COMPLIANCE INFO_FINAL INITIAL STUDY/MITIGATED NEGATIVE DECLARATION 5/25

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Memorandum February 26, 2025 Page 11 21202-23 North County Landfill_Noise DRAFT Traffic Noise Noise levels along the haul route would increase with the additional vehicle trips contributed by project operations. The project would generate a total of 9 truck trips and 31 visitor/worker commute trips during the AM peak hours and 8 visitor/worker commute trips during the PM peak hours. The project-generated traffic noise levels were calculated during the AM peak hour to represent the highest traffic noise increase during project operation. Traffic noise impacts are evaluated for the Existing plus Project condition, which is the 2024 existing condition plus the project-generated trips, and the Cumulative plus Project condition, which is the 2046 horizon year condition plus the project-generate trips. Traffic volumes during the AM peak hour and associated traffic composition were used in the Federal Highway Administration's Traffic Noise Model (TNM2.5) to estimate traffic noise levels for the Existing condition, Existing plus Project condition, Cumulative condition, and Cumulative plus Project condition. The traffic model inputs and outputs are included in Attachment A. The estimated Existing, Existing plus Project, Cumulative, and Cumulative plus Project traffic noise levels for the studied road segments along the haul route are summarized in Table 6. The noise levels reported in Table 6 are AM peak hour Leq levels, but were presented as Ldn levels for comparison with the San Joaquin County’s noise standard of 65-dBA Ldn at noise-sensitive land uses for transportation sources as referenced in Table 3. Generally, during the peak traffic hour under normal traffic conditions, Ldn is within plus or minus 2 dBA of the Leq.9 Based on these estimates, the project would increase traffic noise by up to 2.0 dBA along the haul route compared to the Existing condition and Cumulative condition, which is below the conservative 3-dBA threshold. It is to be noted that where the Existing plus Project and/or Cumulative plus Project noise levels exceed the San Joaquin County’s noise standard of 65-dBA Ldn, the corresponding Existing and Cumulative noise levels have already exceeded the 65-dBA Ldn threshold. Implementation of the project would not result in a new exceedance of the San Joaquin County’s noise standards for transportation sources. Therefore, the project-generated traffic noise increase along the haul route would be less than significant. Vibration The project does not include any new construction. Landfill operation would not involve equipment (such as vibratory rollers and crack-and-seat equipment) or activities (such as pile driving) that would generate excessive groundborne vibration or groundborne noise levels. Typical vibration-generating heavy equipment, such as bulldozers and loaded trucks, is currently being used at the North County Landfill. The project would increase the hours of operation and increase the number of off-road equipment, namely one compactor, one scraper, two dozers, and one loader, but would not change the type of equipment used or the 9 Caltrans, 2013. Technical Noise Supplement to the Traffic Noise Analysis Protocol. September.