1/12 Ramboll
NOISE CHARACTERISTICS, EFFECTS, AND DEFINITIONS Noise Characteristics, Effects, and Definitions Noise is sometimes defined as unwanted sound, and the terms noise and sound are used more or less synonymously in this exhibit. The human ear responds to a very wide range of sound intensities. The decibel scale (dB) used to describe sound is a logarithmic rating system which accounts for the large differences in audible sound intensities. This scale accounts for the human perception of a doubling of loudness as an increase of 10 dB. Therefore, a 70-dB sound level will sound about twice as loud as a 60-dB sound level. People generally cannot detect differences of 1 dB. In ideal laboratory situations, differences of 2 or 3 dB can be detected by people, but such a change probably would not be noticed in a typical outdoor environment. A 5-dB change would probably be clearly perceived by most people under normal listening conditions. On the logarithmic scale used to measure noise, a doubling of sound-generating activity (i.e., a doubling of the sound energy) causes a 3-dB increase in average sound produced by that source, not a doubling of the loudness of the sound (which requires a 10-dB increase). For example, if traffic along a road is causing a 60-dB sound level at a nearby location, a doubling of the number of vehicles on this same road would cause the sound level at this same location to increase to 63 dB. Such an increase might not be discernible in a complex acoustical environment. When addressing the effects of noise on people, it is necessary to consider the frequency response of the human ear, or those frequencies that people hear the best. Sound measuring instruments are therefore often designed to "weight" sounds based on the way people hear. The frequency weighting most often used to evaluate environmental noise is A weighting because it best reflects how humans perceive sound. Measurements from instruments using this system, and associated noise levels, are reported in "A weighted decibels," or dBA. Distance from the source, the frequency of the sound, the absorbency of the intervening ground, obstructions, and duration of the noise-producing event all affect the transmission and perception of noise. The degree of the effect on perception also depends on who is listening (individual physiological and psychological factors) and on existing sound levels (background noise). Although a measured A-weighted noise level will adequately indicate the level of environmental noise at any instant in time, community noise levels typically vary continuously. Several noise descriptors have been developed to characterize community noise by accounting for the total acoustical energy content of the noise over defined periods of time. These include the Equivalent Sound Level (Leq) and the Day-Night Sound Level (Ldn). These metrics are described below. The Leq is the sound level corresponding to a steady-state sound level containing the same total energy as a time-varying signal over a given sample period. That is, an Leq is a single number representing the level of a constant sound containing the same amount of sound energy as the varying sound levels over a specific period. Thus, the Leq is the "energy average" noise level for the measurement time interval. The Leq can be measured for any time period but is typically measured for 1 hour. It is the energy sum of all the events and background noise levels that occur during that time period. The Ldn is widely used to represent 24-hour sound levels and to gauge community response to noise. The Ldn is a 24-hour sound level metric similar to a 24-hour Leq, except the Ldn includes an additional 10 dBA added to sound levels in each hour between 10 PM and 7 AM to account for increased sensitivity to noise during times when people are typically trying to sleep.
6/12 Ramboll
Modeling Parameters Modeling Parameter Value G (ground absorption) 0.8 Reflection Order 2 Receptor/Grid Height 4.92 ft Source Heights Tesla Megapack 2 XL – 9.5 feet Transformer (4.8 MVA pad mounted) – 10.7 feet k0 (Source Directivity Index) Tesla Megapack 2 XL – 2 dB Transformer (4.8 MVA pad mounted) – 0 dB Intervening Structures 3461 Alvoca Street 3451 Main Street 3441 Main Street 3513 Main Street 3517 Main Street 3519 Main Street 3521 Main Street 3523 Main Street Meteorology ISO 9613 default augmented with annual temperature and humidity averages: (59 F / 70% R.H. / 0 mph avg. wind speed) Notes: ft – feet mph avg.– miles per hour average R.H. – relative humidity Partial Sound Level – Nighttime (40% fan duty cycle) Source Partial Level Night Name M. ID R1 R2 R3 R4 R5 R6 R7 R8 MPack !020000!MP01 17.1 29.2 25.9 24 22.5 20.8 20.9 29.6 MPack !020000!MP02 17.8 27.3 23 23.8 22.3 20.6 20.7 29.4 MPack !020000!MP03 18.9 27.7 18.8 22.8 21.1 19.5 19.7 28.3 MPack !020000!MP04 11.6 19.7 17 22.2 20.4 18.8 19.1 27.6 MPack !020000!MP05 11.6 15.7 16 21.9 19.9 18.3 18.6 26.9 MPack !020000!MP06 11.5 15.1 15 21.6 19.6 18 18.3 26.8 MPack !020000!MP07 11.5 14.4 15 21.5 19.3 17.7 18 26.3 MPack !020000!MP08 22.7 14.1 15 21.2 19.1 17.6 17.8 26.7 MPack !020000!MP09 17.8 13.9 14 21.2 18.9 17.4 17.6 26.3 MPack !020000!MP10 17.3 13.8 14 20.9 18.7 17.2 17.5 26.4 MPack !020000!MP11 16.9 13.4 14 20.9 18.5 17.1 17.3 26 MPack !020000!MP12 16.7 13.3 13.8 20.4 18.4 17 17.2 26.1
7/12 Ramboll
Source Partial Level Night Name M. ID R1 R2 R3 R4 R5 R6 R7 R8 MPack !020000!MP13 16.5 13.2 13.6 20.3 18.3 16.8 17.1 25.7 MPack !020000!MP14 16.3 13.1 13.6 20 18.1 16.7 17 24.6 MPack !020000!MP15 15.5 29.2 25.3 24.8 23.1 21.2 21.4 29.6 MPack !020000!MP16 16 25.4 22 23.6 22.2 20.5 20.7 29.3 MPack !020000!MP17 16.7 24.5 22.3 22.6 21 19.4 19.7 28.4 MPack !020000!MP18 17.4 26.4 19.5 22.1 20.4 18.8 19.1 27.6 MPack !020000!MP19 13 20.8 17.6 21.8 19.8 18.3 18.6 27.1 MPack !020000!MP20 11.2 20 16.8 21.5 19.5 18 18.3 26.6 MPack !020000!MP21 11.2 17.4 16.2 21 19.2 17.7 18 26.3 MPack !020000!MP22 11.2 16.7 17.1 20.8 19 17.5 17.8 25.7 MPack !020000!MP23 11.2 16.7 16.8 20.6 18.8 17.3 17.6 25.5 MPack !020000!MP24 11.1 16.6 16.6 20.4 18.7 17.2 17.5 25.4 MPack !020000!MP25 16.7 16.1 16.4 20.3 18.5 17 17.3 25.4 MPack !020000!MP26 20.2 15.9 16.5 20.1 18.4 17 17.2 25.2 MPack !020000!MP27 17.4 15.9 16.7 20 18.3 16.8 17.1 25.1 MPack !020000!MP28 17 15.8 16.7 18.6 18.2 16.8 17 24.9 MPack !020000!MP29 12.4 28 23.5 24.1 23.1 21.3 21.6 29.5 MPack !020000!MP30 12.6 25.5 20.3 23.9 22.9 21.1 21.5 29.3 MPack !020000!MP31 12.9 24.1 20.2 22.9 22 20.2 20.7 28.6 MPack !020000!MP32 11 23.3 21.5 22.3 21.5 19.7 20.2 27.9 MPack !020000!MP33 10.9 23.4 20.2 21.8 21.1 19.3 19.8 27.3 MPack !020000!MP34 11 22.5 20.9 21.6 20.6 19 19.6 26.7 MPack !020000!MP35 11.1 22.3 18.6 21.3 20.5 18.9 19.4 26.3 MPack !020000!MP36 11.3 22.2 18.3 21.2 20.4 18.8 19 26.1 MPack !020000!MP37 11.4 19.4 18 20.5 20.2 18.5 18.7 25.6 MPack !020000!MP38 10.3 19.1 17.9 20.4 20.2 18.4 18.6 25.5 MPack !020000!MP39 10.3 16.9 17.8 20.2 20 18.3 18.4 25.3 MPack !020000!MP40 10.3 15.9 17.7 20.1 20.3 18.2 18.4 25.1 MPack !020000!MP41 11.6 18.5 18 21 18.1 16.6 19.2 24.4 MPack !020000!MP42 11.9 12.5 14.8 20.6 18 16.5 18.9 24.2 MPack !020000!MP43 11.2 21.6 18.2 21 18.2 17.3 19.2 24.7 MPack !020000!MP44 11.4 21.5 18.1 20.7 18.3 16.7 19 24.5
8/12 Ramboll
Source Partial Level Night Name M. ID R1 R2 R3 R4 R5 R6 R7 R8 MPack !020000!MP45 10.7 22 20.7 21.4 19.2 19.5 19.5 25.3 MPack !020000!MP46 10.8 21.8 18.6 21.3 19 19.3 19.4 25 MPack !020000!MP47 11.2 22.9 21.7 21.9 21.2 19.5 20 27.4 MPack !020000!MP48 10.6 21.9 20.9 21.7 21.3 19.5 19.7 27.1 MPack !020000!MP49 11.2 23.4 19.9 23 22 20.3 21 28.8 MPack !020000!MP50 11.4 22.7 19.9 22.4 21.5 19.8 20.3 28 MPack !020000!MP51 12.2 27.2 19.9 24.2 23.1 21.4 21.7 29.7 MPack !020000!MP52 12.3 26.1 20 24 23.3 21.2 21.6 29.4 MPack !020000!MP53 13.3 29 24.2 24.2 23.1 21.3 21.6 29.5 MPack !020000!MP54 13.6 26.9 23.1 24 22.9 21.1 21.5 29.3 MPack !020000!MP55 14 23.9 20.8 23.2 21.9 20.2 20.7 28.5 MPack !020000!MP56 12 23.4 20.8 22.2 21.5 19.6 20.2 28.1 MPack !020100!MP57 12.4 23.2 18.4 22 21.1 19.2 19.8 27.5 MPack !020100!MP58 11.4 23.3 17.1 21.6 20.6 19 19.5 27.1 MPack !020100!MP59 11.6 22.6 18 21.5 20.4 18.7 19.3 26.6 MPack !020100!MP60 11.9 20 17.8 21.2 20.4 18.6 19 26 MPack !020100!MP61 10.3 16.6 17.4 20.5 20.1 18.3 18.7 25.5 MPack !020100!MP62 10.3 16.9 17.3 20.3 19.9 18.3 18.5 25.3 MPack !020100!MP63 10.3 16.2 17.1 18.9 18.6 17 17.1 25.1 MPack !020100!MP64 10.3 16.1 17 18.8 18.4 17 17 24.9 MPack !020100!MP65 10.3 15.7 16.9 18.6 18.3 16.8 16.9 24.7 MPack !020100!MP66 16.4 15.7 14.6 18.5 18.4 16.7 16.8 24.6 MPack !020100!MP67 10.4 15.9 14.7 20 19.3 17.8 18.4 24.8 MPack !020100!MP68 9.3 11.8 14.9 19.9 18 17.7 18.4 23.6 Transformer !020001!TR01 0 5.3 2.6 1.2 1 0 0 7.7 Transformer !020001!TR02 0 4.7 0 0.6 0.3 0 0 7.1 Transformer !020001!TR03 0 0 0 0.4 0.1 0 0 5.9 Transformer !020001!TR04 0 0 0 0.2 0 0 0 5.6 Transformer !020001!TR05 0 0 0 0 0 0 0 5.4 Transformer !020001!TR06 0 0 0 0 0 0 0 5.2 Transformer !020001!TR07 0 0 0 0 0 0 0 5 Transformer !020101!TR08 0 8.1 2.9 1.7 1.3 0 0 7.5
9/12 Ramboll
Source Partial Level Night Name M. ID R1 R2 R3 R4 R5 R6 R7 R8 Transformer !020101!TR09 0 5.8 0.6 2.4 2.1 0.2 0.5 7.5 Transformer !020001!TR10 0 3.4 0.6 1.5 0.8 0 0.2 6.9 Transformer !020001!TR11 0 2.5 1.6 1.1 0.6 0 0 6.5 Transformer !020001!TR12 0 2.3 0 0.9 0.4 0 0 5.6 Transformer !020001!TR13 0 0.3 0 0.7 0 0 0 3.6 Transformer !020001!TR14 0 0 0 0 0 0 0 3.3 Transformer !020001!TR15 0 0 0 0 0 0 0 4.9 Transformer !020001!TR16 0 0 0 0.5 0.8 0 0 6.2 Transformer !020101!TR17 0 0 0 0 0 0 0 5.3 Overall Sound Level Results – Nighttime Receptor Location Applicable Regulatory Sound Level Limit Sound Level (Leq) Height Above Ground Nighttime (dBA) (10 PM to 7 AM on weekdays, 10 PM to 8 AM on weekends) Ft. R1 45 33 4.92 R2 45 41 4.92 R3 45 38 4.92 R4 45 40 4.92 R5 45 39 4.92 R6 45 37 4.92 R7 45 38 4.92 R8 45 45 4.92 Partial Sound Level – Daytime (70% fan duty cycle) Source Partial Level Day Name M. ID R1 R2 R3 R4 R5 R6 R7 R8 MPack !020000!MP01 25.6 37.9 34.5 32.4 31 29.3 29.4 38.1 MPack !020000!MP02 26.3 36.1 31.8 32.3 30.8 29.1 29.2 37.9 MPack !020000!MP03 27.4 36.4 27.5 31.3 29.7 28.1 28.3 36.9 MPack !020000!MP04 20.6 28.7 26 30.8 29.1 27.5 27.7 36.2 MPack !020000!MP05 20.5 24.5 25 30.5 28.6 27 27.3 35.5 MPack !020000!MP06 20.5 23.9 24 30.2 28.3 26.7 27 35.4
10/12 Ramboll
Source Partial Level Day Name M. ID R1 R2 R3 R4 R5 R6 R7 R8 MPack !020000!MP07 20.4 23.2 24 30.1 28 26.5 26.7 34.9 MPack !020000!MP08 31.3 22.9 24 29.8 27.8 26.3 26.5 35.3 MPack !020000!MP09 26.6 22.8 23 29.8 27.6 26.1 26.3 34.9 MPack !020000!MP10 26.1 22.6 23 29.5 27.4 26 26.2 34.9 MPack !020000!MP11 25.8 22.3 23 29.5 27.3 25.8 26 34.6 MPack !020000!MP12 25.6 22.2 22.8 29.1 27.1 25.7 25.9 34.7 MPack !020000!MP13 25.3 22.1 22.7 28.9 27 25.5 25.8 34.2 MPack !020000!MP14 25.2 22 22.6 28.6 26.9 25.4 25.7 33.2 MPack !020000!MP15 24 37.9 33.8 33.3 31.6 29.7 29.9 38.1 MPack !020000!MP16 24.5 34.3 30.8 32.1 30.8 29.1 29.2 37.8 MPack !020000!MP17 25.2 33.3 31 31.2 29.7 28 28.3 36.9 MPack !020000!MP18 25.9 35.1 28.4 30.7 29.1 27.4 27.7 36.2 MPack !020000!MP19 21.7 29.8 26.5 30.4 28.5 27 27.3 35.7 MPack !020000!MP20 20.1 28.8 25.7 30.1 28.2 26.7 27 35.2 MPack !020000!MP21 20.1 25.9 25.1 29.6 28 26.4 26.7 34.9 MPack !020000!MP22 20.1 25.3 25.8 29.4 27.7 26.2 26.5 34.3 MPack !020000!MP23 20.1 25.3 25.6 29.2 27.5 26 26.3 34.1 MPack !020000!MP24 20 25.2 25.4 29.1 27.4 25.9 26.2 34 MPack !020000!MP25 25.7 24.7 25.2 28.9 27.2 25.8 26 34 MPack !020000!MP26 28.8 24.5 25.1 28.8 27.1 25.7 25.9 33.8 MPack !020000!MP27 26.2 24.4 25.4 28.6 27 25.6 25.8 33.7 MPack !020000!MP28 25.8 24.3 25.3 27.3 26.9 25.5 25.7 33.5 MPack !020000!MP29 21.4 36.6 32.1 32.6 31.5 29.8 30.1 38.2 MPack !020000!MP30 21.6 34.1 29.2 32.4 31.4 29.6 30 38 MPack !020000!MP31 21.9 33.3 29.1 31.5 30.5 28.8 29.3 37.4 MPack !020000!MP32 20.3 32.4 30.2 30.9 30 28.3 28.8 36.7 MPack !020000!MP33 19.9 32.2 29.2 30.5 29.7 27.9 28.5 36.2 MPack !020000!MP34 20 31.5 29.8 30.3 29.2 27.6 28.3 35.5 MPack !020000!MP35 20.1 31.3 27.7 30 29.1 27.5 28.1 35.2 MPack !020000!MP36 20.2 31.1 27.5 29.9 29 27.4 27.7 35 MPack !020000!MP37 20.2 28.7 27.2 29.2 28.8 27.1 27.3 34.5 MPack !020000!MP38 19.5 28.1 27 29 28.8 27 27.2 34.3
11/12 Ramboll
Source Partial Level Day Name M. ID R1 R2 R3 R4 R5 R6 R7 R8 MPack !020000!MP39 19.5 26.2 26.9 28.9 28.5 26.9 27.1 34.1 MPack !020000!MP40 19.5 25.2 26.8 28.8 28.8 26.8 27 34 MPack !020000!MP41 20.4 28.1 27.1 29.5 26.9 25.3 27.8 33 MPack !020000!MP42 20.7 21.2 24.2 29.2 26.7 25.2 27.5 32.8 MPack !020000!MP43 20 30.7 27.3 29.6 27 26 27.8 33.4 MPack !020000!MP44 20.2 30.6 27.2 29.3 27 25.4 27.6 33.2 MPack !020000!MP45 19.6 30.9 29.5 30 27.9 28 28.1 34 MPack !020000!MP46 19.7 30.7 27.6 29.9 27.7 27.8 28 33.7 MPack !020000!MP47 20 32 30.3 30.5 30.1 28.1 28.6 36.3 MPack !020000!MP48 19.6 31.1 29.6 30.3 30.2 28.1 28.3 35.9 MPack !020000!MP49 20.1 32.1 28.7 31.5 30.8 28.8 29.5 37.4 MPack !020000!MP50 20.2 31.3 28.7 30.9 30.4 28.4 28.9 36.7 MPack !020000!MP51 20.9 35.8 28.7 32.6 31.8 29.8 30.2 38.3 MPack !020000!MP52 21 34.7 28.8 32.5 32 29.6 30.1 38.1 MPack !020000!MP53 21.9 37.5 32.7 32.7 31.5 29.8 30.1 38 MPack !020000!MP54 22.2 35.9 31.7 32.5 31.4 29.6 30 37.8 MPack !020000!MP55 22.6 32.9 29.5 31.8 30.5 28.8 29.3 37.1 MPack !020000!MP56 20.6 32.4 29.5 30.9 30.1 28.3 28.8 36.7 MPack !020100!MP57 21.4 32.2 27.4 30.6 29.7 27.9 28.4 36.1 MPack !020100!MP58 20.6 32.3 26.3 30.2 29.3 27.7 28.2 35.7 MPack !020100!MP59 20.8 31.7 26.9 30.1 29 27.4 28 35.3 MPack !020100!MP60 21 29.5 27.1 29.8 29 27.3 27.7 34.7 MPack !020100!MP61 19.8 25.7 26.7 29.1 28.7 27 27.3 34.1 MPack !020100!MP62 19.8 25.8 26.6 29 28.5 26.9 27.2 33.9 MPack !020100!MP63 19.8 25.2 26.4 27.6 27.3 25.7 25.9 33.7 MPack !020100!MP64 19.8 25.8 26.3 27.5 27.1 25.7 25.7 33.5 MPack !020100!MP65 19.8 25 26.2 27.3 27 25.5 25.6 33.3 MPack !020100!MP66 25.6 25 23.7 27.2 27.1 25.4 25.5 33.2 MPack !020100!MP67 19.5 25.2 23.8 28.6 27.9 26.4 27 33.4 MPack !020100!MP68 18.2 20.7 24 28.5 26.7 26.3 27.1 32.2 Transformer !020001!TR01 0 5.3 2.6 1.2 1 0 0 7.7 Transformer !020001!TR02 0 4.7 0 0.6 0.3 0 0 7.1
12/12 Ramboll
Source Partial Level Day Name M. ID R1 R2 R3 R4 R5 R6 R7 R8 Transformer !020001!TR03 0 0 0 0.4 0 0 0 5.9 Transformer !020001!TR04 0 0 0 0.2 0 0 0 5.6 Transformer !020001!TR05 0 0 0 0 0 0 0 5.4 Transformer !020001!TR06 0 0 0 0 0 0 0 5.2 Transformer !020001!TR07 0 0 0 0 0 0 0 5 Transformer !020001!TR10 0 8.1 2.9 1.7 1.3 0 0 7.5 Transformer !020001!TR11 0 5.8 0.6 2.4 2.1 0.2 0.5 7.5 Transformer !020001!TR12 0 3.4 0.6 1.5 0.8 0 0.2 6.9 Transformer !020001!TR13 0 2.5 1.6 1.1 0.6 0 0 6.5 Transformer !020001!TR14 0 2.3 0 0.9 0.4 0 0 5.6 Transformer !020001!TR15 0 0.3 0 0.7 0 0 0 3.6 Transformer !020001!TR16 0 0 0 0 0 0 0 3.3 Transformer !020101!TR08 0 0 0 0 0 0 0 4.9 Transformer !020101!TR09 0 3.8 0 0.5 0.8 0 0 6.2 Transformer !020101!TR17 0 0 0 0 0 0 0 5.3 Overall Sound Level Results – Daytime Receptor Location Applicable Regulatory Sound Level Limit Sound Level (Leq) Height Above Ground Daytime (dBA) (7 AM to 10 PM on weekdays, 8 AM to 10 PM on weekends) Ft. R1 55 41 4.92 R2 55 50 4.92 R3 55 47 4.92 R4 55 49 4.92 R5 55 47 4.92 R6 55 46 4.92 R7 55 46 4.92 R8 55 54 4.92