Claims of discrepancies within turbine noise study; Results from noise study on Prairie Breeze released

Difference of opinion and varied interpretation of county regulations consumed the discussion following the report from Hankard Environmental on the Prairie Breeze wind farm noise study, on Tuesday, July 12. 

Michael Hankard, president of Hankard Environmental, Inc., an independent professional acoustics company, distributed reports from the five week noise study to the Antelope County Board of Supervisors.

According to Hankard’s analysis of four residences, the noise level at the Berg, Borer, Hecht and Wilcox residences maximum decibels ranged from 30 to 49, throughout the study, which is in accordance with county zoning regulations. Current county ordinance limits consist of a guideline of up to 50 decibels.

Hankard said they use the highest standard of equipment “to collect quality data that won’t be compromised by rain and wind” and the length of the study allowed for a wide variety of decibel activity and weather conditions.

Hankard stated that national standards are used to measure across the frequency spectrum and separate the different elements. 

“Different sources of noise like wind turbines and crickets and cars put out a different frequency signal so we can review the data and say, ‘Oh, that’s wind turbines or that’s not wind turbines,’” he said. 

“The loudest conditions occur when the turbines are working at or near their capacity.”

Hankard said his mindset throughout the study was to find and report the highest decibel levels. “I understand that my work can be peer reviewed, it’s going to be scrutinized,” Hankard said. “I don’t want to come out of that having reported some average or low number.”

Hankard said he discussed microphone placement with each resident, prior to beginning the study. 

“In terms of placing the microphone at the residence, the standard requires us to stay away from buildings and what not by 25 feet, which we did,” said Hankard.

There was one caveat.

Hankard notified the board that landowner Gary Borer requested a microphone to be placed at the intersect of his home and garage because Borer thought the noise level was loudest at that point.

Hankard accommodated and placed two microphones at Borer’s residence: one at the requested position and the other to meet industry standards 25 feet from the home. 

Although the microphone closest to the home had a higher decibel level, both microphones had noise levels lower than county guidelines. Hankard reported ricochet from the building and paved driveway as a contributing factor to the increased noise level closer to the home.

Supervisor Greg Koinzan asked Hankard about his experience with noise level compliance. 

Hankard noted that Hankard Environmental, Inc. has completed many similar studies in Iowa, Illinois, Michigan, New York and Oregon. 

Koinzan asked if any Hankard Environmental have been confuted. 

Hankard replied, “We’ve had peer reviews and we have found conditions of non-compliance.”

Hankard said that although he is working as a consultant for Invenergy, LLC., he is an independent contractor and his reputation is built on the integrity of his studies.

Supervisor Chairman Jerry Schwager opened the floor to audience members for questions or comments. 

Landowner Judy Wilcox questioned if the noise from the generator was determined or if noise produced by both the generator and blade rotation was reported.

Hankard said, “We are measuring the noise from everything.” 

He said the blade is the primary source of noise when the turbines are in operation. 

Wilcox then questioned the placement of the residences’ microphones, which were placed 25 feet from the homes, stating they should have been placed at the edge of the house per county regulation. 

“You, yourself said, ‘It’s noisier by the house,” said Wilcox.

Hankard said if the microphone is placed directly at the edge of the house and there are multiple turbines in the area, the sound may be louder from one, but shield another and not give an adequate representation of sound. Hankard said that is how they determine placement of the microphones.

Supervisor Charlie Henery asked if the noise level would change when the microphone is placed at the house.

“The turbine that you would be looking at...that turbine would be louder now because I’m going to get the initial sound wave and then it’s going to bounce off the house and I’m going to get another sound wave. But, all of the other turbines, if I can’t see them and they’re blocked, they’re going to be less. So the overall total could go a little higher, it could go a little lower,” said Hankard.

Wilcox also asked why days/times with higher winds were thrown out of the study. Anything over 11 miles per hour wind was omitted.

Hankard said wind turbine noise cannot be measured when the ground winds exceed 11 miles per hour because it creates a sound level over the microphone that is not real. Hankard compared it to blowing over a coca-cola bottle.

Hankard also noted that wind and the noise generated by wind turbines are too close to differentiate on the spectrum of sounds. 

Antelope County Zoning Administrator Liz Doerr asked what would be reported in the peer review, if one was conducted.

Hankard said the consultant would be provided all of the raw data; they would then review the process, analysis and conclusion completed in the initial noise study. 

Judy Wilcox questioned if the board was planning to accept the study that was not completed “at the house”, which is a stipulation of the zoning regulations.

No action was taken on the current noise study. 

Henery made a motion to hire Rand Acoustics to complete a peer review on the Hankard Environmental noise study. The motion carried unanimously. 

In other matters:

• The supervisors accepted the conditional permit application from BlackStrap Enterprises for commercial use of a hoop building, according to the planning commission recommendations. 

• Road Boss Casey Dittrich provided the supervisors with a labeled map of roads for consideration of repairs. Henery suggested driving out on their township roads with Dittrich to determine priority and candidacy. 

The supervisors did not take action on selecting which roads will convert from asphalt to gravel.

• Schwager said roads will be armor coated the second week in August. 

• Jessie Reeseman addressed the board, on behalf of the Elgin Chamber of Commerce requesting a liquor license for the chamber’s annual steak fry. The steak fry will be held on August 13 from 5 p.m. to 1 a.m. 

The supervisors approved the request for a special liquor license.


JUL 15 2016
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