LOWVILLE — Trees are being cleared in the town of Harrisburg to make way for the next wind farm in Lewis County, Invenergy’s Number Three Wind, LLC.
Clearing began Thursday after approval came for “provisional construction” to commence from the state Department of Public Service on Wednesday.
“You are hereby authorized to begin tree clearing activities,” the approval letter said. “However ... clearing must be completed by hand in wetlands and other waters of the U.S. until the Water Quality Certification is issued.”
The company applied to the U.S. Army Corps of Engineers for a federal wetlands permit and to the state Board on Electric Generation and Siting and the Environment for a water quality certification for the project on Feb. 1.
In a meeting held Wednesday morning, the siting board unanimously approved the Chicago-based company’s Dec. 21 petition to amend its environmental compatibility certificate to reflect the replacement of the 26 General Electric turbines in the original project plan with 24 Vestas V150 turbines.
The blade tip height of the Vestas turbines at 591 feet is five feet higher than the 586 feet height approved with the GE turbines. So, Louis Alexander, alternate for state Department of Environmental Conservation Commissioner Basil Seggos, requested confirmation from the Department of Public Safety staff, which is charged with investigating the verifying information provided by energy companies in the Article 10 approval process, that there would be no increase in visual impact or “contrast to existing conditions.”
He also inquired if the fact that the blade span of the new turbines will be 47 feet longer than those originally planned would have any new impact.
According to a study commissioned by Invenergy and performed by Saratoga Associates, there will be a 0.1% increase in visual impact from both inside and out of the project area primarily because the additional height is marginal despite the new turbines having much larger blades.
Andy Davis, chief of the environmental certification and compliance section of the DPS staff, explained “longer blades will let hub heights be reduced” and because FAA warning lights are “generally those hubs, mounted on top of the cell which is essentially the hub height.”
With the hub heights reduced by about 16 feet, Mr. Davis said there “should be a net decrease in visibility of FAA lighting,” although the longer blades are anticipated to increase “the visual effect of the flickering blades as they pass before sunlight.”
Because the original Certificate of Environmental Compatibility and Public Need issued through the Article 10 process in November 2019 limits the annual shadow flicker to 30 hours per year at any non-participating residence regardless of blade length, the increase of flicker found likely through an analysis done by the company would automatically be mitigated, Mr. Davis said.
He also confirmed that the FAA will have to approve the turbine changes before any construction can begin on the project according to conditions placed on the Certificate.
Number Three Wind Project Manager Marguerite Wells said getting FAA approval on any change of turbine height is required, but there are height thresholds that determine how complicated the process will be and how long it will take.
“Any increase in height requires re-approval by (the) FAA, but any time that 500-foot threshold is crossed, the process for approval is double what it is for any structure under 500 feet,” Ms. Wells said. “And the number of structures now falling into that bucket has increased by orders of magnitude.”
Invenergy stated the General Electric turbines approved in the environmental certificate are “no longer commercially available,” requiring the change to the taller Vespa turbines.
The wind company is allowed to “phase the construction activities” relating to site preparation according to the letter allowing tree clearing to commence.
All documents for the Number Three Wind Farm filed in relation to the Article 10 process can be found on the DPS Matter Master website searching for file number 16-F-0328.