Mars Hill wind farm sound-level surveys are flawed

NEW HAMPSHIRE (January 11, 2008). Two independent experts question the methodology employed by UPC Wind's sound-level surveys at the Mars Hill wind farm in Maine, raising questions whether the project is in compliance with Maine State permit conditions.

Industrial Wind Action (IWA) Group filed formal comments[1] with the Maine Department of Environment Protection (MEDEP) in regard to the Department's ongoing investigation into noise complaints at the wind energy facility in Mars Hill, ME.

Problems with intrusive sound levels were reported beginning in December 2006 when the turbines were first turned on. Eighteen families have now cited problems with noise despite repeated assurances by the developer, Evergreen/UPC Wind, and town officials that there would be no noise. Only after problems were reported was it revealed that the permit application included information of potential noise problems[2].

In response to noise complaints, UPC Wind conducted sound level readings at the site over the course of four days in May 2006 to verify whether the project was in compliance with MEDEP permit conditions. UPC Wind submitted its findings to the Department on June 21, 2006[3].

Mountain Landowners Association (MLA), an association of families living adjacent to the project site, submitted a report[4] that critiqued UPC Wind's pre-construction sound modeling and post-construction sound survey reports. MLA's report was prepared by Mr. Richard Bolton of Environmental Compliance Alliance. In addition, MEDEP engaged Warren L. Brown of EnRad Consulting to peer review the studies mentioned above[5].

"It's clear from a careful reading of the reports by UPC Wind and the two independent sound experts, including MEDEP's own consultant, that the methodologies employed by UPC Wind to predict sound levels and in surveying sound at the operating wind plant were flawed," said IWA Executive Director Lisa Linowes.

Problems with the sound studies include,
1) The pre-construction modeling software (CADNA/A) used to predict sound emissions from the operating plant is not suitable for above-ground noise sources. Wind turbine sound emanates from an area over 100-feet above ground level. Sound pressure levels higher than those predicted could well occur due to differences in surface and hub-height wind speeds as well as increased atmospheric refraction effects of the sound.

2) MEDEP granted UPC Wind a variance to survey sound levels at wind speeds above 12 mph without securing assurances that appropriate microphone shielding instrumentation would be employed. The Brown report stated "Ambient and operation sounds measured at high wind speeds (>12 mph) may produce non-noise artifact lessening the integrity of measured data. This confounding element can lead to false conclusions regarding ambient and operation sound levels."

IWA’s comments recognized UPC Wind’s interest in taking further measurements, but asserted that “such measurements would be inconclusive and of little value if corrective actions are not imposed on the developer by Maine DEP.”  Linowes added that given the errors in methodology thus far, MEDEP needs to get serious about the problem including engaging its own third-party sound consultant to conduct an in-field survey. “This issue has festered for over a year. It’s time the State accepts responsibility for the problems and provides Mars Hill residents suffering from turbine noise with a resolution.”  

About IWA: Industrial Wind Action Group seeks to promote knowledge and raise awareness of the risks and damaging environmental impacts of industrial wind energy development. Information and analysis on the subject is available through its website, www.windaction.org. To subscribe to the IWA weekly newsletter, visit http://www.windaction.org/subscribe.

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 [1] IWA Comments: Mars Hill wind farm noise studies.

 [2] Mars Hill: Windmill owners to analyze noise level.

 [3] Mars Hill wind project sound level study.

 [4] Assessment of Mars Hill sound study.

 [5] Mars Hill windfarm post-development sound level study peer review.