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4.Environmental Analysis — Noise was measured by ESA staff at a sand and aggregate processing facility in Tracy.I At a — distance of 100 feet,daytime hourly noise levels reached 78 to 80 dBA Le,with a maximum noise level of about 98 dBA Lo The asphalt plant was not in operation during the time the measurements were taken, and noise from the homer used in the asphalt plant could generate higher noise levels. At the Baldwin quarry in Yuba County ESA measured noise from the asphalt plant to be 82 dBA,L.,at a distance of 50 feet and the rock crusher was louder, 82 dBA at 100 feet.2 It is assumed that noise levels generated by the permanent and portable processing — plants proposed as part of the Applicants' project would be about the same(82 dBA L,,and 98 dBA L.at 100 feet). Processing plant noise could result in increased noise levels at nearby residences. Residences R4 and R5 located adjacent to the northeast side of the site would be most affected by noise from the _ portable temporary processing plant, which would be located approximately 1,600 feet away. At this distance, processing plant noise would attenuate to 58 dBA LW and 74 dBA Lm„at the residential site. Located approximately 2,000 feet away from residence R4,noise generated by the — permanent processing plant would attenuate to 56 dBA L.and 72 dBA L.at the nearest residence(R4). The noise levels generated from both plant locations exceed existing ambient nighttime noise levels at the residence by more than 3 dBA (on weekdays and weekend days)as well as the nighttime maximum standard of 65 dBA L established by the San Joaquin County Development Title.Moreover,project noise levels would also exceed existing weekend daytime noise levels by more than 3 dBA(while not affecting weekday daytime levels).Therefore, — without mitigation,processing plant noise would result in a significant impact. Residence R3 (across the Delta-Mendota Canal) would not be affected by noise generated by the — temporary portable processing plant, which is located approximately 4,400 feet away, but could be affected by the permanent processing plant, which would be located approximately 3,000 feet away. Noise generated by the permanent processing plant, which is located approximately — 3,000 feet away from residence R3, would attenuate to 53 dBA L,and 68.5 dBA L_. While the resultant average noise level would be lower than existing average daytime and nighttime ambient noise levels at the residence,the maximum noise level exceeds the nighttime maximum standard of 65 dBA L established by the San Joaquin County Development Title by slightly more than 3 dBA. This would be a potentially significant impact. The combination of Mitigation _ Measures 4.5.1 a-c has the potential to reduce average noise levels(L,)by up to 20 decibels or more(15 decibels from the earthen berm and an additional 5 to 8 from the solid fences for exterior noise levels, plus 6 to 8 dBA for interior noise levels with the implementation of window and door upgrades). 1 Measurements were collected in 1993 and presented in the noise section of the Granite Construction Company — Vernalis Project EIR, 1993 prepared for Stanislaus County.These measurements are comparable to similar noise measurements of processing plants that are presented in other environmental reviews,including the DSS Engineering Contractors Proposed Koster Road Quarry Excavation Application(QX-96-1)Final Environmental Impact Report(prepared by EDAW for San Joaquin County). 2 Measurements were collected July 14,2004 by ESA using the Metrosonics dB-308 precision sound level meter. RMC Pacific Vernalis Quarry Mining and Reclamation Project 4.5-18 ESA/203015 Draft Environmental Impact Report May 2006