SU0004094 - Laserfiche WebLink

Home Browse Search

4. ENVIRONMENTAL ANALYSIS 4.5 NOISE — receptors if a wall or berm impedes its line of site to the noise source. Mining noise would be _ more noticeable during nighttime hours when ambient noise levels are typically quieter. Mining noise could result in increased noise levels at three separate locations of nearby residences. The residence located adjacent to the northeast side of the site(along the south side of Blewett Road)would be most affected by mining noise generated at the northeast corner of Phase IV. A berm has not been proposed by the applicant along the eastern boundary of Phase _ IV. Assuming mining activity would generate noise levels as high as 91 dBA Leq at a distance of 50 feet,and a worst-case noise attenuation rate of six dBA for every doubling of distance,noise levels from mining operations located only 200 feet from the residence would attenuate to 79 — dBA Leq. As shown in Table 4.5-2,daytime noise levels at this residence are 58 dBA Leq on weekdays and 46 dBA L.eq on Saturdays, and night time noise levels are 48 dBA LeQ on both weekdays and Saturdays. Because the resultant noise level from excavation activity is — considerably higher than ambient daytime and nighttime levels, this would be a significant impact. The residence located west of the southern end of the project site on Koster Road(and across the Delta-Mendota Canal)would be most affected by the noise of mining activity on the west side of Phases III and V. Noise levels at this residence are 52-54 dBA Les during the daytime and 51- 52 dBA L eq at night,as shown by Measurement B in Table 4.5-2,and a berm has not been proposed by the applicant along the west sides of Phases III and V. Generated as close as 500 _ feet away,mining noise would attenuate to 71 dBA Leq at the property line of the residence. This would also be a potentially significant impact because mining noise would be considerably higher than ambient daytime and nighttime noise levels. _ The residence located south of Phase V(also across the Delta-Mendota Canal)would experience noise generated by mining activity, which would be as close as 800 feet. At this distance, mining noise would attenuate to 67.5 dBA Leq. Assuming the ambient noise environment at this residence is similar to the residence located west of the southern end of the project site,this would also be a significant impact. — In all three instances,however,the impact of the resultant noise level would lessen as excavation continues at lower depths; however,haul trips on-site would continue to generate noise at the — surface. Implementation of Mitigation Measure 4.5.1 and 4.5.2 would be necessary to reduce these noise impacts. Mitigation Measure 4.5.1a: The Applicant shall do one of the following measures: a. Construct sound barriers along all sides of the project site that face off-site sensitive receptors that are located within 1,000 feet of the project site. This includes the perimeter of the project site except the eastern boundaries of Phases VI,VII,and VIII,and the southern boundary of Phase VI. The sound barriers must be at sufficient height to block the line of site to the nearest RMC Puirx Vemelis Quant'Mining and Reclamation Pmjecl 4.5-14 ESA/203015 Admioiamfiti a Ihaft ERR Minch 2004