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4. ENVntONMENTAL ANALYSIS 4.5 NOISE sensitive receptor and may be a masonry wall,earthen berm,or some combination thereof. b. Install double pane windows and air conditioning units on all residential homes identified as sensitive receptors that are located within 1,000 feet of the project site. Mitigation Measure 4.5.1b: The Applicant shall conduct additional noise measurements to evaluate the effectiveness of Mitigation Measure 4.5.1a or 4.5.1b in reducing resultant sound levels at nearby sensitive receptors. For those residences requiring additional sound reduction,the Applicant shall fund the construction of solid fences along those property lines of the residences facing the project site. r Sound barriers of sufficient height along the project site boundary are expected to attenuate noise generated by surface-level mining by a 5-10 dBA. If necessary, additional noise protection can be attained by the construction of solid fences at nearby residences. Significance after Mitigation: Less-than-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 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 constructed and would be located in the middle of the plant site on Phase IV,as shown on Figures 3-3 and 3-4. A portable temporary plant would also be used during the final phase of mining, Phase IX, after the permanent plant is demolished and when material excavation occurs at Phase IV. Under the worst case scenario,processing activity would occur 24 hours per day, 6 days a week(Monday through Saturday). RMC Pwfe V�ahs Qua,.y Mining wd R�i�too Project 4.5-15 ESA 1203015 Adtvinistntive D®ft EIR M=h 2004