Adams County learns more about flicker

CORNING — Adams County Board of Supervisors may decide today on scheduling a public hearing for revisions to its wind turbine ordinance as it has been regularly discussed for the past several weeks. Possible dates for he hearing are Aug. 26, Sept. 3 or 9.

In addition to the public hearing, supervisors approved 3-1 Aug. 5 to review its stance on shadow flicker after hearing from a person from a engineering firm who researches shadow flicker. Supervisor Scott Akin was absent.

Shadow flicker is when a wind turbine tower and blades cast shadows when in line with the sun. Those shadows may be cast on residences or other inhabitable properties.

Via telephone, Joann Blank from Stantec in Wisconsin told the supervisors she has more than 20 years experience with the work. She said her work is based on requests from wind energy-related companies to determine impact of the flicker on the surrounding area.

“Developers call upon us to do impact assessment to minimalize flicker,” she said. The common work is to determine the impact on a home with residents. A majority of her work has been in Midwest states with wind turbines.

She said software uses the location of the sun throughout the year, wind direction tendencies, days without clouds and the proposed locations of turbines and established properties, like houses. She noted how cloudy days happen more in winter months.

“A (wind) farm with 25 turbines, the model looks at all at the same time and how often a turbine blade (shadow) would fall on a home,” she said.

Blank said after doing hundreds of these studies, it has become common to have ordinances include 30 hours annually.

“Most ordinances allowed for wind farms to be cited, but it protects residents. That is not a large amount of shadow flicker,” she said. Blank emphasized she is not paid to inform developers, “to tell them what they want to hear.”

The board asked her how accurate are the 30 hours.

“The 30 hours is average over 20 years. You could have a situation of a little more or a year where it’s 31 or 32 a year or where it’s 28 or 29,” she said considering the days with clouds to prevent shadows. Years of her work has showed her the 30 amount is the level of annoyance.

“More complaints are more than 30,” she said. “Thirty is not a scientific number and I’ve never seen a medical impact.” Some have claimed shadow flicker causes seizures.

Blank made it specific.

“Models says shadow is to start on this home at 7:45. I’ve checked that. It might start a minute earlier or end a minute earlier. It’s locational based.”

Blank said “It’s impossible,” to move all the turbines to avoid shadow flicker.