Industrial wind turbine farms are proposed for the towns of Perry, Covington and Warsaw, NY that will permanently alter the towns. Large turbines create strong noise levels not only from wind through the blades but largely by the turbine mechanisms themselves. To capture the wind these turbines are to be installed on hill tops around the town and thus have significant potential to create a noise nuisance. Wind turbine noise added to the prevailing ambient background sound is an important environmental consideration when siting wind turbines since they are a permanent installation and may significantly impair resident’s enjoyment of neighboring lands or even personal health. Also, relevant consideration of noise impacts and mitigation measures are a specific requirement of a NY State Environmental Quality Review procedure, required before approval of permits.

Selected Extracts

2.0 "Dairy Hills Wind Farm"

Dairy Hills Wind Farm, LLC has proposed a large "wind turbine farm" for the Towns of Perry, Covington and Warsaw NY. Up to 62 megawatt-scale turbines are to be erected over 24 square miles of the towns. A NYS Environmental Quality Review is required to assess and mitigate potential environmental damage associated with the project. To conform to NYS Environmental laws a comprehensive noise pollution analysis and mitigation plan must be performed for all potential affected "receptors" throughout the wind farm geography. The sponsor submitted a Draft Environmental Impact Statement that includes a noise analysis as Appendix I, by Hessler Associates (Ref. 1). Hessler chose to follow the DEC's Noise Policy (Ref. 2), designed for the Department but also useful to sponsors or other agencies in assessing and mitigating noise impacts. From Hessler:

The primary basis for evaluating potential project noise is the Program Policy Assessing and Mitigating Noise Impacts issued by the New York State Department of Environmental Conservation (NYCDEC), Feb. 2001. This assessment procedure is incremental in the sense that a fairly simple "first level noise impact evaluation" is initially carried out to determine if any residential receptors may experience a noticeable increase in sound level. If this analysis, which compares the measured background level to very conservatively calculated potential project sound levels, shows that any houses may be impacted a further, "second level noise impact evaluation" is carried out to model project noise in a more realistic and detailed fashion.

2.1 Flawed Noise Analysis

The successful measurement and assessment of the complex noise potential of a large wind turbine farm project is a vital part of the environmental review and mitigation process and there are specific instructions in the DEC Policy about excessive noise:

When a sound level evaluation indicates that receptors may experience sound levels or characteristics that produce significant noise impacts or impairment of property use, the Department is to require the permittee or applicant to employ reasonable and necessary measures to either eliminate or mitigate adverse noise effects.

Hessler however thinks that the noise study purpose is to provide evidence that the noise turbine sounds will be masked, and therefore acceptable.

5.0 Conclusion

Occupying 24 square miles of the towns, the Dairy Hills Wind Farm project is very large and has a potentially large "noise footprint". Hessler tries to conclude, by a variety of methods, that "the project is unlikely to constitute a significant adverse community impact." Also:

At an 8 m/s wind speed, measured at the standard reference height of 10 m above ground level, the Gamesa G87 (or G90) wind turbine produces the maximum amount of noise. At this wind speed the mean background residual (L90) sound level was found to be 44 dBA, meaning that such a sound level is consistently present and available to mask potential turbine noise.

However using its flawed background analysis Hessler derives a 44 dBA "ambient", far above the expected, attenuates the noises in its modeling far more than expected and tries to avoid required mitigation measures required for each affected resident, not the project's noise impact on the community at large.

An accurate and comprehensive noise analysis is essential but clearly the Hessler study must be repeated with far better analysis in terms of a) reasonably accurate background levels b) inclusion of summer vegetation and winter snow c) statistically valid measurement sites that comprehensively represent the likely intrusion on non-leaseholder lands and dwellings and d) reasonable computer modeling to show noise contours encompassing likely atmospheric effects.

These requirements must be satisfied to conform to the Noise Policy and SEQR rules:

In circumstances where noise effects cannot readily be reduced to a level of no significance by project design or operational features in the application, the applicant must evaluate alternatives and mitigation measures in an environmental impact statement to avoid or reduce impacts to the maximum extent practicable per the requirements of the State Environmental Quality Review Act.

Many sites may be found to be unsuitable for use due to unacceptably high noise levels requiring higher setbacks, with 1 mile an expected outcome from a genuine study.

Mitigation suggestions from the DEC Noise Policy include "increasing the setback distance". It is entirely likely that other turbine locations must be sought, or the scale of the wind farm must be reduced.

 

Web link: http://www.barehillsoftware.com/Noise_Analysis_of_...

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