Pre-Construction Wind Turbine Noise Analysis for the proposed Deuel Harvest North Wind Farm March 2019 Prepared for: Deuel Harvest Wind Energy LLC Chicago, Illinois Prepared by: Hankard Environmental, Inc. Verona, Wisconsin Ex. A17-1 E L -C:-~..c::::::: ACOUST I CS AND VIBRATION CONSULTING
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Pre-Construction Wind Turbine Noise Analysis for the proposed
Deuel Harvest North Wind Farm March 2019
Prepared for:
Deuel Harvest Wind Energy LLC Chicago, Illinois
Prepared by:
Hankard Environmental, Inc. Verona, Wisconsin
Ex. A17-1
E L
-C:-~..c::::::: ~ ~~ ACOUST I CS AND VIBRATION CONSULTING
Pre-Construction Wind Turbine Noise Analysis for the proposed Deuel Harvest North Wind Farm
Table 6-1. Potential Construction Equipment to be Employed on a Wind Turbine Project ........ 10
Table 6-2. Noise Source Characteristics of Construction Equipment ............................................. 11
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Appendices
A. Site Plan Figures ................................................................................................................................ A-1
B. Non-Participating Receptor Locations and Noise Levels ........................................................... B-1
C. Participating Receptor Locations and Noise Levels .................................................................... C-1
D. Noise Source Locations .................................................................................................................... D-1
E. Predicted Noise Level Contours ..................................................................................................... E-1
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1. Introduction
This report describes a pre-construction noise analysis conducted by Hankard Environmental for the proposed Deuel Harvest North Wind Farm (the Project) in support of its Energy Facility Permit. Deuel Harvest Wind Energy LLC (Deuel Harvest, the Applicant), an affiliate of Invenergy LLC (Invenergy), is developing the up to 310.1 megawatt (MW) Project to be located in Deuel County, South Dakota. Deuel Harvest intends to construct and operate the Project, which is located in the townships of Portland, Lowe, Altamont, Glenwood, and Herrick. Figure 1-1 shows the general location of the Project, which is bordered by 166th Street to the north, State Line Road to the east, County Highway 309 to the south, and County Highway 443 to the west. This report assesses potential sound levels of the Project and confirms compliance with the Zoning Ordinance of Deuel County, Section 1215: Wind Energy System (WES) Requirement of 45 dBA or less at non-participating residences. Our analysis confirmed that sound levels will not exceed 44.9 dBA at non-participating residences. Described herein are the applicable noise standard, the Project and its environs, the methods and data used to model noise levels, the results of the noise level predictions, and demonstration of compliance with the Zoning Ordinance.
Figure 1-1. General Location of the Proposed Deuel Harvest North Wind Farm
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Pre-Construction Wind Turbine Noise Analysis for the proposed Deuel Harvest North Wind Farm
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2. Applicable Noise Standards
On May 23, 2017, the Board of County Commissioners passed Ordinance 82004-01-23B, which amended the Deuel County Zoning Ordinance, Section 1215.03: General Provisions, Paragraph 13: Noise & Shadow Flicker, Subparagraph a to read:
a. Noise level shall not exceed 45 dBA average A-Weighted Sound pressure at the perimeter of existing residences, for non-participating residences.
This amendment became effective on June 20, 2017. This is the only numerical noise limit applicable to wind energy systems in Deuel County, South Dakota. There are no other numerical local, state or federal noise limits applicable to the Project. At the state level, South Dakota Administrative Rule 20:10:22:33.02 requires that an application for an Energy Facility Permit include “Anticipated noise levels during construction and operation.” The noise levels reported herein are those expected during operation. Construction noise levels will be typical of those produced by standard construction equipment. Refer to Section 6 for a discussion on construction noise levels.
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3. Project Description
The Project is located in a predominantly agricultural area of central-eastern South Dakota; wind turbines and associated facilities are thus sited primarily on agricultural lands. The Project will consist of up to 112 wind turbines generating up to 300 MW of electrical power with a nameplate capacity of 310.1 MW. Associated facilities include gravel roads to access each turbine and below-grade electrical cabling to collect and transmit the power to a project substation. Deuel Harvest is proposing one layout for the Project, which is approximately 42,000 acres in size, which was selected based upon review and analysis of wind resources, economic considerations, landowner interest, availability of easements, access to transmission routes, interconnection of the Project to existing transmission facilities and lines, geographic features, and environmental resources. The Project is located in an area with a strong wind resource and is situated near existing electric transmission infrastructure. Table 3-1 lists the two turbine types that were analyzed for noise compliance. The layout analyzed includes 106 units of General Electric (GE) model 2.82-127 wind turbines and 13 units of GE 2.3-116 wind turbines, all fitted with Low Noise Trailing Edge (LNTE) blades. Note that while the sound modeling included 119 turbines, only up to 112 turbines will be installed: five of the GE 2.82-127 wind turbines and two of the GE 2.3-116 wind turbines included in the noise analysis are alternates. The layout is shown graphically in the figures in Appendix A. Also shown in the figures are the locations of all 122 non-participating and 111 participating residences within two miles of any turbine or the 34.5 kV to 345 kV step-up transformer. The geographic coordinates of each modeled non-participating receptor, each modeled participating receptor, and each Project noise source (turbines and transformers) are provided in Appendices B, C and D, respectively.
Table 3-1. Project Noise Sources
Turbines Transformers
Model Blades Rotor Diameter
(m) Hub Height
(m) Number of Turbines* Type Number
GE 2.3-116 LNTE 116 80.0 13 standard utility scale
2 GE 2.82-127 LNTE 127 88.6 106
* The total number of wind turbines in the noise model is 119, which includes 7 alternates.
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4. Noise Modeling Method
Noise levels from the proposed Deuel Harvest North Wind Farm were predicted using the modeling method set forth in International Organization for Standardization (ISO) Standard 9613-2:1996 Attenuation of Sound During Propagation Outdoors. The method was implemented using the SoundPLAN v7.4 acoustical modeling program and the modeling program results were cross-checked with a spreadsheet calculation. Figure 4-1 shows a representative three-dimensional view of the SoundPLAN model of the Project.
Figure 4-1. Three-Dimensional View of the SoundPLAN Noise Model
There are several parameters in the ISO 9613-2:1996 method, including the locations of the noise sources and receivers, noise source level and frequency characteristics, terrain and ground type, and atmospheric propagation conditions. The ISO method assumes optimal acoustic propagation in all directions, specifically that a “well-developed, moderate ground-based temperature inversion” is present or, equivalently, that all receptors are downwind of all noise sources at all times. The specific ISO 9613-2:1996: settings used in this analysis are described below.
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Receptors In the SoundPLAN model, receptors (prediction points) were located at each of the 122 non-participating and 111 participating residences located within the Project study area, which includes any residence located within approximately two miles of any turbine or main step-up transformer. The geographic locations of the residences were provided by Deuel Harvest. Ground elevations were determined using Digital Elevation Model (DEM) data from the U.S. Geological Survey (USGS) National Elevation Dataset. In accordance with ISO 9613-2:1996, each receptor’s height was set to 1.5 meters (5 feet) above the ground. The location of each receptor is shown in the figures in Appendix A. The geographic coordinates and ground elevation of each modeled non-participating and participating receptor are listed in Appendices B and C, respectively.
Noise Sources In the SoundPLAN model, each turbine was represented as an acoustical point source located at its hub height, which is 80 meters above the ground for the GE 2.3-116 units, 88.6 meters above the ground for the GE 2.82-127 units, and three meters above the ground for the step-up transformers. No directivity was applied to any noise source, thus assuming maximum acoustic output in all directions, and all turbines were assumed to be operating in normal mode (versus noise-reduction mode). The locations of the turbines were provided by Deuel Harvest (County Permit Resubmit_rev02_(119 WTGs)_03202019.shp). The location of the substation containing the two main step-up (34.5 kV to 345 kV) transformers was also provided by Deuel Harvest. The location of each turbine is shown in the site plan figures in Appendix A. The geographic coordinates, ground elevation, and hub-height elevation of each modeled turbine and transformer are listed in Appendix D. The ground elevation for each turbine location was determined using DEM data from the USGS National Elevation Dataset. Table 4-1 lists the octave band sound power levels for all modeled noise sources in the Project. The levels are expressed in terms of unweighted decibels (dB) for each of nine standard frequency bands, as defined by the American National Standards Institute (ANSI) Standard S1.11: Specification for Octave-Band and Fractional-Octave-Band Analog and Digital Filters. The noise level data for each turbine was provided by the manufacturer and was determined according to International Electrotechnical Commission standard 61400-11. This standard requires wind turbine sound power levels to be reported for a number of wind speed bins across the operating range of the turbine. In general, sound levels increase with increasing winds speeds, up to approximately 10 m/s at hub height. Noise levels do not further increase above this wind speed because the turbines reach a maximum rotational speed. This relationship between wind speed and noise level holds true for each octave band. This analysis used octave band noise levels reported by the manufacturer for the 10 m/s wind speed at hub height, as this is the speed at which the overall noise level first reaches its maximum level. The manufacturer’s uncertainty factor was not applied to this data.
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Table 4-1. Source Sound Power Levels
Source
Octave Band Sound Power Level (dB) Overall Sound Power
Transformer 95.0 100.8 102.7 97.2 97.8 91.6 86.4 81.6 72.5 98.0 * For 10 m/s hub-height wind speed The Project’s collector substation will contain two step-up transformers, switch gear, metering, electrical control and communication systems, and other equipment required to transform Project wind-generated power. The only significant noise-producing equipment are the Project’s main step-up transformers. The noise analysis assumed the simultaneous operation of two 120 MVA transformers at the substation. The sound power levels from the transformers are listed in Table 4-1. The substation location is shown in the figures in Appendix A. Ground elevations for the transformers were determined using the USGS National Elevation Dataset. The transformers were modeled as point sources located 3 meters (10 feet) above the ground, with no barriers or directivity reductions. The spectral shape of transformer noise emissions was estimated using published data and adjusted to match the overall sound power level of 98 dBA, which is a typical and achievable level estimated for utility-scale transformers.
Terrain and Ground Effect The terrain in the project area was modeled by importing DEM data from the U.S. Geological Survey National Elevation Dataset into SoundPLAN. The acoustical effect of the ground was modeled using the ISO 9613-2:1996 General Method. This requires the selection of ground absorption factors for the ground near the source, near the receiver, and in between. Ground factors range from 0.0 to 1.0 and represent the proportion of sound that is absorbed or reflected when sound waves interact with the ground. A value of 0.0 represents completely reflective ground material such as pavement or flat water, and results in a higher level of sound reaching a receptor. A value of 1.0 represents absorptive material such as thick grass, crops, or fresh snow, and results in a lower level of sound reaching a receptor. For this project, we conservatively assumed a ground factor of 0.0 (completely reflective). Actual ground conditions could at times be 0.0 when the ground is completely frozen, but would generally be closer to 0.5 when the ground is covered with new snow or crops, or when the ground is bare and unfrozen.
Atmospheric Conditions The air temperature, relative humidity, and atmospheric pressure were set to conditions of 10°C, 70%, and 1 atmosphere, respectively. These values represent the lowest amount of atmospheric absorption of sound available in the ISO 9613-2:1996 method, and result in the highest levels of sound reaching the receptors.
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Validation of Noise Prediction Method The noise level prediction method employed on the Project has been validated by many acoustical consultants, including Hankard Environmental, by comparing predicted noise levels to those measured at operating wind farms. Specifically, Hankard Environmental has conducted in-depth measurements at nine wind farms located across the U.S., encompassing an array of turbine types including some similar in size to those proposed on this Project. As part of these studies, we predicted noise levels at our measurement locations using acoustical modeling methods similar to those described above. Our validation procedures compared the predicted levels to the very highest turbine-only noise levels we measured from the operating turbines. The result of those comparisons is that a majority of the time actual measured turbine noise levels were lower than those predicted by 1 dBA or more. The reason for this is that in addition to the conservative ground attenuation factor and atmospheric absorption conditions, sound levels were predicted assuming maximum turbine operations (which will not always be the case) and the ISO 9613-2:1996 method assumes that all receptors are downwind of all noise sources at all times (a physical impossibility for this turbine layout).
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5. Predicted Noise Levels
Non-Participating Residences Noise levels from the full and continuous operation of 106 GE 2.82-127 LNTE turbines, 13 GE 2.3-116 LNTE turbines, and two main step-up transformers were predicted at each residence. Table 5-1 lists the predicted turbine noise levels at the 12 non-participating residences where the loudest levels are predicted. All of these predicted levels are less than the County’s 45 dBA limit. Predicted noise levels at all other non-participating residences are lower. Overall, levels range from 24 dBA to less than 45 dBA, with an average of 36 dBA. The predicted noise levels at each of the 122 non-participating residences are listed in Appendix B.
Table 5-1. Highest Predicted Noise Levels at Non-Participating Residences
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Participating Residences Table 5-2 lists the 12 participating residences where the highest noise levels are predicted. Overall, levels range from 28 dBA to less than 50 dBA, with an average of 39 dBA. Predicted noise levels at all other participating residences are lower. The predicted noise levels at each of the 111 participating residences are listed in Appendix C.
Table 5-2. Highest Predicted Noise Levels at Participating Residences
Predicted Noise Level Contours Noise levels are indicated graphically in the form of noise level contours in the figure in Appendix E. Each of the green contour lines encircles one or more turbines to indicate the positions at which the predicted noise level is 45 dBA. All of the area between a contour line and any turbine that it surrounds has a predicted noise level in excess of the 45 dBA level. All of the area outside of a contour has a predicted noise level less than 45 dBA.
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6. Construction Noise Levels
Construction for a wind turbine farm is expected to include the wind turbine sites, substation, access roads, and underground transmission lines. The construction will generate temporary noise from a variety equipment. Table 6-1 provides a list of potential construction equipment for each type, phase and sub-phase for construction of a wind farm project. In general, each individual wind turbine site is estimated to take about two to three weeks to construct, with the substation taking about three to four months and the entire wind farm around twelve months.
Table 6-1. Potential Construction Equipment to be Employed on a Wind Turbine Project
Site Finishing --- Track Hoe, Skid Steer, Seed Drill Construction noise at off-site receptor locations will usually be dependent on the loudest one or two pieces of equipment in operation at a particular time. Noise levels from diesel-powered equipment at 50 feet generally range from 80 dBA to 95 dBA. Table 6-2 provides a list of common construction equipment, its maximum noise level expected at 50 feet, the typical duration a particular piece of equipment is used in any one-hour period, and the resulting hourly equivalent noise level (Leq (1 Hr)) for the piece of equipment.
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Table 6-2. Noise Source Characteristics of Construction Equipment
Truck Crane 87 16 80.6 Construction noise from the Project is not expected to create any significant impacts. That said, the following steps could be taken by the Applicant to minimize the impact of construction noise:
Limit any necessary nighttime work near residences to quiet activities such as finishing, Maintain equipment to manufacturers’ specifications, particularly mufflers, Use ambient controlled broadband backup alarms versus tonal back-up alarms, Minimize backing up on site of delivery trucks to the degree practicable, Provide a 24-hour telephone complaint number for residents to use if needed, Attempt to resolve any legitimate problems in a prompt manner, Notify residents of the expected construction schedule for the entire Project.
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7. Conclusions
Noise levels from the full and continuous operation of the Project were predicted at each non-participating and participating residence located within two miles of any Project noise source. Noise levels are predicted to be less than 45 dBA at all non-participating residences. The noise modeling (prediction) method used in this analysis has been demonstrated by Hankard Environmental and other acoustical consultants to result in predicted levels that are at least 1 dBA higher than the loudest measured hourly turbine-only noise levels. Therefore, we confidently conclude that noise levels from the Project, once operational, will be less than the Deuel County limit under any circumstances. A majority of the time, when either turbines are at less than full operation, or off, or when atmospheric conditions are less than ideal for sound propagation, noise levels will be significantly less than those reported herein The noise modeling analysis is based on the following assumptions:
1) The use of a 0.0 ground attenuation factor, which results in higher levels of predicted noise than would result from a higher ground factor. Hankard Environmental has found that measured levels never exceed those predicted using 0.0 and are often lower.
2) The model assumes atmospheric conditions that result in efficient sound propagation and therefore higher noise levels. These conditions, primarily wind direction and the presence of either a temperature inversion or a wind gradient, will only be present a certain percentage of time. When they are not present, noise levels will be lower than those reported herein. In addition, the ISO 9613-2:1996 method assumes that all receptors are downwind of all noise sources at all times. For many receptors (those with turbines located in different directions around them), this is not physically possible.
3) All turbines and transformers are modeled without any source directivity. In reality, these sources project different levels of sound in different directions. In the model, they are assumed to radiate their highest levels in all directions.
4) All turbines and transformers are assumed to be operating in their maximum-noise state, which will not always be the case.
5) All of the GE 2.3-116 and 2.82-127 wind turbines are fitted with LNTE blades. Note that the results described herein are valid for the receptor locations provided, the turbine layout analyzed, and the wind turbine sound power levels as provided by the manufacturer. If the Applicant makes any significant changes to the Project, including layout, turbine type, or mix of standard and LNTE blades, this noise analysis should be updated and compliance with the noise limit again demonstrated.
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APPENDIX A
Site Plan Figures
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A-2
Site Plan – Northwest Area
Ex. A
17-1
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Pre-Construction Wind Turbine Noise Analysis for the
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Hankard Environmental
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A-3
Site Plan – Northeast Area
Ex. A
17-1
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~ Participating
□ Project Boundary
Pre-Construction Wind Turbine Noise Analysis for the proposed Deuel Harvest North Wind Farm
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Site Plan – Southwest Area
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Pre-Construction Wind Turbine Noise Analysis for the
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March 2019
A-5
Site Plan – Southeast Area
Ex. A
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APPENDIX B
Non-Participating Receptor Locations and Noise Levels
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