BAD AXE – A report about noise levels at Apple Blossom Wind Farm in Winsor and McKinley Townships found that all wind turbines were in compliance.
Andrew Johnson, the wind facility manager for Apple Blossom, was present to lead a presentation about the findings.
Johnson brought in Ben Copenhaver, an acoustics sound engineer from Minneapolis-based HDR Engineering who oversaw the noise testing, to explain the findings.
The testing was conducted on four different turbine sites, labeled M1, M2, M4, and M5, located across the wind farm, as Apple Blossom predicted it would get the most noise from turbines in those areas.
The noise monitoring was during the spring of 2019, along with recording ambient sound pressure from May 30 to June 12.
The testing excluded times when wind turbines were at less than 70% operating capacity and any extraneous events such as high wind speeds or precipitation.
If the raw sound captured was found to be above the ordinance limit of 50 decibels, work was done to eliminate any wind noise that was above five meters per second and other sources like birds chirping, cars, farm equipment, and flagpole rattling.
Section M1 had nine valid measuring hours, of which six were within compliance and three were found to be compliant after further review.
Section M2 had 17 measurement hours, of which nine were within compliance, three were compliant after review, and five were excluded due to flagpole rattling and farm equipment.
Section M4 had 13 measurement hours, of which three were in compliance, eight were in compliance after review, and two were excluded due to birds and farm equipment.
Section M5 had 15 measurement hours, of which 11 were in compliance, three were compliant after review, and one was excluded.
The results showed that the turbine noise levels did not exceed 50 dBA or the ambient sound pressure level plus 5 dBA for more than 10% of any hour, as required by the county’s 2010 wind power ordinance.
Planning commission Chairman Robert McLean said the planners expected to see turbine operation data as part of the report.
Planner Bob Tenbusch was adamant about some turbines in M1 and M2 being above the 50-dBA limit.
The planners voted to accept the report by a 6-1 vote, with McLean being the only dissenting vote.
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