20A - AA FIRST ST BRIDGE REPLACEMENT PROJECT

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LSA ASSOCIATES, INC. JULY 2010 INITIAL STUDY/MITIGATED NEGATIVE DECLARATION FIRST STREET BRIDGE REPLACEMENT PROJECT CITY OF SANTA ANA C. A substantial permanent increase in ambient noise levels in the project vicinity above levels existing without the project? Less than significant impact. According to the Noise Analysis (LSA Associates, Inc.) the noise levels under the proposed project conditions will be similar to the existing noise levels. The proposed project does not introduce new land use types and does not generate substantial increase in traffic levels in the project site. Slight increase in noise level may be expected in some locations; 3 sensitive receptor locations were identified along the First Street that will require incorporation of noise abatement measures. Noise levels at these locations approach or exceed 65 dBA CNEL which is the City's noise standard in the General Plan Noise Element. Therefore, three sound barrier walls will be implemented as part of the project (and are described in Section 2.0) to reduce the traffic noise so that it will not affect the nearby receptors. Therefore, with incorporation of these noise abatement measures as part of the project design, less then significant impacts are expected. D. A substantial temporary or periodic increase in ambient noise levels in the project vicinity above levels existing without project? Less than significant impact with mitigation. The proposed project will result in a temporary increase in ambient noise levels during construction. The first type of construction noise would be generated by commuting construction crew and the transport of construction equipment and materials to and off site. The second type of construction noise would be generated during demolition of the bridge, excavation, grading and street widening due to the use of loud construction equipment. The site preparation phase, which includes demolition and grading, tends to generate the highest noise levels, because the noisiest construction equipment is earthmoving equipment which includes excavating machinery such as backfillers, bulldozers, front loaders, and compacting equipment such as compactors, scrapers, and graders. Construction of the proposed project is also expected to require the use of water trucks, and pickup trucks. Table 4.2 shows the typical construction equipment schedule during the construction activities. Table 4.2: Typical Construction Equipment Schedule Type of Equipment Range of Maximum Sound Levels Measured (dBA at 50 feet Suggested Maximum Sound Levels for Analysis (dBA at 50 feet Pile drivers, 12,000 to 18,000 ft-lb/blow 81-96 93 Rock drills 83-99 96 Jackhammers 75-85 82 Pneumatic tools 78-88 85 Pumps 74-84 80 Dozers 77-90 85 Scrapers 83-91 87 Haul trucks 83-94 88 Cranes 79-86 82 Portable generators 71-87 80 Rollers 75-82 80 Tractors 77-82 80 Front-end loaders 77-90 86 Hydraulic backhoes 81-90 86 07/25/10 «PADMJ070l\MND\4.0 Environmental Analysis.doc» 4-32 20A-83