"Wind turbines are loud!" Letter from Somerset County, Pennsylvania
Nov 23, 2008
Print ArticleNovember 22, 2008
I live in Somerset County, one and one-half miles off the main road between two ridgelines.
On the west side of our home is an 18-turbine wind facility with six turbines located 1,390 to 1,500 feet from our back door.
Don’t let any one tell you that they are not loud! They sound like a huge jet hovering above our home. I have been getting readings anywhere from 55 to 70 decibels late at night.
Some people in our area are complaining about the noise a mile away. We checked and, yes, you can hear them that far away.
Now there is another wind company planning to put a wind facility on the ridge 1,800 feet from our front door on the east side of our home. The wind power company did a noise study after we asked them. We are still waiting for the results. The man who did the study told me that we will never be able to live with the noise.
As I write this letter, I am getting shadow flickering from the turbines. The flickering passes through my kitchen this time of day. It makes you dizzy. The only way to avoid it is to pull your blinds and drapes shut. I don’t like living like a bat!
We were not totally against wind turbines when they put them there, but since they began running in September our feelings have changed. They ruined the mountain, and the peace and quiet we once loved is gone.
We were told that the turbines would not cause any problems; in fact we would not even know they were there. They lied.
I would be glad to talk to anyone who would want more information on them. We love Cameron County and own land there; I only hope they never put any on those mountains.
Ginny Deeter
ginrn@wpia.net
Berlin, PA
Reprinted from The Endeavor News
Comment by George Kamperman on 01/28/2009 at 5:29 am
January 27, 2009
To: Ginny Deeter
All wind farm noise immission (Receiver noise level) modeling programs are based on an International Standard ISO 9613-2. As an example I might take eighteen 1.5MW wind turbines in a tight group and project the maximum noise level out to an average distance of 1,450 feet find the computed noise level to be 51 dBA assuming flat hard ground between source(s) and receiver. This may have been the computation done to determine the wind farm noise immission at your home.
The noise modeling programs in most cases consider only distance between each source and receiver and include a simple computation for high frequency sound attenuation due to molecular absorption in the air (about 4 dBA at 1,450 feet). The models assume a neutral atmosphere which is normal daytime conditions. None of the models address nighttime temperature inversion (increasing temperature with elevation). This is normal on most clear non-winter nights with calm winds near the surface. The warmer air aloft increases the velocity of sound and refracts the sky borne turbine noise back down to the surface.
Furthermore, at your home location, when a west wind passes through the line of turbines the downwind turbine sound directivity pattern changes from horizontal to a downward angle into the valley below the ridge. The most significant reason for higher than predicted noise immission is due to the alignment of the 18 wind turbines more or less in a straight line along the top of the ridge to your west. This line of sources form a directive array that focuses more of the wind turbine sound energy out to the side of the array on a line perpendicular to a line along the array axis following the ridge. A better name for this might be the Mars Hill effect.
When directivity and atmospheric effects coincide to increase the wind turbine noise immission at your home I am not surprised the wind turbine noise level is 70 dBA. By contrast the nighttime ambient noise level outside your home when the wind was calm may have been about 20 dBA.
There are virtually no rules governing wind farm noise immission. At most the developer is required to show the wind farm computed noise immission using ISO 9613-2. There are no requirements to disclose the nighttime wind farm noise impact or even attempt to compute the worst case nighttime wind farm noise immission levels.
George Kamperman
Editor’s note: See Mr. Kamperman’s credentials and his work featured under How Loud Is Too Loud?