Introduction (1.0)

Prompted by the introduction of the Green Energy Act, the Noise Unit of the Ministry of the Environment’s (MOE) – Environmental Assessment and Approvals Branch was requested to develop a conservative method for addressing noise impact on receptors due to wind power projects. Specifically, the requirement was to establish a “setback” for noise (i.e. minimum distance between a receptor and the closest wind turbine) with the intention of facilitating the planning and review process of such projects while protecting human health and the environment.

The existing MOE approval process requires proposed wind farm projects to comply with the guidance document titled “Noise Guidelines for Wind Farms – October 2008” (the Guide). This document provides substantial background information for this study. The overall objective for this study was to produce a practical guide for enabling proponents of wind farms to produce effective project plans, while maintaining the noise performance limits compatible with the Ministry policy to protect human health and the environment.

This report presents some background, identifies variables affecting setbacks, defines the scope of a practical scenario, proposes a technical approach for establishing setbacks, and presents results of setback values applicable for wind farms typical to a rural setting in Ontario.

Background (2.0)

In order to understand how to approach this problem, it is necessary to identify the variables that affect noise levels and setbacks in a wind farm project. These variables must balance the complexities of wind farm design with the need to achieve target noise limits at receptors. Following are the main variables for consideration:

  • Wind turbine acoustic emission levels at different wind speeds.
  • Site specific wind-shear effects on wind turbine acoustic emission levels.
  • Frequency spectra of wind turbine acoustic emissions.
  • Number of wind turbine units within an area of influence from a receptor.
  • Wind turbine layout relative to the closest wind turbine unit to a receptor.
  • Selection of sound propagation parameters for predicting noise levels at receptors.
  • Location of Point of Reception relative to the type of building (i.e., height and siting on the property).
  • Classification of ambient noise area at receptors according to MOE publications NPC-205 and NPC-232.
  • Applicable noise limit at receptors.
  • Background noise levels at receptors.
  • Range of wind turbine generator electrical power rating and size.
  • Topography (i.e., land-based, near-shore, or off-shore).
  • Noise contributions from Transformer Substation(s).
  • Noise contributions from adjacent wind farms.

Due to the number of variables involved in a typical wind farm, there are many permutations affecting the noise impact at any given receptor. Consequently, there is no single setback that can accommodate all the variable aspects of a wind turbine project design as well as the compliance with the applicable noise limits. A matrix of setbacks would be more appropriate.

Scope (3.0)

Given the different scenarios found in typical wind farms and based on projects reviewed to date, the scope was set to address land-based wind turbine generating projects with unobstructed and relatively flat landscape. This would include wind turbine generators in the range of about 50 kW to 3 MW. Furthermore, it was selected to address projects set predominately in low ambient noise areas, such rural, wilderness, or quiet suburban areas (i.e. classified as Class 3 Areas in the Guide).

Method (4.0)

The general approach taken for this study was to derive a setback using a conservative approach. This included utilizing the procedure for predicting the noise impact at Points of Reception described in the MOE “Noise Guidelines for Wind Farms – October 2008”. Using one receptor relative to a selected array of wind turbines, the noise impact at the receptor was calculated by the standard method recommended in the International Standard ISO 9613-2. The separation distance required between a receptor and the closest turbine in the array that would satisfy the MOE noise limit was then determined. The result would be the minimum setback for the given set of variables. Based on this premise, the following steps were taken:

4.1 For the purpose of this study, the term “setback” was defined as the plan distance separating the centre of a dwelling (or a specific location on a vacant lot) and the base of the closest wind turbine. Note that the resulting distance could be about 30 m longer if the location of the receptor was taken to be at the Point of Reception as defined in the Guide. The reason for this approach was to simplify the method of accounting for the locations and distance between a wind turbine and a receptor using only two sets of coordinates. Also, this approach can be shown to satisfy the noise limit required at the locations defined by Point of Reception.

4.2 As mentioned earlier no single setback would be appropriate for most wind power projects, therefore it was chosen for this study to develop a matrix with setbacks corresponding to a practical set of defined variables. Two of these variables are the number of units and the type of wind turbines in a project.

4.3 Based on MOE experience, typical wind farms in Ontario consist of a number of wind turbine units ranging from about three up to about one hundred-forty units, with many wind farms consisting of five units. These wind turbine units may be spread over an area ranging from about 1 to 100 km2. For the purpose of this study and based on typical projects reviewed by MOE to date, three types of projects were considered, namely: - Projects consisting of either five (5), ten (10), or twenty-five (25) wind turbine units.

4.4 A simple layout was formulated for each group of wind turbines based on an array in a grid pattern with 400 m separation between the units. Based on experience with wind farms in Ontario, this separation between wind turbines is normal for ensuring proper wind distribution amongst the turbines. The separation distance between wind turbines is often greater due to other project and site constraints. The assumed array of wind turbines relative to a receptor and the setback distance are illustrated for two scenarios in Figure 1. The array was positioned at a setback distance “d” between the closest wind turbine unit and the receptor. This provided a reasonable simulation of wind turbine distance ranging from about 1 km to 3 km for the groups of 5 and 25 wind turbines, respectively.

4.5 In order to address the various acoustic emissions data that correspond to different wind turbine makes, sizes, power capacity and operating conditions, the approach was to identify a suitable quantity for analysis and reference. This data, which is normally supplied by the manufacturer, relies on a testing procedure performed in accordance with the International Standard IEC 61400-11 (also adopted by Canadian Standards Association in Canada). Since the noise from a wind turbine generally varies with wind speed, there can be several values for the acoustic emissions data. Also, the data may be subject to adjustments due to wind shear effects prevailing in the local area. In order to account for such variances, the quantity adopted for this study was the guaranteed values of the Sound Power Level corresponding to 95% rated power output.

4.6 Based on current information, for most wind turbines the electrical power capacity and the acoustic emissions are variable and thus not well correlated. Consequently, it was decided to rely on the acoustic emissions alone for categorizing wind turbines regardless of its other specifications. Based on the acoustic emissions from some of the currently available wind turbine generating equipment, four groups of acoustic emissions were identified for analysis. These groups were classified in terms of the overall Sound Power Levels corresponding to 95% rated power output as follows: 102, 104, 105, and 107 dBA.

4.7 The coordinates for the receptor were selected to correspond with the centre of the dwelling, as defined in 4.1 above, and the height above grade was 4.5 m (the height of an upper room in a two-storey dwelling).

4.8 The current Guide sets the noise limits at a receptor in rural areas ranging from 40 dBA up to 51 dBA depending on wind speeds in the range of 6 to 10 m/s (at 10 m height). In most cases, due to the profile of the acoustic emission with respect to wind speed, the critical condition for compliance with the noise limits occurs at the 6 m/s wind speed or 40 dBA limit. Therefore, consistent with the proposed approach, the noise limit at the receptor was taken to be the same for all wind speeds and wind turbine operating conditions at 40 dBA.

Based on the method outlined, the resulting setbacks may be considered to be conservative with respect to noise impact at receptors as compared to the detailed procedure indicated in the Guide.

Analysis (5.0)

The computations were done using a spreadsheet set to calculate the sound level at a receptor using the Sound Power Level from the noise sources, in terms of full octave frequency bands, based on the International Standard ISO 9613-2.

The receptor height was set at 4.5 m and all other parameters affecting sound propagation were set, as required in the Guide. Contribution from transformer substation noise was not included.

Sample results from the computations corresponding to each of the four groups of wind turbine acoustic emissions are shown in the Appendix.

Results and Conclusions (6.0)

Based on the foregoing conditions set in the analysis, the results are summarized in Table 1.

Table 1 – Proposed Setbacks for Land-based Wind Power Projects
Number of Wind Turbines1Minimum Setback to Closest Wind Turbine per Group (107 dBA2)Minimum Setback to Closest Wind Turbine per Group (105 dBA2)Minimum Setback to Closest Wind Turbine per Group (104 dBA2)Minimum Setback to Closest Wind Turbine per Group (102 dBA2)
251500 m1250 m850 m750 m
101200 m1000 m700 m650 m
5950 m850 m600 m550 m

1 Refers to the number of wind turbines (25, 10 and 5) within a radius from a receptor of 3, 2, and 1 km, respectively.

2 Value is the Sound Power Level in dBA re 1 pW, corresponding to the wind turbine operating at 95 % of rated electrical power capacity.

Based on the results shown in Table 1, the minimum setback distances required between a receptor location (centre of dwelling) and the base of the closest wind turbine range from 550 m up to 1500 m. This depends on the number of units within a radius from the receptor of up to 3 km and on the specified Sound Power Level of the wind turbine.

Table 1 may be applied to any wind power project, including any other wind turbines from adjacent wind farms located within the above noted range of 3 km from the receptor.

In conclusion, a matrix of setbacks suitable for most land-based wind power projects was developed for possible use as simple screening criteria for planning and approval of wind power projects.

References

Noise Guidelines for Wind Farms – Interpretation for Applying MOE NPC Publications to Wind Power Generating Facilities - October 2008

ISO 9613-2 Acoustics – Attenuation of Sound During Propagation Outdoors, Part 2: General Method of Calculation.

CAN/CSA-C61400-11-07, “Wind Turbine Generator Systems – Part 11: Acoustic Noise Measurement techniques”

Appendix

Figure 1: Assumed Array of Wind Turbines For purposes of the method described in section 4.0 of this document, Figure 1 shows the assumed array of wind turbines used for 2 scenarios involving a 5 wind turbine project and a 25 wind turbine project.

Wind Turbine Sound Level at Minimum Setbacks
107 dBA 25 Turbines
Turbine NumberSource63 Hz125 Hz250 Hz500 Hz1,000 Hz2,000 Hz4,000 Hz8,000 HzdBA
1Dist to POR = 1502 m16.818.624.024.321.99.9-26.7-162.629.1
2Dist to POR = 1554 m16.518.323.723.921.49.1-28.7-169.128.7
3Dist to POR = 1554 m16.518.323.723.921.49.1-28.7-169.128.7
4Dist to POR = 1702 m15.717.422.722.920.16.9-34.3-187.127.6
5Dist to POR = 1702 m15.717.422.722.920.16.9-34.3-187.127.6
14Dist to POR = 1901 m14.716.421.621.518.44.0-41.8-211.426.3
6Dist to POR = 1922 m14.616.321.421.418.23.7-42.6-214.026.2
7Dist to POR = 1922 m14.616.321.421.418.23.7-42.6-214.026.2
13Dist to POR = 1943 m14.516.221.321.218.03.4-43.4-216.526.1
15Dist to POR = 1943 m14.516.221.321.218.03.4-43.4-216.526.1
12Dist to POR = 2063 m14.015.620.720.517.11.7-47.8-231.025.4
16Dist to POR = 2063 m14.015.620.720.517.11.7-47.8-231.025.4
8Dist to POR = 2194 m13.515.020.019.716.1-0.1-52.7-247.024.6
9Dist to POR = 2194 m13.515.020.019.716.1-0.1-52.7-247.024.6
11Dist to POR = 2248 m13.214.819.719.415.7-0.8-54.7-253.524.3
17Dist to POR = 2248 m13.214.819.719.415.7-0.8-54.7-253.524.3
22Dist to POR = 2301 m13.014.619.519.115.3-1.6-56.6-259.924.0
21Dist to POR = 2336 m12.914.419.318.915.0-2.0-57.9-264.023.9
23Dist to POR = 2336 m12.914.419.318.915.0-2.0-57.9-264.023.9
20Dist to POR = 2436 m12.514.018.918.314.3-3.4-61.5-276.223.3
24Dist to POR = 2436 m12.514.018.918.314.3-3.4-61.5-276.223.3
10Dist to POR = 2485 m12.413.818.618.113.9-4.0-63.3-282.123.1
18Dist to POR = 2485 m12.413.818.618.113.9-4.0-63.3-282.123.1
19Dist to POR = 2595 m12.013.418.217.513.1-5.4-67.3-295.322.6
25Dist to POR = 2595 m12.013.418.217.513.1-5.4-67.3-295.322.6
TotalN/A28.229.834.934.831.717.6-22.3-161.039.7
Wind Turbine Sound Level at Minimum Setbacks
107 dBA 10 Turbines
Turbine NumberSource63 Hz125 Hz250 Hz500 Hz1,000 Hz2,000 Hz4,000 Hz8,000 HzdBA
1Dist to POR = 1202 m18.820.726.226.825.014.7-14.9-125.731.6
2Dist to POR = 1267 m18.320.225.726.224.313.7-17.5-133.731.0
3Dist to POR = 1267 m18.320.225.726.224.313.7-17.5-133.731.0
4Dist to POR = 1444 m17.219.024.424.822.510.8-24.5-155.629.5
5Dist to POR = 1444 m17.219.024.424.822.510.8-24.5-155.629.5
14Dist to POR = 1602 m16.318.023.323.621.08.4-30.5-174.928.3
13Dist to POR = 1651 m16.017.723.023.220.57.6-32.4-180.928.0
15Dist to POR = 1651 m16.017.723.023.220.57.6-32.4-180.928.0
6Dist to POR = 1699 m15.717.422.722.920.16.9-34.2-186.727.7
7Dist to POR = 1699 m15.717.422.722.920.16.9-34.2-186.727.7
TotalN/A27.228.934.334.732.521.1-11.1-124.539.5
Wind Turbine Sound Level at Minimum Setbacks
107 dBA 5 Turbines
Turbine NumberSource63 Hz125 Hz250 Hz500 Hz1,000 Hz2,000 Hz4,000 Hz8,000 HzdBA
1Dist to POR = 953 m20.822.828.529.327.919.2-4.7-94.534.1
2Dist to POR = 1034 m20.122.127.728.526.917.7-8.1-104.633.2
3Dist to POR = 1034 m20.122.127.728.526.917.7-8.1-104.633.2
4Dist to POR = 1244 m18.520.325.926.424.514.0-16.6-130.931.2
5Dist to POR = 1244 m18.520.325.926.424.514.0-16.6-130.931.2
TotalN/A26.928.734.335.033.324.0-1.6-93.739.8
Wind Turbine Sound Level at Minimum Setbacks
105 dBA 25 Turbines
Turbine NumberSource63 Hz125 Hz250 Hz500 Hz1,000 Hz2,000 Hz4,000 Hz8,000 HzdBA
1Dist to POR = 1252 m15.318.325.627.020.98.8-25.0-135.530.4
2Dist to POR = 1315 m14.917.825.126.420.37.8-27.5-143.229.9
3Dist to POR = 1315 m14.917.825.126.420.37.8-27.5-143.229.9
4Dist to POR = 1486 m13.816.723.925.018.65.1-34.2-164.328.5
5Dist to POR = 1486 m13.816.723.925.018.65.1-34.2-164.328.5
14Dist to POR = 1652 m12.915.722.823.817.02.5-40.5-184.627.3
13Dist to POR = 1699 m12.615.422.523.516.61.8-42.3-190.427.0
15Dist to POR = 1699 m12.615.422.523.516.61.8-42.3-190.427.0
6Dist to POR = 1734 m12.515.222.323.216.31.3-43.7-194.726.8
7Dist to POR = 1734 m12.515.222.323.216.31.3-43.7-194.726.8
12Dist to POR = 1835 m12.014.721.722.515.4-0.2-47.5-207.026.1
16Dist to POR = 1835 m12.014.721.722.515.4-0.2-47.5-207.026.1
8Dist to POR = 2032 m11.013.820.621.313.8-3.0-54.8-230.924.9
9Dist to POR = 2032 m11.013.820.621.313.8-3.0-54.8-230.924.9
11Dist to POR = 2042 m11.013.720.621.213.8-3.1-55.2-232.124.9
17Dist to POR = 2042 m11.013.720.621.213.8-3.1-55.2-232.124.9
22Dist to POR = 2051 m11.013.720.521.213.7-3.2-55.5-233.224.8
21Dist to POR = 2090 m10.813.520.320.913.4-3.8-56.9-237.924.6
23Dist to POR = 2090 m10.813.520.320.913.4-3.8-56.9-237.924.6
20Dist to POR = 2202 m10.313.019.820.312.5-5.3-61.1-251.524.0
24Dist to POR = 2202 m10.313.019.820.312.5-5.3-61.1-251.524.0
10Dist to POR = 2300 m9.912.619.319.711.8-6.6-64.7-263.323.5
18Dist to POR = 2300 m9.912.619.319.711.8-6.6-64.7-263.323.5
19Dist to POR = 2377 m9.712.318.919.311.2-7.7-67.5-272.623.1
25Dist to POR = 2377 m9.712.318.919.311.2-7.7-67.5-272.623.1
TotalN/A26.229.036.037.030.116.0-21.1-134.240.5
Wind Turbine Sound Level at Minimum Setbacks
105 dBA 10 Turbines
Turbine NumberSource63 Hz125 Hz250 Hz500 Hz1,000 Hz2,000 Hz4,000 Hz8,000 HzdBA
1Dist to POR = 1003 m17.320.327.829.423.813.2-14.9-104.332.8
2Dist to POR = 1080 m16.619.727.128.622.811.8-18.1-114.032.0
3Dist to POR = 1080 m16.619.727.128.622.811.8-18.1-114.032.0
4Dist to POR = 1283 m15.118.125.426.720.68.3-26.2-139.230.1
5Dist to POR = 1283 m15.118.125.426.720.68.3-26.2-139.230.1
14Dist to POR = 1402 m14.317.224.525.719.46.4-30.9-154.029.2
13Dist to POR = 1458 m14.016.924.125.318.85.5-33.1-160.928.7
15Dist to POR = 1458 m14.016.924.125.318.85.5-33.1-160.928.7
6Dist to POR = 1564 m13.416.223.424.517.83.9-37.2-173.827.9
7Dist to POR = 1564 m13.416.223.424.517.83.9-37.2-173.827.9
TotalN/A25.328.235.536.930.819.1-11.5-103.540.3
Wind Turbine Sound Level at Minimum Setbacks
105 dBA 5 Turbines
Turbine NumberSource63 Hz125 Hz250 Hz500 Hz1,000 Hz2,000 Hz4,000 Hz8,000 HzdBA
1Dist to POR = 853 m18.721.829.431.125.716.0-8.6-85.534.4
2Dist to POR = 942 m17.820.928.430.024.514.3-12.4-96.733.4
3Dist to POR = 942 m17.820.928.430.024.514.3-12.4-96.733.4
4Dist to POR = 1170 m15.918.926.327.721.810.2-21.7-125.231.1
5Dist to POR = 1170 m15.918.926.327.721.810.2-21.7-125.231.1
TotalN/A24.527.534.936.531.020.6-5.7-84.939.9
Wind Turbine Sound Level at Minimum Setbacks
104 dBA 25 Turbines
Turbine NumberSource63 Hz125 Hz250 Hz500 Hz1,000 Hz2,000 Hz4,000 Hz8,000 HzdBA
1Dist to POR = 853 m19.318.323.525.727.120.0-1.7-82.631.3
2Dist to POR = 942 m18.417.422.524.625.918.3-5.5-93.830.2
3Dist to POR = 942 m18.417.422.524.625.918.3-5.5-93.830.2
4Dist to POR = 1170 m16.515.420.422.323.214.2-14.8-122.327.8
5Dist to POR = 1170 m16.515.420.422.323.214.2-14.8-122.327.8
14Dist to POR = 1252 m15.914.819.721.622.312.8-18.1-132.627.0
13Dist to POR = 1315 m15.514.319.221.021.711.8-20.6-140.326.4
15Dist to POR = 1315 m15.514.319.221.021.711.8-20.6-140.326.4
6Dist to POR = 1472 m14.513.318.119.720.19.3-26.8-159.725.0
7Dist to POR = 1472 m14.513.318.119.720.19.3-26.8-159.725.0
12Dist to POR = 1486 m14.413.218.019.620.09.1-27.3-161.424.9
16Dist to POR = 1486 m14.413.218.019.620.09.1-27.3-161.424.9
22Dist to POR = 1652 m13.512.216.918.418.46.5-33.6-181.723.7
21Dist to POR = 1699 m13.211.916.618.118.05.8-35.4-187.523.3
23Dist to POR = 1699 m13.211.916.618.118.05.8-35.4-187.523.3
11Dist to POR = 1734 m13.111.716.417.817.75.3-36.8-191.823.1
17Dist to POR = 1734 m13.111.716.417.817.75.3-36.8-191.823.1
8Dist to POR = 1813 m12.711.316.017.317.04.1-39.7-201.422.5
9Dist to POR = 1813 m12.711.316.017.317.04.1-39.7-201.422.5
20Dist to POR = 1835 m12.611.215.817.116.83.8-40.6-204.122.4
24Dist to POR = 1835 m12.611.215.817.116.83.8-40.6-204.122.4
10Dist to POR = 2032 m11.610.314.715.915.21.0-47.9-228.021.1
18Dist to POR = 2032 m11.610.314.715.915.21.0-47.9-228.021.1
19Dist to POR = 2042 m11.610.214.715.815.20.9-48.3-229.221.0
25Dist to POR = 2042 m11.610.214.715.815.20.9-48.3-229.221.0
TotalN/A28.927.732.634.435.126.11.3-82.039.8
Wind Turbine Sound Level at Minimum Setbacks
104 dBA 10 Turbines
Turbine NumberSource63 Hz125 Hz250 Hz500 Hz1,000 Hz2,000 Hz4,000 Hz8,000 HzdBA
1Dist to POR = 704 m20.920.625.027.729.223.35.1-63.133.4
2Dist to POR = 810 m19.719.223.726.327.521.10.4-76.731.9
3Dist to POR = 810 m19.719.223.726.327.521.10.4-76.731.9
4Dist to POR = 1066 m17.216.721.023.424.216.2-10.4-109.028.8
5Dist to POR = 1066 m17.216.721.023.424.216.2-10.4-109.028.8
14Dist to POR = 1103 m16.916.420.723.123.815.6-11.9-113.628.4
13Dist to POR = 1173 m16.415.820.122.423.014.3-14.7-122.427.7
15Dist to POR = 1173 m16.415.820.122.423.014.3-14.7-122.427.7
12Dist to POR = 1362 m15.114.418.620.721.011.2-22.3-145.925.9
16Dist to POR = 1362 m15.114.418.620.721.011.2-22.3-145.925.9
TotalN/A27.927.431.834.335.328.37.6-62.839.7
Wind Turbine Sound Level at Minimum Setbacks
104 dBA 5 Turbines
Turbine NumberSource63 Hz125 Hz250 Hz500 Hz1,000 Hz2,000 Hz4,000 Hz8,000 HzdBA
1Dist to POR = 605 m22.222.026.429.230.825.69.6-50.235.0
2Dist to POR = 725 m20.620.324.727.428.822.94.1-65.833.1
3Dist to POR = 725 m20.620.324.727.428.822.94.1-65.833.1
4Dist to POR = 1003 m17.817.221.624.125.017.4-7.8-101.129.5
5Dist to POR = 1003 m17.817.221.624.125.017.4-7.8-101.129.5
TotalN/A27.226.831.233.935.329.311.7-49.939.6
Wind Turbine Sound Level at Minimum Setbacks
102 dBA 25 Turbines
Turbine NumberSource63 Hz125 Hz250 Hz500 Hz1,000 Hz2,000 Hz4,000 Hz8,000 HzdBA
1Dist to POR = 754 m18.520.625.128.026.519.1-3.2-76.132.2
2Dist to POR = 853 m17.419.424.026.825.017.0-7.5-88.930.9
3Dist to POR = 853 m17.419.424.026.825.017.0-7.5-88.930.9
4Dist to POR = 1099 m15.217.121.524.121.912.4-17.8-119.828.2
5Dist to POR = 1099 m15.217.121.524.121.912.4-17.8-119.828.2
14Dist to POR = 1152 m14.816.621.023.621.311.5-19.9-126.527.6
13Dist to POR = 1220 m14.316.120.523.020.610.3-22.6-134.827.0
15Dist to POR = 1220 m14.316.120.523.020.610.3-22.6-134.827.0
12Dist to POR = 1403 m13.014.819.121.418.77.4-29.8-157.525.4
16Dist to POR = 1403 m13.014.819.121.418.77.4-29.8-157.525.4
6Dist to POR = 1417 m12.914.719.021.318.57.1-30.4-159.225.3
7Dist to POR = 1417 m12.914.719.021.318.57.1-30.4-159.225.3
22Dist to POR = 1552 m12.113.918.120.217.25.0-35.6-175.824.3
21Dist to POR = 1603 m11.913.617.719.916.84.3-37.6-182.023.9
23Dist to POR = 1603 m11.913.617.719.916.84.3-37.6-182.023.9
11Dist to POR = 1664 m11.513.217.319.416.23.3-39.9-189.523.4
17Dist to POR = 1664 m11.513.217.319.416.23.3-39.9-189.523.4
20Dist to POR = 1746 m11.112.816.818.815.52.1-43.0-199.522.9
24Dist to POR = 1746 m11.112.816.818.815.52.1-43.0-199.522.9
8Dist to POR = 1769 m11.012.716.718.715.31.8-43.9-202.322.7
9Dist to POR = 1769 m11.012.716.718.715.31.8-43.9-202.322.7
19Dist to POR = 1962 m10.111.715.617.413.7-1.0-51.1-225.821.5
25Dist to POR = 1962 m10.111.715.617.413.7-1.0-51.1-225.821.5
10Dist to POR = 1972 m10.011.615.617.413.6-1.1-51.5-227.021.4
18Dist to POR = 1972 m10.011.615.617.413.6-1.1-51.5-227.021.4
TotalN/A27.629.533.836.334.024.7-0.5-75.740.4
Wind Turbine Sound Level at Minimum Setbacks
102 dBA 10 Turbines
Turbine NumberSource63 Hz125 Hz250 Hz500 Hz1,000 Hz2,000 Hz4,000 Hz8,000 HzdBA
1Dist to POR = 654 m19.721.926.529.428.121.21.3-63.333.7
2Dist to POR = 767 m18.320.425.027.926.318.8-3.7-77.832.1
3Dist to POR = 767 m18.320.425.027.926.318.8-3.7-77.832.1
4Dist to POR = 1034 m15.717.722.124.822.713.6-15.1-111.628.8
5Dist to POR = 1034 m15.717.722.124.822.713.6-15.1-111.628.8
14Dist to POR = 1053 m15.617.521.924.622.513.3-15.9-114.028.6
13Dist to POR = 1126 m15.016.921.323.821.612.0-18.9-123.227.9
15Dist to POR = 1126 m15.016.921.323.821.612.0-18.9-123.227.9
12Dist to POR = 1322 m13.515.419.722.119.58.7-26.7-147.526.1
16Dist to POR = 1322 m13.515.419.722.119.58.7-26.7-147.526.1
TotalN/A26.628.633.035.834.026.03.7-63.039.9
Wind Turbine Sound Level at Minimum Setbacks
102 dBA 5 Turbines
Turbine NumberSource63 Hz125 Hz250 Hz500 Hz1,000 Hz2,000 Hz4,000 Hz8,000 HzdBA
1Dist to POR = 555 m21.223.528.031.129.923.66.0-50.235.4
2Dist to POR = 684 m19.321.526.029.027.620.60.0-67.233.2
3Dist to POR = 684 m19.321.526.029.027.620.60.0-67.233.2
4Dist to POR = 974 m16.218.222.725.423.414.7-12.6-104.129.5
5Dist to POR = 974 m16.218.222.725.423.414.7-12.6-104.129.5
TotalN/A26.028.132.635.534.127.17.8-50.139.8