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CEQA Noise Level Increase Criteria The California Environmental Quality Act (CEQA) requires that noise impacts of a project be evaluated not only relative to local noise standards, but also relative to project-related increases in ambient noise levels. As noted previously, this facility has historically operated at night when necessary to service night paving projects with approval from the County on a project-by-project - basis. Technically, therefore. the project would result in the continuation of those periodic nighttime operations which have historically occurred at the project site, and would not result in an increase in noise relative to those historic operations. In cases where a project would result in changes to ambient conditions, the significance of those project-related noise level increases can be evaluated using the Table 4 criteria. Table 4 was developed by the Federal Interagency Committee on Noise (FICON) as a means of developing thresholds for impact identification for project-related noise level increases. The rationale for the graduated scales is that test subject's reactions to increases in noise levels varied depending on the starting level of noise. Specifically, with lower ambient noise environments, such as those below 60 dB Ldn, a larger increase in noise levels was required to achieve a negative reaction than was necessary in environments that are already elevated. - Table 4 Significance of Changes in Cumulative Noise Exposure Munn & Perkins Expanded Hours of Operations San Joaquin County, California Ambient Noise Level Without Project, Ltl„ Increase Required for Significant Impact Less than 60 dB +5.0 dB or more 60 to 65 dB +3.0 dB or more Greater than 65 dB +1.5 dB or more Source:Federal Interagency Committee on Noise (FICON) As indicated by Table 4, an increase in the traffic noise levels becomes more significant as the ambient noise levels increase. For instance, a significant increase in traffic noise levels is expected to be 1.5 dB when the no-project traffic noise levels exceed 65 dB Ldl. However, a significant increase in traffic noise levels is expected to be 5 dB when the no-project traffic noise levels are less than 60 dB L,;,,. In other words, as ambient noise levels increase, a smaller increase in noise resulting from the project is sufficient to cause significant annoyance. -- Environniental Noise Analysis Munn&Perkins Expanded Hours of Operations—San Joaquin County Page 9