Agenda - 09-04-2014 - 6a - Laserfiche WebLink

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37 1 2 Note that the noise level 104 feet from the inverter station at the Petranka/Gewalt property line 3 would be at least 47.54 dB. This is much higher than the figure that the applicants state in the 4 Binks Solar Project Narrative (p.11 of the Hearing Agenda): "The sound generated by the Binks 5 Solar project will be less than 38 dB(a) at any point along the property boundary...". Using the 6 site plan's actual triple inverter locations and the noise levels recalculated here, one would need 7 to be approximately 310 feet from a triple inverter station before reaching Binks' 38 dB threshold 8 (source: Estimating Sound levels With the Inverse Square Law; http://hyperphysics.phy- 9 astr.gsu.edu/hbase/acoustic/isprob2.html ). Again, the noise added by a step-up transformer 10 was not included in the Binks analysis; including transformer noise would cause overall noise 11 levels to be even higher at nearby properties. 12 13 4. What are Current Noise levels at the Nearest Property Line? Sound levels at the 14 Petranka/Gewalt property line were estimated using the Sound Meter application on a Nexus 7 15 tablet on Monday May 26, at approximately 2:30 PM. Although we were not able to obtain a 16 calibrated sound meter on short notice, this tool should provide a reasonable estimate of 17 background sound levels. Readings were taken on the Petranka/Gewalt property line near the 18 corner of Cascade Drive and Falls Drive at a point nearest the proposed location of the 19 Cascade Drive inverter station. A photo of the location at which the measurements were made 20 and a close-up of the Sound Meter application reading are shown in Appendix II. The current 21 ambient sound readings were around 32 dB, with occasional spikes of up to ca. 40 dB that 22 correlated with nearby birdsong. 23 24 5. What Would the Perceived Noise Levels be at the Projected 47.5 dB versus the Current 25 32 dB Ambient Level? Noise levels at the Petranka/Gewalt property line would be 26 approximately 15.5 dB louder than the current rural background sounds. This equates to a 27 perceived tripling of sound levels (psycho-acoustic studies have determined that people 28 perceive a doubling in sound levels with each 10 dB increase in sound, so an additional 15 dB 29 would cause a tripling; Reference: Perceptual attributes of acoustic waves — Loudness, 30 http://acousticslab.orq/psychoacoustics/ ). 31 32 • Conclusion: The applicants' noise level data incorrectly states the locations, types and 33 combined noise levels of inverter/transformers at the Binks site. At the Petranka/Gewalt 34 property boundary there will be a continuous 47.5 dB or greater inverter drone during sunny 35 days that will be perceived as being at least three times louder than the current ambient 36 rural sounds. Since the applicants did not base their laboratory noise analysis on triple 37 inverter units and apparently did not factor in transformer noise, the noise levels could be 38 even higher at property lines bordering this development. 39 • The applicants' noise impact assessment is faulty as a result of using false 40 assumptions about the types, configurations and locations of the inverter/transformer 41 units. The applicants should be required to submit sound level testing data for the 42 actual inverter/transformer configurations that they have proposed to use and then 43 estimate noise impacts from their true locations as depicted in the site plan. 44 45 46 This noise impact will be a completely unacceptable intrusion on our privacy and our right to 47 peace and quiet in this long-established neighborhood. We urge the Planning Board and County 48 Commissioners to reject this project as being inappropriately sited, and also as inappropriate to 49 the ideals and policy goals for which the Rural Buffer was established. 50 51