N.H. Admin. Code § Site 301.18

Current through Register No. 50, December 12, 2024

Section Site 301.18 - Sound Study Methodology

(a) The methodology for conducting a preconstruction sound background study for a wind energy system shall include:

(1) Adherence to the standard of ANSI/ASA S12.9-2013 Part 3, available as noted in Appendix B, a standard that requires short-term attended measurements;

(2) Long-term unattended monitoring shall be conducted in accordance with the standard of ANSI S12.9-1992 2013 Part 2, available as noted in Appendix B, provided that audio recordings are taken in order to clearly identify and remove transient noises from the data, with frequencies above 1250 hertz 1/3 octave band to be filtered out of the data;

(3) Measurements shall be conducted at the nearest properties from the proposed wind turbines that are representative of all residential properties within 2 miles of any turbine; and

(4) Sound measurements shall be omitted when the wind velocity is greater than 4 meters per second at the microphone position, when there is rain, or with temperatures below instrumentation minima; following the protocol of ANSI S12.9-2013 Part 3, available as noted in Appendix B:

a. Microphones shall be placed 1 to 2 meters above ground level, and at least 7.5 meters from any reflective surface;

b. A windscreen of the type recommended by the monitoring instrument's manufacturer must be used for all data collection;

c. Microphones should be field-calibrated before and after measurements; and

d. An anemometer shall be located within close proximity to each microphone.

(b) Pre-construction sound reports shall include a map or diagram clearly showing the following:

(1) Layout of the project area, including topography, project boundary lines, and property lines;

(2) Locations of the sound measurement points;

(3) Distance between any sound measurement point and the nearest wind turbine;

(4) Location of significant local non-turbine sound and vibration sources;

(5) Distance between all sound measurement points and significant local sound sources;

(6) Location of all sensitive receptors including schools, day-care centers, health care facilities, residences, residential neighborhoods, places of worship, and elderly care facilities;

(7) Indication of temperature, weather conditions, sources of ambient sound, and prevailing wind direction and speed for the monitoring period; and

(8) Final report shall provide A-weighted and C-weighted sound levels for L-10, Leq, and L-90.

(c) The predictive sound modeling study shall:

(1) Be conducted in accordance with the standards and specifications of ISO 9613-2 1996-12-15, available as noted in Appendix B;

(2) Include an adjustment to the Leq sound level produced by the model applied in order to adjust for turbine manufacturer uncertainty, such adjustment to be determined in accordance with the most recent release of the IEC 61400 Part 11 standard (Edition 3.0 2012-11), available as noted in Appendix B;

(3) Include predictions to be made at all properties within 2 miles from the project wind turbines for the wind speed and operating mode that would result in the worst case wind turbine sound emissions during the hours before 8:00 a.m. and after 8:00 p.m. each day; and

(4) Incorporate other corrections for model algorithm error to be disclosed and accounted for in the model.

(d) The predictive sound modeling study report shall:

(1) Include the results of the modeling described in (c)(3) above as well as a map with sound contour lines showing dBA sound emitted from the proposed wind energy system at 5 dBA intervals;

(2) Include locations out to 2 miles from any wind turbine included in the proposed facility; and

(3) Show proposed wind turbine locations and the location of all sensitive receptors, including schools, day-care centers, health care facilities, residences, residential neighborhoods, places of worship, and elderly care facilities.

(e) Post-construction noise compliance monitoring shall include:

(1) Adherence to the standard of ANSI/ASA S12.9-2013 Part 3, available as noted in Appendix B, that requires short-term attended measurements to ensure transient noises are removed from the data, and measurements shall include at least one nighttime hour where turbines are operating at full sound power with winds less than 3 meters per second at the microphone;

(2) Unattended long-term monitoring shall also be conducted;

(3) Sound measurements shall be omitted when there is rain, or when temperatures are below instrumentation minima, and shall comply with the following additional specifications:

a. Microphones shall be placed 1 to 2 meters above ground level and at least 7.5 meters from any reflective surface, following the protocols of ANSI/ASA S12.9-2013 Part 3, available as noted in Appendix B;

b. Proper microphone screens shall be required;

c. Microphones shall be field-calibrated before and after measurements; and

d. An anemometer shall be located within close proximity to each microphone;

(4) Monitoring shall involve measurements being made with the turbines in both operating and non-operating modes, and supervisory control and data acquisition system data shall be used to record hub height wind speed and turbine power output;

(5) Locations shall be pre-selected where noise measurements will be taken that shall be the same locations at which predictive sound modeling study measurements were taken pursuant to subsection (c) above, and the measurements shall be performed at night with winds above 4.5 meters per second at hub height and less than 3 meters per second at ground level;

(6) All sound measurements during post-construction monitoring shall be taken at 0.125-second intervals measuring both fast response and Leq metrics; and

(7) Post-construction monitoring surveys shall be conducted once within 3 months of commissioning and once during each season thereafter for the first year, provided that:

a. Additional surveys shall be conducted at the request of the committee or the administrator; and

b. Adjustments to this schedule shall be permitted, subject to review by the committee or the administrator.

(f) Post-construction sound monitoring reports shall include a map or diagram clearly showing the following:

(1) Layout of the project area, including topography, project boundary lines, and property lines;

(2) Locations of the sound measurement points; and

(3) Distance between any sound measurement point and the nearest wind turbine.

(g) For each sound measurement period during post-construction monitoring, reports shall include each of the following measurements:

(1) LAeq, LA-10, and LA-90; and

(2) LCeq, LC-10, and LC-90.

(h) Noise emissions shall be free of audible tones, and if the presence of a pure tone frequency is detected, a 5 dB penalty shall be added to the measured dBA sound level.

(i) Validation of noise complaints submitted to the committee shall require field sound surveys, except as determined by the administrator to be unwarranted, which field studies shall be conducted under the same meteorological conditions as occurred at the time of the alleged exceedance that is the subject of the complaint.

N.H. Admin. Code § Site 301.18

Derived From Volume XXXVI Number 01, Filed January 7, 2016, Proposed by #10994, Effective 12/16/2015, Expires 12/16/2025.