For the past couple of years the Lake Winds Energy Park in Mason County, Michigan has been embroiled in a contentious dispute about its noise levels (image to left is the “Park” under construction).  In April 2013, five months after the 56 turbines began operating, 17 neighbors filed suit, claiming that wind farm noise, vibrations and flickering lights were adversely affecting their health. After commissioning an independent sound study, the Mason County Planning Commission formally declared the wind farm out of compliance and demanded a mitigation plan; the developer, Consumers Energy, disputed the findings yet lost two appeals, one at the Zoning Board of Appeals and one in Circuit Court. During that series of challenges, Consumers developed a plan to modify turbine operations for 7 turbines closest to the four sites where they were found to be marginally too loud.

Marginal is indeed the word: the sound study found 4 locations where the sound level peaked at 0.3 to 1.2 decibels over the 45dBA noise limit (it takes 3dB for a difference between two sounds to be audible); when using 10-minute averages, there were no violations.  The various explanations by the consultant, Brian Howe, illustrated the fine line that the turbine operations were walking.  His report stressed “general compliance with sound level criteria,” and noted that the brief violations “do not represent a statistically significant portion of time and do not indicate a systemic exceedance.” In his initial testimony at an August Planning Commission meeting, he said that there are no recommendations to correct for these times because “there is not a situation where they are predictably going over 45.”  Later, in a November letter to the Commission, after learning that the county had previously decided NOT to allow for occasional exceedances, he stressed that “I can assure the County that competent, material and substantive evidence supports the conclusion that the turbines are not in compliance at certain residences on occasion” and elaborated:

And this the first half of the central lesson here: it’s essential that enough of a safety factor is built in to the sound models to account for known variability in sound production (how loud the blades are in various unsteady wind conditions) and sound propagation (how far sound travels as it gradually loses power).  Regular readers will know that variability is indeed, as Howe mentioned, often more than the simplified 3dB margin of error that was neglected here (see AEI’s 2012 report). The second half the lesson is related: when noise limits—for the sound of the turbines when it reaches nearby homes—are set as high as 45dBA, they will be regularly audible at these homes, and likely well above night-time ambient sound levels.  As many acousticians have stressed for years, these situations are very apt to trigger a significant number of complaints, especially if there are dozens of homes in that nearby range.  Here, we had the worst of both worlds: turbine siting plans that pushed sound right at the limit into nearby homes, and a limit that was on the high end of tolerability for many neighbors.  Indeed, after one such cautionary report was presented to the Mason County Planning Board, it decided to lower the limit to 40dB, but that change was revoked after push-back from Consumers Energy.

With this backdrop, this week the 17 original plaintiffs in the noise nuisance lawsuit agreed to a settlement offer from Consumers;
the financial and possible operational details are confidential (2 later additional litigants are yet to settle, but negotiations are ongoing).  While many such lawsuits languish, as it can be very hard to prove causality of health effects or to prove nuisance, it is always notable when a company decides it’s more advantageous to settle than to push through a court hearing (which was set to begin, with the jury already seated).  This is the latest of several such suits that were settled behind closed doors—other high profile compensation cases include Mars Hill, Maine and the Davis family in the UK, while property buy-outs of people who’ve either moved from their homes or become vocal about their issues are widespread, if not common, including a recent buy-out settlement with a family in Vermont, and purchases of multiple homes in Ontario’s Bruce and DufferinCounties.  It’s unfortunate that confidentiality clauses leave the rest of us in the dark, for one of the ways forward is for the wind industry to more willingly compensate those most impacted by their operations, and these cases could offer some guidance as to what level of compensation may be mutually agreeable.

Meanwhile, to the best of my knowledge, Consumers Energy’s challenge to the Mason County demand for mitigation is ongoing; the latest report I’ve found is that the company filed an appeal in July after its loss in Circuit Court.  The implications of how that plays out could be far-reaching.  The challenge consists of two related technical points: whether instantaneous exceedances should be considered violations, and  whether unattended sound monitoring can reliably identify violations. The latter question gets down into the technical weeds, including accounting for the presence of other ambient noise as well as turbine sounds, and the choice of measurement metric (L90 or Leq, as well as strict adherence to other sound measurement standards identified in the ordinance, which, like many local ordinances, is not necessarily savvy about all the implications and options for measurement).  As reported by Michigan Capital Confidential, a good source for coverage of this issue:

Arguing that the County’s decision was an “erroneous ruling,” the utility filed a 38-page appeal with the Michigan Court of Appeals on July 18. In addition, Consumers Energy is saying that if the ruling by 51st Circuit Court Judge Richard Cooper were allowed to stand, it could have an impact on many other wind turbine plants across the state.

“This has implications beyond just Mason County,” Dennis Marvin, spokesman for Consumers Energy told Capitol Confidential. “We believe the study the county based its decision on was flawed. We took this decision (to appeal) very seriously, but ultimately our legal staff determined this was in the best interest of our customers and the landowners at the wind park.”

Rick James, of East Lansing-based E-Coustic Solutions, is an acoustician specializing in the production, control, transmission, reception and effects of sound. According to James, Consumers Energy is not exaggerating when it talks about the potential impact of the Lake Winds case.

“Consumers’ appeal has less to do with the supposed 1 decibel error, the topic of the appeal, and more to do with the wind industry’s broader concerns,” James said. “A decision by the Appeals Court in favor of Mason County would make it easier for other counties and townships with wind energy utility noise regulations to prove non-compliance.”

“Consumers would have been better advised if they had not accepted the conclusions of their acoustical consultant that the proposed project could be fit into the host community without causing problems,” James continued.