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Forward Landfill LFG Acoustical Analysis Page 8 <br />May 18, 2011 <br />5 NOISE CONTROL REQUIREMENTS <br />The computed off-site noise levels shown in Table 3 are based on the noise emissions <br />levels provided by equipment manufacturers and a 15 dB indoor to outdoor attenuation <br />factor for the metal building surrounding the generator engines. To achieve this degree <br />of sound insulation for noise sources producing significant low frequency noise, <br />ventilation openings should employ acoustic treatment such as 12 -inch thick lined <br />acoustic louvers and the wall and ceiling surfaces should be lined with perforated metal - <br />faced fiberglass or mineral fiber sound absorbing treatment. Nominally, the surface <br />density of the building skin should be at least one pound per square foot. Note in Figure <br />5 that the louver banks are incorporated on the south side of the building, configured to <br />reduce flow velocity for prevention of rain ingestion. In view of the great distance to <br />noise sensitive receptors in the southerly direction, it would be possible to make the noise <br />reduction louvers optional at this installation. They could easily be added at a future date <br />if additional noise suppression is desired. <br />6 CONCLUSION <br />Based on manufacturers' noise emission levels for proposed equipment, noise levels <br />below the San Joaquin County 50 dB daytime and 45 dB nighttime limit and further <br />reduction to match probable nighttime ambient noise levels will be achieved through use <br />of acoustic enclosures and high efficiency engine exhaust silencers. <br />n <br />I <br />0 <br />u <br />0 <br />11 <br />C <br />U <br />