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Table 4.6-4 r Mining Noise Sources and Predicted Noise Levels Alternatives 1, 2 & 3 Reference Level Receiving Distance Predicted LddLeq Source at 100 feet LBq, Location from Source at Receiver' I (feet)3 Mining Equipment 65 dB Nearest PIL 30 73 Residence 1 1,500 41 Residence 2 800 47 y 1 - Reference levels obtained from noise level measurements of similar equipment conducted in recent years. 2 - Residential receiver location are identified on Figure 4.6-1. 3 - Approximate distance in feet from nearest position of noise source to receiving location. 4- Levels predicted at the receiver are based on a noise level reduction of 4.5 or 6 dB per doubling of distance from the source, depending on the proximity of source to receiver, and do not include corrections for atmospheric absorption of sound and shielding by intervening topography and orchards. PIL = property line .l Al�arry_Excavation Alternatives (1 2, and 3l Because the same areas would be mined under each of these three Alternatives, the potential for adverse noise impacts associated with project-related mining and reclamation activities are essentially similar. Table 4.6-4 indicates that predicted worst-case mining operations (scrapers at existing grade operating in close proximity to the pit boundaries) would notenerate noise levels in g e excess of the 75 dB LdR standard at the nearest property lines or 65 dB Ldp at the nearest residences to the mining sites. In addition, the worst-case mining generated noise levels are not expected to significantly exceed existing ambient noise levels at the existing residential areas. Therefore, this impact is considered less- than-significant. + Impact 4.6-3 ,3 p Unacceptable Noise Levels from Truck Traffic The proposed aggregate operation would result in increased heavy truck traffic on project area roadways. Because the plant operations would not require many on-site employees �? (approximately 10), a perceptible traffic noise level increase would not result from employee traffic. The analysis of traffic noise levels therefore focuses on the increase in heavy truck noise levels resulting from the proposed aggregate operation. Existing truck traffic information for the project area roadways was obtained from the 1995 r. . Annual Average Daily Truck Traffic on the California State Highway System publication compiled by the California Department of Transportation (Caltrans) and by the EIR 3 transportation consultant. .Estimated project-generated heavy truck traffic was provided by the EIR transportation consultant. Draft Environmental Impact Report 4-93 ER-96-3