06 16 20 PWA_02_02 Exh2 - IS-MND

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L w FAIRVIEw BRIDGE REPLACEMENT AND STREET IMPROVEMENTS INITIAL STUDY/MITIGATED NEGATIVE DECLARATION `J' (9TH STREET TO 16TH STREET) PROJECT MAY 2020 SANTA ANAL CALIFORNIA Typical noise levels at 50 ft from an active construction area range up to 88 dBA Lmax during the noisiest construction phases. The site preparation phase, which includes grading and paving, tends to generate the highest noise levels because the noisiest construction equipment is earthmoving equipment. Earthmoving equipment includes excavating machinery (e.g., backfillers, bulldozers, and front loaders). Earthmoving and compacting equipment includes compactors, scrapers, and graders. Typical operating cycles for these types of construction equipment may involve 1 or 2 minutes of full -power operation followed by 3 or 4 minutes at lower power settings. Construction of the proposed Project is expected to require the use of graders, bulldozers, and water trucks/pickup trucks. Noise associated with the use of construction equipment is estimated to be between 55 and 85 dBA Lmax at a distance of 50 ft from the active construction area for the grading phase. As seen in Table 3.13.C, the maximum noise level generated by each grader is assumed to be approximately 85 dBA Lmax at 50 ft from the grader in operation. Each bulldozer would generate approximately 85 dBA Lmax at 50 ft. The maximum noise level generated by water trucks/pickup trucks is estimated to be approximately 55 dBA Lmax at 50 ft from these vehicles. Each doubling of the sound source with equal strength increases the noise level by 3 dBA. Each piece of construction equipment operates as an individual point source. The worst -case composite noise level at the nearest residence during this phase of construction would be 88 dBA Lmax at a distance of 50 ft from an active construction area. Based on a usage factor of 40 percent, the worst -case combined noise level during this phase of construction would be 84 dBA Leq at a distance of 50 ft from the active construction area. The closest residences are located approximately 50 ft from the Project construction areas. Therefore, the closest residences may be subject to short-term noise reaching 88 dBA Lmax generated by construction activities in the Project area. As identified above, construction noise is exempt from noise standards in the City's Municipal Code, but construction activities are limited to daytime periods—i.e., no construction activities between the hours of 8:00 p.m. and 7:00 a.m. on weekdays and Saturdays, or at any time on Sundays and federal holidays.50 The Project is also subject to Caltrans Standard Specifications or Greenbook (2018 or most current) equivalent specifications because the Project would utilize federal transportation funding. In addition to adherence to the City's Municipal Code construction activity time limits, standard noise controls are required to be implemented to avoid potentially significant construction noise impacts to adjacent residences. These controls include maintaining mufflers on equipment, directing stationary noise away from the nearest receptors, and staging equipment as far as possible from receptors. These controls, as well as compliance with the City's Municipal Code hour restrictions, are included in Mitigation Measure N0I-1. Therefore, with implementation of Mitigation Measure N0I-1, short-term noise impacts related to construction of the proposed Project would be less than significant. 50 City of Santa Ana. 2019b. op. cit. 3-80 R:\WKE1702\ISMND\Final ISMND\Fairview Street Bridge Final ISMND.docx (05/26/20)