BAD AXE – Sound levels are within legal ranges at two of the county’s newest wind energy projects, officials recently reported.
Huron County’s wind energy ordinance requires developers to conduct post-construction sound studies. Measurements were taken at DTE Energy’s Brookfield and Echo Wind parks. Both projects were completed in 2014.
DTE officials say all turbines complied with the county ordinance, and meet state and federal requirements.
Massachusetts-based Epsilon Associates Inc. conducted the testing in a process approved by Huron officials. All measurements were taken at turbines that were within 1,500 to 2,000 feet from residences, according to DTE. The goal was to take measurements during periods when sound power level was at or near maximum levels, but as DTE’s report states, the forecast did not always pan out.
The county’s 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.
In spring 2014, at Brookfield Wind Park in southwestern Huron County, Epsilon conducted testing near 15 turbines using sound level meters. DTE’s report noted that at several locations, strong winds knocked down testing equipment, which was situated on a tripod staked to the ground.
Only one of the 70 turbines in DTE’s 22,000-acre Echo Wind Park is in McKinley Township, which operates under county zoning. Most are in Oliver and Chandler townships, both self-zoned. There, measurements were taken this spring at turbines within about 1,300 to more than 2,100 feet from residences.
As officials work to overhaul the county’s wind energy ordinance, drafting a more defined turbine rulebook than a 2010 version, they’ve spent the most time ironing out sections on turbine sound and noise. If approved, developers would face stricter guidelines.
And while DTE presented a simplified version of the reports to county planners last week, another issue befuddled the county’s building and zoning director.
Jeff Smith questioned how the county could enforce a proposed lower decibel limit – 45 dBA – when an independent acoustics firm recorded 63 dBA from truck traffic that skewed results at a testing site earlier this year.
The county is playing the waiting game while Grand Rapids-based Acoustics By Design reviews the ordinance’s new sound and noise regulations.
“The team’s already working on it,” Smith said, adding that planners are at a standstill until at least Aug. 18.
Officials have until the end of October if they want to ink the new ordinance in time before the county’s moratorium on new wind projects lifts.
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