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Acoustical Analysis Report Griffith Energy Storage Project Off-site topography was obtained using the publicly available United States Geological Survey digital elevation data.A default ground attenuation factor of 0.5 was assumed for off-site sound propagation over acoustically"mixed"ground. The output from Cadna-A includes tabular sound level results at selected receiver locations and colored noise contour maps(isopleths)that show areas of equal and similar sound levels. 6.2 Input to the Noise Prediction Model The Project's general arrangement was reviewed and directly imported into the acoustic model so that on-site equipment could be easily identified; buildings and structures could be added;and sound emission data could be assigned to sources as appropriate. Figure 2 shows the Project equipment layout based on the layout,which was provided to Tetra Tech from Griffith Energy Storage, LLC. The primary noise sources during operations are the transformers and battery storage heating, ventilation and air conditioning units. It is expected that all equipment would operate in a consistent manner during both daytime and nighttime hours. Reference sound power levels input to Cadna-A were provided by Griffith Energy Storage, LLC (Burns&McDonnell 2021).The sound levels that were provided show that operation of the inverter/transformers will produce a sound pressure level of 80.5 dBA measured at 3 feet,and that operation of the battery storage and heating,ventilation and air conditioning equipment will produce 70 dBA measured at 3 feet. The proposed battery energy storage system would deliver power to the Tesla Substation located adjacent to the Project Site in Alameda County through a new 230 kilovolt gen-tie line.The Applicant would construct the gen-tie from the Project substation to the point south of the Tesla Substation. There are no planned modifications to the Tesla Substation as part of the Project.The Electric Power Research Institute has conducted several studies of corona effects (EPRI 1978, 1987).The typical noise levels for transmission lines with wet conductors are shown in Table 7,and as such a noise level of 40 dBA was used for the transmission line in the noise model. Table 7. Transmission and Sub-transmission Line Voltage and Audible Noise Levels VoltageLine . . Conductor(W) Below the d: 138 34 240 40 360 51 OTETRA TECH 14 August 2023