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6.3 Significant Unavoidable ADVERSE IMPACTS 6.3.2 Unavoidable Adverse Impacts Noise Noise generated by mining equipment and excavation activities would result in an increase in the ambient noise levels at the nearest residence(s). Mitigation Measures have(4.5.la-d) have been identified and are feasible noise reduction measures that can be implemented for the project. However, 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). Thus the noise impact of the project would remain significant at these residences. Traffic associated with operation of the project would result in an increase in ambient noise levels on nearby roadways used to access the mine. Given the effect they would have on the rural character and aesthetic value of the area,fences and sound walls may not be desired or feasible for all the residences potentially affected by noise from project haul trucks. In addition to the issue of feasibility, the height, mass,and linear extent of fences and walls needed to effectively reduce noise impacts from the haul route options on sensitive receptors raises the possibility that such barriers would result in impacts on the visual character of the existing landscape and on scenic views of the Coastal Range Mountains and the San Joaquin Valley. The fences and walls _ would be large-scale features with simplified linear forms that could appear visually obtrusive as well as obstructing long-range views. Thus the noise impact of haul truck traffic resulting from the project would remain significant at these residences. Cumulative noise impacts related to traffic would be significant. Cumulative traffic in combination with the project would significantly increase noise levels under all three haul route ` options along the majority of the modeled roadway segments. The significant project-related increases in noise levels along Segment I and 8 under Haul Route Option 1, along Segments 1, 5 and 8 under Haul Route Option 2 and along Segments 1,2, 3, and 9 under Haul Route Option 3 would be incremental effects that are cumulatively considerable at these locations. With implementation of mitigation,the project's contribution to cumulative noise impacts would remain significant. Air Quality The proposed surface mining of topsoil, sand and gravel would take place on approximately 659 acres within the project site,consisting of the extraction and processing of 1.7 to 4.0 million tons per year of aggregate materials over a 26 to 60 year period. Total ROG emissions from the quarry operations are significant for production levels of 4 and 2.85 million tons per year in 2008 and less than significant for the other scenarios. However,total NO,emissions from the quarry operations are significant under all production levels for 2008 and 2020.These results are largely due to operation of the sand dryer and haul truck operations, with additional contributions from the on-site equipment(especially the on-site haul trucks,excavators, and loaders).While several emission-reducing measures are currently available,the extent to which quantification of these reductions can be conducted at this time is uncertain. Emission-reducing measures are not RMC Pacific Vernalis Quarry Mining and Reclamation Project 6-17 ESA/203015 Draft Environmental Impact Report May 2006