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�.! <br /> buffer zone between the noise source and receiver to attenuate plant area noise <br /> levels to acceptable limits. t <br /> OR <br /> Mitigation Measure 4.6-1b (Altemative 3) <br /> After aggregate plant start up, conduct a noise investigation of the plant to <br /> determine additional industrial noise control measures to be incorporated in the <br /> plant design to reduce overall processing equipment and asphalt plant noise <br /> emissions to a level of 55 dB Leq or less at Residence #2. <br /> Leve!of Significance After Mitigation: <br /> Implementation of Mitigation Measure 4.6-1a or 4.6-1b would reduce noise impacts <br /> at the adjacent residence to an acceptable level, and the impact would therefore be <br /> reduced to a Less-than-significant level. <br /> AN 4: No Project <br /> Under this alternative there would be no on-site aggregate processing activity. Therefore, <br /> this alternative would not result in significant noise impacts. <br /> No mitigation is required. <br /> Impact 4.6-2 <br /> Unacceptable Noise Levels from Mining And/Or Reclamation Activities <br /> Noise measurements and modeling techniques were used to predict noise levels <br /> generated by the proposed mining operations. Operational information for aggregates <br /> excavation in the area was obtained from the proponent. <br /> Excavation and reclamation operations in the aggregate pits would be conducted primarily <br /> by self-elevating scrapers. Conveyors would also be used in the pit area to transfer the <br /> mined aggregate to the processing plant. A typical sound exposure level (SEL) of 90 dB <br /> at a distance of 50 feet was used for the noise emission of a single scraper passby, based <br /> on scraper noise measurements conducted at several similar excavation areas in the <br /> Sacramento and San Joaquin Valley regions. Based on a conservative assumption of 30 <br /> scraper passages per hour during excavation and reclamation, an average hourly noise <br /> level of 69 dB Lam,would be generated at a distance of 50 feet from the operating scrapers. <br /> Table 4.6-4 shows the distances from the nearest mining sites to the nearest existing <br /> residential uses and the predicted scraper noise levels at those locations. <br /> Draft Environmental Impact Report 4-92 ER-96-3 '� <br />