Question and response on wind turbine planning ordinances

Dear Dr. Womersley,

I found your email address at your Unity webpage. I am writing because a developer has proposed to build three wind turbines approximately 1,500 from my residence in XXXX, Maine. Currently, our town has no ordinance to regulate such development.

You mentioned on your webpage that some towns in Maine have passed ordinances to regulate this development. Could you provide me with a list of such towns, as well as some example ordinances? I have asked our town manager to contact the Maine Municipal Association, but I hoped that you might be able to help as well.

Thank you.

Kind regards,
XXXX

Dear XXXX,

The State Planning Office now has a model ordinance, which although still in draft form, has been released to some towns and folks with situations not unlike yours already.

I copied Mr. Phil Carey on this email. He is the person at the Planning Office that I have been in contact with. I expect he can send you a copy too. I could just send you the one I have, but Mr. Carey would have the latest version.

A far more restrictive draft ordinance is also available for viewing, at the web site of the Jackson Wind Power Subcommittee (of the Jackson Planning Board). I do not believe this particular draft will be enacted as written, as my take on it is that it is too restrictive for the majority of Jackson voters and will be modified by the Planning Board or amended in Town Meeting, but it is another model to study.
http://sites.google.com/site/jacksonwindproject/

The default regulation, already in force for all development affecting a certain amount of acreage in Maine, currently 20 acres, is the DEP's Site Location of Development Law. That is available here:
http://www.maine.gov/dep/blwq/docstand/sitelawpage.htm

In general, I think ordinances are only part of the problem towns and residents face. No matter what the ordinances say, it's still possible to site wind turbines poorly, and so proper planning is important. In the current climate of high interest in turbines, Maine towns are definitely outgunned in this department by the companies and their representatives, and expertise for the towns to use is hard to come by. Most consulting engineers and planners in Maine do not have experience or training in turbine planning and siting. I've seen some pretty basic mistakes made by otherwise very competent people. I would recommend that your town proceed slowly. A moratorium for a period of time while an ordinance is studied is not unreasonable. The language for such a moratorium is right there on the Jackson webpage.

One important set of facts that no planning regulation has yet taken into account and that engineers and planners routinely ignore or do not know, is that noise impacts from turbines are somewhat predictable, and periodically much more severe in some locations regularly downwind of the turbine than others.

One reason is that most turbines have a cut-in speed of 4 to 5 meters per second. The turbine makes little or no noise when it is not turning. Another is that the sound of a turbine travels on the wind. Also, the turbine runs only a fraction of the time. More noise may be heard from wind playing in leaves and trees and buildings than from the turbine, particularly if the listener is upwind. Finally, and counter-intuitively, the average wind that is actually strong enough to turn the turbine may come from a different direction than the so-called "prevailing wind."

My feeling is that the worst disamenity a residence or residents receive when a turbine is constructed is when the regular, metronomic swooshing noise of the turbine blades are heard very often for long periods at the residence at a fairly audible level.

Put all these together and you have considerably and unexpectedly more noise at some sites and less at others. But these impacts are somewhat predictable, based on the wind direction of the site and the acoustic characteristics of a particular turbine make and model. A competent planner can predict the impacts and avoid them.

So, for instance, at a site where I measured the wind for two years in Waldo County, the majority of wind strong enough to turn most turbines, about 70% of the total, came out of the northeast quadrant. The remainder came out of the southeast quadrant. A negligible amount came from the other compass points.

This would mean that the majority of sound impacts on residents at this site would occur to the southwest of any eventual turbine, with a minority to the northeast. A turbine on this particular site would be very quiet or virtually inaudible at 1500 feet most of the time in any other direction, except for the occasional period of random wind.

This would also mean that this town, even if it had a setback regulation of 1500 feet, or even more, might allow a turbine to be sited such that a residence or residences in the southwest quadrant downwind of the turbine receive a very severe disamenity, while other residences get off very lightly.

(Please understand that the directionality in this example applies only to the site I measured.)

For this reason, I would recommend that towns legally require companies or individuals wishing to construct turbines to provide their anemometry data, which can be used to double-check company claims about noise. Generally the companies prefer to keep their data secret for reasons of competition. Acoustic data is often available from the turbine manufacturers.

I also recommend more reliance on planning technique and noise performance standards, and less on setbacks. So if your town enacts a noise performance standard of say 43 or 40 dBA (considerably less than the 45 dBA in the state's Site Location Law) then the onus is on the turbine owners to live up to the standard. They can't turn around and say "it's outside of the setback so we have no responsibility."

I expect this is more information than you were expecting, but these thoughts have been on my mind lately. I am going to be away on business all next week, but if you email me any questions you may have, I will eventually get back to you.

Regards,

Mick


Mick Womersley, PhD
Associate Professor
Unity College
www.unity.edu/facultypages/womersley/windweb.htm
www.ucsustainability.blogspot.com