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City of San Leandro 2824 Halcyon Drive Residential Project 86 up to approximately 89 dBA Lmax with an hourly average of up to 85 dBA Leq (Appendix NOI). However, these noise levels would be temporary during the site preparation phase. Although there could be a relatively high single-event noise exposure potential, the effect of construction activities on hourly or daily ambient noise levels would not be significant but could result in a temporary increase in ambient noise levels in the project vicinity that could result in annoyance or sleep disturbance of nearby sensitive receivers. Therefore, compliance with SLMC Section 4.1.1115(b) restricting construction activity to 7 a.m. to 7 p.m. on weekdays and 8 a.m. to 7 p.m. on weekends would prohibit construction activities at night and would not be associated with any nighttime noise-related impacts. Compliance with SLMC Section 4.1.1115(b) and General Plan EIR Mitigation Measure NOI-4 would reduce noise impacts related to project construction to less than significant levels. This would be consistent with the General Plan EIR’s findings that construction noise would have a less than significant impact as a result of the exposure of nearby receivers to construction noise. Operational Impacts SITE OPERATION Noise levels from typical residential mechanical ventilation equipment have sound levels ranging from 45 dBA to 60 dBA Leq as measured at approximately 3 feet from the operating unit (Appendix NOI). Based on the proposed site plan, mechanical ventilation systems could be located as close as 15 feet from the nearest off-site residential receptor. Assuming a standard attenuation rate of 6 dBA per doubling of distance, a noise level of 60 dBA Leq at 3 feet would attenuate to 46 dBA Leq at 15 feet at the nearest residential property line (Appendix NOI). This would be below the documented existing ambient noise level recorded at the project site which was 61.5 dBA CNEL (Appendix NOI). Therefore, the operation of mechanical ventilation equipment would not exceed existing ambient noise levels and the impact would be less than significant. TRANSPORTATION The nearest highway is I-880 approximately 0.6 mile to the west of the project site. Traffic along Halcyon Drive is the main source of exterior noise in the project vicinity. The project would generate vehicle trips that would increase traffic volumes on road segments in the city. As described in Section 17, Transportation/Traffic, the project would generate approximately 13 a.m. peak-hour vehicle trips, 18 p.m. peak-hour vehicle trips, and 170 daily trips (Appendix TRA). The estimated average daily traffic volume on Halcyon Drive is approximately 20,800 trips (City of San Leandro 2016b). The project’s trip generation would increase the existing average daily traffic volumes on Halcyon Drive by approximately 0.8 percent. Modeling of traffic noise indicates that, in general, a 10 percent increase in traffic volume would raise traffic noise by approximately 0.4 dBA. A 0.8 percent increase in traffic would increase ambient noise along Halcyon Drive by less than 0.4 dBA. As discussed in the City’s General Plan, changes in environmental noise levels of 3 dB Ldn would be a significant adverse impact pursuant to General Plan Policy EH-7.4. The estimated increase of less than 0.4 dBA in traffic noise would not exceed this 3-dBA threshold of significance. The modeled traffic noise levels predicted that noise levels adjacent to the project site could range up to 67.3 dBA CNEL which would be above the 60 dBA threshold for adjacent single-family residences and included as General Plan Policy EH-7.3. In accordance with General Plan Action EH- 7.1.A and General Plan Policy EH-7.6 focused on minimizing noise in new residential areas, the