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4.5 Noise 11. levels are estimated to be 61 dBA L. (71 - 10)at residence R3 and 55 dBA L.,(55 -0)at residences Ra and R2(earthen berms of sufficient height already appear to be in place to protect these residences). ` Solid fences approximately 8 feet in height along the exposed property boundary would be expected to attenuate noise generated by surface-level mining by an additional 5 to 8 dBA in outdoor activity areas. The solid fences would block views in some directions and could potentially affect views of the Coastal Range Mountains from residences R4 and R5. However,these homes are oriented away from these views now and any impact would be less than significant because of the minor overall change that the fences would have in the context of the large, flat area that defines the project site and surrounding vicinity.The solid fences would not obstruct or substantially impair views of the Coastal Range Mountains and the San Joaquin Valley (see Impact 4.12.1). Mitigation Measures 4.5.1a-d are feasible noise reduction measures that can be implemented for the project. It is likely that noise levels could still exceed the San Joaquin County Development Title daytime L�standard of 50 dBA at the exterior property line of the three residences nearest to the project site (R3, R4,and R5)for a short period of time until mining moves deeper or further away from the residences. Thus the noise impact of the project would remain significant and unavoidable at these residences. ` Impact Significance After Mitigation: Significant. Impact 4.5.2: Operation of the processing plant could potentially increase ambient noise ` levels at nearby residence(s).This would be a potentially significant impact. Primary sources of stationary noise from the processing plant would be the crushing of aggregates r and the operation of the asphalt plant and concrete batch plant-once these facilities are installed. Other sources of stationary noise would include conveyor belt drives,electric motors, material loading at the feed hopper and noises from mechanical moving parts such as conveyor belt rollers and pulleys. Crushing plants would generate noise when their rotating hammers hit the larger pieces of raw material fed into the crushing chamber. The intensity of sound would vary depending on the composition of the material,humidity, and size of the boulders. A smooth and steady flow of smaller-sized material would produce an even and steady noise, while large pieces of uneven feed would result in intermittent loud and jarring noise. Noise would also be generated by the load-out of materials involving front-loaders and heavy trucks. The permanent processing plant would be located in Phase IX off Koster Road. A portable temporary plant would be used for a period of about two years while the permanent plant is being 6, constructed and would be located in the middle of the plant site on Phase IV, as shown on Figures 3-3 and 3-4. Under the worst-case scenario,processing activity would occur 24 hours per day,6 days a week(Monday through Saturday). r RMC Pacific Vernalis Quarry Mining and Reclamation Project 4.5-17 ESA/203015 Draft Environmental Impact Report May 2006