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Given the combination of conditions which most be present in order for the 65 dB SEL objective to be exceeded within bedrooms located along East River Road, the probability of such exceedances is considered very low. Furthermore, Table S indicates that, at the 7 residences where such exceedances could occur if the required conditions are satisfied, the interior SEL values would exceed the 65 dB SEL objective by 1-4 dB, which is considered a relatively small exceedance. Nonetheless, because the potential exists for interior noise levels to exceed 65 dB SEL within bedrooms located within 115 feet of the centerline of East River Road with windows open (and directly-facing the roadway) during nighttime passages of project heavy trucks, this impact is considered potentially significant. Traffic Noise Impacts Relative to Existing Ldn Noise Levels without the Project As noted in Table 3, a significant project-related noise impact would result if the project related- increase in traffic noise levels exceeds 1.5 dB in noise environments above 65 dB Ldn, and 3 dB in noise environments between 60 and 65 dB Ldn. In terms of increases in traffic noise levels as defined by Ldn, the project is estimated to result in a traffic noise increase of approximately 1 dB (worst-case project traffic noise level of approximately 64 dB Ldn at 60 feet from the centerline added to existing levels of 69-72 dB Ldn as reported in Table 6). Given the elevated background traffic noise environment, the project-related increase of approximately 1 dB Ldn would not be considered significant at either interior or exterior locations. As a result, the 1 dB project-related increase in Ldn is not anticipated to result in adverse noise impacts at either outdoor activity areas or interior of existing residences located along East River Road. This impact is considered less than significant. Traffic Noise Impacts Relative to Existing Nighttime Hourly Noise Levels without the Project Appendix D shows the averaged hourly noise levels (Leq) at each of the five traffic noise measurement locations for both weekend and weekday periods. These data are shown as black lines in Appendix D, with averaged weekday noise levels denoted with solid triangles and averaged weekend noise levels denoted with solid squares. Appendix D also shows predicted hourly noise levels associated with varying numbers of heavy truck passbys, ranging from 10 per hour to the maximum of 66 per hour. During hours in which the red line representing noise generated by project truck traffic would be below the existing hourly average noise level shown in Black, the project would not be expected to result in noticeable increases in hourly average noise levels. However, during hours in which the opposite it true, where red line representing project truck traffic noise generation is above the black line representing ambient conditions without the project, the project-related change in hourly average noise levels would be clearly noticeable. The magnitude of project-related traffic noise level increases in any given hour would depend on the number of project truck trips generated during that hour and the ambient noise level present without the project during the same hour. Appendix D illustrates that, during most hours of the Environmental Noise Analysis Munn&Perkins Expanded Hours of Operations-San Joaquin County Page 34