Velco Noise Report Southern Loop fans, the transformer is 6 dB below the 88 dBA NEMA TR-1 standard. Figure 2 shows the results from 50-foot measurements taken around the transformer

Preconstruction Noise Report for:

THE SOUTHERN LOOP PROJECT Vermont

Prepared for:

VT Transco

19 September 2007

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Exhibit Petitioners KK-3

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TABLE OF CONTENTS

1. INTRODUCTION.....................................................................................................................................1

2. MEASURING THE EXISTING SOUND LEVELS.....................................................................................1

2.1 VERNON SUBSTATION ....................................................................................................................2

2.2 COOLIDGE SUBSTATION.................................................................................................................5

2.3. DUMMERSTON SUBSTATION........................................................................................................8

2.4. NEWFANE SUBSTATION (PROPOSED) ......................................................................................10

3. MODELING OF SUBSTATION NOISE ................................................................................................13

3.1. MODELING METHODOLOGY ........................................................................................................13

3.2 VERNON SUBSTATION ..................................................................................................................13

3.3 NEWFANE SUBSTATION................................................................................................................19

4. POST-CONSTRUCTION MONITORING ..............................................................................................24

5. SUMMARY AND CONCLUSIONS .......................................................................................................24

1. INTRODUCTION

Vermont Electric Company (VELCO) is proposing its Southern Loop project to improve service reliability. Resource Systems Group was retained to evaluate the noise impacts from the existing and proposed infrastructure. The substations evaluated in this report include Vernon, Coolidge, and Newfane. This report includes:

• pre-construction noise monitoring

• post-construction noise forecasts

• recommendations for mitigation

2. MEASURING THE EXISTING SOUND LEVELS

RSG staff conducted sound level monitoring at three locations. These included: 1) Vernon – at the existing Vermont Yankee Substation and at their property boundary

2) Coolidge – at the substation and along the fence line

3) West Dummerston – between the CVPS substation and the road

4) Newfane – at two property boundaries nearest to neighbors

Various sound level meters were used, including:

1) Cesva 310, ANSI Type I integrating sound level meters and analyzer

2) Brüel and Kjaer 2236, ANSI Type I integrating sound level meter and analyzer

Sound level meters were calibrated before and after the measurements and fitted with windscreens. Table 1 identifies when the substations were monitored and the weather conditions observed.

Table 1: Sound Monitoring Information Weather Conditions

Substation Dates

Monitored Temperature Wind Skies Vernon 7/26 to 7/27/2007 68-88 ˚F Calm to 15 mph Scattered Clouds

Coolidge 7/26/2007 74-84 ˚F Calm to 6 mph Partly Cloudy Dummerston 7/26 to 7/30/2007 68-88 ˚F Calm to 15 mph Scattered Clouds

Newfane 8/8 to 8/13/2007 48-87 ˚F Calm to 17 mph Varied - No Rain

Each existing substation (Vernon and Coolidge) consists of one active transformer as well as other ancillary equipment with negligible noise emissions. At the transformer, sound levels were recorded at both 1/3 and 2/3 of the transformer height at 1 meter increments 0.3 meters from the transformer

Velco Southern Loop Noise Report Resource Systems Group, Inc.

19 September 2007 page 2

with the cooling fans off.1 The cooling fans were then turned on and we recorded at both 1/3 and 2/3 height, but at 2 meters away for points near the activated cooling fans. The total sound power level for each transformer was calculated according to IEC 60076-10 (“Power Transformers – Part 10: Determination of Sound Levels”).

Directionality of sound was calculated using sound level measurements taken 15 meters from and 45 degree increments around the Vermont Yankee transformer. We measured sound levels along the fence line at Coolidge to further understand the sound propagation from the source. Multi-day monitoring was conducted at Vernon, Dummerston, and Newfane.

The results for each substation are described in the following sections.

2.1 VERNON SUBSTATION

Figure 1 shows the sound power levels at each octave band at the Vermont Yankee 345 kV/115 kV transformer. The sound levels were highest at the 125 Hz, 250 Hz, and 500 Hz octave bands. This corresponds with the magneto-restriction frequency of the transformer of 120 Hz (twice the current cycle of 60 Hz) and the lower order harmonic of 240 Hz, 360 Hz, and 480 Hz.

Figure 1: Sound Power Levels (Lw) for the Vernon Substation Transformer

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1 This follows the guidelines set forth in IEEE Standards Test Code for Liquid-Immersed Distribution, Power, and Regulating Transformers (IEEE Std. C57. 12.90-1999). The IEEE code sets forth larger setbacks for the fan side when they are operating. A Cesva 310 Type I integrating sound level meter was used to record 1/1 octave band sound levels.



The average sound pressure level from this transformer is 82 dBA without fans, which is 3 dB under the NEMA TR-1 standard of 85 dBA. With fans, the transformer is 6 dB below the 88 dBA NEMA TR-1 standard.

Figure 2 shows the results from 50-foot measurements taken around the transformer. Note that the lowest sound levels are at 45 degree angles to the transformer. The higher levels to the southwest may have been due to the proximity of the sound level meter to a capacitor bank, rather than from the transformer. Sound levels in the corners are as much as 6 dB lower than from the sides with fans off.

Figure 2: Sound Pressure Levels 50’ from Existing Vermont Yankee Transformer

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Background sound level monitoring was conducted at the property line near the closest residential area. Figure 3 identifies the monitoring location with respect to the existing transformer and the proposed site plan. Background sounds included the Vermont Yankee Power Plant, especially the cooling towers, the wind blowing through vegetation, and distant traffic noise.

Monitoring results at the property line are shown in Figure 4. The average hourly sound levels ranged from 43 dBA in the morning to approximately 52 dBA.



Figure 3: Background Sound Monitor Location with Proposed Site Plan for the Vernon Site

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Figure 4: Monitored Sound Levels at the Vermont Yankee Property Line

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2.2 COOLIDGE SUBSTATION

Sound measurements were made around the existing 345/115 kV transformer and along the fence line for both fans-off and fans-on conditions.

Figure 5 summarizes the sound power levels for the Coolidge transformer. As expected, the fans-on condition (FOA) is louder than the fans-off condition (OA). The sound levels were highest at the 125 Hz and 250 Hz octave bands. This corresponds with the magneto-restriction frequency of the transformer of 120 Hz (twice the current cycle of 60 Hz) and the lower order harmonic of 240 Hz.



Figure 5: Sound Power Levels (Lw) for the Coolidge Substation Transformer

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The overall sound pressure level from the transformer is 80 dBA with no fans. This is 5 dBA below the NEMA TR-1 standard. With fans, the transformer operates at 9 dBA below the NEMA TR-1 standard of 88 dBA.

Further measurements were taken at the substation fence-line for both fans-off and fans-on conditions. These measurements are summarized in Figure 6.

During the fence line measurements, the crackle of corona noise was observed near a wave trap to the south, and some tonal noise was also observed near a capacitor bank to the northeast. However, both noise sources were not audible beyond a distance of about 100 meters.

The octave band sound levels at the northwest corner of the substation (the point closest to residences) are shown in Figure 7.



Figure 6: Sound Levels (LA90) Monitored at Coolidge Fence Line with Fans Off (top) & Fans On (bottom)



Figure 7: Octave Band Sound Levels at Northwest Corner of Fenceline for Fans Off and Fans On

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2.3. WEST DUMMERSTON SUBSTATION

Continuous sound level measurements were made near the CVPS West Dummerston substation to assess daytime and nighttime background sound levels. The meter was located approximately 100 meters south of the existing substation and 130 north of VT 30. The location is shown in Figure 8.

The background monitoring (Figure 9) shows that sound levels generally range from about 33 dBA at night to 49 dBA during the day without rain. Sound levels with rain are generally 50 to 60 dBA.



Figure 8: Location of Sound Monitoring – West Dummerston



Figure 9: Sound Monitoring Results – West Dummerston

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2.4. NEWFANE SUBSTATION (PROPOSED)

Background sound monitoring at the proposed Newfane site was conducted in two locations shown in Figure 10. The monitoring results at these two locations are shown in Figure 11 and Figure 12. The western monitor was 30 meter from VT 30 and the eastern monitor was 43 meters from River Road.

The average hourly sound levels at the eastern monitor ranged from 28 dBA at night to approximately 50 dBA during the day. The western monitor was higher due to its proximity with VT30. The average hourly sound levels at the western monitor ranged from 49 dBA at night to 63 dBA during the day.



Figure 10: Background Sound Monitor Locations with Proposed Site Plan for the Newfane Site



Figure 11: Monitored Sound Levels at the Eastern Monitor at the Proposed Newfane Site

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Figure 12: Monitored Sound Levels at the Western Monitor at the Proposed Newfane Site

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3. MODELING OF SUBSTATION NOISE

Sound level modeling was conducted for the Vernon and Newfane substations. The purpose of the modeling was to determine sound levels at neighboring properties for both the current conditions and the proposed conditions following the system upgrades. We based the sound emissions from these sources on the monitoring of the existing transformers and National Electrical Manufacturers Association (NEMA) TR-1 sound level standards for transformers.1

3.1. MODELING METHODOLOGY

Modeling was completed for the project using CADNA A acoustical modeling software. This modeling tool, made by Datakustik GmbH, is an internationally accepted acoustical model, and is used by many other noise control professionals in the United States and abroad. The software has a high level of reliability and follows methods specified by the International Standards Organization in their ISO 9613-2 standard, “Acoustics – Attenuation of sound during propagation outdoors, Part 2: General Method of Calculation.” The standard states,

“This part of ISO 9613 specifies an engineering method for calculating the attenuation of sound during propagation outdoors in order to predict the levels of environmental noise at a distance from a variety of sources. The method predicts the equivalent continuous A-weighted sound pressure level … under meteorological conditions favourable to propagation from sources of known sound emissions. These conditions are for downwind propagation … propagation under a well-developed moderate ground-based temperature inversion, such as commonly occurs at night.”

The model takes into account source sound power levels, surface reflection and absorption, atmospheric absorption, geometric divergence, meteorological conditions, walls, barriers, berms, and terrain.

A 5 meter by 5 meter grid of receivers was set up covering several acres around each site. In addition, modeled receivers were placed adjacent the nearest residential homes.

Note that the results of the modeling shown in the following pages do not include background sounds. That is, they only represent the sound sources at the individual substations.

3.2 VERNON SUBSTATION

The proposed Vernon substation will be just north of Vermont Yankee. The existing 345 kV/115 kV transformer at the Plant will be moved to the new site and will be accompanied by a new 345 kV/115 kV transformer.

1 “NEMA Standards Publication No. TR-1-1993 (R2000), Transformers, Regulators and Reactors,” NEMA, 2000



We monitored sound levels at distances of 0.3/2.0/15 meters from the Vermont Yankee transformer. The calculated source sound power level is summarized in Table 2 below.

Table 2: Unweighted Sound Power for the Vermont Yankee Transformers

31.5 Hz 63 Hz 125 Hz 250 Hz 500 Hz 1 kHz 2 kHz 4 kHz 8 kHzExisting - Fans Off 86 93 110 107 106 91 81 71 63 113Existing - Fans On 91 96 113 108 105 97 92 85 79 115Proposed - Fans Off 81 88 104 102 101 86 76 66 58 107Proposed - Fans On 88 94 110 105 103 95 89 82 76 112

Octave Band FrequencyTransformer and Condition LZ (dB)

These transformers were included in a sound propagation model of the area surrounding the substation.

The modeling results for the current transformer at Vermont Yankee for both fans off and fans on conditions are shown in Figures 11 and 12, respectively. The closest homes to the existing site are along Governor Hunt Road. With the cooling fans off the highest level at these homes is 40 dBA, and with the cooling fans on the highest level is 42 dBA. These sound levels are lower than the monitored background sound levels shown in Figure 4.

The modeling results for the proposed site with the relocated existing transformer and the proposed new transformer for both fans off and fans on conditions are shown in Figures 13 and 14, respectively. The closest home to the transformers at the proposed site is approximately 1,120 feet away on Governor Hunt Road. This home is shown in Figures 13 and 14. With the cooling fans off the sound pressure level at the closest home is 40 dBA, and it is 43 dBA with the cooling fans on. This is lower than the monitored background sound levels shown in Figure 4.



Figure 13: Modeled Sound Levels at Vernon – Existing Conditions without Cooling Fans



Figure 14: Modeled Sound Levels at Vernon – Existing Conditions with Cooling Fans



Figure 15: Modeled Sound Levels at Vernon– Proposed Layout without Cooling Fans



Figure 16: Modeled Sound Levels at Vernon – Proposed Layout with Cooling Fans



3.3 NEWFANE SUBSTATION

The Newfane Substation is a new substation, and is proposed to include one 345 kV/115 kV transformer and one 115 kV/46 kV transformer. There will be other added ancillary equipment with negligible noise emissions.

The new transformers will be specified with a guaranteed sound level that is 10 dB below NEMA TR-1 standards. That is, the larger 345 kV/115 kV transformer will be specified at no more than 80 dBA and the 115 kV/46 kV transformer will be specified at no more than 67 dBA, both with second stage cooling. With oil cooling (ONAN), the guarantees will be 3 dB lower.

The model was run for two conditions with cooling fans on and cooling fans off. The modeling results are shown in Figures 15 and 16. The closest receiver to the transformers on the proposed site is 625 feet to the southeast, but due to the terrain the receiver with the highest levels is actually 770 feet to the south. Both of these receivers are shown in the figures. The highest levels at the home to the south are 40 dBA with the cooling fans off and 44 dBA with the cooling fans on.

This home would have background sound levels similar to that monitored at the eastern monitor shown in Figure 11. The modeled sound levels are similar to the daytime sound levels shown in Figure 11, but are approximately 12 dB higher than the lowest nighttime hourly average sound levels. Realistically, the deep stand of foliage between the substation and the homes to the south would actually attenuate the levels by an additional 8 dB, making the highest levels at the home to the south 32 dBA with the cooling fans off and 36 dBA with the cooling fans off. The results of model including this foliage stand are shown in Figures 17 and 18. If the attenuation of the southern stand of foliage is taken into account, the sound levels at the home to the south are below the daytime background levels shown in Figure 11 and approximately 4 dB greater than the nighttime background levels.



Figure 17: Modeled Sound Levels at Proposed Newfane Site without Cooling Fans



Figure 18: Modeled Sound Levels at Proposed Newfane Site with Cooling Fans



Figure 19: Modeled Sound Levels at Proposed Newfane Site without Cooling Fans, With Foliage



Figure 20: Modeled Sound Levels at Proposed Newfane Site without Cooling Fans, With Foliage



4. POST-CONSTRUCTION MONITORING

After construction is completed at these substations, post-construction sound level monitoring will be conducted. Sound monitoring will take place at the fence line and/or property lines, depending on the site. Sound power measurements will be made for the new transformers to confirm that they meet a specification of 10 dB below the NEMA TR-1 standard

Corona noise around the 345 kV yard should be controlled using appropriate measures, such as rounded busbars and low-corona equipment.

5. SUMMARY AND CONCLUSIONS

Sound level monitoring was conducted at three substations: Vernon, Coolidge, and Newfane. At the former two substations, sound power levels for each transformer were determined using IEC standard procedures. Measurements were made at 10 to 15 meters from the transformers to determine whether the sound emissions are directional. Finally, fence line and/or property line measurements were made to establish levels further from the transformers.

During the measurements, it was noted that the transformer at the Vernon Station is inaudible at the property line primarily due to other noise from the Vermont Yankee power plant, such as the cooling towers. While the Vermont Yankee transformer will be moved further to the north and will be joined by a new transformer, the new transformer will be 3 to 6 dB quieter. Overall sound levels will be 43 dBA with fans on and 40 with fans off at the closest residence. This is equivalent to the lowest existing sound levels measured at the property line.

At the Coolidge substation, the existing transformer is audible at the fenceline, and certain components of the substation exhibit corona noise. The overall sound power level of the transformer was 103 dBA with and without the fans on. Much of the sound is attenuated over distance and terrain as is indicated by the fence line measurements.

Background monitoring near the CVPS West Dummerston substation indicated sound levels ranging from 33 dBA during the night to 49 dBA during the day.

Modeling of the proposed Newfane substation shows that the highest sound levels are at a home to the south where it is 40 dBA with the cooling fans off and 44 dBA with the cooling fans on. If the attenuation from the existing stand of foliage to the south is accounted for the sound levels would be 8 dB less. This results in sound levels (32 for fans-off and 36 for fan-on) which are below the daytime background sound levels, but 4 dB above the lowest monitored nighttime background sound levels.

Documents

Velco Noise Report Southern Loop fans, the transformer is 6 dB below the 88 dBA NEMA TR-1 standard. Figure 2 shows the results from 50-foot measurements taken around the transformer