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4.Environmental Analysis — The two more southerly residences (residences RI and R2)located southwest of Phase V(also — across the Delta-Mendota Canal) would experience noise generated by mining activity,at a distance of about 800 feet. At this distance,mining noise would attenuate to 67 dBA L,,by distance alone, and substantial earthen berms on both sides of the Delta-Mendota Canal already block the line of sight from these residences to the location of the mining. When considering the attenuation from both distance and the earthen berms,the noise levels at these residences would be approximately 55 dBA from the closest mining activity in Phase V.Assuming the ambient — noise environment at residences RI and R2 is similar to that at residence R3, this would also be a significant impact. At residences R1, R2,and R3, noise levels would be significant because — project mining activities would increase noise levels by more than 3 dBA and the resulting noise levels from the stationary sources would exceed the daytime L,noise daytime standard(50 dBA) and the Lw nighttime standard (45 dBA) in the San Joaquin County Development Title. _ At residences RI -R5,the impact of the noise levels resulting from the project would lessen as post-stripping activities and excavation continue at lower depths;however, haul trips on-site would continue to generate noise at the surface. Mitigation Measures Measure 4.5.1a: At the start of stripping operations for each phase,the applicant shall construct an earthen berm along the portions of the project site that face sensitive receptors located within 2,000 feet of mining operations for that phase. This includes residences R4 and R5 northeast of Phase IV (this earthen berm would also attenuate noise to residences R5, R6,and R7) and residences RI, R2, and R3, west of Phase III and southwest of Phase V. The sound barriers must be at sufficient height(approximately 10 feet)to block the line of sight to the nearest sensitive receptor. If continuous earthen berms of adequate height are already in place,additional berms would not be needed. Mitigation Measure 4.5.1b: The Applicant shall conduct additional noise measurements — after the completion of initial stripping activities to evaluate the effectiveness of Mitigation Measure 4.5.1a in reducing resultant sound levels at outdoor activity areas of nearby — sensitive receptors. For those residences requiring additional sound reduction,the Applicant shall fund the construction of solid(masonry or similar construction) walls along those property lines of the residences facing the project site, if desired and allowed by the subject property owners. — Mitigation Measure 4.5.1c: For any residences that would exceed a noise level of 45 dBA,L2 indoors,the applicant shall upgrade house noise reduction via window and — door upgrades on the side of the houses facing the mine, if the landowner desires and allows the work to be done. Mitigation Measure 4.5.1d: Nighttime mining shall be prohibited within 1,000 feet of residences unless noise measurements confirm that noise levels are below 45 dBA,L.,at the outdoor activity areas of adjacent residences. The earthen berms constructed pursuant to Mitigation Measure 4.5.1a could reduce noise levels up to 10 dBA.The resulting maximum exterior noise levels are estimated to be 69 dBA Lw(79 - 10)at Residences R4 and R5 immediately to the northeast. The resulting, — maximum exterior noise levels are estimated to be 52 dBA L.(62- 10)at residences R6, R7, and R8 farther to the northeast of Phase IV. The resulting, maximum exterior noise RMC Pacific Vernalis Quant'Mining and Reclamation Project4.5-_f6__ ESA/203015 Draft Environmental Impact Report May 2006