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Draft noise regulation, Clear Creek County, Colo.

This draft regulation references many ordinances laws and regulations in effect by many cities and counties in the U. S. and other countries. Also, referenced are technical papers, reports and nationally recognized standards relating to wind turbines. …

Wind Farm Noise Emissions
Noise emission from the site shall not be greater than the dB(A) slow and dB(C) slow, one-hour energy equivalent exceedance levels:

Exceedance Value – % Hourly Exceedance Level Turbine Noise
dB(A) Slow – Leq dB(C) Slow – Leq
1 60 75
5 55 70
10 50 65
50 45 60
90 40 55
99 35 50

Pure Tones
Pure tones shall be defined using un-weighted one-third octave level as existing when the one-third octave band levels adjacent to the one-third octave band containing the tone are 5 dB or more less at frequencies greater than 500 Hz. Below 500 Hz, the differences must be 8 dB for center frequencies, 160, 200, 250. For center frequencies of 125 Hz and lower the differences must be 10 dB. If there are pure tones present as described in this section, then the audible noise standard shall be reduced by 5 dB.

Low Frequency Noise or Infrasound Noise
No low frequency noise or infrasound noise from wind turbine operations shall be created which causes the noise level at the project boundary or at a one-mile radius beyond the closest turbine, which ever is greater to exceed the following limits:

1/3 Octave Band Center Frequency (Hz) Sound Pressure Level (Leq)
5 70
6.3 70
8 70
10 70
12 70
16 69
20 68
25 67
31.5 65
40 62
50 60
63 57
80 55
100 52

Impulsivity
No impulsive noise from wind turbine operations shall be created which causes the noise level at the project boundary or at a one-mile radius beyond the project boundary or noise setback boundary that exceeds the following limits as measured by either of the two following methods.

Vibration
Clear Creek County Planning Department may require seismic (ground vibration) measurements at selected locations, when the site is in operation.

Download original document: “Draft wind turbine noise regulation [1]