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Ambrose Nudges DEP on FGW Compliance

February 16, 2019

He doesn’t say it in so many words. But with his latest comment to the MassDEP, Stephen Ambrose points out it doesn’t take rocket science to predict that people living near wind turbines will experience excessive noise. He recommends the Department continues investigating the sound study of Plymouth’s Future Generation Wind project.

As if resident complaints weren’t enough, there are also the things left out of the Plymouth Sound Compliance Monitoring Report.

Skepticism is warranted for omitting critical information: 1) wind turbine SCADA files with noise measurements. 2) turbine specifications for electric power output and sound power levels with and w/o NRO. 3) noise model predictions with input parameters and results. 4) noise level vs time history plots showing wind turbine fluctuations. 5) name, title and qualifications for author, reviewer, and approver.

Ambrose said in an earlier message to the DEP, “This review finds FGW exceeds the MassDEP noise policy by 10 to 20 dB at all locations.” His analysis cites the report issued in May 2018 by Waltham-based Tech Environmental.

One Comment leave one →
  1. Chris Kapsambelis permalink
    February 24, 2019 9:26 am

    A major flaw in in the measurements to determine MassDEP compliance is the assessment of ambient sound levels. It is well known that wind flow interrupted by an object generates sound. This is the scientific principle on which all wind instruments are based. Studies of operating wind turbines have documented the emission of a noise component known as Aerodynamic Amplitude Modulation (AAM). In the protocols, approved by MassDEP for assessing the increase above ambient, ambient measurements are taken with the wind turbine off. The assumption is made that with the turbine off all noise emissions from the wind turbine cease.

    The assumption that all noise emissions cease with the wind turbine off is false. While the AAM ceases to modulate after the rotor stops, the strong winds aloft continue to be interrupted by the stationary rotor, the nacelle, and the large monopole to generate a steady amount of unmodulated noise that serves to increase the post construction ambient sound level. Preconstruction ambient sound levels, submitted s part of the Special Permit process to Plymouth, are 7 to 18 dBA lower than the ambient sound levels measured by Tech using the MassDEP approved post construction protocol.

    Aerodynamic sound emissions are the dominant sound emissions generated after the wind turbines are installed. For these emissions to be included in the assessment of compliance with MassDEP noise policy, ambient sound levels need to be measured before any wind turbines are installed. In the case of FGW, the project fails to comply with MassDEP policy, since post construction sound increase exceeds 10 dBA above preconstruction ambient sound levels.

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