Friends of Maine's Mountains applauds New Rule on Noise Emissions

Comment

Comment by alice mckay barnett on September 16, 2011 at 10:59pm

ty

Comment by Jim Cummings/AcousticEcologyInst on September 16, 2011 at 4:21pm

How likely is the legislature to revisit the nuts and bolts, do you think?

I don't know how common 5dB AM (blade swish) is, but I'd think it'd be pretty usual; 3 or so dB is "just barely audible," so whenever blade swish is really clear to hear, I'd expect it'd be 5.  But I don't do any sound measuring, just word-reading, so can't be positive.  I know it CAN get to 10dB or more in extreme situations.  Anyway, that really is a bit of a trojan horse, potentially, which would make it an effective 37dB limit; unless the wind farm can adapt its operations only when AM is happening, they'd have to plan to include the penalty.  It's become common practice worldwide to include a 5dB penalty for AM, so I don't think it'd be hard to protect this clause if it was challenged, so long as it doesn't get removed in some stealth mode (so, be sure friendly committee members in the legislature are on the lookout).

I just wrote more on the 12 ten-minute periods on my blog AEInews.org, along with a link to the final rule.  That section of the rule is short, you can read it.  It's really a day-long average of 55, and night-long average of 42, that the new rule calls for; measured by averaging recordings of 10-minute periods in which there are no cars, planes, birds, crickets, peepers, wind in trees, neighbors screaming in frustration, or other loud sounds that elevate the recordings.

My guess is that what I came to on the blog is the situation: they probably average any and all 10-minute periods in which turbines are dominant; I can't really imagine they would allow cherry-picking periods to average....that would be ridikilis!  But the rule doesn't appear to be totally clear on this point.  And averaging them all just makes it more likely that quite a few "out of compliance" 10-minute periods could be balanced out by quiet times when they do the averaging, leading to a finding of compliance.

 

Comment by alice mckay barnett on September 16, 2011 at 12:38pm

Jim, how can we use this information to our advantage?  Or do we protect it in legislation? 

I wish I understood it all.

Comment by Jim Cummings/AcousticEcologyInst on September 16, 2011 at 12:14am

There's a nice little wild card in there: the 5dB penalty for any amplitude modulation over 5dB, which brings it down to a (pulsing) 37dB at night.  BUT, the compliance threshold appears to be for the average of any 12 10-minute periods in a 12 hour monitoring period.....can they cherry-pick to avoid loud times during the day or night?  They have to submit all data, but compliance is based on a subset, rather than on all periods in which turbine sounds are clearly dominant (they want, obviously, to exclude periods when a car or plane or other noise raises the level).  Nothing about contiguous 10-minute periods in that section.