12.0 Standards for Setbacks, Noise, Shadow Flicker, and Mitigation Waivers
This section addresses the interrelated standards of setbacks, noise, shadow flicker and mitigation waivers and applies to all WTGs.
Setbacks provide a number of important Ordinance functions, including but not limited to: 1) working in conjunction with noise standards as a primary means of mitigating potential and unforeseen noise complaints; 2) providing for public safety in the event of a catastrophic turbine failure or ice throw; 3) mitigating the effects of shadow flicker from larger turbines
In general, the taller the turbine, and the greater the number of turbines in a WTG, the greater the setback needed to mitigate noise, debris hazards, and shadow flicker. However, setbacks for noise must also be implemented in conjunction with specific wind turbine noise limits (see Section 12.2 ).
Although larger wind turbines appear to generate the highest proportion of published noise complaints, poorly designed smaller turbines can also cause serious noise.
Setbacks to property lines are a minimum buffer of one mile from the Project Boundary. This is assuming a 1.5 MW industrial wind turbine, which has a Turbine Height of approximately 400 feet. However, larger wind turbines are louder, so a varying setback basis is required. A one mile setback is approximately equal to 13 times the turbine height for a 400 foot turbine. Therefore, the Setback Distance is defined as the larger of one mile or 13 times the Turbine Height, measured horizontally from the Project Boundary to the nearest property line. Setbacks for public roads are based on an approximation of an 1800-foot debris field for ice throw. Four times the turbine height for a 440 foot Wind Turbine is equal to 1760 feet.
12.1 Setback Standards
12.1.1 Setback to Non-participating Landowner Property Lines – Given the abundant evidence that wind turbines sited too close to humans has deleterious effects on them, and given that the most effective means of preventing negative health effects is proper setbacks, WTGs must be located no closer than the Setback Distance from non-participating property lines. Property owners may waive this setback with a written Mitigation Waiver. (See Section 12.4 ).
12.1.2 Setback to Public Roads - Wind Turbines will be set back from any public road a distance no less than 4 times the turbine height, measured horizontally.
12.2 Noise Standards
For all wind turbines, the primary guiding principle is that their operation must not be disruptive at any time of day or night. Current sound limitations in the state of Maine regulating noise from WTG reflect sound limits applicable to urban residential and urban mixed neighborhoods instead of the deep quiet of rural areas such as Montville to which this Ordinance pertains.
12.2.1 Principles Governing Sound Measurements
184.108.40.206 Section 27.0 applies in addition to relevant paragraphs of Section 28.0 . Procedures in Section 27.0 and Section 28.0 are mandatory and additional to the relevant
220.127.116.11 Sound measurements must be made to all non-participating property lines within and up to two (2) miles measured horizontally from the Project Boundary.
18.104.22.168 All sound measurements will be filtered for both dBA and dBC.
22.214.171.124 All sound measurements before construction, and after will be made by a Professional Engineer who is a Full Member of the Institute of Noise Control Engineering (INCE).
126.96.36.199 This engineer must be an independent contractor to the Town of Montville, and have no ties to wind developers or related conflicts of interest.
12.2.2 Noise Limits at Non-participating Property Lines No WTG turbine shall be located so as to cause an exceedence of the preconstruction/operation background sound levels by more than 5 dBA or dBC. The background sound levels shall be the L90 dB sound levels sound descriptor (both A and C weighing) measured during a pre-construction noise study during the quietest time of evening or night. Measurements shall be for ten (10) minutes or more. L90 results are valid when L10 results are no more than 15 dB above L90 for the same time period. Noise sensitive sites are to be selected based on the WTG’s predicted sound emissions (in dBA, dBC and 1/3 octaves to blade passage frequency), which are to be provided by the Applicant.
188.8.131.52 Audible noise levels (dBA) due to wind turbine operation will not exceed the preconstruction ambient noise level by more than 5 dBA as measured at any property line.
Property owners may waive this noise restriction with a written Mitigation Waiver. (See Section 12.4 .)
184.108.40.206 Low frequency noise levels (dBC) due to wind turbine operation as measured inside or at any Property Line will not exceed:
1. 20 decibels (measured as dBC) above the pre-development ambient noise level (measured as dBA).
2. A maximum not-to-exceed level of 50 dBC. Property owners may waive this noise restriction with a written Mitigation Waiver. (See Section 12.4 .)
220.127.116.11 Noise measurement standards and procedures are described in Section 27.0 .