many residents of Dufferin County were experiencing a blackout, and they remained out of service Wednesday.

“The severe weather experienced on Friday (Dec. 1) caused heavy ice buildup on the blades at the Melancthon wind plant,” said Project Manager Geoff Carnegie.

“Operation of the turbines in these conditions will cause excessive stress on the turbines and it is a good industry practice not to operate the machines under these conditions. As a result, the turbines have been parked until the weather conditions improve. The forecast looks favourable to have the machines back in operation within the next few days,” he said.

And, in Calgary, CHD’s CEO, John Keating described the Friday evening combination of weather conditions as “highly unusual - high wind, low temperatures but not low enough for snow.”

In a phone interview, Mr. Keating said that when icing starts in such conditions “we shut the wind plant down.” He noted that none of the CHD poles were down, so the transmission lines to the substation remain alive. “The power line is shut off (only) at the substation.”

On Wednesday, Mr. Keating said he believed the ice on the blades had begun to thaw. As soon as it all thawed, “the plant will be up and running.”

GE Energy manufactures the turbines used by CHD. At GE’s Georgia office, public relations director Dennis Murphy said in a phone interview that “icing is an issue across the entire wind industry,” not just in southern Ontario.

“There are clear icing guidelines.” Mr. Murphy echoed Mr. Carnegie’s statement to the effect that the weight of the ice would cause too much stress on the machines. He added that to include a de-icing mechanism would be to also add weight,” leaving the turbines less efficient.

Mr. Murphy compared the turbines to commercial airplanes. “There are certain conditions under which the airlines don’t fly (because of icing conditions).”

The CHD procedure follows the industry guidelines on icing.

In the meantime, the company has been given the go-ahead to erect a noise barrier around the transformer at Amaranth 10th Line and 15 Sideroad.

In a letter to the township planner, lawyer Jeffrey Wilker of Thomson, Rogers said in effect that he had arranged for the construction to proceed subject to a future filing of certain documents. (A site-plan amendment had been executed.)

The site plan agreement had a “built-in alternative process that allows Canadian Hydro to commence construction in advance of fulfilling certain details, e.g. posting the letter of credit, and providing solicitor’s certificate of title etc., while requiring us (CHD) to comply with those details within a specified time line.

“As such, (CHD) will be able to take advantage of the current favourable weather forecast, which should assist in having the noise barrier wall constructed.”

Within the site plan agreement, CHD has to consult with the township’s officials and consultants and with

“the affected residents owning properties identified as receptors in the design and preparation of the monitoring program.”