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COMMENTS & TECHNICAL INFORMATION

PROPOSED RULE 5.700

5.11.2017

55 Railroad Row White River Junction, VT 05001

802.295.4999 www.rsginc.com

PREPARED FOR:

VERMONT PUBLIC SERVICE BOARD

SUBMITTED BY:

RSG

55 Railroad Row 802.295.4999 White River Junction, Vermont 05001 www.rsginc.com

May 11, 2017

Vermont Public Service Board

112 State Street, 4th Floor

Montpelier, VT 05620-2701

RE: Rule 5.700, Wind Generation Facility Sound Rulemaking

Dear Public Service Board:

RSG would like to thank the Board for the opportunity to present at the workshop on May 4. As

stated at the workshop, we appreciate the hard work the Board is putting into this process, and we

recognize the difficult nature of the technical material covered in the proposed rule.

This document provides information that supports some of what we presented at the workshop and

some additional information based on topics discussed by other parties at the workshop. We also

provide in the Appendix a copy of our presentation from May 4, and a copy of the proposed rule

with suggested changes. We hope you find this information useful as you continue to develop the

proposed rule.

Sincerely,

RSG

EDDIE DUNCAN, INCE BD. CERT.

Director

PROPOSED RULE 5.700

PREPARED FOR: VERMONT PUBLIC SERVICE BOARD

i

CONTENTS

1.0 INTRODUCTION ............................................................................................................................... 1

2.0 SOUND PROPAGATION MODELING ............................................................................................. 2

3.0 BUILDING ATTENUATION WITH WINDOWS OPEN AND CLOSED ............................................ 4

3.1 | Vermont Measurments .................................................................................................................. 4

3.2 | Literature ....................................................................................................................................... 4

3.3 | Building Attenuation Summary ...................................................................................................... 6

4.0 ANNOYANCE RESEARCH SUMMARY .......................................................................................... 7

5.0 NOISE REDUCED OPERATION (NRO) & EFFECTIVE LIMITS ..................................................... 9

6.0 INFRASOUND ................................................................................................................................ 10

7.0 SUMMARY ...................................................................................................................................... 13

8.0 WORKS CITED ............................................................................................................................... 14

APPENDIX A. RSG PRESENTATION TO THE PSB AT THE RULEMAKING WORKSHOP .............. 16

APPENDIX B. RSG SUGGESTED EDITS TO THE PROPOSED RULE .............................................. 60

List of Figures

FIGURE 1:COMPARISON OF RECENT WIND TURBINE DOSE-RESPONSE STUDY RESULTS .................................................. 8

FIGURE 2: COMPARISON OF TURBINE ON (TON) AND TURBINE OFF (TOFF) SOUND LEVELS WITH CONFIDENCE

INTERVALS AT SITE 8B (MOUNTAINOUS MULTI-TURBINE SITE) FOR THREE WIND SPEED RANGES AT 650 METERS ..... 11

FIGURE 3: WIND TURBINE SOUND PERCEPTION LEVEL RESULTS FROM YOKOYAMA ET AL, 2014 ................................... 12

1

1.0 INTRODUCTION

At the rulemaking workshop on May 4, 2017, RSG presented information on five topics that

we thought would be helpful to the Board including:

• Post-construction compliance measurements

• Aesthetics, noise annoyance, and acoustical metrics

• Outdoor-to-indoor attenuation

• Noise reduced operation of wind turbines

• PSB precedent & the proposed rule – acoustical context

A copy of the presentation is attached to this document as Appendix A.

In addition to the topics discussed during the presentation, we are providing in this

document further technical and relevant on:

• Sound propagation modeling

• Building attenuation with windows open and closed

• Annoyance research for wind turbines

• Noise reduced operation of wind turbines

• Infrasound from wind turbines.

Lastly, given the information presented at the workshop and in this document, we provide,

in Appendix B, an edited version of the proposed rule with our suggested changes.

Vermont Public Service Board Proposed Rule 5.700

2

2.0 SOUND PROPAGATION MODELING

Although, ISO 9613-2 is the most widely accepted wind turbine noise modeling algorithm,

other algorithms that have been used in wind power projects include:

• CONCAWE;

• Nord2000;

• Harmonoise; and

• NZS 6808-1998.

Both Nord2000 and NZS 6808-1998 are the approved method for specific countries (New

Zealand and Australia for NZS 6808-1998 and Nordic countries for Nord2000). NZS 6808-

1998 is a simplified method that assumes hemispherical sound propagation and uses the air

absorption method from ISO 9613-2. Nord2000 is more in-depth, complicated, and is of

similar scope to ISO 9613-2.

Harmonoise, was originally based on Nord 2000 with some refinements and was developed

over several years with the aim of becoming the standard algorithm for noise predictions in

Europe. The algorithm is available as an open source code and is implemented in several

noise prediction software packages. Harmonoise allows modeling of various meteorological

conditions, beyond the capabilities of ISO 9613-2, along with more sophisticated methods

of handling shielding and ground effects. The use of this model for wind turbine noise has

been limited, with few studies validating its accuracy.

CONCAWE was originally developed for the petroleum energy industry in Europe.

Characteristics of the model that are unique, are the ability to predict sound levels for

particular wind speeds and stability classes. The model has been used internationally for

wind turbine noise with some validation studies, though ISO 9613-2 is still more widely used

and validated.

None of these algorithms were originally developed for wind turbine noise prediction.

In the United States ISO 9613-2 is by far the most common algorithm used for sound

propagation modeling, particularly for wind turbine noise. To our knowledge, the only other

algorithm used is CONCAWE, but only in conjunction with ISO 9613-2 for special cases of

modeling annualized sound levels under varying meteorological conditions.

ISO 9613-2 assumes downwind sound propagation between every source and every

receptor, consequently, all wind directions, including the prevailing wind directions, are

taken into account. Turbines should be modeled as a single point source, located at the hub-

height of the turbine.

Selection of appropriate model input parameters is crucial to achieve conservative yet

accurate modeling results with ISO 9613-2. There have been several studies comparing

3

measured sound levels with sound propagation modeling results using ISO 9613-2.1,2,3,4

Results have shown that modeling is most accurate with the assumption of either mixed

(G=0.5) or hard (G=0) ground. Mixed ground (G=0.5), with a 2 dB 95 percent confidence

interval added to the sound power, is appropriate where the ground between the turbines

and receivers is flat or constant-gradient.

For situations where the gradient between the source and receiver is concave, hard ground is

the most appropriate, without the 95 percent confidence interval added. The modeled sound

power should be the maximum guaranteed sound power published by the turbine

manufacturer, that does not include the “K factor.” This is usually called the “apparent”

sound power.

Different receiver heights result in different interference patterns. The 4-meter (13-foot)

receiver height mimics the height of a second story bedroom and generally results in 1 to 2

dB higher predictions than a 1.5-meter (5-foot) receiver height. If a 1.5-meter microphone

height is used for post-construction monitoring, then model results should be produced at

both the 4-meter and 1.5-meter receiver height, so the model can be verified with the post-

construction data collection.

Results calculated with the parameters discuss here represent the highest 1-hour equivalent

average sound level (Leq1h) that will be emitted by a wind power project.

1 Duncan, E., and Kaliski, K., “Improving Sound Propagation Modeling for Wind Power Projects”, Acoustics ’08, 2008, Paris, France. 2 Bowdler, Dick et al,. “Prediction and Assessment of Wind Turbine Noise: Agreement about Relevant Factors for Noise Assessment from Wind Energy Projects.” Acoustics Bulletin. 34(2), pp. 35-37.

3 Evans, Tom and Cooper, Jonathan. “Comparison of Predicted and Measured Wind Farm Noise Levels and Implications for Assessments of New Wind Farms.” Acoustics Australia: April 2012. Vol. 40, No. 1. 4 RSG, et al., “Massachusetts Study on Wind Turbine Acoustics,” Massachusetts Clean Energy Center and Massachusetts Department of Environmental Protection, 2016 Chapter 6.


4

3.0 BUILDING ATTENUATION WITH WINDOWS OPEN AND CLOSED

Recent Vermont Public Service Board (PSB) dockets for wind power projects have included

sound level limits for both inside and outside of residences. This has followed the World

Health Organization (WHO) Guidelines for Community Noise (1999) that have based

exterior sound level guidelines on interior health-based sound level thresholds and assumed

building façade attenuations. The WHO assumes that residential building facades with the

windows partially open will provide 15 dB of attenuation. As a result, WHO derives their

recommended 45 dBA L(8hr) exterior sound level limit from an ideal threshold of 30 dBA

L(8hr) inside bedrooms.

Here we discuss measured and assumed façade attenuations with windows open and closed.

3.1 | VERMONT MEASURMENTS

In Vermont, there have been two cases where a residence façade was tested to determine

windows-open and close attenuation – Brouha in Sheffield and Fitzgerald in Georgia. In

Brouha, the test resulted in a sound level reduction of less than 5 dB with the windows open.

The tested residence was an anomalous example, with a large window located in a small

bedroom, and window panes that could be rotated until perpendicular with the façade, and

facing directly at the wind project. In effect, this allowed a large portion of the wall for this

room to be fully open to the outside, resulting in a low attenuation. Measurements with the

windows closed showed a sound level reduction of 25 dB.

At Fitzgerald, RSG conducted outdoor-indoor noise reduction measurements near Georgia

Mountain Community Wind (GMCW) during the winter of 2013. Results from this

measurement are detailed in the RSG memo to Martha Staskus.5 Results from this memo

indicated that that the bedroom façade with windows open resulted in an overall sound level

reduction of 15 dB, with the windows closed, the sound level reduction was 29 dB.

3.2 | LITERATURE

To determine what more “typical” windows-open and window-close façade attenuations are,

RSG conducted a literature search. Most literature lists façade attenuation as either a

weighted overall attenuation, as defined by different standards, or as the sound level

reduction of a certain sound source. The sound level reduction is achieved by subtracting the

sound attenuation value of a façade from the spectrum of a particular sound source (such as

aircraft, traffic, and railway).

Waters-Fuller and Lurcock (2007)

A thorough study on this subject was performed by Tim Waters-Fuller and Daniel Lurcock.6

The study looked at the laboratory-measured sound attenuation of several different window

types in various operational positions that included closed, closed but unlatched, and three

5 RSG. “Complaint Resolution Update – Fitzgerald Residence.” April 16, 2013 6 Waters-Fuller and Lurcock, Department for Environment, Food and Rural Affairs, UK, 2007

5

levels of openness (0.05 m2, 0.1 m2, and 0.2 m2). This was reported as either overall sound

attenuation values (Rw from ISO 717) or sound level reductions for various transportation

sound sources. Along with actual measurement results there is an extensive literature review

of other studies on the same subject. This literature review shows sound level differences for

aircraft noise between 9 and 11 dB with a 200 mm (8 inch) window opening and between 14

and 16 dB for a 25 mm (1 inch) window opening. A different study found a level difference

of 16 dB for a 100 mm opening. For road traffic, a sound level difference of 9 to 11 dB was

found when the window opening was 7 to 8 percent of the façade. Values for windows-

closed sound level reduction ranged from 21 to 30 dB for road traffic noise.

Results from the actual study showed weighted level differences between 7 and 26 dB with

windows open 0.2 m2. Most values were in the 10 to 17 dB range. Since this paper did not

look at the specific sound level difference for wind turbine noise, RSG used the sound level

attenuation for the worst-case window configuration (0.2 m2 opening) and applied it to a

wind turbine sound spectrum. The result was a sound level difference of 14 dB. For the best

case window construction the level difference was 18 dB. For the windows closed situation,

weighted level differences ranged from 33 to 46 dB. The paper does not show octave band

attenuation levels for a windows closed condition, so the values shown are generalized

reductions.

Hayes Mckenzie Partnership (2006)

In 2006 Hayes Mckenzie Partnership, Ltd published a report for the UK’s Department of

Trade and Industry (DTI).7 The report primarily concerned measurements of wind turbine

low frequency noise, but included the only in-situ measurement of windows-open wind

turbine sound level reduction measurement that we are aware of. There was only one

location, where a windows-open value was measured, which was 10 dB. Windows-closed

attenuation was measured at two locations, with sound level reduction values of 15 and 16

dB.

Environmental Protection Agency (1974)

The United States Environmental Protection Agency (EPA) developed typical windows-

open sound level reductions for transportation noise in both warm and cold climates.8 For

warm climates a 12 dB sound level reduction was specified and for cold climates a 17 dB

sound level reduction was specified for cold climates. This assumes an open area of 2 ft2

(0.19 m2). With the windows closed, a sound level reduction of 24 dB was specified for

warm climates and 27 dB for cold climates.

7 Hayes McKenzie Partnership, Department of Trade and Industry, UK, 2006. 8 U.S. Environmental Protection Agency Office of Noise Abatement and Control. Information on Levels of Environmental Noise Requisite to Protect Public Health and Welfare. Arlington, Virginia, 1974.


6

Federal Highway Administration (2011)

The Federal Highway Administration has a specified a 10 dB windows-open “noise

reduction,” used to estimate interior levels of traffic noise.9 There is no mention in the

document of what this value is based on. Note that this is paired with a noise abatement

criteria level of 67 dBA Leq1h during the maximum traffic noise hour. With the windows

closed, noise reductions between 20 and 35 dB are specified depending on the type of

window and type of building construction.

3.3 | BUILDING ATTENUATION SUMMARY

In the majority of tests, windows-open wind turbine sound level reduction, were 10 dB or

greater. Sound level reductions in excess of 15 dB are also possible and in some cases, even

20 dB may occur. In light of this, the Brouha attenuation of less than 5 dB is just one data

point at the extreme end of the low attenuation range and shouldn’t be used as a basis for

developing noise policy.

With the windows closed, sound level reductions range between 16 and 46 dB with most

values ranging between 20 and 30 dB. This value will also depend on a variety of factors.

The windows open and closed sound level reductions will be dependent on many factors

including:

• The size of the window;

• The window type;

• The amount the window is open, if it is open;

• The relative area of the façade occupied by the window;

• Sound insulation of the wall;

• Sound insulation of the window;

• Bedroom size;

• Bedroom furnishings (i.e. sound absorption); and,

• Bedroom orientation relative to the sound source.

9 Federal Highway Administration. "Highway Traffic Noise: Analysis and Abatement Guidance." 2011.

7

4.0 ANNOYANCE RESEARCH SUMMARY

Old and Kaliski, 2017 compares results from recent major dose-response studies that looked

at the relationship between modeled wind turbine sound pressure levels and the subjective

response of residents exposed to those levels.10 There have been four large, well performed

dose-response studies or series of dose-response studies performed since the year 2000. Of

these, three of the studies provide detailed information on how turbine-only sound levels

were modeled. All of these studies looked at sites that were generally rural and would have

background sound levels that are similar to Vermont.

To determine the level of agreement between the studies, differences between different

sound propagation modeling methods and parameters, and the relationship between

different sound level metrics were determined. Results were then normalized to a common

sound propagation modeling method, parameter set, and sound level metric. The sound

propagation modeling algorithm used was ISO 9613-2, with mixed ground attenuation

(G=0.5), a 4-meter receiver height, and no measurement uncertainty added to the wind

turbine sound power. These parameters are used to represent a median Leq1h for wind

turbine noise in flat and constant-gradient terrain with all turbines emitting maximum sound

power. These parameters are approximately 2 dB less conservative than what has typically

been used in Vermont for wind power project permitting. Modeling for Vermont projects

has tended to model a worst-case result instead of a median result. So, a 40 dBA result in this

paper would be equivalent to the 42 dBA modeled result for most Vermont projects.

Results are shown in Figure 1. For an exterior level of 40 dBA Leq1h (42 dBA using typically

modeled parameters in Vermont), between 7 and 10 percent are expected to be highly

annoyed outdoors and approximately 4 percent are expected to be highly annoyed indoors.

At an exterior level of 35 dBA Leq1h (37 dBA using VT modeling parameters), between 3 and

5 percent are expected to be highly annoyed outdoors and approximately 1 percent indoors.

For the sound level limit used at current utility wind power projects in Vermont (45 dBA

Leq1h) the percent highly annoyed is expected to be between 10 and 17 percent outdoors and

approximately 7 percent indoors. These levels of “percent highly annoyed” are typical for

other sources of noise. Some populations will exhibit higher or lower levels of response,

depending on non-acoustic factors.

10 Old, I., and Kaliski, K., (2017). Wind turbine noise dose response – comparison of recent studies. Proceedings of the 7th International Conference on Wind Turbine Noise, Rotterdam.


8

FIGURE 1:COMPARISON OF RECENT WIND TURBINE DOSE-RESPONSE STUDY RESULTS

9

5.0 NOISE REDUCED OPERATION (NRO) & EFFECTIVE LIMITS

It was not until after the rulemaking workshop on May 4 that we realized that Section 5.705

of the proposed rule does not allow for the use of NRO mode in the pre-construction

modeling. It states:

“[…] shall include a sound model developed for the proposed facility that reports the

expected maximum project sound levels, without using NRO mode, experienced out to a

distance where such levels are not greater than 30 dBA.” (emphasis added)

At the workshop, we contemplated how the limits to NRO technology, which can generally

achieve a 1 to 4 dB reduction, effectively make the limits in the proposed rule 35 dBA

nighttime and 39 dBA daytime. If NRO is not allowed per the draft rule, then the effective

limit would actually be 35 dBA nighttime and 35 dBA daytime. Having a different daytime

limit and nighttime limit and disallowing the use of NRO, means that the only tool a

developer has to meet the quieter nighttime limit is turbine shutdowns.

If the rule disallows the use of NRO mode, it takes away one of the noise control engineer’s

primary tools to mitigate potential impacts. It would be like making a rule for cars to be

quiet, but disallowing the use of mufflers.


10

6.0 INFRASOUND

Wind turbine-caused infrasound has become a frequently discussed topic during wind power

project permitting. The assertion has been that infrasound from wind turbines, even though

it is below the threshold of human hearing, is capable of being sensed and can cause a series

of health effects for some people. These concerns have led to research on the subject. Some

studies have focused on measuring wind turbine infrasound levels and others have studied

the human body’s ability to detect infrasound through hearing and other paths.

Recent measurement projects have shown that wind turbine-caused infrasound is several

orders of magnitude below measured hearing thresholds. The graphs in Figure 2 were taken

from the Massachusetts Study on Wind Turbine Acoustics.11 This shows that while wind

turbine-caused infrasound is measurable, it is well below established hearing thresholds at

receiver distances. The exact levels measured vary depending on the turbine model, but wind

turbine sound is almost always below measured audibility thresholds for 1/3 octave bands

with the center frequency below 25 Hz.

The Japanese Working Group on wind turbine acoustics performed a study where a

recording of wind turbine noise was filtered to eliminate different parts of the sound

spectrum and then reproduced to test subjects to test the audibility of wind turbine-caused

sound.12 Results from the study, shown in Figure 3, indicate that the audibility of wind

turbine sound emulates that of measured pure-tone thresholds. A paper by Tonin and Brett

looked at perception of infrasound and the influence expectations have regarding the effects

of infrasound on humans.13 Results showed, that any response to infrasound was more tied

to expected effects than actual infrasound exposure.

11 RSG. "Massachusetts Study on Wind Turbine Acoustics." 2016. 12 Yokoyama, Sakae, Shinichi Sakamoto and Tachibana Hideki. "Perception of Low Frequency

Components in Wind Turbine Noise." Noise Control Engineering Journal 65.5 (2014): 295-305.

13 Tonin, Renzo, James Brett and Ben Colaguiri. "The Effect of Infrasound and Negative Expectations to Adverse Pathological Symptons from Wind Farms." Journal of Low Frequency Noise, Vibration, and Active Control 0.0 (2016): 1-14.

11

FIGURE 2: COMPARISON OF TURBINE ON (TON) AND TURBINE OFF (TOFF) SOUND LEVELS WITH CONFIDENCE INTERVALS AT SITE 8B (MOUNTAINOUS MULTI-TURBINE SITE) FOR THREE WIND SPEED RANGES AT 650 METERS

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

0.5 0.63 0.8 1 1.25 1.6 2 2.5 3.15 4 5 6.3 8 10 12.5 16 20

So

un

d P

res

su

re L

eve

l (d

BZ

)

1/3 - Octave Band Frequencies (Hz)

3-6 m/s (T - On) 3-6 m/s (T - Off)

90 dBG contour

Watanabe and Moller - 1990

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

0.5 0.63 0.8 1 1.25 1.6 2 2.5 3.15 4 5 6.3 8 10 12.5 16 20

So

un

d P

res

su

re L

eve

l (d

BZ

)

6-9 m/s (T - On) 6-9 m/s (T - Off)

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

0.5 0.63 0.8 1 1.25 1.6 2 2.5 3.15 4 5 6.3 8 10 12.5 16 20

So

un

d P

res

su

re L

eve

l (d

BZ

)

>9 m/s (T - On) >9 m/s (T - Off)


12

FIGURE 3: WIND TURBINE SOUND PERCEPTION LEVEL RESULTS FROM YOKOYAMA ET AL, 2014

13

7.0 SUMMARY

Based on the information presented at the workshop and in this document, we offer the

following comments:

1. Compliance monitoring must account for background sound levels. (see Appendix

A and the Department’s presentation by Aercoustics)

2. The current PSB precedent of 45 dBA one-hour maximum protects against public

health impacts and undue adverse impact on aesthetics per the Act 250 framework.

3. Based on our experience, we think Kingdom Community Wind and other projects

built under the 45 dBA precedent would not have been built under the proposed

rule.

4. If a different limit is contemplated for aesthetics, an evening limit (5 p.m. to 9 p.m.)

that differs from the rest of the 24-hour period may make the most sense.

5. Use of NRO in pre-construction modeling should be allowed by the rule.

6. If the rule is to have different specified limits by time-of-day, decrease the difference

to not more than 4 dB. The proposed rule currently has a difference of 7 dB

between daytime and nighttime.

7. Most outdoor-to-indoor attenuation values from a variety of papers show a

reduction of 10 to 17 dB with windows open.


14

8.0 WORKS CITED

Evans, Tom and Jonathan Cooper. "Comparison of Predicted and Measured Wind Farm

Noise Levels and Implications for Assessments of New Wind Farms." Acoustics

Australia (2012): 28-36.

Federal Highway Administration. "Highway Traffic Noise: Analysis and Abatement

Guidance." 2011.

Fukushima, Akinori, et al. "Study on the Amplitude Modulation of Wind Turbine Noise:

Part 1 - Physical Investigation." Internoise. Innsbruck, Austria, 2013.

Hayes Mckenzie Partmership. "The Measurement of Low Frequency Noise at Three UK

Wind Farms." 2006.

Janssen, Sabine, et al. "A Comparison Between Exposure-response Relationships for Wind

Turbine Annoyance and Annoyance Due to other Noise Sources." Journal of the

Acoustical Society of America (2011): 3746-3753.

Kuwano, Sonoko, et al. "Social Survey on Wind Turbine Noise in Japan." Noise Control

Engineering Journal (2014): 503-520.

Michaud, David, et al. "Exposure to Wind Turbine Noise: Perceptual Responses and

Reported Health Effects." Journal of the Acoustical Society of America (2016): 1443-1453.

—. "Self-reported and Measured Stress Related Responses Associated with Exposure to

Wind Turbine Noise." Journal of the Acoustical Society of America (2016): 1467-1479.

Pedersen, Eja and Kerstin Persson-Waye. "Perception and Annoyance Due to Wind Turbine

Noise - a Dose-response Relationship." Journal of the Acoustical Society of America

(2004): 3460-3470.

—. "Wind Turbine Noise, Annoyance and Self-Reported Health and Well-being in Different

Living Environments." Occupational and Environmental Medicine (2007): 480-486.

Pedersen, Eja, et al. "Response to Noise From Modern Wind Farms in the Netherlands."

Journal of the Acoustical Society of America (2009): 634-642.

RSG. "Massachusetts Study on Wind Turbine Acoustics." 2016.

Tonin, Renzo, James Brett and Ben Colaguiri. "The Effect of Infrasound and Negative

Expectations to Adverse Pathological Symptons from Wind Farms." Journal of Low

Frequency Noise, Vibration, and Active Control 0.0 (2016): 1-14.

U.S. Environmental Protection Agency Office of Noise Abatement and Control. Information

on Levels of Environmental Noise Requisite to Protect Public Health and Welfare. Arlington,

Virginia, 1974.

Van Den Berg, Frits. "Criteria for Wind Farm Noise: Lmax and Lden." Acoustics. Paris:

European Acoustical Association, 2008. 4043-4048.

15

Waters-Fuller, Tim and Daniel Lurcock. NANR116: 'Open/Closed Window Research' Sound

Insulation Through Ventilated Domestic Windows. London, England: Department for

Environment, Food and Rural Affairs, 2007.

Yokoyama, Sakae, Shinichi Sakamoto and Tachibana Hideki. "Perception of Low Frequency

Components in Wind Turbine Noise." Noise Control Engineering Journal 65.5 (2014):

295-305.


16

APPENDIX A. RSG PRESENTATION TO THE PSB AT

THE RULEMAKING WORKSHOP

PSB Workshop,

Rule 5.700 Wind Generation Facility Sound Rulemaking

2

Introduction

Eddie Duncan, Director

• Board Certified, Institute of Noise Control Engineering

• Member of the Acoustical Society of America

- Technical Committee on Architectural Acoustics

• Education:

- M.S. Green Mountain College

Environmental Studies, Focus: Environmental Law &

Policy, Specifically Noise Policy

- B.S. Rensselaer Polytechnic Institute

Engineering Science, Focus: Acoustics

3

Introduction

RSG’s Experience

• Involved in noise assessments of wind power since 1993.

- Maine Land Use Regulatory Commission

• Studied over 80 proposed or installed wind power projects.

- Maine to Hawaii

- Including Deerfield Wind, Kingdom Community Wind, Georgia

Mountain Community Wind, and others in development

• Conduct research on wind turbine acoustics.

- Massachusetts Clean Energy Center

- Lawrence Berkeley National Laboratory (U.S. DOE)

• Staff regularly publish papers and technical presentations on wind

turbine acoustics.

• Staff co-chair of INCE Wind Turbine Technical Activity Committee.

4

Introduction

Presentation Topics

• Post-Construction Compliance Measurements

• Aesthetics, Noise Annoyance, and Acoustical Metrics

• Outdoor-to-Indoor Attenuation

• Noise Reduced Operation of Wind Turbines

• PSB Precedent & the Proposed Rule – Acoustical Context

Post-Construction Compliance

Measurements

6

Post-Construction Compliance Measurements

RSG’s experience is that the proposed methodology does not cost less than

other alternatives and will not necessarily yield accurate results.

Proposed Rule’s Economic Impact Statement

• The Board’s rule results in “…Compliance costs that are relatively

lower than other alternatives considered.”

• “…by requiring that monitoring occur under worst-case conditions

where turbine sound levels will be at their loudest output, and

background sound levels at their lowest.”

• Does away with accounting for background sound levels.

• Hypothesizes that the proposed methodology, “…allows for

monitoring campaigns to be of significantly shorter duration…”

7


Proposed rule is similar to Maine’s compliance procedure.

• Arithmetic average of twelve, 10-minute intervals from the same

measurement period. (5.704)

• Measurements when wind turbine sound is dominant.

- Nighttime

- Downwind – within 45° of the acoustic center of the five nearest

turbines

- Maximum surface wind speeds (at 10 meters) of 6 mph or less

- Hub height wind speeds able to generate maximum turbine

sound power ±1 dB

This requires:

• Long-term monitoring similar to other methods because finding these

conditions can be very difficult.

• Installation of a temporary 10-meter mast in a cleared location.

8


Example1: Maine Project

• 4 compliance monitor

locations = 4 wind directions

• Weather forecasts monitored

on a weekly basis for nine

months.

• Monitored over 7 periods for

53 total days.

• Valid Periods

– Monitor A: 7, not 12

– Monitor B: 0, not 12

– Monitor C: 8, not 12

– Monitor D: 0, not 12

9


Example 2: Maine Project• 1 continuous sound monitor

• Valid Periods

– Year 1: 5 days of data analyzed to

find 12 periods


find 12 periods

– Year 3: 11 days of data analyzed

to find 12 periods


find 12 periods


find 12 periods

• Still had to filter out extraneous

events such as bird calls.

10


Proposed rule is similar to Maine’s compliance procedure.

• Arithmetic average of twelve, 10-minute intervals from the same

measurement period. (5.704)

• Measurements when wind turbine sound is dominant.

- Nighttime

- Downwind – within 45° of the acoustic center of the five nearest

turbines

- Maximum surface wind speeds (at 10 meters) of 6 mph or less

- Hub height wind speeds able to generate maximum turbine

sound power ±1 dB

Quite problematic to capture.

Significant data analysis required.

Amounts to a Continuous Monitoring Exercise.

11


Turbines are not the only

sound sources that are aloft

Wind

Gradient

12


Turbines are not the only

sound sources that are aloft

Wind

Gradient

In a forested landscape with

hills or mountains, high

winds aloft and low winds

below results in sound

generated not only from

wind turbines but from the

forest as well.

High winds in a forest, particularly with no

leaves, can easily be confused with wind

turbine sound.

13


Recommendations

1. Account for background sound levels.

a) Turbine shut-down method works well.

b) Shielding method also works if locations are selected properly.

c) Proxy monitor locations are problematic for hilly terrain and

heterogeneous landscapes. Don’t seem to work well in the

Northeast.

2. Keep the current instrumentation, personnel, and calibration

requirements in Section 5.707.

3. Use the post-construction measurements to verify and modify, if

necessary, the pre-construction sound modeling.

Aesthetics, Noise Annoyance,

& Acoustical Metrics

15

Aesthetics, Noise Annoyance, & Metrics

Generally, aesthetics is not something the professional acoustics community

studies or talks about.

• Sound quality – typically applied to product design

• Natural & cultural sounds as a natural resource – National Park Service

• Acoustical aesthetics in rural working landscapes – not addressed

Except in Act 250

• Criterion 1 – Air Pollution – Noise covered as a health impact.

• Criterion 8 – Aesthetics

- Noise not explicitly mentioned in the statute

- Case law covers it as an aesthetics issue

16


Quechee Test

• Developed by landscape architects for the Environmental Board in

Quechee Lakes Corporation, 1985

• Two Part Test

1. Is the project adverse? Does it fit the context of the area?

2. If found to be adverse, Is the project unduly adverse?

a. Does the project violate a clear, written community standard

intended to preserve the aesthetics or scenic natural beauty of

the area?

b. Does the project offend the sensibilities of the average

person?

c. Has the Applicant failed to take generally available mitigating

steps which a reasonable person would take to improve the

harmony of the proposed project with its surroundings?

17


Quechee Test


person?

Threshold: Would the sound be considered shocking and

offensive to the average person?

18


Quechee Test


person?

Threshold: Would the sound be considered shocking and

offensive to the average person?

If the Board is considering aesthetics in it’s decision-making

process, is a daytime limit of 42 dBA and a nighttime limit of 35

dBA necessary to keep the average person from being shocked

and offended?

19


Noise Annoyance

• More commonly studied in acoustics than aesthetics

• Fairly standardized methodologies (ISO/TS 15666:2003)1

- Social surveying methods

- 0 to 100 scale, 28/50/72 - lightly/moderately/highly annoyed2

- Dose-response relationships – at sound level of X dBA, causes % of

a population to be lightly, moderately, or highly annoyed.

• WHO’s Guidelines for Community Noise3

- Serious Annoyance, daytime and evening, 55 dBA Leq16hr

- Moderate Annoyance, daytime and evening, 50 dBA Leq16hr

1. ISO/TS 15666:2003. Acoustics – Assessment of noise annoyance by means of social and socio-acoustic surveys.

2. Miedema, H.M.E., & Vos, H. (2004). Noise annoyance from stationary sources: Relationships with exposure metric day-evening-night level (DENL) and their confidence

intervals. The Journal of the Acoustical Society of America, 116(1), 334-343.

3. Berglund, B., Lindvall, T., & Schwela, D.A. (1999). Guidelines for community noise. World Health Organization.

20


Noise Annoyance – Wind Turbine Specific Studies

• Several studies, but most use different acoustical metrics.1,2,3

• Results from Swedish & Dutch, Japanese, and Canadian studies have

been normalized to a common metric.4

- A-weighted hourly equivalent average sound level: LAeq1hr

- Modeled using ISO 9613-2, G=0.5, 4 meter high receivers

o These modeling parameters would yield results 2 dB lower than

what is currently used in Vermont.

o Doesn’t include turbine sound power uncertainty.

1. Janssen, S., Vos, H., Eisses, A., & Pedersen, E. (2011). A comparison between exposure-response relationships for wind turbine annoyance and annoyance due to other

noise sources. The Journal of the Acoustical Society of America, 130(6), 3746-3753.

2. Kuwano, S., Yano, T., Kageyama, T., Sueoka, S., and Tachibana, H., (2014). Social survey on wind turbine noise in Japan. Noise Control Engineering Journal, 62(6),

503-520.

3. Michaud, D., et.al. (2016). Exposure to wind turbine noise: Perceptual responses and reported health effects. The Journal of the Acoustical Society of America, 139(3),

1443-1454.

4. Old, I., and Kaliski, K., (2017). Wind turbine noise dose response – comparison of recent studies. Proceedings of the 7th International Conference on Wind Turbine Noise,

Rotterdam.

21


• At 43 dBA (equivalent to Vermont’s 45 dBA one-hour maximum):

- 15% highly annoyed - Swedish, Dutch, & Health Canada Studies

- 10% highly annoyed – Japanese Study

22


Noise Annoyance – Additional Observations

• Attitudinal variables strongly affect noise annoyance1,2,3,4

- Fear

- Belief that the noise could be prevented

- Perceived fairness in the decision making process

- Awareness of non-noise problems related to the noise source

- Perceived importance of the source of noise

- Personal benefit

• Annoyance occurs primarily when spending time outdoors with

activities such as relaxing, picnicking, or barbecuing.6

1. Fields, J.M. (1993). Effect of personal and situational variables on noise annoyance in residential areas. The Journal of the Acoustical Society of America, 93(5), 2753-

2763.

2. Miedema, H.M.E., & Vos, H. (1999). Demographic and attitudinal factors that modify annoyance from transportation noise. The Journal of the Acoustical Society of

America, 105(6), 3336-3344.

3. Miedema, H.M.E., & Vos, H. (2004). Noise annoyance from stationary sources: Relationships with exposure metric day-evening-night level (DENL) and their confidence

intervals. The Journal of the Acoustical Society of America, 116(1), 334-343.

4. Michaud, D.S., et.al. (2016). Personal and situational variables associated with wind turbine noise annoyance. The Journal of the Acoustical Society of America, 139(3),

1455-1466.

5. van Kamp, I., Job, R.F.S., Hatfield, J., Haines, M., Stellato, R.K., & Stansfeld, S.A. (2004). The role of noise sensitivity in the noise-response relation: A comparison of

three international airport studies. The Journal of the Acoustical Society of America, 116(6), 3471-3479.

6. Pedersen, E., & Waye, K.P. (2004). Perception and annoyance due to wind turbine noise—a does-response relationship. The Journal of the Acoustical Society of

America, 116(6), 3460-3470.

23


Given: Annoyance occurs primarily when spending time outdoors with

activities such as relaxing, picnicking, or barbecuing.

• Does it even make sense to have nighttime limits to address

aesthetics?

• Perhaps, if a different limit was needed for aesthetics, an evening limit

(5 p.m. to 9 p.m.) that differs from the rest of the 24 hour period would

make the most sense.


America, 116(6), 3460-3470.

24


Given:

• Per annoyance research, the current 45 dBA one-hour maximum level

limit used in Vermont results in 10 to 15% of population exposed to

those levels being highly annoyed.

• For the proposed rule:

- 35 dBA night: 2.5% highly annoyed (outdoors)

- 42 dBA day: 6 to 9% highly annoyed (outdoors)

Propose:

• The current PSB precedent protects against the average person being

shocked and offended.

• The current PSB precedent protects against undue adverse impact to

aesthetics.


America, 116(6), 3460-3470.

Outdoor-to-Indoor Attenuation

26


• Current PSB precedent has been based on the World Health

Organization (WHO) guideline of 45 dBA L8hr outside bedroom

windows which is derived from a threshold of 30 dBA L8hr inside

bedrooms to protect against sleep disturbance.

- 15 dB of attenuation for a partially open window

• Vermont tests (2 data points)

- Sheffield (Brouha): less than 5 dB of attenuation (windows open)

o Large windows located in a small bedroom

o Window panes that can rotate perpendicular with the façade

- Georgia (Fitzgerald): 15 dB of attenuation (windows open)

o Standard sized window

27


Literature Review (Additional Data Points)

• Waters-Fuller 7 Lurcock (2007)1

- 7 to 26 dB reduction with windows open 0.2 m2 (2.2 ft2)

- Most values between 10 to 17 dB reduction

- When attenuation values applied to a wind turbine sound

spectrum:

o 14 dB worst-case

o 18 dB best-case

• Hayes McKenzie Partnership (2006) 2

- Focused on wind turbine acoustics

- One window-open measurement: 10 dB reduction

1. Waters-Fuller and Lurcock, Department for Environment, Food and Rural Affairs, UK, 2007.

2. Hayes McKenzie Partnership, Department of Trade and Industry, UK, 2006.

28


Literature Review (Additional Data Points)

• Environmental Protection Agency (1974)

- 12 dB reduction for warm climates, windows open 0.19 m2 (2 ft2)

- 17 dB reduction for cold climates, windows open 0.19 m2 (2 ft2)

• Federal Highway Administration (2011)

- Uses a 10 dB reduction for windows open, all climates

29


Takeaway

• While 5 dB or less of attenuation is possible, it is only one data point.

• Reductions between 10 and 15 dB are more common.

• In some cases, 20 dB reductions may be present.

• Depends on a number of factors:

- Window size and type

- Amount open

- Window area relative to that of the façade

- Sound insulation of the wall and window

- Bedroom size, furnishings, and orientation to the sound source

Noise Reduced Operation (NRO)

of Wind Turbines

31

Noise Reduced Operation of Wind Turbines

Section 5.703 of the proposed rule

• Daytime 42 dBA

• Nighttime 35 dBA

Sound Generation by Wind Turbines

• Aerodynamics – primary source

• Mechanical (nacelle) – secondary

• Noise Reduced Operation (NRO)

reduces aerodynamic noise.

32


Designing a Wind Power Project

• Developers design the entire project to the most stringent sound

level limit.

- Array layout

- Turbine model

- NRO

- Shutdowns

• When daytime and nighttime standards vary, NRO is the tool that is

used to regulate sound emissions.

• Shutdowns effect the economics of a project too strongly making

them infeasible.

33


How does NRO work?

• Blades are pitched

• Often a slight RPM reduction

• Often modest power losses

• Operational protocols, typically driven by software

- Time of day

- Wind direction

- Wind speed

- Different protocols for individual turbines

34


Limits to it’s usefulness

• 1 to 3 dB reduction is typical

• Greater than 4 dB, only offered by one manufacturer

• 1 to 2 dB reduction - modest power losses

• 3 to 4 dB reduction – greater than modest power losses

Proposed Rule 5.700 Context

• 7 dB difference between daytime and nighttime limits (42 dBA to 35

dBA).

• Projects will need to be designed to 35 dBA, likely using NROs.

• If shutdowns are needed, project economics are affected too

strongly.

• With 4 dB NRO, the effective daytime limit is 39 dBA.

35


Developers have tools to reduce sound emissions from wind turbines,

But

There are limits to the range of reductions that are achievable.

Recommendation

1. If Rule 5.700 is to have different specified limits by time-of-day,

decrease the difference to not more than 4 dB.

PSB Precedent & the Proposed

Rule – Acoustical Context

37

PSB Precedent & the Proposed Rule

From previous testimony, presentations, and submissions:

• Current precedent 45 dBA one-hour maximum, exterior, guards against

public health impacts.

• Same limit used in Kingdom Community Wind, Georgia Mountain

Community Wind, and Deerfield Wind.

Proposed Rule of 35 dBA nighttime and 42 dBA daytime goes beyond

protecting public health.

38


Effective Limit is Lower than Proposed

• With limitations to NRO technology and how projects are designed,

the effective limit is 35 dBA nighttime and 40 dBA daytime.

• Since Section 5.705 requires potential model error to also be added

on to each source emission, the effective limits are even lower than

35 dBA nighttime and 40 dBA daytime.

39


Closing Thoughts

• Under the proposed rule, Kingdom Community Wind, which has provided

over 700,000 MWhs of clean power to the Vermont grid and likely other

projects built under the 45 dBA precedent, would not have been built.

40


Closing Thoughts




• Compliance monitoring must account for background sound levels.

41


Closing Thoughts





• The current PSB precedent of 45 dBA one-hour maximum protects against

public health impacts and undue adverse impact on aesthetics per Act 250

framework.

42


Closing Thoughts





• The current PSB precedent of 45 dBA one-hour maximum protects against

public health impacts and undue adverse impact on aesthetics per Act 250

framework.

• If a different limit was needed for aesthetics, an evening limit (5 p.m. to 9

p.m.) that differs from the rest of the 24 hour period would make the most

sense.

www.rsginc.com

Contacts

www.rsginc.com

ContactsEddie Duncan, INCE Bd. Cert.Director

[email protected]


60

APPENDIX B. RSG SUGGESTED EDITS TO THE

PROPOSED RULE

Effective Date: Vermont

Public Service Board

Rule 5.700

Page 1 of 11

5.700 RULE ON SOUND LEVELS FROM WIND GENERATION FACILITIES

5.701 Purpose and Applicability This rule establishes standards and procedures related to sound emissions from wind

generation facilities that apply for a certificate of public good (“CPG”) pursuant to 30 V.S.A.

§ 248 or § 8010 on or after July 1, 2017.

5.702 Definitions For the purposes of this Rule, the following definitions shall apply: (A) Board: the Vermont Public Service Board.

(B) CPG: certificate of public good.

(C) CPG Holder: a person or company who has received a CPG pursuant to 30 V.S.A.

§ 248 or § 8010 for a wind generation facility.

(D) dB: a unit used to measure the intensity of a sound wave using a logarithmic scale.

(E) dBA: A-weighted decibel

(F) Department: the Vermont Department of Public Service.

(G) Petitioner: a person or company who has filed a petition for a CPG pursuant to 30

V.S.A. § 248 or 8010 to construct and/or operate a wind generation facility.

(H) Plant capacity: pursuant to 30 V.S.A. § 8002, “plant capacity” means the rated

electrical nameplate for a wind generation facility.

(I) Residence: a permanent structure for human habitation that is occupied by one or

more people for a minimum of 90 days each year.

(J) SCADA: supervisory control and data acquisition or similar system capable of

measuring and recording turbine operation and meteorological data in one-minute

time intervals.

(K) Wind generation facility: a wind-driven electric generation facility for which a

petition for a CPG pursuant to 30 V.S.A. § 248 or § 8010 is submitted to the Board

on or after July 1, 2017.

(L) Leq: Continuous sound level in dB equivalent to the total sound energy over a given

period of time.

(M) LA90: Sound level exceeded during 90% of a measurement period.

(N) LA10: Sound level exceeded during 10% of a measurement period.

(O) LA50: Sound level exceeded during 50% of a measurement period. (P) Participating landowner: a landowner who has signed a written agreement with a

Petitioner stating that the sound emissions standards established by this rule do not

apply to the landowner’s property.

(Q) NRO mode: Noise Reduced Operation mode, in which the rotational speed of wind

turbines is limited in order to reduce their sound emissions.

(R) Facility-only sound: Sound attributable to a wind generation facility not including

background sound.

(S) Background sound: The sound attributed to all sources, other than the Facility-only

sound.

5.703 General Rule No wind generation facility shall emit sound levels in excess of the following during

operation:



Rule 5.700

Page 2 of 11

(A) Facilities with a plant capacity of 150 kilowatts or less. Operation of facilities with a

plant capacity of 150 kilowatts (“kW”) or less shall not result in: (1) audible

prominent discrete-frequency tones pursuant to the latest revision of ANSI S1.13

Annex A at a distance of 100 feet from the residences of non-participating

landowners; and (2) Facility-only sound pressure levels in excess of 42 dBA

between the hours of

7 A.M. and 9 P.M. and 35 dBA between the hours of 9 P.M. and 7 A.M. at a

distance of 100 feet from the residences of non-participating landowners. In lieu of

demonstrating compliance with this limit, a petitioner may propose to locate a wind

generation facility such that every sound-producing element of the facility will be set

back horizontally no less than ten (10) times the turbine’s height, as measured from

base to the tip of a blade in the upright, vertical position, from the residences of non-

participating landowners.

(B) Facilities with a plant capacity of greater than 150 kW. Operation of facilities with a

plant capacity of greater than 150 kW shall not result in: (1) audible prominent

discrete-frequency tones pursuant to the latest revision of ANSI S1.13 Annex A at a

distance of 100 feet from the residences of non-participating landowners; and (2)

Facility-only sound pressure levels in excess of 42 *** dBA between the hours of 7

A.M. and 9 P.M. and 35 *** dBA between the hours of 9 P.M. and 7 A.M. at a

distance of 100 feet from the residences of non-participating landowners. Each

sound-producing element of such facilities shall be set back horizontally no less than

ten (10) times the turbines’ height, as measured from base to the tip of a blade in the

upright, vertical position, from the residences of non-participating landowners.

5.704 Compliance with the Sound Level Limits

Compliance with the sound level limits shall be determined in accordance with the following:

(A) Sound level data shall be aggregated in 10-minute measurement intervals within a

given compliance measurement period under the conditions set forth in Section 5.707

of this rule. Each hour of the compliance measurement period shall have six discrete

10-minute measurement intervals.

(B) Compliance will be demonstrated when the arithmetic average of the equivalent

sound level of, at a minimum, twelve 10-minute measurement intervals in a given

compliance measurement period is less than or equal to the sound level limit set forth

in Section 5.703. The loudest valid 10-minute measurement intervals shall be

included in the calculation of the arithmetic average.

(C) If a given compliance measurement period does not produce a minimum of twelve

10-minute measurement intervals under the atmospheric and site conditions set forth

in Section 5.708(E) of this rule, six or more 10-minute measurement intervals from

one compliance measurement period may be combined with six or more 10-minute

intervals from other compliance measurement periods (e.g., other days). Compliance

will be demonstrated when the arithmetic average of the combined 10-minute

measurement intervals is less than or equal to the applicable equivalent sound level

Commented [A1]: See Sections 3, 4, 5, and 7 and Appendix A of Comments & Technical Information provided by RSG in the May 11, 2017 submission to the Board. To the extent that the lower limits, are meant to public health impacts, the current limit of 45 dBA already does that. To the extent that the lower limits are meant to address aesthetic concerns, the current limit of 45 dBA already does that per Act 250’s Quechee test framework and scientific studies regarding noise annoyance due to wind turbine sound. To the extent that the lower limits are meant to indirectly address indoor sound levels based on assumptions that the indoor-outdoor attenuation is low, we refer the Board to the literature that shows 10-17 dB reduction with windows open is most typical. If the rule is to have different specified limits by time-of-day, the practical limit to the range is 4 dB based on NRO technology.



Rule 5.700

Page 3 of 11

limit set forth in Section 5.703. The loudest valid 10-minute measurement intervals

shall be included in the calculation of the arithmetic average.

5.705 Pre-Construction Sound Modeling

All petitions to construct and operate a wind generation facility, except for those for a wind generation facility with a capacity of 50 kW or less, shall include a sound model developed

for the proposed facility that reports the expected maximum project sound levels, without using

NRO mode, experienced out to a distance where such levels are no greater than 30 dBA. A

petitioner must submit the following information with its petition:

(A) A map depicting the location of all proposed sound sources associated with the wind

generation facility, property boundaries for the proposed facility, and all residences

within the 30 dBA contour.

(B) A description of the major sound sources, including tonal sound sources, associated

with operation and maintenance of the facility. The sound model shall be based on

the technical specifications of the turbine model(s) with the highest manufacturer

apparent sound power level under consideration for use at the facility.

(C) The results of sound modeling pursuant to ISO 9613-2, including a description of the

equivalent continuous sound levels expected to be produced by the sound sources at a

distance of 100 feet from the residences of non-participating landowners. The

description shall include a full-page isopleths map depicting the predicted sound

pressure levels expected to be produced by the wind generation facility at a distance

of 100 feet from each residence of a non-participating landowner within the 30 dBA

isopleth. The predictive model used to generate the equivalent sound levels expected

to be produced by the sound sources shall be designed to represent the “predictable

worst case scenario.” All model inputs shall be the most realistic and conservative

available for each of the items listed below unless otherwise approved by the Board,

and shall include, at a minimum, the following:

(1) The maximum apparent sound power output (IEC 61400-11) of the sound

sources;

(2) Modeling in accordance with ISO 9613-2, with each turbine modeled as a

point source at hub height;

(3) All turbines operating at full rated sound output;

(4) Attenuation due to air absorption, with conditions set to 10ºC and 70%

relative humidity;

(5) Attenuation due to ground absorption/reflection, based on mixed ground

conditions (G=0.5) for propagation over land and hard conditions (G=0.0)

for propagation over water;

(6) Attenuation due to three-dimensional terrain;

(7) A receiver heights of four (4) meters and one and a half (1.5) meter;

(8) Attenuation due to meteorological factors such as relative wind speed and

direction (wind rose data), temperature/vertical profiles and relative

humidity, sky conditions, and atmospheric profiles;

Commented [A2]: See Workshop Presentation in Appendix A of Comments & Technical Information provided by RSG in the May 11, 2017 submission to the Board. We recommend rewriting this Section to reflect a methodology that accounts for background sound levels using either the turbine shutdown method, shielding method, or perhaps the method proposed by the Department’s expert.

Commented [A3]: See Section 5 of Comments & Technical Information provided by RSG in the May 11, 2017 submission to the Board.

Commented [A4]: See Section 2 of Comments & Technical Information provided by RSG in the May 11, 2017 submission to the Board. This is also in response to a question from the Board during the workshop on what height should be used. Four meters is recommended for preconstruction compliance demonstration, but one and a half meter should be provided as well, so that post-construction compliance monitoring can be conducted at 1.5 meters for model validation.



Rule 5.700

Page 4 of 11

(9) An adjustment to the maximum rated output of the turbines to

account for turbine manufacturer uncertainty, determined in accordance

with the most recent version of the IEC 61400 Part 11 standard; and

(10) A disclosure of the model’s error, which is intended to account for

uncertainties in the modeling of sound propagation for wind energy

developments. This error shall be accounted for and incorporated as an

addition to the maximum rated output of the sound sources.

(D) A description of proposed major sound control measures, including their locations

and expected acoustical performance;

(E) A comparison of the expected sound pressure levels from the proposed wind

generation facility with the applicable sound pressure level limits of Section 5.703.

(F) A description and map identifying compliance testing locations on or near the

proposed wind generation facility site. The identified compliance testing locations

shall be selected to take advantage of prevailing downwind conditions and shall be

able to meet the site selection criteria outlined in Section 5.707(D). The identified

locations should include those locations that are expected to experience the highest

model-predicted equivalent sound levels. The locations should be free from sources

of material sound contamination.

(G) Prior to commencing site preparation or construction of the facility, a CPG Holder

shall update, supplement, and/or amend the sound modeling to reflect any changes to

the sound-producing elements of the facility. An opportunity to review and comment

on any change to the sound modeling, and to request a hearing, shall be given to all

parties to the 30 V.S.A. § 248 proceeding who have standing on the issue of sound.

The Board may, in its discretion, grant a hearing if a party who has standing on the

issue of sound demonstrates that the revised sound modeling represents a likelihood

of an exceedance of the applicable sound emissions standard specified in Section

5.703. If the Board holds a hearing, the CPG Holder may not commence site

preparation or construction of the facility until the Board resolves the issue.

5.706 Post-Construction Sound Monitoring

Sound monitoring shall take place during the times specified in section 5.708(D), in accordance with the requirements of this rule and any requirements of the CPG, which shall

specify the minimum number of compliance monitoring locations, the radius from the nearest

facility turbine in which monitoring locations may be selected, and the time period of

monitoring. The monitoring will be used to verify the accuracy of the pre-construction modeling

and facility compliance with CPG conditions and the requirements of this rule. In addition to the

requirements of this rule and the CPG, at its discretion, the Board may require additional

monitoring if the results of the initial post-construction sound monitoring or changes to the

facility or its operation indicate that exceedances of the sound-level limit are likely.

(A) Monitoring by the State. Post-construction sound monitoring shall be conducted

under the direct supervision and control of a State of Vermont agency or agencies

Commented [A5]: This is not needed per wind turbine model verification studies discussed in Section 2 of Comments & Technical Information provided by RSG in the May 11, 2017 submission to the Board.



Rule 5.700

Page 5 of 11

designated by the Board. The post-construction sound monitoring shall be paid for by

the CPG Holder.

(B) Monitoring Locations. A petition for a CPG for a wind generation facility shall

include proposed monitoring locations for post-construction monitoring. The

proposed locations shall include residential locations that are expected to experience

the highest model-predicted equivalent sound levels and are consistent with the

requirements of Section 5.707(D). The proposed locations should be free from

sources of material sound contamination. Any change in monitoring locations must

be approved in advance by the Board.

(C) Modification of pre-construction sound modeling. A CPG Holder is required to

identify the appropriate inputs and/or assumptions, and modify the pre-construction

sound modeling if the post-construction sound monitoring indicates that there is a

reasonable likelihood that the expected highest sound levels at any of the monitoring

locations would be equal to or greater than 3 dBA above those modeled, or would

result in an exceedance of the sound level standard specified in Section 5.703. All

parties to the 30 V.S.A. § 248 or § 8010 proceeding who have standing on the issue of

sound shall be given an opportunity to review and comment on any change to the

sound modeling. The Board may, in its discretion, grant a hearing if a party who has

standing on the issue of sound demonstrates that the revised sound modeling indicates

a likelihood of an exceedance of the applicable sound emissions standard specified in

Section 5.703.

5.707 Sound Monitoring Methodology

(A) Measurement Personnel Measurements shall be supervised by personnel who are

well qualified by training and experience in measurement and evaluation of

environmental sound. Certification through the Institute of Noise Control Engineering

shall meet the qualification requirements of this section.

(B) Measurement Instrumentation The sound meter or alternative sound measurement

system used shall meet all appropriate industry standards and specifications. Each

monitoring site shall include installation of an anemometer and other equipment or

sensors capable of gathering and recording weather conditions at the microphone (10-

meter-level wind speed, wind direction, temperature, and precipitation) and be equipped

with enhanced-performance windscreens capable of significantly reducing or eliminating

wind-induced noise contamination over the microphone. The measurement

instrumentation shall meet the following specifications unless otherwise approved by the

Board:

1. A sound level meter or alternative sound level measurement system used

shall meet the Type 1 performance requirements of American National

Standard Specifications for Sound Level Meters, ANSI S1.4.

2. An integrating sound level meter (or measurement system) shall also meet the

Commented [A6]: 10-meter wind speed monitoring is not necessary and makes the post-construction monitoring process cumbersome. Monitoring wind speeds at microphone height would suffice.



Rule 5.700

Page 6 of 11

Type 1 performance requirements for integrating/averaging in the

International Electrotechnical Commission Standard on Integrating-Averaging

Sound Level Meters, IEC Publication 61672-1.

3. A filter for determining the existence of tonal sounds shall meet all the

requirements of the American National Standard Specification for Octave-

Band and Fractional Octave-Band Analog and Digital Filters, ANSI S1.11 and

IEC 61260, Type 3-D performance.

4. The acoustical calibrator used shall be of a type recommended by the

manufacturer of the sound level meter and one that meets the requirements of

American National Standard Specification for Acoustical Calibrators, ANSI

S1.40.

5. Anemometer(s) used for surface (10 meter (m)) (32.8 feet) wind speeds shall

have a minimum manufacturer specified accuracy of ±1 mph providing data in

10-second integrations and 10 minute average/maximum values for the

evaluation of atmospheric stability.

6. Audio recording devices shall be time stamped (hh:mm:ss), recording the

sound signal output from the measurement microphone to be used for

identifying events. Audio recording and compliance data collection shall be

measured through the same microphone/sound meter and bear the same time

stamp.

(C) Equipment Calibration

1. The sound level meter shall have been calibrated to the manufacturer’s

specification no more than 24 months prior to completion of a measurement

campaign, and the microphone’s response shall be traceable to the National

Institute of Standards and Technology.

2. Field calibrations shall be recorded and documented in compliance monitoring

reports.

3. The 10-meter anemometer(s) and vane(s) shall have been calibrated to the

manufacturer’s specification no more than 24 months prior to completion of a

measurement campaign.

(D) Compliance Measurement Location, Configuration, and Environment

1. Compliance measurement locations shall be approved by the Board during its

review of a facility’s request for a CPG and shall be representative of the non-

participating residences expected to experience the highest equivalent sound

levels from routine operation of the wind generation facility, subject to

permission from the respective property owner(s).



Rule 5.700

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a. To the greatest extent possible, compliance measurement locations shall

be at the center of unobstructed areas that are maintained free of

vegetation and other structures or material that is greater than 2 feet in

height for a 75-foot radius around the sound and audio monitoring

equipment.

b. To the greatest extent possible, meteorological measurement locations

shall be at the center of open flat terrain, inclusive of grass and minimum

number of obstacles that are greater than 6 feet in height for a 250-foot

radius around the anemometer location. Meteorological measurements

shall be taken at the monitoring location at or above the height of the

audio/acoustic microphone.

c. Meteorological measurements of wind speed and direction shall be

collected using anemometers at a 10-meter height (32.8 feet) above the

ground. Results shall be reported, based on 10-second integration

intervals, synchronously with turbine nacelle measurements and

measurements made at the sound-meter level at 10-minute measurement

intervals. The wind speed average and maximum for each 10-minute

interval shall be reported.

d. The sound microphone shall be positioned at a height of approximately 4

to 5 feet above the ground, and oriented in accordance with the

manufacturer’s recommendations.

e. When possible, measurement locations should be at least 50 feet from any

sound source. The proposed locations should be free from sources of

material sound contamination. Any non-facility sources of sound shall be

noted in the analysis.

4. The CPG Holder shall provide all relevant turbine operational data for the

monitoring period, including SCADA data for all turbines, the date, time, and

duration of any noise reduction operation or other operational changes that

occur during the compliance measurement period.

5.708 Compliance Data Collection, Measurement, and Retention Procedures

(A) Measurements of operational, sound, audio, and meteorological data shall occur as set forth in Section 5.707.

(B) All operational, sound, audio, and meteorological data collected shall be retained by

the State of Vermont agency or agencies designated by the Board for the life of the

project and subject to inspection upon request.

(C) Monitoring and data collection shall occur at a minimum:

1. Once during each of the first four years of facility operation, provided, however,



Rule 5.700

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that if after three years the monitoring does not detect and the updated sound

model does not predict any exceedances of the applicable equivalent sound

pressure level in Section 5.703, the fourth year of monitoring and data collection

under this subsection shall not be required;

2. Once during each successive fifth year thereafter until the facility is

decommissioned; and

3. In response to a complaint if ordered by the Board.

a. The Board in its discretion may require sound monitoring for a wind

generation facility in response to a complaint if the Board determines that

a complaint raises a reasonable possibility that a wind generation facility

is operating in excess of the sound level limits required by this rule. In

making its determination, the Board shall consider:

i. The details of the complaint;

ii. Any response thereto filed by the operator of the wind generation

facility; and

iii. Any response and recommendation by the Department of Public

Service after its review of the complaint, the facility operator’s

response, and any attempts made to resolve the complaint under

the complaint response procedure(s) issued by the Vermont

Department of Public Service pursuant to Section 5c of Public Act

130 (2016 Vt., Adj. Sess.). As part of any recommendation, the

Department may propose a plan for additional sound monitoring of

the subject wind generation facility. Any such proposal should

incorporate the requirements and standards set forth in subsection

(b), below, or set forth an explanation why different requirements

and standards are being proposed.

b. Any monitoring ordered by the Board pursuant to this subsection:

i. Shall conform to the meteorological requirements set forth in

Section 5.708(E) of this rule, if possible.

ii. Shall be done under meteorological conditions as similar as

possible to the conditions existing at the time of the complaint.

iii. In the event that the monitoring cannot be performed pursuant to

the meteorological requirements set forth in Section 5.708(E) of

this rule due to prevailing meteorological or environmental

conditions at the time the complaint is filed and when the

monitoring will take place, then the Department of Public Service

may propose a plan of sound monitoring for review and approval

by the Board. Any such proposed monitoring plan should:

1. Require that sound monitoring be performed under

meteorological conditions similar to those that existed at

the time the complaint was made;

2. Provide for sound monitoring compliance testing consistent

with the requirements of Section 5.704 of this rule with



Rule 5.700

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monitoring continuing until the requisite number of

measurement intervals are collected.

iv. The sound monitoring methodology for any such proposal shall be

consistent with the requirements of Section 5.707 of this rule.

v. Microphones shall be placed in locations that avoid material sound

contamination. All microphone locations must be approved by the

Board.

vi. Primary microphones shall not be placed such that any structure

blocks the line of sight between the microphone and the facility’s

turbines (if otherwise visible).

vii. Provide a process for determination of facility-only sound. In the

event the determination of facility-only sound will rely on

subtracting background sound levels from overall sound levels (i.e.

sound levels with the facility’s turbines in operation), such

background sound levels shall be determined by measurements

taken with the facility’s wind turbines shut down for a period of at

least 30 minutes both before and after sound monitoring is

performed to determine total sound levels with the facility in

operation.

viii. The monitoring shall be performed with at least 90% of the

facility’s turbines operating at within 1dB of maximum sound

power levels. Monitoring shall continue until the requisite

amount of data is collected under these operating conditions.

ix. Measurement intervals affected by increased biological activities,

leaf rustling, traffic, high water flow, aircraft flyovers, or other

extraneous ambient noise sources that affect the ability to

demonstrate compliance shall be excluded from all compliance

report data.

x. Reporting of the results of the monitoring shall be done consistent

with the requirements of section 5.709 of this rule.

(D) All operational (SCADA), sound level and meteorological data collected during a

compliance measurement period that meets or exceeds the specified wind speed

parameters shall be submitted by the State of Vermont agency or agencies designated

by the Board to the Board for review and approval. All data shall be submitted to the

Board within 60 days of completion of the monitoring period as part of the post-

monitoring report. Audio recordings will only be submitted upon request and may be

filtered to exclude private conversations and/or submitted under a confidentiality

order.

(E) Measurements shall be obtained during weather conditions when the wind turbine

sound is dominant and overall sound levels are not influenced by non-facility sounds.

Such conditions are generally expected at night, when the measurement location is

downwind of the wind generation facility and maximum surface wind speeds (10-

meter height) are equal to or less than 6 miles per hour (mph) with concurrent turbine

hub-elevation wind speeds sufficient to generate the highest continuous apparent

Commented [A7]: To increase the likelihood finding valid periods and reduce the amount of time needed to find valid monitoring periods, consider decreasing the percentage to less than 90% or allowing turbines to be operating to within 1 dB of maximum sound power levels.



Rule 5.700

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sound power, +/- 1 dB, from the nearest wind turbines to the measurement location. A

downwind location is defined as within 45º of the direction between a specific

measurement location and the acoustic center of the five nearest wind turbines, or

fewer if the wind generation facility does not have five wind turbines. In some

circumstances, it may not be feasible to meet the wind speed and operations criteria

due to terrain features or limited elevation change between the wind turbines and

monitoring locations. In these cases, measurement periods are acceptable if the

following conditions are met:

1. The difference between the LA90 and LA10 during any 10-minute period is less than

5 dBA; and

2. The surface wind speed (10-meter height) (32.8 feet) is 6 mph or less for 80% of

the 10-minute measurement period and does not exceed 10 mph at any time, or

the turbines are shut down during the monitoring period and the difference in the

observed LA50 after shutdown is equal to or greater than 6 dBA; and

3. Observer logs or recorded sound files clearly indicate the dominance of wind

turbine(s).

(F) 4. Measurement intervals affected by increased biological activities, leaf rustling, traffic,

high water flow, aircraft flyovers, or other extraneous ambient noise sources that affect the

ability to demonstrate compliance shall be excluded from all compliance report data. The intent

is to obtain 10-minute measurement intervals that entirely meet the specific criteria and

represent facility-only sound pressure levels.

5.709 Reporting of Compliance Measurement Data

Compliance Reports shall be submitted to the Board within 60 days of the completion of the sound monitoring period. The Board will make the report publicly available. The report

shall include a certification that the required monitoring conditions were present and, at a

minimum, the following:

(A) A narrative description of the sound from the wind generation facility for the

compliance measurement period;

(B) The dates, days of the week, and hours of the day when measurements were made;

(C) The wind direction and speed, temperature, humidity, and sky condition;

(D) Identification of all measurement equipment by make, model, and serial number;

(E) All meteorological, sound, windscreen, and audio instrumentation specifications and

calibrations;

(F) All A-weighted equivalent sound levels for each 10-minute measurement interval;

Formatted: Indent: Left: 0", First line: 0"

Commented [A8]: See Workshop Presentation in Appendix A of Comments & Technical Information provided by RSG in the May 11, 2017 submission to the Board. We recommend rewriting this Section to reflect a methodology that accounts for background sound levels using either the turbine shutdown method, shielding method, or perhaps the method proposed by the Department’s expert.

Commented [A9]: If the Board decides to retain the methodology in the current proposed rule, this subsection should apply to all measurement intervals not just the circumstances where it is “not feasible to meet the wind speed and operations criteria …”, so we moved it from (E) 4. to (F)



Rule 5.700

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(G) Short-period sound level measurements (50 milliseconds or less);

(H) All LA10, LA50, and LA90 percentile levels for each 10-minute

measurement interval;

(I) All 10-minute 1/3 octave band unweighted and equivalent continuous sound levels

(dB);

(J) Should any sound data collection be observed by a trained attendant, the attendant’s

notes and observations shall be summarized and included with the Compliance

Report;

(K) All concurrent time-stamped, turbine-operational data including the date, time, and

duration of any noise-reduction operation or other interruptions in operations, if

present; and

(L) All other information determined necessary by the Board.

5.710 Complaint Response Procedures Complaints raised by residents located near the wind generation facility shall be

responded to in a manner consistent with the complaint response procedure(s) issued by the

Vermont Department of Public Service pursuant to Section 5c of Public Act 130 (2016 Vt., Adj.

Sess.)

Commented [A10]: This is not needed, and it is irrelevant to the proposed limits.

Commented [A11]: Required more specificity related to time interval.

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