A workshop the Public Service Board convened on sound standards for new wind turbines drew about 50 people Friday in Montpelier, where board members heard from scientists, town officials and other Vermonters.
The proposed standards would prohibit wind energy developments from emitting sound loud enough to measure 45 decibels outside any nearby homes.
Under consideration is whether to establish a separate sound limit to be measured inside residences.
Speakers for and against wind energy both opposed a separate interior sound limit.
An interior sound standard now in effect for many Vermont wind farms, hasn’t worked well in practice, Public Service Commissioner Chris Recchia told board members.
Mandatory setbacks – or specified distances that turbines must be from residences – should be avoided as well, said consultants who spoke on behalf of Recchia’s department and the Vermont Public Interest Research Group.
Chris Ollson, an environmental health scientist from Ontario hired by the Department of Public Service, recommended that the board adopt a standard that models sound levels in a wind project’s vicinity and bar the developer from producing sounds greater than 45 decibels as measured at the exterior of any nearby residence.
Computer modeling to map out the decibel levels of sound from turbines from different locations would be the most effective method for measuring sound, said Payam Ashtianti, a sound consultant with Ontario-based Aercoustics Engineering, who also testified for the Department of Public Service. The sound could then be monitored after turbines are built, to ensure they aren’t too loud once in operation, he said.
It should be up to wind energy developers to ensure their models don’t inaccurately forecast sound levels lower than what their projects produce, he said.
Consultant Stephen Ambrose, of S.E. Ambrose & Associates, representing the group Vermonters for a Clean Environment, argued that sound whose frequency is below the human hearing range, called “infrasound,” harms human health.
Ambrose offered anecdotes about a baby crying when brought near wind turbines and said he knew of several suicides and home abandonments caused by proximity to turbines. He did not provide scientific evidence showing cause and effect.
A massive two-year study by the Canadian government that ended in 2014 found – as has the overwhelming majority of modern peer-reviewed scientific research – that sound from wind turbines does not damage health.
Public Service Board member Margaret Cheney said the rules under consideration have not yet entered the formal rulemaking process. Further public hearings and comment periods will occur once the formal process begins, she said.
The next hearing on the sound standards has not been scheduled.
The standards are a requirement of Act 174, adopted by the Legislature this year.
(This story has been updated to add Stephen Ambrose’s affiliation.)