The following is a letter submitted by Kathleen J. Zuelsdorff, Environmental Review Coordinator, Gas and Energy Division, in regards to the application of Highland Wind Farm, LLC, for a Certificate of Public Convenience and Necessity to Construct a 102.5 Megawatt Wind Electric Generation Facility and Associated Electric Facilities, to be located in the Towns of Forest and Cylon, St. Croix County, Wisconsin:
Highland Wind Farm, LLC (Highland) applied to the Public Service Commission of Wisconsin (PSC) for authority to construct the Highland Wind Farm Project in the towns of Forest and Cylon, in northeastern St. Croix County. Highland would construct, operate, and maintain between 41 and 44 wind turbines with a total capacity of about 102 megawatts (MW).
This is a Type II action under Wis. Admin. Code § PSC 4.10(2). Type II actions require the preparation of an environmental assessment (EA) to determine if an environmental impact statement (EIS) is necessary under Wis. Stat. §1.11. An EA was prepared by Commission staff in consultation with the Wisconsin Department of Natural Resources (DNR). Based on the detailed environmental review of this project, a determination was made that the potential impacts of the project would not have a significant environmental effect on the human environment and therefore, preparation of an EIS for this project proposal is not required.
Subsequent to the completion of the EA, a report investigating infrasound and low frequency noise (ILFN) at a recently constructed wind farm in Wisconsin was completed and submitted to the Public Service Commission. The Commission has prepared a supplemental EA for the Highland project focusing solely on this report titled “A Cooperative Measurement Survey and Analysis of Low Frequency and Infrasound at the Shirley Wind Farm (Shirley) in Brown County, Wisconsin” (Shirley Report)
The Shirley Report contains information that corroborates some previous wind turbine ILFN measurements. It is also points to the need for additional measurements and test designs related to ILFN. However, due to the limitations of the measurements which are discussed in more detail below, the Shirley Report does not lead to a different conclusion than the EA regarding wind turbines and potential health effects. Therefore, preparation of an EIS is not required. Comments on this determination regarding the need for an EIS can be directed to the contact listed at the end of this letter.
The remainder of this letter briefly summarizes the supplemental EA. To obtain a copy of the supplemental EA, please request a copy from the contact person listed at the end of this letter.
Infrasound and Low Frequency Noise Measurements
The noise evaluation in the EA relied substantially on a comprehensive literature review completed in 2012 by the Massachusetts Department of Health and Department of Environmental Protection that includes an extensive discussion of potential health effects of ILFN. This review specifically mentions infrasound measurements taken inside and outside of a home in Falmouth, Massachusetts in spring 2011. One of the coauthors of the Falmouth study is also one the acousticians who collaborated on the Shirley Report.
The Falmouth project report’s graphic representation of the inside/outside sound measurements at the home shows patterns and levels of infrasound and low frequency noise that are similar in many ways to those presented for the R2 residence in the Shirley Report. The similarities present in both reports’ infrasound range sound level peaks, are described as being harmonic frequencies of the turbine’s blade passage rate. The blade pass rate for turbines at both sites was 0.7 Hz. The harmonic sound level peaks appear to be present at the same frequencies (1.4, 2.1, 2.8, 3.5, 4.2, and 4.7 Hz). The graphic representations from both studies also show reduced indoor noise attenuation compared to outdoor sound levels in the low frequency range of about 10–30 Hz. The magnitude of the sound levels measured at both Falmouth and Shirley were also similar in the infrasound and low frequency ranges.
However, the absence of turbine on/off measurements at the Shirley site and the lack of data regarding the turbine operating conditions during the testing period, limit the confidence that can be assigned to the measured magnitude of the ILFN component of the wind turbine noise relative to the ambient sound levels.
Possible Health Effects
In both studies the researchers recorded what they felt while collecting the ILFN data. These physical observations range from feeling no effects at all to reported feelings of nausea and headache. The physical feelings of neighbors in the Shirley area were also noted by one of the researchers. While these health observations are valid in that they represent what the individuals reported, such observations do not specifically add to the scientific analysis of documented health effects or the cause of these effects.
The consensus section of the Shirley Report includes a discussion of vibration-induced flight simulator motion sickness by the U.S. Navy and notes that the Navy studies may provide a “probable cause or direction of study.” (Shirley Study at page 9 of 13). While the discussion suggests a possible hypothesis for further consideration, the Shirley measurements are not designed to evaluate or test the hypothesis.
The supplemental EA looks at the Shirley Report in light of whether the study results provide “(N)ew information that would adversely affect the quality of the human environment in a significant manner or to a significant extent not already considered in the EA.” (Wisconsin Admin. Code § PSC 4..35(1)(a)(2).
The Shirley Report results do provide information characterizing the patterns and magnitude of ILFN near large wind turbines and they also provide some corroboration of the ILFN previously measured at a residence in Falmouth Massachusetts. But the lack of turbine on/off measurement limits the confidence in the magnitude of the ILFN relative to the ambient sound levels.
In addition, the observations reported by the Shirley study team members and some neighbors of how they felt during the testing add to the record of such observations but do not, in and of themselves, provide new information that adds to the knowledge base that can be used to establish the cause of adverse health effects. The EA acknowledged that there is a wide variability in how people react to wind turbine noise and that noise produced by wind turbines could be unusually noticeable or distressing to individuals with increased sensitivity to auditory stimuli.
The Shirley Report aids in defining several avenues for future noise and health effect measurements and testing. It also shows the need for full cooperation of the wind turbine operator during future testing. However, the Shirley ILFN measurements and reported health observations do not lead to different conclusions regarding the link between possible adverse health effects and wind turbine sound than those discussed in the Massachusetts review or described in the EA. Thus, preparation of an EIS for the proposed action, as described under Wis. Stat. §1.11, is not warranted.
Comments on the finding of no significant impact or requests for an electronic version of the supplemental EA that has been prepared should be made to Kathleen Zuelsdorff at the Public Service Commission of Wisconsin, by telephone at (608) 266-2730, or by e-mail at email@example.com. Requests for a paper copy can also be accommodated if an address is provided. Comments must be received by Friday, February 8, 2013.