Study: Turbine noise within acceptable limit 

HURON COUNTY – Sound levels measured at the county’s biggest wind park meet county limits for wind energy facilities, according to a report given by an environmental and consulting company.

Ryan Pumford, project manager at the Florida-headquartered NextEra Energy, said microphones were placed at 15 testing locations at Pheasant Run and Brookfield Wind, including one stationed on the property of a non-participating resident, with permission.

“Somebody who wrote a letter to this commission months back complaining about the sound, so we wanted to make sure we were definitely in compliance at his property,” Pumford said.

NextEra owns half of the 88 turbines between the two parks. Earlier this year, DTE Energy purchased the other half, previously owned by NextEra, and renamed its new portion Brookfield Wind. The 150-megawatt parks span sections of Brookfield, Winsor, Sebewaing and Grant townships. It was completed in mid-February.

After announcing the project’s completion, Pumford said the company would start on post-construction sound compliance testing by the end of February, to be presented in March. County planners received the report last Wednesday.

The study, commissioned by NextEra and conducted by the Massachusetts-based Epsilon Associates Inc. from March 4 to April 2, sought to examine sound produced by wind turbines.

Methodology made use of microphones fixed to tripods placed about five feet above ground. Sensors measured wind direction and speed, recording continuous, unattended measurements, and ambient sound levels, said Richard Lampeter, senior consultant at Epsilon Associates.

Ultimately, it was determined that sound levels were measured as required by county ordinance, and all 15 locations met the limit, Lampeter said.

County ordinance stipulates that sound from wind energy facilities “shall not exceed 50 dBA or the ambient sound pressure level plus five dBA, whichever is greater, for more than 10 percent of any hour, measured at any residence.”

Sound levels produced by a quiet suburb are generally the benchmark decibel level for 50 dBA. A large electrical transformer from 100 feet may produce similar levels. Sounds above 85 dBA for extended periods can cause permanent hearing loss, according to the American Academy of Audiology.

Noise from turbines has been a prime focus of the county’s Wind Energy Zoning Committee, a subcommittee of the planning commission. Members recently interviewed acoustics firms based in Grand Rapids and Lansing to help with amending the county wind ordinance.

Residents also have zeroed in on turbine noise. At the subcommittee’s first meeting, eight residents – two of which live near Pheasant Run and Brookfield Wind parks – voiced complaints to the board and representatives from utilities in attendance.

Brookfield Township Clerk Mike Lorencz said he hears noise from turbines across the road from his Sebewaing Road home, and that he’s “getting the same turbine noise that somebody would get that is in a (wind energy) overlay district.”

Charles Bumhoffer, a Sebewaing Township resident, said he hears noise from two turbines located within a half-mile of his house.