Current through February, 2024
Section 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 on or after July
1, 2017.
Section
5.702 Definitions
For the purposes of this Rule,
the following definitions shall apply:
Commission: the Vermont
Public Utility Commission
Contributing turbines: the
turbine or group of turbines at a wind generation facility whose
removal from a facility sound model results in a residual
project-only predicted sound pressure level at the receptor of less
than 30 dBA or a reduction in predicted turbine contribution of at
least 6 dB at the point of measurement
CPG: certificate of public
good
CPG Holder: a person or
company who holds a CPG granted pursuant to
30
V.S.A. §
248 for a wind
generation facility
dB: a unit used to measure
the intensity of a sound wave using a logarithmic scale
dBA: A-weighted
decibel
Department: the Vermont
Department of Public Service
L A10: Sound level exceeded
during 10% of a measurement period
L A50: Sound level exceeded
during 50% of a measurement period
L A90: Sound level exceeded
during 90% of a measurement period
L eq: Continuous sound level
in dB equivalent to the total sound energy over a given period of
time
NRO mode: Noise Reduced
Operation mode, in which the rotational speed of wind turbines is
limited in order to reduce their sound emissions
Parti cipating landowner: a
landowner who has signed a written agreement with a Petitioner
stating that the sound emission and setback standards established by
this rule do not apply to the landowner's
property
Petitioner: a person or
company who has filed a petition for a CPG pursuant to
30
V.S.A. §
248 to construct
and/or operate a wind generation
facility
Plant capacity:
pursuant to
30 V.S.A. §
8002, "plant capacity" means the
rated electrical nameplate for a wind generation
facility
Residence: a permanent
structure for human habitation that is occupied by one or more people
for a minimum of 90 days each
year
SCADA: supervisory control
and data acquisition or similar system capable of measuring and
recording turbine operation and meteorological data in one-minute
time intervals
Wind generation
facility: a wind-driven electric generation facility for
which a petition for a CPG pursuant to
30
V.S.A. §
248 is submitted to
the Commission on or after July 1, 2017
Section 5.703 General Rule
No
wind generation facility shall emit sound levels in excess of the
following during operation:
(A)
Facilities
with a plant capacity up to and including 50
kilowatts . Operation of facilities with a plant
capacity up to and including 50 kilowatts shall not result in:
(1) sound pressure levels that
exceed 42 dBA more than 5% of the time at a distance of 100 feet from
the residence of a non-participating landowner; or
(2) audible prominent
discrete-frequency tones pursuant to the latest revision of ANSI
S1.13 Annex A at a distance of 100 feet from the residence of a
non-participating landowner.
(B)
Facilities
with a plant capacity greater than 50 and up to and including 150
kilowatts . Operation of facilities with a plant
capacity greater than 50 kilowatts and up to and including 150
kilowatts shall not result in sound pressure levels in excess of 42
dBA, including any penalty for tonality pursuant to Section 5.710, at
a distance of 100 feet from the residence of a non-participating
landowner.
(C)
Facilities with a plant capacity greater than 150
kilowatts . Operation of facilities with a plant
capacity greater than 150 kW shall not result in sound pressure
levels in excess of 42 dBA between the hours of 7 A.M. and 9 P.M. or
39 dBA between the hours of 9 P.M. and 7 A.M., including any penalty
for tonality pursuant to Section 5.710, at a distance of 100 feet
from the residence of a non-participating landowner.
Section 5.704
Pre-Construction Sound Modeling
(A)
Facilities with a plant capacity up to and
including 50 kilowatts . In lieu of submitting
sound modeling pursuant to Section 5.704(B), below, petitions to
construct and operate a wind generation facility with a plant
capacity up to and including 50 kilowatts may instead file the
following information with its petition:
1. All certification documents from
the Small Wind Certification Council showing the results of acoustic
sound testing;
2. The
distance to the nearest residence(s) in each cardinal direction, as
well as an analysis of the expected sound pressure level at those
residences calculated using spherical spreading.
(B)
Facilities
with a plant capacity of more than 50 kilowatts .
All petitions to construct and operate a wind generation facility
with a plant capacity of more than 50 kW shall include a sound model
developed for the proposed facility that reports the expected maximum
project sound pressure levels, without using NRO mode, modeled out to
a distance where such levels are no greater than 30 dBA. Nothing in
this subsection prohibits the submission of additional information,
including the results of additional sound modeling, that relies on
the use of NRO mode. A petitioner must submit the following
information with its petition:
1. 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.
2. 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.
3. 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 Commission,
and shall include, at a minimum, the following:
a. The maximum apparent sound power
output of the sound sources pursuant to IEC 61400-11;
b. Modeling in accordance with ISO
9613-2, with each turbine modeled as a point source at hub
height;
c. All turbines
operating at maximum apparent sound output;
d. Attenuation due to air
absorption, with conditions set to 100C and 70% relative
humidity;
e. 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;
f. Attenuation due to
three-dimensional terrain;
g. Receiver height modeled at both
1.5 and 4 meters;
h.
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;
i. An
adjustment to the maximum apparent sound power output of the turbines
to account for turbine manufacturer uncertainty, determined in
accordance with the most recent version of the IEC 61400-11 standard;
and
4. A
disclosure of any applicable error in the model;
5. A description of proposed major
sound control measures, including their locations and expected
acoustical performance;
6. 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;
7. A description
and map identifying potential 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. The identified locations shall
include those locations that are expected to experience the highest
model-predicted equivalent sound levels. The locations shall be free
from sources of material sound contamination.
8. Prior to commencing site
preparation or construction of a 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
had standing on the issue of sound. The Commission shall review and
consider all comments received on any change to the sound modeling,
and shall convene a hearing on those changes in response to a request
for a hearing from a party who had standing on the issue of sound. If
a hearing is requested, the CPG Holder may not commence site
preparation or construction of the facility until the Commission
resolves the issue.
Section 5.705 Post-Construction
Sound Monitoring Applicability
(A)
Facilities with a plant capacity up to and
including 50 kilowatts. Post-construction sound
monitoring may be required by the Commission for a facility in this
category if it is determined that exceedances of the applicable
sound-level limit are probable or as part of an investigation into
one or more complaints or for cause shown.
(B)
Facilities
with a plant capacity greater than 50 and up to and including 150
kilowatts . Sound monitoring shall take place in
accordance with Section 5.707, below, or pursuant to an alternative
monitoring plan adopted in the facility's CPG. In lieu of verifying
compliance with the applicable sound-level limit through sound
monitoring, a petitioner may propose to locate a wind generation
facility in this category such that every sound-producing element of
the facility within the turbine footprint 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 residence of a non-participating landowner.
Notwithstanding, the Commission may require sound monitoring for such
a facility if it is determined that exceedances of the applicable
sound-level limit are probable, as part of an investigation into one
or more complaints, or for cause shown.
(C)
Facilities
with a plant capacity greater than 150 kilowatts
. Sound monitoring shall take place during the times specified in
section 5.711, 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, the Commission may, at its
discretion, 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 probable, or if it is determined that exceedances of the
applicable sound-level limit are probable, as part of an
investigation into one or more complaints, or for cause shown.
Nothing in this section shall limit the ability of
the Department of Public Service to include a requirement for
additional sound monitoring as part of an administrative citation
issued pursuant to
30 V.S.A. §
30(h).
Section 5.706
Post-Construction Sound Monitoring General Requirements
(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 designated by the Commission. 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. The
proposed locations shall be free from sources of material sound
contamination. Any change in monitoring locations must be approved in
advance by the Commission.
(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 proceeding in
which a CPG was granted who had standing on the issue of sound shall
be given an opportunity to review and comment on any change to the
sound modeling, and to request a hearing. The Commission shall review
and consider all comments received on any change to the sound
modeling, and shall convene a hearing on those changes in response to
a request for a hearing from a party who had standing on the issue of
sound.
Section
5.707 Post-Construction 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, humidity,
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 Commission:
1. The sound level meter or
alternative sound level measurement system shall meet the Type 1
performance requirements of American National Standard Specifications
for Sound Level Meters, ANSI S1.4.
2. The integrating sound level
meter (or measurement system) shall also meet the Type 1 performance
requirements for integrating/averaging in the International
Electrotechnical Commission Standard on Integrating-Averaging Sound
Level Meters, IEC Publication 61672-1.
3. The 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 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) for surface (10
meter (m)) (32.8 feet) wind speeds shall have a minimum manufacturer
specified accuracy of 11 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 Commission 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
model-predicted facility-only sound levels from routine operation of
the wind generation facility, subject to permission from the
respective property owner(s). Measurement locations shall reasonably
be expected to experience downwind conditions from acoustically
significant turbines and shall be free from sources of material sound
contamination, such as high-traffic roadways, industrial or
silvicultural activity, etc. Should a site previously designated as a
monitoring location by the Commission no longer be able to meet the
requirements of this subsection, the State of Vermont agency
implementing the monitoring plan shall propose an alternative
monitoring location. An alternative measurement location shall
require Commission approval following an opportunity for comment by
all parties to the
30
V.S.A. §
248 proceeding in
which the CPG was granted who had standing on the issue of sound.
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 one-minute measurement intervals. The wind speed
average and maximum for each one-minute interval shall be
reported.
d. The sound
microphone shall be positioned at a height of approximately 1.5
meters 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 shall be free from sources of material sound
contamination. Any non-facility sources of sound shall be noted in
the analysis.
Section 5.708 Determination of
Background/Ambient Sound Levels
In order to determine the
ambient sound levels at a receptor, turbine shutdowns will be
required as part of post-construction sound monitoring. A CPG Holder
shall conduct turbine shutdowns in accordance with the requirements
of its CPG. The CPG shall specify the minimum number and duration of
turbine shutdowns during the post-construction sound monitoring. The
timing of turbine shutdowns shall be determined by the State of
Vermont agency overseeing post-construction sound monitoring in
consultation with the project operator. In the event that turbine
shutdowns are technically infeasible, background sound levels may be
determined using a primary and shielded secondary sound level
meter.
Section
5.709 Post-construction Sound Monitoring Specific
Measurements
The following data shall be measured and recorded
in one-minute increments:
(A) Acoustic parameters:
1. Overall L Aeq (20-20,000 Hz);
2. Unweighted 1/3 [rd ]
octave spectra (20-20,000 Hz);
3. Narrowband spectra (20-4,000 Hz,
1-Hz resolution, harming window).
(B) Meteorological data. All
meteorological data as specified in Section 5.712 shall be measured
and recorded synchronously with the acoustic parameters listed in
Section 5.709(A) 1, above.
(C) Turbine operational data
including power output, rotor rotational speed, and the
meteorological data listed in Section 5.707.
Section 5.710 Post-Construction
Sound Monitoring Data Analysis
(A)
All recorded data shall be categorized as "Turbine On" or "Ambient,"
or shall be excluded.
1. Turbine On
data shall meet the following criteria:
a. All Contributing Turbines for a
specific receptor shall be operational. The minimum power output for
each Contributing Turbine shall be specified in the project's
CPG.
b. The monitoring
location receptor shall be within 450 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.
2. Ambient data shall be
categorized as such only when all Contributing Turbines are shut down
or generating less than 1% of nameplate capacity.
3. Data meeting any of the
following criteria shall be excluded from analysis:
a. Data that cannot be categorized
as Turbine On or Ambient;
b. Periods between 10 minutes prior
to and one hour after precipitation at the monitoring location is
detected;
c. Intervals
contaminated by transient ambient sound sources, such as passing
cars, barking dogs, etc.;
d. Periods when 10-meter wind speed
is greater than 5 meters per second.
(B) Additional frequency-based
filtering of the data may be performed if unique conditions at the
monitoring location(s) justify such action. In such an instance, the
designated individual, agency, or company responsible for sound
monitoring data analysis shall notify the Commission of the intent to
apply additional filtering to an identified set of data and the basis
for such action. An opportunity to review and comment on any proposed
additional filtering shall be given to all parties to the
30
V.S.A. §
248 proceeding in
which a CPG was granted who had standing on the issue of sound prior
to the commencement of any additional filtering.
(C) Filtered sound monitoring data
shall be analyzed consistent with the following protocols.
1. Overall sound levels shall be
derived using the following methodology:
a. Filtered one-minute L Aeq sound
levels shall be separated into Turbine On and Ambient
datasets.
b. Turbine On
and Ambient datasets shall be sorted into one-meter-per-second
integer wind bins based on the measured average wind speed for each
interval at the monitoring location.
c. Mean average Turbine On and
Ambient sound level shall be computed in each wind bin.
d. The average Ambient sound level
shall be logarithmically subtracted from the average Turbine On sound
level in each wind bin to derive the project-only sound
level.
e. Wind bin
averages shall not be reported if the difference between the Turbine
On average sound level and Ambient sound level in a wind bin is less
than 3 dBA.
2.
Sound monitoring data analysis shall be based on a minimum of 120
filtered one-minute L Aeq data points. In the event that 20 valid
data points in each of the six wind bins are not available, wind bin
averages may be reported when there are a minimum of 40 one-minute L
Aeq sound levels in at least three wind bins. If sufficient valid
data are not obtained after ten (10) weeks of monitoring, the State
of Vermont agency designated by the Commission shall provide a status
update and recommendation for any additional monitoring to the
Commission.
3. Tonality
shall be determined and applied to the overall sound level using the
following methodology.
a. Filtered
narrowband spectra shall be separated into Turbine On and Ambient
datasets.
b. Turbine On
and Ambient datasets shall be sorted into one-meter-per-second
integer wind bins based on the measured average wind speed for each
interval at the monitoring location.
c. The overall average tonal
audibility for each wind bin shall be calculated pursuant to the
methodology contained in IEC 61400-11 or the latest revision of the
same.
d. If tonal
audibility in any wind bin is greater than 2 dB, a penalty to the
project-only sound level in that wind bin shall be applied pursuant
to ISO 1996-2, Figure C.1 or the latest revision of the
same.
Section 5.711 Compliance Data
Collection, Measurement, and Retention Procedures
(A) All operational, sound, audio,
and meteorological data collected shall be retained by the State of
Vermont agency or agencies designated by the Commission for the life
of the project and subject to inspection upon request.
(B) Monitoring and data collection
shall occur at a minimum:
1. Once
during the first year of facility operation, including sound power
testing pursuant to IEC 61400-11 for each turbine;
2. Once during each successive
fifth year thereafter until the facility is decommissioned;
and
3. In response to a
complaint if ordered by the Commission. The Commission in its
discretion may require additional sound monitoring or sound power
testing for a wind generation facility in response to a complaint if
the Commission 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 Commission shall consider:
a. The details of the
complaint;
b. Any
response thereto filed by the operator of the wind generation
facility; and
c. 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 or sound power testing 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.
(C) All relevant turbine
operational data (SCADA); the date, time, and duration of any NRO or
other operational changes that occur during the sound monitoring
period; and 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 Commission to the Commission for
its review and approval. All data shall be submitted to the
Commission 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.
Section
5.712 Post-Construction Sound Monitoring Data Analysis
(A) Compliance reports shall be
submitted to the Commission within 60 days of the completion of the
sound monitoring period. The Commission 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:
1. A narrative description of the
sound from the wind generation facility for the compliance
measurement period;
2.
The dates, days of the week, and hours of the day when measurements
were made;
3. The wind
direction and speed, temperature, humidity, and sky
condition;
4.
Identification of all measurement equipment by make, model, and
serial number;
5. All
meteorological, sound, windscreen, and audio instrumentation
specifications and calibrations;
6. All A-weighted equivalent sound
levels for each 1-minute measurement interval;
7. All 1-minute 1/3 octave band
unweighted and equivalent continuous sound levels (dB);
8. Should any sound data collection
be observed by a trained attendant, a summary of the attendant's
notes and observations;
9. 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
10. All
other information determined necessary by the Commission.
(B) In addition to the
reporting requirements in subsection (A), above, the following data
shall be retained for the life of the project and subject to
inspection upon request:
1.
Short-period sound level measurements (1 second or less);
and
2. All L A10, L A50,
and L A90 percentile levels;
Section 5.713 Complaint Response
Procedures
CPG Holders shall respond to complaints raised by
residents located near the wind generation facility 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.).
STATUTORY AUTHORITY:
Section
12(a)
of Act 174 of 2016;
30
V.S.A. §
248;
30 V.S.A. §
3